Roofing/Ventilation Works

[Naam]

If you place both power and intake vents high then the lower air in the attic space will eventually become the warmest remaining air and will rise to the peak.

please dear Sir, i beg of you! stop torturing me

Naam, I have probably forgotten more than you have ever learned about sound construction practices so try to breathe deep and think happy thoughts ;-)

i am sure you beat me in that respect by many lengths because all i have to show is a doctorate in physics and a master's in mechanical engineering. the factories i built during 18 years in tropical countries just added to my knowledge about exotic cocktails.

[chiang mai]

Not to change the subject or to redirect it, but, have you ever listened to Ronnie Woods, Kieth Richards and Buddy Guy play together, absolutely phenomenally amazing, go to Utube and watch champagne and reefer, a magical experience.

What has the the above got to do with the subject post you ask? Nada, just thought a change of pace might help cool things!

Love and peace

[Naam]

Let me summarize, for my benefit:

Ventilation is key, power ventilation is optimal here.

Closed soffits for air intake are not a major problem since they can be drilled/vented.

Air intake (where ever it might be located) must exceed exhaust capacity.

Sprayed foam is probably not worthwhile nor good value for money.

Attic rafter insulation has benefits.

Under roof panels/insulation are not optimal.

Whirly birds (powered and thermostated) are inexpensive, lower profile, solar powered, US style vents are optimal - anybody seen them for sale here?

All those things being true, it's now a case of trying to find the exhaust unit and a contractor.

Thanks to all, it's been useful and I've got my way forward on this..

IF soffits are drilled vented--they must be screened to prevent unwanted insects and critters AND ceiling insulation must be kept 24"-36" away from outside wall so it does not block soffit ventholes.

Attic rafter (framing from outside wall to ridge) insulation is not good.

Ceiling joist (on top of living space ceiling) insulation is good.

Best to find an electrician to do the wiring and a roofer to install the vents. Roofers understand the Zen of water but not electrical current and Sparkies just the opposite ;-)

forget about any drilling! the minimum airflow to ventilate an attic of a rather small house is ~200m³/h which can be achieved with a 40watt fan (700-900 Baht). remove flaps because they don't serve a purpose if installed inside a whirly bird. i am not in the mood to calculate how many intake holes have to be drilled to match that exhaust volume.

solution: cut out 2 openings in the eaves on each side, each opening at least 80x25cm, get aluminium frames with insect screen made and install.

total cost whirly bird, fan, eaves cutting and frames should not exceed 10-12k Baht (both material and work).

note: exhaust fan should be on a switchable on/off timer (Amorn 250 Baht) because there might be temperatures (e.g. in Chiang Mai or somewhere up north) when attic ventilation is not necessary.

Edited June 13, 2014 by Naam

[evenstevens]

Let me summarize, for my benefit:

Whirly birds (powered and thermostated) are inexpensive, lower profile, solar powered, US style vents are optimal - anybody seen them for sale here?

All those things being true, it's now a case of trying to find the exhaust unit and a contractor.

last post from the doctor of physics,and the master of engineering, wow , how exciting (naam) seems to fit with your above summary,

and your comment of finding a contractor or two might now be the case

this is when the fun starts,or getting kicked in the ankles so to speak

just a word of warning, when u dare to go outside the box,as in this case,they will run circles around you

a old mate told me when i was planning my build etc etc many years back always apply the * the kiss * rule

which is

Keep...It...Simple...Stupid..

the very best of luck.u will need every bit of it,

and a very nice evening to all

[kaptainrob]

Let me summarize, for my benefit:

Whirly birds (powered and thermostated) are inexpensive, lower profile, solar powered, US style vents are optimal - anybody seen them for sale here?

