Need Help Cooling My House/Attic in Bangkok

[longstebe]

What about an electrical fan at the top of the apex at both sides (not on the roof)?

Maybe not perfect but at least you'll never have any leaks from the roof. As another poster had mentioned, putting vents in the lower part of the attic aswell.

This is more of a question really :-)

[jsgatse]

So, it seems like the foam, if installed properly - is the best (albiet most expensive) solution - is that a good takeaway?

Standard insulation works, but can become a haven for rats - especially if they can squeeze in thru my soffits.

The whirlybirds work, and are a decent/cheap solution to take a dent out of the problem.

Agreed? Comments?

Thanks!

[Naam]

So, it seems like the foam, if installed properly - is the best (albiet most expensive) solution - is that a good takeaway?

Standard insulation works, but can become a haven for rats - especially if they can squeeze in thru my soffits.

The whirlybirds work, and are a decent/cheap solution to take a dent out of the problem.

Agreed? Comments?

Thanks!

the foam, applied to the back of the tiles is wasted money. the heat-up of the attic is only delayed. foam on the ceiling of the rooms below the attic is quite efficient but a ventilation of the attic is still required preferably by a powered fan.

[Naam]

What about an electrical fan at the top of the apex at both sides (not on the roof)?

Maybe not perfect but at least you'll never have any leaks from the roof. As another poster had mentioned, putting vents in the lower part of the attic aswell.

This is more of a question really :-)

a good solution to avoid roof leakage. there's no need to have more than one fan but vents that outside can flow are mandatory.

[Naam]

I would be wary of putting those blanket type insulations in the ceiling,

as you maybe just making a home for rats,tree rats,that seem to be a

problem here,especially in the rainy season when they move in to get

out of the rain.

Plant trees and bushes around the house,use water features,(if you can)

it will make your house look much nicer and keep your house cooler.but

that will be a long term project till the trees grow.

regards Worgeordie

to keep your attic slightly cooler with shade trees you need Australian Mammoth trees and a waiting period of 50 years. but even these won't shade your roof at noon plus minus 1½ hours.

[chiang mai]

I disagree, PU foam applied to the back of roof tiles has been proven by many posters to be a viable solution that reduces roof void tempreture by up to 10 degrees.

[sfokevin]

I had the same issue - I would walk up stairs and get hit with a wall of heat...

I installed the fan linked below in the ceiling if the upper floor of my townhouse above the stairwell landing... It is quiet and uses little electricity (25w)and i calculate it replaces the air in the attic space every 20 minutes or so... I leave it running from early morning until after sun down... It sucks the hot air from the upper floor into the attic space (replacing the even hotter air thats there)... Simple to wire as I ran wire right down to the stairwell landing light switch box...

http://www.directtoshop.com/webapp/wcs/stores/servlet/ProductDisplay?urlRequestType=Base&catalogId=10001&categoryId=17760&productId=122705&errorViewName=ProductDisplayErrorView&urlLangId=-11&langId=-11&top_category=14065&parent_category_rn=14216&storeId=10001

Also note at Homepro they have two models of this - a VC20 and a VC25... get the 25 it sucks almost twice as much as the 20

Oh and you can order from Lazada too...

Edited April 22, 2015 by sfokevin

[Forkinhades]

^ how does it expel the hot air in the attic?

[longstebe]

What about an electrical fan at the top of the apex at both sides (not on the roof)?

Maybe not perfect but at least you'll never have any leaks from the roof. As another poster had mentioned, putting vents in the lower part of the attic aswell.

This is more of a question really :-)

a good solution to avoid roof leakage. there's no need to have more than one fan but vents that outside can flow are mandatory.

So if you have the fan at the top of the apex(attic) would you suggest having the vents at the bottom of the attic?

[Naam]

What about an electrical fan at the top of the apex at both sides (not on the roof)?

Maybe not perfect but at least you'll never have any leaks from the roof. As another poster had mentioned, putting vents in the lower part of the attic aswell.

