Insulation

[Carmine6]

Why all the emphasis on ceiling insulation? Heat rises so it makes sense to let it escape through the ceiling. Keep the area above your ceiling well ventilated, tint and seal your windows and insulate the walls if at all possible. Solar powered attic ventilators are a great idea. They only run when there is a lot of sun. Unfortunately they are expensive and not commonly available.

More importantly than all the prior thermal transfer explanations, h90 in post #3 mentioned he thought about placing insulation on top of the hanging ceiling to fix his problem. Doesn't seem like walls were his concern.

I agree with venting the attic athough I think wind powered turbines work great in most places. They move more air than most people think and if they pull cooler air through at night it delays the heating of the attic until later in the day.

[Gary A]

That is true and that is exactly why you want to pump ambient air into your attic to displace the heat coming through your roofing. Insulating the roof itself is a better idea than insulating the ceiling. Unfortunately the spray on foam is great but few offer it and those that do are very EXPENSIVE.

[chownah]

From a practical standpoint, if you are not using the attic space, then insulating the ceiling is probablly just as good as insulating the roof...and in some cases it is better. In the northern part of the US, if an attic space is not being used, the insulation is put in the ceiling, not in the roof....it is cheaper and easier.

[elkangorito]

It is also recommended that Sisalation be placed on the underside of your roofing material (tiles, tin etc). Sisalation is a paper/tar product & will burn but not easily.

This insulation is placed in between the tile/tin and the battens (rafters), which the tiles/tin rest upon. It is normally blue coloured on one side & silver on the other side. Both pieces are stuck together by a tar like substance. This type of "pre-insulation" is commonly used throughout Australia where ambient temperatures are quite often 40 to 50 degrees celcius. Disregarding this, this insulation 'helps' the ceiling insulation. It must be remembered that the ceiling space is an enclosed space. To properly & fully ventilate it with 'ambient air' would take kilowatts of electrical fans or, even more ludicrous, have an open roof...much like a 'fly' on a tent. Of course, the 'fly' method is seldom used as it is an invitation for the wind to rip off the roof, should the wind become strong enough.

From an engineering point of view, using 'convection' operated "whirly's" with appropriate ceiling insulation is prescribed in order to reduce the energy costs associated with heating & cooling of spaces within the house, minimise ongoing maintenance costs & minimise installation costs.

It is wise to note that with every piece of equipment, there are 3 costs...the installation cost (fixed), the ongoing maintenance costs (never ending) & the repair/replacement cost of failed/faulty equipment. Without insulation, particularly in the ceiling, the a/c will have to work harder (reducing it's life...repair/replacement cost. Increased running costs) & also increasing the maintenance costs (replacement of TX valves, compressors, condensor fan motors etc).

[h90]

on what we make new I'll use styropor, as it is cheap and the construction people reject to work with the glasfiber (even it is sealed in aluminum) because of cancer and don't want to work with the bubble PE, because it does not work good and it is too expensive (their concerns??) (my guess is they get somewhere commission).....

For the ceiling I'll a bit later use 3 or 6 inch glasfiber, but later as I am very low on money at the moment. I won't use it on the roof, because I plan to change the roof later (make it higher or make one more floor).

But thanks for all your comments!

I feel a lot more educated now!

Why all the emphasis on ceiling insulation? Heat rises so it makes sense to let it escape through the ceiling. Keep the area above your ceiling well ventilated, tint and seal your windows and insulate the walls if at all possible. Solar powered attic ventilators are a great idea. They only run when there is a lot of sun. Unfortunately they are expensive and not commonly available.

More importantly than all the prior thermal transfer explanations, h90 in post #3 mentioned he thought about placing insulation on top of the hanging ceiling to fix his problem. Doesn't seem like walls were his concern.

I agree with venting the attic athough I think wind powered turbines work great in most places. They move more air than most people think and if they pull cooler air through at night it delays the heating of the attic until later in the day.

