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Roof Ventilation Blog

education comes at a cost.... it time or money ....often both....
and this before you ..... is that not lost


Roof Ventilator Choices
To ventilate and sleep well
Solar Roof Ventilation
The Ventilation Flim Flam man
Ventilating your home
with Ceiling & Wall Vents
Ignorance sells best
Smoking Fireplace
Ventilation of Indoor Pools and Spas
Roof Services Industry
Ventilation of a Low Pitched Steel Roof
Bathroom Ventilation against mould
How to vent a raked ceiling

How to vent a cathedral ceiling

Roof and room ventilation for a double storey dwelling
Roof Ventilation Fans pt1
Roof Ventilation Fans pt2
Sub Floor Ventilation
Does Roof Ventilation Work?
Cooler Home during Summer Months
Reverse engineering in consumer purchase of ventilation

Steel v Tile Roof
Insulation Realities


Roof Ventilator Choices

What type of roof ventilator do I get?, ......everything looks the same,....... how do I know which ventilator is best for my situation?…and the questions continue on with the frustration allowing you to fall prey to the first person who sounds as though they know what they’re talking about when discussing roof ventilators and ventilation products….maybe they do…chances are they don’t.

And let’s face it, in all fairness one doesn’t go out and buy a roof ventilator that often that they acquire some smarts about what to buy as they would in say, buying a car the next time around. Roof ventilation is a one time purchase for most.

In the past ventilation in general, and roof ventilation in particular, was something that was intrinsically present in the design of a house, along with other features such as eaves vents, ceiling vents, wall vents and sub floor vents, all part of the fundamental house prerequisite as regards to ventilation products.

Today these venting features are only present in architecturally designed homes, very rarely in spec homes unless the client has had the foresight to include ventilation items in his/her building specifications.

Never the less the task at hand is to choose a ventilation product and or ventilation system. I say ventilation system because you want both the means of ingress and egress. One without the other doesn’t work well and sales people are in the habit of selling the easiest quick profit products such as the roof ventilator leaving you to discover you only purchased one half of what was essential.

Roof ventilators come in different sizes and modes of operation, there’s the ‘wind driven’, the type that makes your home look like a factory roof but allows you to believe you’re getting something for nothing.
Then after you've purchased the first one or two you're told you don't have enough, so you need to decide whether to buy more in order to achieve the end result you were hoping for.

Then there’s the ‘passive, ‘static’ vent. the terms are meant to describe a motionless ventilator in an attempt to diminish it’s validity against the so called - dynamic’- ‘turbo’- turbine’- wind driven’- supa doopa roof ventilator.

Then we also have the roof ventilation gimmick of the decade, ‘the solar vent’ which presents itself as high tech and has poor overall performance values and being totally useless of an evening when you need ventilation the most. Again casting the illusion that you’re getting great benefit at zero cost. Not when you consider the overall poor performance of the unit coupled with the early degeneration of the solar cell, rendering the unit next to useless in a short period of time.

The life/performance of the fan itself comes into question.

Remember roof ventilation starts with the correct hole size in the roof, with only one correctly sized roof ventilator or cupola protecting and maintaining it's integrity regarding external elements.

So when you’re considering roof ventilation, think beyond making the possums more comfortable,....... to what is going to leave you with a pleasant taste in your mouth after your selection of roof ventilator and ventilation system has been installed.

The purpose of roof ventilation is to improve the comfort levels in the rooms below

Ventilation solutions will differ between Brisbane, Sydney, Melbourne and Hobart


Reverse engineering in consumer purchase of roof ventilation

Reverse engineering in this instance is where a company has a particular roof ventilation product(s) and advertised it as being suitable for a whole gamut of things. The consumer, without thinking, thinks ‘this must be what I need’ ………Big mistake

The company might be saying that their roof ventilator is suitable for all and in sundry but it’s not saying it it ideal to your purpose or problem.

That responsibility falls on you.....

For instance, history in building as regards to ventilation, particularly roof ventilation, has always said that that the escape (roof ventilator on the roof) must be proportional to the air ingress via the eaves vents

Ingress around the periphery via eaves vents, and exit from one centrally located escape point being the roof ventilator, or cupola, on the roof.

Roof cupolas were developed and built at the same time as the construction of the roof, as can be witnessed today on the older type residences up until the forties

Nowhere does it say that you need to place (roof ventilators) all over the roof for greater efficiency in roof ventilation

No! this was purely a marketing gimmick foisted on the masses who were ripe for the taking

The fact that it is too small for most residential applications was immaterial as the responsibility of the purchase lay with the consumer, and as with the blind leading the blind, the consumer ended up with several on his roof instead of one larger, but then if one larger vent were to be used his house would end up looking like a factory.

The reality is that one large roof ventilator works far more efficiently than several smaller and it need not be wind driven as Cupolas have proven over the centuries

Today the roof ventilator is used as an inducement, or freebie if you will, to entice a prospective client into using the roofing company’s services.