This is more of a question really :-)

a good solution to avoid roof leakage. there's no need to have more than one fan but vents that outside can flow are mandatory.

So if you have the fan at the top of the apex(attic) would you suggest having the vents at the bottom of the attic?

having the vents lower would be a small advantage. important is to have the exhaust fan installed as high as possible.

[Naam]

^ how does it expel the hot air in the attic?

perhaps beamed out by Scotty?

[jsgatse]

What about an electrical fan at the top of the apex at both sides (not on the roof)?

Maybe not perfect but at least you'll never have any leaks from the roof. As another poster had mentioned, putting vents in the lower part of the attic aswell.

This is more of a question really :-)

a good solution to avoid roof leakage. there's no need to have more than one fan but vents that outside can flow are mandatory.

So if you have the fan at the top of the apex(attic) would you suggest having the vents at the bottom of the attic?

having the vents lower would be a small advantage. important is to have the exhaust fan installed as high as possible.

Sorry, a bit lost here. You are suggesting installing an electrical exhaust fan (like the types they often have here in bathrooms, but a bit bigger, I assume) at the high point of the roof. But, then, what is allowing the air to escape? You must have some sort of hole in the roof, right? This is basically just a electric version of the whirlybird, right? Or, am I missing something?

[longstebe]

What about an electrical fan at the top of the apex at both sides (not on the roof)?

Maybe not perfect but at least you'll never have any leaks from the roof. As another poster had mentioned, putting vents in the lower part of the attic aswell.

This is more of a question really :-)

a good solution to avoid roof leakage. there's no need to have more than one fan but vents that outside can flow are mandatory.

So if you have the fan at the top of the apex(attic) would you suggest having the vents at the bottom of the attic?

having the vents lower would be a small advantage. important is to have the exhaust fan installed as high as possible.

Sorry, a bit lost here. You are suggesting installing an electrical exhaust fan (like the types they often have here in bathrooms, but a bit bigger, I assume) at the high point of the roof. But, then, what is allowing the air to escape? You must have some sort of hole in the roof, right? This is basically just a electric version of the whirlybird, right? Or, am I missing something?

Well it was more of a question really.

Yes, I was asking if placing an electrical fan (like an exhaust fan in a bathroom but bigger) at the highest point inside the attic but attached to the inside walls instead of the roof would work. Also having two air vents at the bottom of your attic at just above floor level.

[sfokevin]

^ how does it expel the hot air in the attic?

perhaps beamed out by Scotty?

My attic is like most other attics here in Thailand - A series of tiles laid one on another... When your in the attic you can see light between most of the tiles... Air can flow out these cracks and in addition my house has a large vent edge on the overhangs - many places for air to escape with a little help...

Sorry my humble, cost effective and effective solution does not have the galactic wizardry of Naam's turbo wind tunnel exhaust system...

Edited April 22, 2015 by sfokevin

[Forkinhades]

^ how does it expel the hot air in the attic?

perhaps beamed out by Scotty?

Starting to wish that he would be beam me up.

OK back on topic, that ceiling extract fan would work well with an whirly bird.

[HooHaa]

why not just install a big extractor fan and put it on a timer? why do you need a thermostat?

[bazza40]

I disagree, PU foam applied to the back of roof tiles has been proven by many posters to be a viable solution that reduces roof void tempreture by up to 10 degrees.

There's one post on this thread that says in his bitter experience it did nothing. Where are these "many posters"? The heat is being sealed in, not even an opportunity for the air to escape through gaps in the tiles. As for PU foam - fine if you have a death wish, toxic gases from polyurethane combustion are the worst hazard in a house fire.

[chiang mai]

I disagree, PU foam applied to the back of roof tiles has been proven by many posters to be a viable solution that reduces roof void tempreture by up to 10 degrees.