[scotsman]

I find that most thai houses have lots of gaps in the overhangs of the roof so this lets the cooler air come in as you pump out the hot air. The electrical pump does not use that much electric as it is controled with a temp switch set at 30 deg. The metal fans that fit on your roof look so ugly thats why I went for the hidden electric one. The spray foam they use now is very good and last a very longtime. but it is expensive. It is a better insulating material than most other materials on the market in thailand. I was very happy with the results but I also have upvc double glassed windows which also help in keeping the heat out and the noise.

[elkangorito]

There is certainly no need for an electric extraction fan in the roof. It will become an added source of maintenance & an added electricity cost. Heat can be freely & effectively extracted from the ceiling space by using a "Whirly". Actually, 2 or more of these devices in the ceiling space are very effective. They are cheap to buy & easy to install.

Ceiling Insulation.

There are many varieties of ceiling insulation but by far the cheapest & safest is fibreglass. Wool (from sheep) insulation is superior to fibreglass but more expensive & difficult to source. Wool insulation is also very fire retardant, does not give off poisonous fumes when it is under extreme heat stress, is good for people who are hyperallergic (wool is hypoallergenic, fibre glass is not) & easy to install. Very important: if any type of thermal insulation is used in your ceiling, ensure that your electrical wiring is not laid in amongst the insulation. Wiring that is laid amongst such insulation will have a reduced current carrying capacity. In this situation, if your cables get hot from excess current, thermal insulation will help to keep them hotter longer, which can lead to an electrical insulation failure & consequently, a fire.

It is also recommended that Sisalation be placed on the underside of your roofing material (tiles, tin etc). Sisalation is a paper/tar product & will burn but not easily.

In Thailand, many brick homes are "single brick", which affords little to no insulation from the outside heat. Remember, bricks that are hot, stay hot. If one chooses to use a "single brick" design, special heat rejecting bricks can be purchased in Thailand.

A much more effective way to reduce heat transfer when building a brick house, is to use a "double brick with cavity" design. Lots of bricks but very effective. Also greatly reduces outside noises from entering the house.

If the house is not of double brick design, then wall insulation must be considered (if you are serious about reducing energy costs).

Always keep in mind the "fire safety" aspect of insulation. Many of the Foam types are highly flammable & give off poisonous fumes when burnt. They can also "degrade" after a number of years & create undesirable side effects ie hyper allergic reactions etc.

Do not forget Window Insulation, aka tinting. The colour of the tint is not important. What is important is the tint's ability to filter out the "heat-causing" Infra Red radiation. UV radiation does not create much heat at all. Using "shade cloth" instead of window tinting is a more efficient way of doing this but reduces visibility to the outside world.

If the installers of the fibreglass insulation (bats) wear paper overalls (unbearably hot) & a "particle" mask, then they are safe. Fibreglass does not cause cancer in anyone who does not work with it for long periods each day. The worst situation that can be caused by fibreglass is Emphasaema...and only if exposed to the fibre dust for long periods over a long period of time (years). My grandfather died of this as a result of working for years (15) in a fibreglass factory in Sydney. That was a long time before proper safety measures were implemented & enforced.

Switches, pumps....if you guys want to have the extra cost & maintenance of such equipment for such a tiny savings, go ahead. Again, GOOD engineering practice indicates that the use of "convection controlled" roof space ventilation devices saves money & will do the job adequately. Ceiling insulation does the rest.

[raro]

Styrofoam: Excellent in moderate climates, but not good in the tropics because it is hygroscopic and accumulates moisture. This will eventually lead to mould and the styrofoam rots away. There are now building blocks awailable in Thailand which are hollow and filled with styrofoam. Basically like a double brick concept. Here the styrofoam is inside and has no contact to the ambience, hence no moisture problem.

Still better is PU, albeit more expensive.

You may want to contact the ECC (Energy Competence Center) in Chonburi, they developed bungalows for resorts which are energy autarc - no electricity from outside is needed to operate a/c, fridge, TV... PM me for a contact.

[h90]

I got told that Styropor (or foam) is not hygroscopic, but of course that can be wrong. But I got also told that ant love it

I am not looking to a autarc solution, just for improvements, an I have the feel I am the only one....

opening the windows+let the aircon running at full speed (alternative close the windows let the aircon cool the room to 20 degree and wear winter clothes) are the normal behaviour......

Now starting with insulation, than warm wather from the sun.....