Ventilation solutions will differ between Brisbane, Sydney, Melbourne and Hobart


Solar Roof Ventilation products

To those who turn to Google to find a roof ventilation solution to their situation, be prepared to get confused and disillusioned.

Even architects are so confused with all the claims to the point where they advise their clients to choose at the time of installing the roof.

With the battle for page one presence being waged, the last thing being offered is assistance in defining your specific problem, and the knowledge to finding an appropriate solution.

The name of the game is…… “pick me, I’ve got what you want”...whatever it is

In all cases, the answer is going to be in your hands, and as in situations such as these, knowing less is better than thinking you know more than you do, because if they are all selling the same product the printing on the box isn’t going to make a big difference

If you do not truly understand what is being proposed leave it alone, because this is one situation where being uninformed can work in your favour

The sites are quick to tell you what your ventilation problem is and what types of ventilation systems they have in stock for you to resolve your ventilation problem with, whether it be roof ventilation, bathroom ventilation, or ventilating the dreaded ‘mould' in the roof’

And you find yourself with a whole lot of answers that don’t match up with the questions you may have.

Therein lays the secret, make sure they answer your question.


Prospective purchaser says, 'I've heard this roof ventilator can be quite noisy.
Salesman responds, these roof ventilators have now got nylon bearings.

Did the salesman say, this roof ventilator is not noisy?

No! he left it to you to presume what you wish without committing himself

Being in the business of selling roof ventilators, and or ventilation systems, is not the same as having the expertise in solving ventilation problems.

A little like going to the butcher to discuss impending surgery

As with the wonder ventilation gimmick of the moment, the solar roof ventilator. That which is going to give you something for nothing….after you’ve purchased the solar roof ventilator, and installed or had it installed.

The Roof Ventilation product of the decade……

a roof ventilator that has a 12v fan hooked up to a solar panel inside a plastic housing exposed to the elements, with the claim that it’s going to perform wonders because it’s a solar powered roof ventilator….the wonder product of the century…if only the Romans knew about it.

So, putting vague ventilator performance values aside,

how long is the solar panel going to last,?

and the fan, what is rated at ? in full sun of course because if there’s no sun…no workee,

how often do you plan to replace this wonder roof ventilator?

and are you going to do periodical inspections up on the roof or are you going to pay someone to do it?

and the biggie….how is this going work regarding night time purging, the most critical time for venting a house, a room or roof space?

On one occasion I asked a solar vent salesman what was going to happen of an evening when night time purging was critical…his answer without skipping a beat was…the solar vent was so efficient during the day that it didn’t need to work at night…. now that, to me, is a considerable feat, as those words would have stuck in my throat had I attempted to utter them, even in jest.

and take note…rocket science didn’t feel any loss when the salesman or tradie chose his vocation….flim flam is alive and well.

Ventilation solutions will differ between Brisbane, Sydney, Melbourne and Hobart


The Ventilation Flim Flam man

Ever notice how the number of professional assistants are getting fewer and fewer and the number of faceless promoters are ever increasing.
You want this, but you end up with that, because you thought, whereas in reality you made a decision in a confused state brought about by the ‘flim flam’ man….and it’s all online.
Online auctions are where you will find vague ambiguous claims that suggest one thing but in fact are saying something else, you need to read carefully
You enquire online about ventilation and all of a sudden you’re hijacked into considering insulation
This is one of the better attempts of flim flam…..

Then you get sites like Efficiency Matrix who sideline the reader from his initial enquiry with, 'before we answer the question of “Does roof ventilation work?” lets talk about insulation'

The entity, probably an SEO practioner, had no idea about ventilation, and or the benefit of ventilation systems in the home, so the reader is not going to get any joy whatsoever and more likely end up getting confused about ventilation products in general

The moment you realize nothing makes sense, you’re getting caught in flim flam….drop it cold and move on
‘In the land of the blind, the one eyed man is king’ and you are going to be out of your league.

Ventilation solutions will differ between Brisbane, Sydney, Melbourne and Hobart


Ventilating your home with Ceiling & Wall Vents

There are three types of ceiling vents or ceiling registers, in the main you will have seen two types, those that are designed to be used in ducted air conditioning and those sold in hardware stores.

95% of the ceiling vents sold in hardware stores are vents priced for the naive consumer who knows next to nothing about what he/she is attempting to do. The rest will likely have a short use by date especially if moving parts are involved

The type used in air conditioning are designed for air delivery under pressure, normally a set and forget unit provided with the package.
They are not designed for atmospheric natural ventilation, so whereas the name may be the same it’s design function is not, but hey, like religion, you’re entitled to believe as you choose.

The hardware store type ceiling vent or wall vent is a product providing the bare minimum in performance and reliability at a price, here again, believe as you choose at your own risk.

A vent with very small apertures is guaranteed to require constant cleaning to free it of dust adhesion not to mention high resistance to air flow
The type you don’t see are those designed and constructed to be adjustable, with long life, good flow efficiency and low resistance, being the most suited to the purpose of natural ventilation particularly in the home

A high efficiency low resistance ceiling vent is not only serviceable and adjustable, but is also a precision unit likely to be made of steel as opposed to plastic as moveable parts do not fare well in plastic.
It is highly unlikely you will find an efficient ceiling vent or register, such as the one mentioned, in a hardware store that has a high life expectancy. The plasicizers migrate out of the plastic rendering it brittle with discolouration

In short plastic vents with movable parts have a short use by date.