There's one post on this thread that says in his bitter experience it did nothing. Where are these "many posters"? The heat is being sealed in, not even an opportunity for the air to escape through gaps in the tiles. As for PU foam - fine if you have a death wish, toxic gases from polyurethane combustion are the worst hazard in a house fire.

Two parts to this:

Firstly, this topic has been discussed on TVF with great regularity over many years, the "many posters" I mention refers to previous discussions on this topic - try and do a search to see what has been said previously.

Secondly, if you read what I wrote earlier in this thread I made it clear that no solution would work well unless the roof space was properly vented.

[chiang mai]

I'm not quite sure that some posters understand the concept of roof void cooling, for it to work effectively it requires an exit point for hot air at the highest point of the roof and an entry point for cooler air at the lowest point of the roof (eves). That exit and entry gateway need to be correspondingly sized to some degree, having a large exit and relying on cracks for entry, simply wont work very well. The mechanics of the process is that the cooler air is dragged into the roof void to replace the hotter air, in doing so the cooler air is dragged across the hotter roof tiles which in itself has a cooling effect on the tiles. The main benefit however of that process is that hot air in the roof void is not allowed to accumulate, not allowed to enter the upper floor rooms and is not allowed to heat internal walls that terminate in the roof void.

So, however you chose to eliminate the hot air in the roof void, whirly bird, exhaust fan in the gable end, or simply a gable vent, corresponding input vents are required to allow the process to work properly. PU foam, as stated previously, simply slows down the roof void heating process, potentially to a level that requires no further action.

[bazza40]

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I disagree, PU foam applied to the back of roof tiles has been proven by many posters to be a viable solution that reduces roof void tempreture by up to 10 degrees.

There's one post on this thread that says in his bitter experience it did nothing. Where are these "many posters"? The heat is being sealed in, not even an opportunity for the air to escape through gaps in the tiles. As for PU foam - fine if you have a death wish, toxic gases from polyurethane combustion are the worst hazard in a house fire.

Two parts to this:

Firstly, this topic has been discussed on TVF with great regularity over many years, the "many posters" I mention refers to previous discussions on this topic - try and do a search to see what has been said previously.

Secondly, if you read what I wrote earlier in this thread I made it clear that no solution would work well unless the roof space was properly vented.

Fair enough, there's mixed experience on foam; however, the majority seem to be in favour. And you did make it clear on venting.

Personally, I prefer fibreglass because it doesn't burn - however, it can be a bitch to instal. Each to his own.

[chiang mai]

A final thought from me on insulation:

I think that insulation on the floor of the roof void does a fairly decent job of preventing heat from entering the living space, but it only does a partial job.

Most house construction in Thailand involves vertical walls that extend into the roof void, one to two feet above any insulation. Unless the top of those walls are insulated they willl quickly absorbe heat that is radiated from the roof tiles and travel down the walls into the living space and make it hot. That heat transfer process is exactly the same as used in a night storage heater and it's the last thing you want in a house in Thailand.

If in doubt about this aspect, wait until around 3 pm on a hot day and feel how hot the walls are at the top and at the bottom, if they are hot at the top and you have already installed insulation on the attic floor, you've got some more work to do.

So on reflection, I can now better understand why naam believes that PU foam sprayed on the ceiling (and on the walls that extend into the roof) is a better solution, cheaper the alternative of course is to cover the top of those walls with insulation when insulating the attic floor.

Finally, house fire risk in Thailand is quite low since there are so few combustibles used in modern construction hence PU foam is low risk.,

[IMHO]

The basics of a cool house are simple:

1. First, create shade - trees, solar panels, roof overhangs, shutters, awnings etc. Not just the roof - the walls too - especially those facing to the West or South.