Styrofoam: Excellent in moderate climates, but not good in the tropics because it is hygroscopic and accumulates moisture. This will eventually lead to mould and the styrofoam rots away. There are now building blocks awailable in Thailand which are hollow and filled with styrofoam. Basically like a double brick concept. Here the styrofoam is inside and has no contact to the ambience, hence no moisture problem.

Still better is PU, albeit more expensive.

You may want to contact the ECC (Energy Competence Center) in Chonburi, they developed bungalows for resorts which are energy autarc - no electricity from outside is needed to operate a/c, fridge, TV... PM me for a contact.

[raro]

I got told that Styropor (or foam) is not hygroscopic, but of course that can be wrong. But I got also told that ant love it

I am not looking to a autarc solution, just for improvements, an I have the feel I am the only one....

opening the windows+let the aircon running at full speed (alternative close the windows let the aircon cool the room to 20 degree and wear winter clothes) are the normal behaviour......

Now starting with insulation, than warm wather from the sun.....

Styrofoam: Excellent in moderate climates, but not good in the tropics because it is hygroscopic and accumulates moisture. This will eventually lead to mould and the styrofoam rots away. There are now building blocks awailable in Thailand which are hollow and filled with styrofoam. Basically like a double brick concept. Here the styrofoam is inside and has no contact to the ambience, hence no moisture problem.

Still better is PU, albeit more expensive.

You may want to contact the ECC (Energy Competence Center) in Chonburi, they developed bungalows for resorts which are energy autarc - no electricity from outside is needed to operate a/c, fridge, TV... PM me for a contact.

I've got my info about styrofoam from the ECC, actually we are in contact with them for a new office building. The bungalows mentioned are an extreme solution, just to demonstrate what is possible. Our office will not be that extreme, but still with a focus on energy conservation.

[chownah]

I just remembered that some of the bats of insulation (bats are like blankets...meaning usually fibre glass) that I've seen do not actually have fibre glass in them but rather they have some sort of plastic fibre it seems. I even asked the store people what was in them and they showed me a sample of the fibre and it was not glass...so I asked them if it burned and they immediately replied that by itself it would only burn very slowly but not hot and fast. They answered without hesitation so I believe them...also they have always been reliable and knowledgeable....anyway...you might want to see if you can find these non-glass fibre bats if you want to stay away from fibreglass.

[tango]

yes I got my house sprayed with foam and also got a electric fan extractor that has a temp switch set at 30 deg to extract the air out of the roof space with a small plastic extract comming out at the overhang of the roof so it looks nice but it works very well.

Hi Scotsman,

I've been looking all over CMai for an 'electric fan extractor that has a temp switch'. Was wondering what was the price, where did you buy it; and, would appreciate any photos of it with one of the extract exiting at the roof overhang. Thanks in advance. Tango.

[sleepyjohn]

Why use electricity to draw the heat out of the loft?

Why not use convection. And the clearest way to get convection is to have high ceilings that are in fact the roof. I have done this in the UK. I did it top quality and the building regs required slates or tiles on top, then waterproof barrier ( like extra strong bin liner type material, so strong there's an ad with Geoff Capes standing on it), then two inch air gap ventilated at top and bottom to prevent condensation, then four inches of polyurethane foam (yellowish stuff, high quality), then your skimmed plasterboard. This would be marvellous here but i think you could reduce the spec and I'm not sure if the condensation gap is necessary in this warm climate.

So one now has a high ceiling....much more pleasing, especially if one has high windows at the side or rooflights.

So now one simply adds a ventilated slat area either side on the vertical walls at the peak for outflow, just as old fashioned thai houses have, and allowances for inflow of air from a much lower area...maybe the flyscreened windows. Natural convection will do all the work. Perfect.

(Convection by the way gains power greatly with added height. In the days of the early skysrapers dangerous wind speeds occurred at the entrance doors as there were clear stairwells. Revolving doors were quickly brought in to solve the problem.)