It’s these little things, such as a ceiling registers or ceiling vents, that provide greater comfort levels, not to mention healthier environment, without having to continually maintain or replace them every change of season

You may ask, how did we get by without them?…we didn’t. All houses built up to the sixties and seventies had wall vents.

The disadvantage of this manner of venting in that they were fixed. Great for keeping your home cool in summer but not so great in winter particularly with the higher costs in heating.

The presence of good ventilation systems allows doors to open and close easier, and by increasing air displacement, rooms are fresher with less odour retention, a lighter less oppressive feel about the area.

Its the little things that are barely noticed that often make the biggest difference and ceiling vents is one of them.

A good ventilation system in the home promotes well being and good health particularly at night, in bedrooms, during the sleep cycle

There’s little point to exercising in the morning, jogging and the like, to increase your fresh air intake if you’re going to spend the eight hours before breathing spent stale air

Ventilation solutions will differ between Brisbane, Sydney, Melbourne and Hobart


Smoking Fireplace

Many years ago I had a very distressed gentleman call me to ask if it was true that building a house in a certain location prevented him from having a properly functioning fireplace i.e. one that didn’t smoke the house out.

I asked as to how he came by my name and he told me that the architect had heard that I was the person to call when nothing made sense. Flattering?, not really because it usually means everyone else has gotten paid, while I get presented with the problem and no money to fix it.

The house was meant to be his dream home that had seemingly turned into a nightmare as his 40 year desire in retirement was to have a house, as it was, with a fireplace.

I agreed to go out and look at the fireplace. The 400 s/m architecturally designed home sat on a hill on about twenty acres with scenic and serene views on all sides with the fireplace sitting majestically in a large living room.

I asked him why he was under the impression he had built his dream home in an unsuitable position regarding a properly functioning fireplace.

He said his architect had advised him as much after several attempts to rectify the problem.

Now, fireplaces are a relatively simple construct, the only thing being is that you build them observing nature’s principles, not dictate your own. Drawing a fireplace and building one are two different skil sets.

A good bricklayer or stone mason does not translate into a good fireplace builder and very often you hear, ‘beautiful fireplace, pity it doesn't’t work’….or ‘it only smokes a little’

Aesthetics are introduced to a working design, they do not form the basis of the design.

The balance between the size of the combustion chamber and the flue needs to be proportional, with the transition (area connecting the chamber and the flue) constructed with minimal resistance

Suffice as to say that the transition was preventing the escape of the smoke from the chamber into the flue and coming into the room.

A course of brickwork was removed, a Condor terminal fitted to the top of the chimney to introduce the correct back pressure……and I’ve had my feet kissed ever since.

I should mention that a considerable amount of money had already been spent by those not having any idea of what they were doing, including the architect, prior to my involvement

To be fair, architects tend to rely on the supposed trades people aka experts, perhaps a little too much, but in today’s day and age where everyone knows a little, but too often, never enough.

Ventilation solutions will differ between Brisbane, Sydney, Melbourne and Hobart


Ignorance sells best…..

A professional has a difficult time in lying…..why? you may ask ….because when they spend years in gleaning the facts on which their profession is to be based on, it’s actually very difficult to ignore that awareness and pretend it doesn't’t exist when trying to advantage themselves through deception.

This is not to say that professionals are above misrepresenting facts, quite the contrary, only that they are likely to be unconvincing when lying about matters regarding their expertise as to the facts within their profession.

The most convincing salesman is one who believes in what they are saying about that which they are selling.

You take a relatively unaware individual, program him/ her with ‘the facts’ you wish them to be aware of and they will repeat those ‘facts’ with the conviction of their belief…….ergo a convincing salesman….simply because he is conveying the story honestly. He/she is not aware that the information being conveyed is not true and therefore is likely to be almost emphatic in his/her sincerity.

That is when you inquire about their history in the industry

An informed individual will know what the salesperson is saying is not true however very few are informed sufficiently well enough to question what is being said, especially if what is being presented is what they want to believe.

A professional liar on the other hand can be convincing with most of what he/she says because they employ a degree of charm which encourages you to overlook any warning signs as being simply apprehension without cause.

You are encouraged to deceive yourself because in wanting the conceptual product, or something like it, you’re already half way into the purchase unless the warning signs become to intense to ignore.

An industry professional will always answer the question and not try to deflect you to some trivia that contributes very little to the answer.

Ventilation solutions will differ between Brisbane, Sydney, Melbourne and Hobart


To ventilate & sleep well

When one takes a look at healthy lifestyles around the world they all see that they have one thing in common, breathing, clean fresh air relative to their environment. Outside air is what it is.

The quality of inside air is within your control.