2. What you can't shade, reflect - foil under tiles, solar glass etc.

3. What you can't reflect, insulate - double brick walls, Thermaline gypsum, insulation batts/sprays etc

When it comes to heat in the roof crawl space, there are two factors to consider:

1. Thermal expansion - i.e. hot air expands - make sure when it does this it's venting outside, not in.

2. Thermal buoyancy - i.e. hot air rises - make sure you're not trapping it when it wants to rise.

#1 is actually more of a phenomenon than #2 - whirlybirds and gable vents are not enough - you must have vented soffits (big areas of them, not just some of them) to truly let expanding air evacuate. The added bonus from having all of your soffits vented is that you will then also be able to take full advantage of prevailing winds to vent the crawl space too - and that's way more effective than any whirlybird or gable vent.

Edited April 23, 2015 by IMHO

[chiang mai]

It's not simply convected heat alone that's the problem. When it comes to heat in the roof void it's also important to look at the effects of radiated heat from concrete roof tiles on concrete walls and ceilings below, that's the missing link for many people.

[Crossy]

It's not simply convected heat alone that's the problem. When it comes to heat in the roof void it's also important to look at the effects of radiated heat from concrete roof tiles on concrete walls and ceilings below, that's the missing link for many people.

Agreed, although it's likely less of a problem than conducted / convected.

• Foil under the tiles, no need for insulation here (insulation may actually hurt as it stops the roof space cooling quickly at night).
• Foil backed insulation on the ceiling (foil up to reflect back into the roof space), but ensure that damp air cannot contact the cold gypsum and cause condensation (no gaps in the insulation)

And

• As much airflow through the attic as practical.

[Preacher]

Considering what kind of roof insulation to get myself. Will be a closed roof, with airholes at the underside of the roof, th part that overhangs the walls.

I have 3 options:

1. directly under the roof tiles
2. directly above the ceiling
3. do both.

Anybody a good idea about what would be best. I lke option 3, the most expensive, but not that much more, however might also trap heat in the inside of the roof and most compnies seem to promote either 1 or 2 and not option 3.

Can someone answer my question what is best.

So far it seems best to isolate the wals and top of the ceiling above directly under the cpac tiles. Or is doing both a better option (but does seem to trap the heat).

[Crossy]

Preacher.

Can you get airflow through the attic space? This is the number one requirement - vent the hot air and replace it with cooler air via soffit vents.

EDIT and see my post immediately above yours.

[chiang mai]

Preacher: I think it's sensible to try and isolate the house from the roof and the roof void since that achieves the desired effect. But trying to isloate both the house and the roof, from each other, might prove difficult and expensive. As Crossy says, ventilation and circulation in the roof void are key and vital to whatever you do.

[Crossy]

One more question preacher, is this a new build that you can adjust?

[Naam]

I disagree, PU foam applied to the back of roof tiles has been proven by many posters to be a viable solution that reduces roof void tempreture by up to 10 degrees.

a Thai bullshit fairy tale does not change the laws of thermo-physics. many posters who claim the above have actually no idea what they are talking about. the application of foam insulation is only propagated by many contractors because the preparation to apply foam on ceilings is quite difficult (ceiling lamps, electrical distribution boxes, etc. must be still accessible and have to be protected). spraying foam on the roof tiles is a breeze. any honest contractor with a minimum of technical knowledge will admit that my claim is correct.

[jsgatse]

I disagree, PU foam applied to the back of roof tiles has been proven by many posters to be a viable solution that reduces roof void tempreture by up to 10 degrees.

a Thai bullshit fairy tale does not change the laws of thermo-physics. many posters who claim the above have actually no idea what they are talking about. the application of foam insulation is only propagated by many contractors because the preparation to apply foam on ceilings is quite difficult (ceiling lamps, electrical distribution boxes, etc. must be still accessible and have to be protected). spraying foam on the roof tiles is a breeze. any honest contractor with a minimum of technical knowledge will admit that my claim is correct.

So, you are saying that the PU foam - such as what this guy offers - http://www.lohr-trade.com/foam - sprayed to the underside of the roof tiles is a GOOD or a BAD thing? Thanks.