If no high ceilings then have a vent in the ceiling in each room, again not forgetting about inflow venting also. then have the same large slatted vents on the side walls in the loft, and use your silvered rockwool on top of the ceilings in the normal way. Do not worry about rockwool, just wear gloves and tuck your sleeves in so it doesn't itch and by all means use a mask. Glass fibres break longitudinally in a harmless way, unlike asbestos which breaks across the fibre. The dangers of asbestos by the way are also greatly exaggerated. if you have to deal with some just damp it down and wear a mask, and get it all out including any sweepings.

I think the need for wall insulation depends on whether one has much of an overhang on the roof.

If not I recommend a cavity brick wall, and I have a Thai architect aquaintance who has used burnt coconut in the cavity. I believe it is burnt to keep the insects out. i'm told the difference is enormous.

Good luck, and consider yourself lucky. I once did a job in Alaska where we had to put 18 inches of rockwool on top and 12 inches UNDERNEATH as well. It was so cold we had to defrost our gloved hands on the hot air outlet every 15 minutes.

[chownah]

A word about vapor barriers. Warm, humid air (like outside air in Thailand) contains alot of water vapor. If this air is cooled it can not hold so much water and the water will condense out of the air. Place a dry glass on a table....put ice inside...wait a couple of minutes and observe the water on the outside of the glass...it came from water condensing out of the air. So...you don't want warm moist air infiltrating into your insulation because when it reaches the inner surface of the insulation which is cold, the water will condense out of the air and into your insulation. To prevent this you put a vapor barrier on the outside of your insulation. By outside I mean the side of the insulation which contacts the warm air outside the living space. This will keep the warm moist air from slowly infiltrating into your insulation and causing the problem.

If the cool air on the inside of the room infiltrates into the insulation and comes in contact with the outer surface of the insulation it will be warmed in this process and this causes no problem because cool air being warmed does not cause water to condense out.

I hope my explanation makes sense.

Quick edit: Notice that in cold climates where the insulation is to keep the inside warm when the outside is cold the vapor barrier is placed just inside of the insulation...exactly the reverse of what is done in a tropical climate.

[elkangorito]

A word about vapor barriers. Warm, humid air (like outside air in Thailand) contains alot of water vapor. If this air is cooled it can not hold so much water and the water will condense out of the air. Place a dry glass on a table....put ice inside...wait a couple of minutes and observe the water on the outside of the glass...it came from water condensing out of the air. So...you don't want warm moist air infiltrating into your insulation because when it reaches the inner surface of the insulation which is cold, the water will condense out of the air and into your insulation. To prevent this you put a vapor barrier on the outside of your insulation. By outside I mean the side of the insulation which contacts the warm air outside the living space. This will keep the warm moist air from slowly infiltrating into your insulation and causing the problem.

If the cool air on the inside of the room infiltrates into the insulation and comes in contact with the outer surface of the insulation it will be warmed in this process and this causes no problem because cool air being warmed does not cause water to condense out.

I hope my explanation makes sense.

Quick edit: Notice that in cold climates where the insulation is to keep the inside warm when the outside is cold the vapor barrier is placed just inside of the insulation...exactly the reverse of what is done in a tropical climate.

What chownah is describing "typically" applies to constantly cold climates...like the UK etc.

Also, a nett condensation of water vapour occurs on surfaces when the temperature of the surface is at or below the dew point temperature of the atmosphere. If you have paper thin walls or ceilings, this could happen in Thailand if you air condition the inside of your home to a very cold temperature.

In modern construction, vapour barriers are typically not used between the home's interior and a ventilated "roof space". If the "roof space" has a continuous flow of air through it that is created by fans or vents, the moisture from inside the house passes through the insulation and is removed from the "roof space" by the air flow. Of course, if you are using plaster board as wall & ceiling panelling, it's own insulation value is such that condensation will not occur...especially in Thailand where "dew points" are usually in the mid to high 20's (degrees Celcius) & ambient temperatures are in the mid to high 30's. Or unless you live in Chaing Mai...even so, the most of the time the temperature will be high enough to evaporate any condensate quickly...especially in the "roof space", where the temperatures are predominantly higher.

When the dew point temperature and air temperature are equal, the air is said to be saturated. Dew point temperature is never greater than the air temperature. Therefore, if the air cools, moisture must be removed from the air and this is accomplished through condensation. Unless you have paper thin walls/ceilings & use air conditioning, this type of condensation will not be a problem in Thailand.