Living in a heated environment should not be about how much heat you can retain or avoid loosing, but more a case of ‘how can I ventilate contaminated air efficiently whilst retaining comfort levels at an acceptable cost?’.
To our minds no cost is ever acceptable, unless we’re gratifying ourselves, however being that inside air requires replacement if only to replenish oxygen levels, one need to consider just how this is to occur.

The human respiratory system is at it’s greatest risk from artificially heated environment systems such as air conditioning installed without consideration to maintaining air quality levels.
Everyone would like to simply walk in, turn on a switch, and have everything taken care of, and if you have the means of installing a programmable system, why not? The rest of us need to be proactive and give consideration to the air quality you choose to live in.
Going on ‘walks’ and ‘runs’ for the purpose of being fit and maintaining your lung capacity is rather self defeating if your indoor environment, sleeping hours in particular, is compromising those endeavours.

Yeah but! ……doesn't apply

You can talk about how much money you’ve saved over the years in heating costs by living in a ‘plastic bag’ environment but what says it all is that the story is being told from a bed in an emphysema ward of a hospital.

How much would one pay not to be there? …….Exactly!

One is not suggesting that you go wailing off into the sunset and start becoming fanatical about the issue of healthy breathing inside your home. Just be mindful that a balanced approach toward a healthy indoor environment can only be of benefit you.

Inside air can be worse that outside air, whether it’s emissions of plasticizers in plastics, fibres, cooking residue and odours from numerous and various sources.
What is ‘good’ what is ‘bad’ is down to a judgment call on your part.

Some people sleep with a partially open window, some have the window tightly shut and sealed, of course the geographical location will have a bearing on this reality.

A good ventilation system in a home can do more to maintain a healthy atmosphere than imitating life in a plastic bag which is what you end up doing by denying appropriate room ventilation particularly in bedrooms

The truth is that being well informed enables you to make better decisions assisted by that information
In the end it’s your choice…

Ventilation solutions will differ between Brisbane, Sydney, Melbourne and Hobart

Cooler Home during Summer Months

In all societies there are the gullible, the ignorant and the well informed.

The gullible, listen to whom ever has a little knowledge but far from what needs to be known.

The ignorant, are those who insist that whatever they think, or have, is the best.

The well informed, seek out the knowledge and implement it, despite their seemingly isolated social choice

That having been said......

Often it's presumed that just ventilating the roof is going to be sufficient whereas the reality it is only half the story which provides less than half the potential of keeping a home cooler naturally in the summer months.

Yes, venting the roof will reduce the overall heat retention of the building however the exercise is to be proactive and make living conditions comfortable in the rooms below without incurring the high and higher cost of air conditioning

Obviously those with 2.7m ceilings are going to have a cooler home longer than those with 2.4m ceilings

Those with raked or cathedral ceilings will have a situation proportional to the height of the roof and the resistance (insulation) contained within.

To begin with the homeowner needs to feel confident that the concept of ventilation is a worthwhile and cost efficient exercise.

To explain this simply consider the following,

Fill a bucket with water and obviously if you put a hole in the bucket the water is going to escape. The bucket will empty proportional to the hole, the bigger the hole the faster the escape.

This is the physical principle governing water in a bucket

The physical principles governing heat in a bucket is the inverse, or opposite to, water in a bucket

Turn the bucket upside down like a hot air balloon and pour heat into it, the warmest air is going to be at the top of the air balloon, which is the energy that causes a hot air balloon to rise

If you put a hole in the top of the air balloon the heat is going to escape.

Ventilating a roof, is precisely that, allowing the heat to escape so it doesn't build up and transfer into the rooms below.

The hole is what all escapes through.

The efficiency of the hole is governed by the device placed over the hole.

This is called a roof ventilator......and all roof ventilators are not equal

To gain the optimum performance out of roof roof ventilation refinements.

Ventilation solutions will differ between Brisbane, Sydney, Melbourne and Hobart


Roof Services Industry

With the avaricious consumption of poor quality roof ventilation and skylight products as exists at present, and given the average life expectancy of the low cost products where the cost of installation outweighs the cost of the product, the service industry as regards to these roof ventilators and ventilation equipment is going to go gang busters.

The home owner is setting himself for ongoing pain and suffering unless he has a son, son in law, nephew or mate to help him out....and they're only going to do it once especially if they don't like what they see in the ongoing maintenance of roof ventilator or skylight.

The greater the demand the greater the chance of the shonks appearing on the landscape armed only with a tube of silicone and a dispenser offering you a price you can't refuse.

When in doubt ask for bona fide and not his mate down the pub with a mobile no.

The worst aspect is that you're probably not going to discover the quality of work performed until the next season

When roof ventilator products fail someone has to get up on the roof, usually at a price. Then the product has to be repaired or replaced, usually replaced because the product is not designed to be repaired. Now you're set for another five years, hopefully.

Well built homes require less in the way of ongoing maintenance, but those built on a stick and a prayer weellll....hand on heart.....'trust me I wouldn't lie to you"........SELL!

Some young fellow with a lot of energy looking for a project to focus on might be just what he needs...on the other hand there are plenty of slum landlords out there looking to increase their presence on the govt rental assistance schemes.

Ventilation solutions will differ between Brisbane, Sydney, Melbourne and Hobart


Ventilation of a Low Pitched Steel Roof 1 - 5 degrees

The ventilation of a low pitched roof is critical when it comes to the incidence of water precipitation during frost conditions (absence of natural air movement)
This is the reason why smoke pots are employed in vineyards an orchards around the world to create some movement however slight to offset the damage to pants and fruit as may occur when subjected to these conditions

Without air natural movement natural ventilation is not possible.

To avoid the occurrence of water precipitation to the underside of steel, glass in a building, the surface(s) need to be isolated from any air volume as may exist.

To illustrate the point using a case study consisting of a building of approx 100 s/m, rectangular in shape, walls well insulated with R2.5 and internally lined in cement fibre sheeting, situated in the Adelaide hills
The roof was of a steel cladding, pitched at 4 degrees, and flashings well sealed

The ceiling lining, consisting of compressed wood and cement tiles was installed approx 150mm under the roof and R3 Insulation was located above the ceiling tiles.

A well insulated area by any standard.....nevertheless.... toward the end of every winter season the white ceiling tiles showed signs of discoloration due to water presence.

No matter what means were employed the only one that worked, was when the roof was removed and foil was placed in direct contact with the underside of the roofing material....a simple foil vapour membrane.

Where glass exists in similar somewhat horizontal conditions, the glass will need to have a sheet of non conductive material laminated, applied, to the underside so as to offset the precipitation potential of the ambient air volume.

Ventilation solutions will differ between Brisbane, Sydney, Melbourne and Hobart


Ventilation of Indoor Pools and Spas


Natural ventilation is an aspect that needs to be considered in the initial stages of wet area building design.

Before the selection and implementation of natural ventilation equipment to wet area enclosures an understanding of the dynamics involved needs to be understood

It is not that mechanical services should not be employed in establishing the correct ventilation necessary, but more that they should be a refinement to the theme and not the theme itself.

Very often one loses focus as to the purpose of venting a wet area.

The two principle concerns are

moisture precipitation & odour

The phenomena of indoor rain, known as moisture precipitation, is a situation brought about by the sharp contrast of thermal differentials within and outside the area, occurring principally of an evening during frost conditions being zero movement of air

The spread of odour created by varying forms of chlorination, mould etc.can also contribute to a degree of discomfort throughout a building particularly those of a residential situation where the natural inclination is to close everything up when the building, or area, is unoccupied.

The problem of odour can only be resolved by air washing (ventilating) the area so as to offset any mould and mildew as might grow as a consequence of moisture saturation in the building materials.

The air volume exchange need to be proportional to the moisture level in the air as well as temperature.

The higher the temperature the greater the venting air flow. This does not mean that the flow of air needs to be high velocity but more higher volume

In initial building design, careful consideration as to the nature and character of the area ultimately determines the necessary equipment required to establish the correct ventilation dynamics deemed suitable

In retro fitting, a complete and accurate assessment of the existing dynamics is required before the solution can be determined. This can be a costly affair in contrast to the implementation of natural ventilation during the initial building construction phase.

It usually means that you'll end up chasing your tail because as you resolve one issue, another takes it's place, as a consequence of the ventilation solution employed in the first instance.

Then you throw your hands up and install a high velocity fan, in the hope that it will resolve everything and when that reveals itself to be less than ideal you'll put the house up for sale

In conclusion, ensure you do not resolve the problem by creating another problem.
It is fundamentally important that wet areas are able to ventilate efficiently without dependency on equipment such as de-humidifiers, fans, and / or other mechanical services, particularly in commercial facilities, when the area is not being used.

Do not presume the architect has the knowledge required to resolve or address the aspect of ventilation in a Swimming Pool / Spa enclosure as the dynamics are unique to the individual area.

Today the concept of indoor bathing areas and the benefits to be derived from them is taken for granted. Unfortunately the necessity of ventilation is forgotten until all manner of problems arise, particularly those of odour.

Deterioration of building materials, due to excessive moisture absorption is a common occurrence. The lack of appropriate ventilation brings about costly repairs, which could have been prevented.

Correct ventilation of enclosure design is paramount in ensuring that the building provides the maximum benefits whilst requiring minimal maintenance. Too much is made of trying to have the swimming pool enclosure conform to the overall design theme of the home without appropriate consideration to the essential fundamentals as is required for wet areas, heated or otherwise.

Wet areas need continuous and effective ventilation, and in an appropriate manner. Fundamental to venting a pool enclosure is peripheral air entry 400 mm from ground level, and a central convergence of the air mass discharging to atmosphere. The higher the peripheral air ingress, the greater the incidence of moisture precipitation within the building, especially with a heated water mass.

Cross Flow venting is inefficient and never appropriate for heated enclosures. Mechanical venting such as exhaust fans are only capable extraction whilst on and can never be as effective or cost efficient as an appropriate natural system.