Also, polystyrene is an excellent insulator & very cheap. It is commonly used in "freezer room" applications but only if it is about 100 to 150mm thick (about the thickness of a fibre glass bat). This is generally not used unless it is completely encased in metal as it is very flammable & gives of poisonous fumes when it burns.

[scotsman]

yes I got my house sprayed with foam and also got a electric fan extractor that has a temp switch set at 30 deg to extract the air out of the roof space with a small plastic extract comming out at the overhang of the roof so it looks nice but it works very well.

Hi Scotsman,

I've been looking all over CMai for an 'electric fan extractor that has a temp switch'. Was wondering what was the price, where did you buy it; and, would appreciate any photos of it with one of the extract exiting at the roof overhang. Thanks in advance. Tango.

I think you are not going to like my answer The companys name is www.arcaircon.com in pattaya they sprayed the roof & installed the electric extractor I think it was approx 11,000 baht for the electric fan & temp switch with all the electric cables & pipeing plus the time to fit it. The extract exiting from the overhang is not that big and is made of white plastic and is flush with the surface so you cant realy see it. I will try and get a photo but I dont know if I can get it on to a post but will try. I hope this has been of some help.

[chownah]

The main body of my previous post in fact applies to Thailand and any other warm moist region and that my short note at the bottom indicated what is done in cold climates. Just to make sure that you understand what I wrote (I think my description is not the best) here is a link which talks about this same thing:

http://www.greenhouse.gov.au/yourhome/technical/fs16b.htm

The following is a short excerpt from that same website:

"

Install vapour barriers on the 'warm' side of the insulation.

In cold climates place the vapour barrier on the inside of the insulation (directly above the ceiling lining and next to the internal wall lining).

In warm climates place the vapour barrier on the outside of the insulation.

"

As you can see, this agrees with what I said in my previous post.

[penzman]

Mistakenly imported my old bookmarks and found these about foam and fiberglass insulation in Thailand.

Here

and here

[scotsman]

yes I got my house sprayed with foam and also got a electric fan extractor that has a temp switch set at 30 deg to extract the air out of the roof space with a small plastic extract comming out at the overhang of the roof so it looks nice but it works very well.

Hi Scotsman,

I've been looking all over CMai for an 'electric fan extractor that has a temp switch'. Was wondering what was the price, where did you buy it; and, would appreciate any photos of it with one of the extract exiting at the roof overhang. Thanks in advance. Tango.

I hope this pictures will help you

[chownah]

yes I got my house sprayed with foam and also got a electric fan extractor that has a temp switch set at 30 deg to extract the air out of the roof space with a small plastic extract comming out at the overhang of the roof so it looks nice but it works very well.

Hi Scotsman,

I've been looking all over CMai for an 'electric fan extractor that has a temp switch'. Was wondering what was the price, where did you buy it; and, would appreciate any photos of it with one of the extract exiting at the roof overhang. Thanks in advance. Tango.

I hope this pictures will help you

I would think that this system would be more effective if it blew air INTO the attic space.....are you sure that it is an EXTRACTOR fan which would mean that it is pulling air OUT of the attic?

[scotsman]

yes I got my house sprayed with foam and also got a electric fan extractor that has a temp switch set at 30 deg to extract the air out of the roof space with a small plastic extract comming out at the overhang of the roof so it looks nice but it works very well.

Hi Scotsman,

I've been looking all over CMai for an 'electric fan extractor that has a temp switch'. Was wondering what was the price, where did you buy it; and, would appreciate any photos of it with one of the extract exiting at the roof overhang. Thanks in advance. Tango.

I hope this pictures will help you

I would think that this system would be more effective if it blew air INTO the attic space.....are you sure that it is an EXTRACTOR fan which would mean that it is pulling air OUT of the attic?

Yes I am sure and the german company who instaled it told me that when it extracts hot air from the roof space then it will drag the cooler air from outside in through all the cracks and holes that you can see around the edge of the over hang. The roof on Thai houses are never sealed completely.

[elkangorito]

Yes I am sure and the german company who instaled it told me that when it extracts hot air from the roof space then it will drag the cooler air from outside in through all the cracks and holes that you can see around the edge of the over hang. The roof on Thai houses are never sealed completely.

To scotsman, extracting "hot" air form the eaves is not very energy efficient. Reason? The eaves are the lowest part of the roof & since hot air rises, it will require lots of airflow to be effective. Basically, this "airflow" is going against the natural desire for hot air to flow...that is, UP! Conversely, having "convection" extraction fans ('whirlies') will do the same job for free, providing there are holes in the eaves to allow the introduction of outside air. Air cannot flow into a space if there is no entry for it to do so...'air in' equals 'air out'. Question: in Thailand, when do you think that your roof-space will be below 30 degrees celcius? To hazard a guess, I would say NOT TOO OFTEN, IF AT ALL. Consequently, this exraction fan SHOULD be running most of the time. Having worked in many and varied jobs, one of them as a TV antenna installer (I was previously a radio technician), I can tell you that sealed roofs (standard 'holes in eaves' ventilation only) are bloody hot. Working with TV antennas usually requires entry to roof-spaces. In summer in Australia (30-45 deg C), I can assure you that the roof-space temp is F*CKING HIGH). Eg if the ambient temp is about 35 deg C, the inside of the roof can easily be double this. It puzzles me why anyone would think that a roof-space in Thailand will ever be lower than 30 deg C, since the ambient temp in Thailand is generally above this temp...unless of course, you live in Northern Thailand at high altitudes. Even if the temp at night drops to 28 deg C, the "latent" energy in the building will probably mean that the roof-space is somewhat hotter. I think your power bill will reflect this. If not, the frequency that you need to replace "burnt out" fans will reflect this, since these fans (I suspect) are not designed to run at a 100% duty cycle at such high ambient temperatures. Fan motors that are designed to run at 100% duty cycle at high temp ambients are quite expensive.

To chownah, when you say "warm" climate, it is not the same as saying "hot & humid".

I have attached a pdf file which contradicts what you suggest. Mind you, & to your defense, I have looked at many articles on the web & it appears that there is a HUGE debate going on with regard to "vapour barriers". Also, I work as a Facilities Engineer...have done so for the last 7 years. Generally, I look after all the engineering/technical aspects of large buildings (I currently have 2 buildings in my portfilio...a total of 3000 people in these 2 buildings). This means that I must deal with Electrical, Hydraulic, Essential Services (fire) & Mechanical Services (HVAC aka air cond). Just before I made this post, I called some Construction Engineers whom I know quite well. I asked them about "vapour barriers". All of them said that these devices are not used for "hot, humid climates" (many parts of Australia) UNLESS the application requires strict humidity control. Mould, structural problems & condensation problems normally occur in colder climates as a result of "heating".

It appears that a properly ventilated roof-space (convection is adequate) along with non-directional insulation (no foil etc on bats) in a hot, humid climate is perfectly ok. The web link you posted was Australian. I have never lived in, or never known, any house in Australia to use a vapour barrier. This is obviously a marketing ploy & also the extreme in Australia due to it's "temperate" climate...unless you live in Tasmania. But who wants to live in a refrigerator?

[scotsman]

Yes I am sure and the german company who instaled it told me that when it extracts hot air from the roof space then it will drag the cooler air from outside in through all the cracks and holes that you can see around the edge of the over hang. The roof on Thai houses are never sealed completely.