Whilst drafts may be considered to be a form of ventilation they should be avoided as their presence often promotes thermal shock giving rise to colds and other respiratory problems

The Condor Roof Ventilator can be structurally mounted to the roof making it ideal for cyclonic regions.

Fabrication is stainless steel and finished with polyester resin in colorbond colours.

Ventilation solutions will differ between Brisbane, Sydney, Melbourne and Hobart


Bathroom Ventilation against Mould

The creation of mould in wet areas such as bathrooms and laundry is the end result primarily of two things, water and heat, along with a lack of appropriate air movement referred to as ventilation.

The mould itself is a product of air borne yeast and fungi spores ever present in the atmosphere.

The presence of mould, black spot, moss on bathroom walls and ceiling is an indication of moisture retention within building materials within a warm environment which in turn allows the mould and fungi bacteria to multiply.

The moisture may well be the end result of water precipitation unable to be removed by an adequate air flow or some manner of water ingress into the building materials

Mould on the grouting of bathroom tiles is probably the best example of this phenomena, and the fact that cleaning agents are employed to momentarily kill off the mould and fungi bacteria.

To apply the most effective form of ventilation to a wet area, an exhaust fan should be employed and is best placed over the shower area. A means of fixed ingress should be provided especially when the door is closed.

The difference between using outdoor ambient as a means of volume replacement medium, in the ventilation cycle as opposed to using internal volume, is that outdoor ambient air will always be fresh oxygen enriched air

Ventilation solutions will differ between Brisbane, Sydney, Melbourne and Hobart


How to ventilate a raked ceiling

Rooms with raked and cathedral ceilings have one common problem during the summer months ....they get hot... and they stay hot.

Obviously venting the heat out is the answer, but how to do it without creating other issues as a consequence.

Remember heat is energy just looking to be released and you want a roof ventilator that does just that

First you select a roof ventilator or cupola, the size of which is determined by the size of the room and the means of low level air ingress (via door and windows)

Then you match it with a ceiling vent or register that can be opened and closed at will, either manually, push / pull with a rod of suitable length, or if it's too high with a electrically operated ceiling vent via switch or remote controlled.

It's advisable to choose a ceiling vent able to open incrementally as it will be used to freshen the area at various times during the year.

The difference experienced as a consequence will be quite remarkable, a different room altogether especially if the room is on an upper level. The roof ventilator chosen in such a case will need to be larger as the total heat load of the house will be trying to get out of the roof ventilator/ cupola

It may seem like an unwelcome expense but ventilation properly done will be well worth the transformation

Ventilation solutions will differ between Brisbane, Sydney, Melbourne and Hobart


Roof and room ventilation for a double storey dwelling

The venting and cooling of a double story house is more complex than a ground level dwelling.

The common statement heard made by owners is.....'I only want to ventilate the upper level as the ground level is cool, so that area doesn't need it!'

well of course it doesn't need it, it's cool as a consequence of the heat migrating to the upper level....all the heat absorbed by the whole house has moved up into the upper level....even the heat off the downstairs refrigerator coils has moved you could say that the upper level has the combined heat load of the whole house, making the exercise of venting the upper level more critical.

In the quest for making our homes more naturally responsive in maintaining comfort levels, and reducing costs, one need to apply a little logic and common sense

Electricity costs are going to go in one of two directions, ......and down is not one of them.

So there you are, a high heat load in the upper level and the concept of cross ventilation isn't working for you.

Bedrooms are hot, no one is getting any sleep and what makes is worse, there's a cool breeze outside where the temperature is several degrees cooler.....and none of it is coming inside.

So what to do?....other than rip the roof off.

So unless you can master the art of blowing air into a bottle you're faced with the reality of accepting the fact that the only way you are going to get the cool air to come inside is to let the hot air out....and the best way of getting the hot air out is straight up install on large roof ventilator or cupola...not some mickey mouse product that works on solar power and you delude yourself that you're going to get free power

If you were to punch a hole in the bottom of a full water tank you wouldn't use a pump to take the water out.

So too the roof, once there's a nice big hole, the heat will come barrelling out.

That's the roof space/attic area taken care for the rooms.

A ceiling vent placed in each of the rooms which will allow the heat trapped above door heights to escape into the roof space....and as it's escaping, it pulls the cooler air in from outside to replace it.

You can't remove one thing without replacing it with another...even if it's air.

Like I said previously....ever try blowing air into a bottle?

The ceiling vent needs to be adjustable, preferably with a push / pull action, so you can open and close it incrementally. Whatever you do, DO NOT USE A PLASTIC TYPE....they break easily and at the worst possible time.

Metal ceiling vents come in two types, manually operated, using a rod of appropriate length with a hook, and 12v electrical, with a remote option.

Not only do you vent the room(s) naturally but you end up with fresher and cleaner odourless rooms because you are introducing fresh clean oxygen

Ventilation solutions will differ between Brisbane, Sydney, Melbourne and Hobart


Roof Ventilation Fans

The idea of a fan in the roof for the purpose of venting the heat out is a seemingly attractive one.