To scotsman, extracting "hot" air form the eaves is not very energy efficient. Reason? The eaves are the lowest part of the roof & since hot air rises, it will require lots of airflow to be effective. Basically, this "airflow" is going against the natural desire for hot air to flow...that is, UP! Conversely, having "convection" extraction fans ('whirlies') will do the same job for free, providing there are holes in the eaves to allow the introduction of outside air. Air cannot flow into a space if there is no entry for it to do so...'air in' equals 'air out'. Question: in Thailand, when do you think that your roof-space will be below 30 degrees celcius? To hazard a guess, I would say NOT TOO OFTEN, IF AT ALL. Consequently, this exraction fan SHOULD be running most of the time. Having worked in many and varied jobs, one of them as a TV antenna installer (I was previously a radio technician), I can tell you that sealed roofs (standard 'holes in eaves' ventilation only) are bloody hot. Working with TV antennas usually requires entry to roof-spaces. In summer in Australia (30-45 deg C), I can assure you that the roof-space temp is F*CKING HIGH). Eg if the ambient temp is about 35 deg C, the inside of the roof can easily be double this. It puzzles me why anyone would think that a roof-space in Thailand will ever be lower than 30 deg C, since the ambient temp in Thailand is generally above this temp...unless of course, you live in Northern Thailand at high altitudes. Even if the temp at night drops to 28 deg C, the "latent" energy in the building will probably mean that the roof-space is somewhat hotter. I think your power bill will reflect this. If not, the frequency that you need to replace "burnt out" fans will reflect this, since these fans (I suspect) are not designed to run at a 100% duty cycle at such high ambient temperatures. Fan motors that are designed to run at 100% duty cycle at high temp ambients are quite expensive.

To chownah, when you say "warm" climate, it is not the same as saying "hot & humid".

I have attached a pdf file which contradicts what you suggest. Mind you, & to your defense, I have looked at many articles on the web & it appears that there is a HUGE debate going on with regard to "vapour barriers". Also, I work as a Facilities Engineer...have done so for the last 7 years. Generally, I look after all the engineering/technical aspects of large buildings (I currently have 2 buildings in my portfilio...a total of 3000 people in these 2 buildings). This means that I must deal with Electrical, Hydraulic, Essential Services (fire) & Mechanical Services (HVAC aka air cond). Just before I made this post, I called some Construction Engineers whom I know quite well. I asked them about "vapour barriers". All of them said that these devices are not used for "hot, humid climates" (many parts of Australia) UNLESS the application requires strict humidity control. Mould, structural problems & condensation problems normally occur in colder climates as a result of "heating".

It appears that a properly ventilated roof-space (convection is adequate) along with non-directional insulation (no foil etc on bats) in a hot, humid climate is perfectly ok. The web link you posted was Australian. I have never lived in, or never known, any house in Australia to use a vapour barrier. This is obviously a marketing ploy & also the extreme in Australia due to it's "temperate" climate...unless you live in Tasmania. But who wants to live in a refrigerator?

Yes you are quite right about this but the air fan is installed up high and has a long silver pipe coming down to the extract vent. The temp switch might be set higher than I said as I forget but I can tell you that when its cooler outside or after its been raining then there is no hot air coming out of the vent so it must switch off. The electric bills are not that high as I dont use aircon very much about 1 hour or so at night to get to sleep or when its very hot in the summer as my house is not that hot approx 800 baht winter and 1000 baht summer. The fan has been installed for about 6 years now and with no problems but thanks for all your insight its very informative Ps. I still dont like the big silver extracts they would look so ugle on my house thats why I bought this one.

[chownah]

Elkangorito has posted an interesting link. It's advice is mostly for Austin Texas and the Gulf Coast region of the US. I think that they have some cold days there in the winter unlike Thailand which really has no cold days. It is the cold days in winter that pose a potential problem with the vapor barrier on the outside of the insulation. I'm not sure that I would follow their advice in Thailand but reading the link was very informative and their explanation of how condensation occurs in the wall cavity seems pretty good. The one piece of advice they gave that I agree with and that I think is good for Thailand is that ventilation is very very important..... and my view is that it is even more important if you are going to have an insulated ceiling with attic space above and an aircondition space below...meaning cold air all year round and don't have a vapor barrier....I think I'd use the vapor barrier but I'd probably go check the insulation every few months for a year or so to see if it was getting damp....or maybe I'd NOT use the vapor barrier and go check the insulation every few months to see if it was getting damp.

I have no insulation right now....I live in the north and its not so critical here...I do have excellent ventillation in the attic space. I have a 1.5 metre square opening at each end wall in the attic and a strip vent about 10 cm wide running the full length of both sides of the house under the eaves right next to the exterior wall. I plan on insulating the ceiling in the future and my plans now are to use the fibre bat insulation which has reflectorized plastic all around. This plastic envelope around the insulation will act somewhat as a vapor barrier and after I install it I will monitor it for moisture accumulation...I'm not anticipating a problem given the excellent ventillation conditions. I designed my attic space so that it is strong enough for a floor so it will be easy to walk around and inspect everything.