Note, the fan being used here is a 240v axial or centrifugal fan not a solar whiz bang

There it is, 'a fan sucking the heat out'...... fantastic...modern day roof ventilation......if only the Romans had them.

The fan sucks the heat out of the roof it obviously draws ambient air in to replace that which has been removed, using the path of least resistance.

So ideally the ingress points have to be the furtherest away from the fan so as to air wash the distance in between the two points, and the ingress (eaves vents) need to have minimal resistance as the ingress efficiency is going to affect the venting efficiency of the fan.

In the case of a ventilating the roof space of a skillion roof, where the distance between ceiling and roof lining can be as little as 200mm having a dedicated ingress with a fan at the opposite end, there would be some benefit in both relieving the heat gain and offsetting the saturation of the ceiling insulation.

This certainly would offset the need to have several vents dotted across the roof.

So bearing in mind that the average roof space temperature is around 68 degrees and the heat transfer via conduction of the steel roof will be proportional to the airflow of the fan.

How long is the fan going to last given that manufacturers such as EBM Papst and Zeihl Abegg do not recommend their fans be used beyond 60 degrees?

Ventilation solutions will differ between Brisbane, Sydney, Melbourne and Hobart


Roof Ventilation Fans pt 2

The prevailing wisdom would seem to be against using fans for venting the heat out of the roof, particularly during summer months as regards to operational life and efficiency of the fan.

Of course there is nothing to prevent you from using a fan(s) for air ingress (eaves) into the roof space as the ambient air flowing over the motor is never going to be critical and as long as the roof ventilator does not create too much resistance so as to cause the fan motor to overheat, then it could be considered an alternative in creating a positive flow in ventilating the heat out of the roof space.

In all cases the roof ventilator needs to be able to cope with the flow required to ventilate the roof efficiently and the duty of the fan needs to be proportional to the release as a pressurised roof under these circumstances is something to avoid

Ventilation solutions will differ between Brisbane, Sydney, Melbourne and Hobart


Sub Floor Ventilation

The purpose of venting the area beneath a timber floor is to prevent the incidence of wood rot and consequential odour arising from high humidity levels caused by lack of sufficient ventilation as my be required to remove moisture gain.

One needs to remember that all space needs to breathe (ventilate) The space under a timber floor is one such area, however it should be noted that a vented sub floor area will always be cooler as a consequence.

A moisture barrier can be employed to partially address this problem however the necessity to vent the area will always be required.

Obviously the most desirable form of aspiration or venting of an area is a natural one, where thermal and pressure differentials about the building perform the task of ventilating the area as is required.

Natural ventilation is often referred to as 'passive' by those wanting to sell you a powered 'positive' ventilation solution inferring that passive is equal to submissive and therefore not as effective.

There's eating and there's overeating....and as with anything overdone there are always unpleasant consequences

The more open the sub floor area is, then obviously the more efficient the ventilation, however there is a level to which sufficient ventilation is considered appropriate and going beyond that point can often lead to adverse results. The more the better attitude regarding sub floor ventilation, or any form of ventilation in fact, is not a wise one.

In many cases the sub floor area is going to be difficult to assess due to inaccessibility and this is where you may find yourself at the greatest disadvantage because the assessment of the problem may simply be the result of conjecture and supposition.

There are tell tale signs of certain conditions arising from poor ventilation being obvious to someone who is experienced in these matters. You will not know, so it is important that the assessment be presented to you in writing, so that if you need to get or want a second opinion you are not trying to think of what was said previously

When a sub floor venting problem presents itself it is imperative that the prevailing dynamics causing the lack of appropriate ventilation be understood before any solution is proposed or implemented.

In any efficient venting solution there are ingress and egress points as may be required to facilitate a balanced displacement of air in the area.

A ventilation professional will never proposed a fan be used from the outset, as a ventilation fan can never be considered as a solution. It can be a refinement to a venting theme but never the theme itself.

For instance, if the problem is caused by poor water drainage, as are most, then the obvious solution is addressing the drainage, not putting in a so called 'turbo vent fan' as a band aid.

The obvious outcome being the salesperson's got the money and you're still stuck with the problem....'Oh yeah but',.... 'we tried', ....'wait 'til next season and see how it goes'....'give it a chance to dry out', .......doesn't quite do it.

A product is something that is purchased and employed where a problem arises out of poor building design and no means of rectification is available.

The so called solar, or packaged products, bear careful consideration as their performance efficiency and work life needs to be questioned.
A packaged product is one that is sold and used for all situations.

It is not an individual solution designed for your situation

Forums are useful up to a point but even there there is no guarantee....just opinion.

Where fans are used for assisting in the venting of such areas you have a choice of 'negative' or 'positive' modes

Negative venting is where the fan is employed in a exhaust duty in drawing the air volume out of the sub floor area and the supply is via fixed vents of various size to position are used for ingress.

Positive venting is where a fan is used to fill the sub floor area and discharge occurs with the same size to location fixed vents.