[JAS21]

To Scotsman

Thanks for your detailed info..wish my bills were that low..just had one for 2400Baht and we have been away a bit.

The roof is not fully lagged..we are in dispute with the building company at the minute.

Think we will go for the fan. I see a problem of hot air recircing back up into the roof..any views on this.

Yes wirleygigs are free but would you like one.

Do you have an override (off) switch for when you are out or away?

[h90]

2400 lool!

My biggest was 12.000 2 or 3 aircon 24/7, 2 computer 24/7 some lightings.

reducing to 1 computer and 1 aircon set at 27 degree reduced the bill to 800 (and a letter from the electricity company that they have to check/replace the meter because 12000 and than 800 is not normal.

To Scotsman

Thanks for your detailed info..wish my bills were that low..just had one for 2400Baht and we have been away a bit.

The roof is not fully lagged..we are in dispute with the building company at the minute.

Think we will go for the fan. I see a problem of hot air recircing back up into the roof..any views on this.

Yes wirleygigs are free but would you like one.

Do you have an override (off) switch for when you are out or away?

[scotsman]

To Scotsman

Thanks for your detailed info..wish my bills were that low..just had one for 2400Baht and we have been away a bit.

The roof is not fully lagged..we are in dispute with the building company at the minute.

Think we will go for the fan. I see a problem of hot air recircing back up into the roof..any views on this.

Yes wirleygigs are free but would you like one.

Do you have an override (off) switch for when you are out or away?

No I have not got one unless its on the main switch board like one of the trip switches but there is always someone at home and if not its only for a week at most, but thats a good idea.

[sleepyjohn]

yes I got my house sprayed with foam and also got a electric fan extractor that has a temp switch set at 30 deg to extract the air out of the roof space with a small plastic extract comming out at the overhang of the roof so it looks nice but it works very well.

Hi Scotsman,

I've been looking all over CMai for an 'electric fan extractor that has a temp switch'. Was wondering what was the price, where did you buy it; and, would appreciate any photos of it with one of the extract exiting at the roof overhang. Thanks in advance. Tango.

I hope this pictures will help you

El Kangarito is right.....your arrangement I'm afraid looks almost bizarrelly inefficient and undersized, and wrongly placed.

I just don't get why you want to run a fan when natural convection will do the work for you.

All you have to do is put the ingress and egress ducts in the right places....low and high....and big as possible. If you draw the ingress air through your rooms as I explained in a previous post you will also keep those rooms at the outside ambient temperature.

If you have a simple pitched roof you can put your egress ducts at the ends up high. If you have a gable roof you might consider special vent tiles or better still a seperate "raised doubled roof" section as seen on old fashioned Thai houses where there is a vent all the way round and under the raised section.

[Carmine6]

Ridge vents don't seem to be common in Thailand, but they are a way to have a clean looking roof and they vent the attic naturally. They've replaced wind powered turbines in more expensive and larger houses in the US. Not all that hard to retrofit most US contruction, but tile roofs wouldn't work so well.

It's like having a mini double roof. There are special baffled ones to keep rain from driving in. It doesn't seem like it'd be all that hard to lift ridge tiles somehow, cut a slot in the peak of the roof, and cover it up with screen.

Ridge Vent Installation

Ridge vents for rain

[chownah]

Ridge vents don't seem to be common in Thailand, but they are a way to have a clean looking roof and they vent the attic naturally. They've replaced wind powered turbines in more expensive and larger houses in the US. Not all that hard to retrofit most US contruction, but tile roofs wouldn't work so well.

It's like having a mini double roof. There are special baffled ones to keep rain from driving in. It doesn't seem like it'd be all that hard to lift ridge tiles somehow, cut a slot in the peak of the roof, and cover it up with screen.

Ridge Vent Installation

Ridge vents for rain

I suggested a ridge vent for our house and everyone thought that was kind of humorous so I asked why...they said that was for chicken houses. They thought it was funny but it was obvioius that they thought it was not a good idea....so I gave in to keep the wife happy.