Ideally the fixed vents should be3 of stainless steel irrespective of aesthetic colour

There are other more specialised venting themes one can use depending on the circumstances and nature of the building

Ventilation solutions will differ between Brisbane, Sydney, Melbourne and Hobart


Roofing Materials

Steel v Tile

There are principally two categories of roofing materials.

Metal and Substrate (clay, concrete, slate etc)

The oldest of these being substrate (clay tiles) developed over the ages virtually in conjunction when man was able to control fire with the clay tile being the consequence as regards to roofing materials.

So let's imagine that iron sheeting developed at the same time, which material do you suppose would have been used. I think we would all agree that kiln fired tiles were used, not because it was the best but it was the only commercial product available.

Initially the corrugated iron roof sheet was limited in size and it was used in much the same way a large tile, under and over with an overlap on the side

When you look at cost and speed, a metal roof is constructed faster than tile. Both materials have their respective advantages and disadvantages

A tile roof absorbs sound whereas a metal roof transmits sound

A steel roof comes in a continuous length whereas a tile is much the same size as it has always been.

As regards to heat a steel roof transmits heat and sheds heat the minute the sun sets, whereas a tile roof absorbs and retains heat for a longer period of time

Today much of the shortcomings can be nullified with the use of insulative and absorptive materials so the question becomes more relevant,...which is the better material to use.

Personally I believe steel is, in that it's lighter, tighter, cleaner, flashings are simpler to apply and any penetrations can be sealed more efficiently. I say better because the trades that were aware of the traditional and proven modes of tile flashing do not exist any more and one needs to consider future maintenance as may arise.

As regards to ventilation, whether it be roof ventilation or room ventilation, the efficiency of which is better with steel as opposed to substrate.

The variables which can be employed are greater in number and of the two materials steel can provide greater aesthetic regard with minimal maintenance

Ventilation solutions will differ between Brisbane, Sydney, Melbourne and Hobart

Insulation Realities

The purpose of which is to limit heat loss or gain.

In domestic and general buildings, during winter months, to limit heat loss through the ceiling and walls where the manner of construction consists of a thin membrane material such as plasterboard as a lining. beyond the primary membrane.

Its corresponding performance during the summer months comes with a plus minus effect, in that the greater the amount of insulation, the greater the storage potential, therefore the longer the building will take to purge itself of the heat load during the evening cycle.

The house is less resistant to ambient change

Various entities including govt. based organisations will attempt to suggest that insulation will provide all the necessary comfort levels desirable but disappear into the wilderness when asked to show their rationale, or attempt to change the narrative.

The reality is that there is no advantage without a corresponding disadvantage and anyone advising differently should be questioned as to rationale.

Bigger is not Better!

In most conditions, the use of an insulative medium above r3.0 is not warranted and even then should be used in a manner so saturation does not occur, and any high heat load absorbed can be dissipated quickly and efficiently.

A decision should never be made until full awareness has been acquired.

Unfortunately there are those that think that when a word ends in ‘ion’, one is a substitute for the other.
A dangerous presumption!

Insulation, Ventilation, Air conditioning have totally separate areas of function and one does not replace, and or, is a substitute for, the other. Just as do the tyres, steering wheel and brakes in a car.

In simple terms:

Insulation – is like putting an on overcoat, to prevent heat loss or gain
Ventilation – is like breathing
Air Conditioning -cooling -a cost based climate system controlling living conditions reliant on consumption of electrical energy with or without water.

Putting on an overcoat is not going to make you breathe any better,
and the air conditioner is not going to improve the quality of air.

Conversely, breathing well is not going to make you any warmer, but it will contribute to your remaining cooler, and is guaranteed to keeping you healthier.

Use the right product for the right reasons and avoid trying to demean the validity of the product, or approach, on the basis of financial outlay because in the end you are the one that is ultimately going to wear the outcome

As with anything, correct understanding always produces the best decisions.

Ventilation solutions will differ between Brisbane, Sydney, Melbourne and Hobart



Conjecture & Supposition by Isa Stralian

There was a time early in my career as an Industrial Designer specialising in new materials and processes, one of them being sound absorption, when I was asked to investigate a situation where a woman was complaining of a high pitched noise in her area causing her untold grief when attempting to sleep in the evening

The University had gone out with their sophisticated noise detection equipment and found nothing. It was presumed at the time that she may benefit by sound proofing her room in an appropriate manner.

After a couple of interviews with the woman where she was obviously distraut and beginning to believe that she was being fobbed off by all and any involved....the city council, the EPA, the University.

I assured her that there was no doubt in my mind that she was hearing what she claimed to be hearing, but would she indulge me by visiting her dentist and asking him to check the alignment of her teeth as regards to pressure on the nerves.

Because she had a molar removed some six months prior her her jaw began to misalign and her teeth were starting to grind causing uneven pressure on the nerves connecting to the aural canal.

The teeth were corrected, the jaw realigned and the distressing sound gone.

I make mention of this experience so as to amplify the fact that all things may not be as they initially seem and very often the answer may be elsewhere.

Proper assessment of a problem is essential to determining a solution