All those things being true, it's now a case of trying to find the exhaust unit and a contractor.

last post from the doctor of physics,and the master of engineering, wow , how exciting (naam) seems to fit with your above summary,

and your comment of finding a contractor or two might now be the case

this is when the fun starts,or getting kicked in the ankles so to speak

just a word of warning, when u dare to go outside the box,as in this case,they will run circles around you

a old mate told me when i was planning my build etc etc many years back always apply the * the kiss * rule

which is

Keep...It...Simple...Stupid..

the very best of luck.u will need every bit of it,

and a very nice evening to all

I apply the KISS principle to everything in Th yet my TW surprised by ordering ventilated soffits .... she already had it figured! 555

A few facts:

Ceiling insulation/foil wrapped GRP/Batts is inexpensive. Measure room [ceiling height] temps at various times of day and compare with insulated/non-insulated.

Hot air rises and CPAC tile roofs breathe, to a small extent even with sarking, therefore ceiling 'batts' can make a huge difference.

NB: Townsville Qld homes traditionally had [corrugated] iron roofs and did not 'breathe', + there was no insulation way back then... similar to Isaan homes now.

Passive cooling is easy as and inexpensive to maintain long term.

[ClutchClark]

Let me summarize, for my benefit:

Ventilation is key, power ventilation is optimal here.

Closed soffits for air intake are not a major problem since they can be drilled/vented.

Air intake (where ever it might be located) must exceed exhaust capacity.

Sprayed foam is probably not worthwhile nor good value for money.

Attic rafter insulation has benefits.

Under roof panels/insulation are not optimal.

Whirly birds (powered and thermostated) are inexpensive, lower profile, solar powered, US style vents are optimal - anybody seen them for sale here?

All those things being true, it's now a case of trying to find the exhaust unit and a contractor.

Thanks to all, it's been useful and I've got my way forward on this..

IF soffits are drilled vented--they must be screened to prevent unwanted insects and critters AND ceiling insulation must be kept 24"-36" away from outside wall so it does not block soffit ventholes.

Attic rafter (framing from outside wall to ridge) insulation is not good.

Ceiling joist (on top of living space ceiling) insulation is good.

Best to find an electrician to do the wiring and a roofer to install the vents. Roofers understand the Zen of water but not electrical current and Sparkies just the opposite ;-)

forget about any drilling! the minimum airflow to ventilate an attic of a rather small house is ~200m³/h which can be achieved with a 40watt fan (700-900 Baht). remove flaps because they don't serve a purpose if installed inside a whirly bird. i am not in the mood to calculate how many intake holes have to be drilled to match that exhaust volume.

solution: cut out 2 openings in the eaves on each side, each opening at least 80x25cm, get aluminium frames with insect screen made and install.

total cost whirly bird, fan, eaves cutting and frames should not exceed 10-12k Baht (both material and work).

note: exhaust fan should be on a switchable on/off timer (Amorn 250 Baht) because there might be temperatures (e.g. in Chiang Mai or somewhere up north) when attic ventilation is not necessary.

CM,

Power Roof Vents are installed and operated by a thermostat-controlled switch so that the homeowner does not have to attempt to monitor the temperature of the attic space throughout the day...every day.

As for the soffit vents these vents can not replace an intake vent, they can supplement it and improve overall air circulation in the attic which is beneficial to remove moisture.

[onthedarkside]

Flame, as in an insult, removed.

[ClutchClark]

Flame, as in an insult, removed.

That would have been my post to the fella with all the degrees.

I did not mean to insult, I had attempted to inform that poster that a cooperative attitude is by far the best way to get people to hear your message.

[Naam]

CM,

Power Roof Vents are installed and operated by a thermostat-controlled switch so that the homeowner does not have to attempt to monitor the temperature of the attic space throughout the day...every day.

As for the soffit vents these vents can not replace an intake vent, they can supplement it and improve overall air circulation in the attic which is beneficial to remove moisture.

during "winter" i have read in this forum dozens of complaints from forum members living up north about being too cold and their questions where to buy electric heaters. during this period attic temperature would rise too and a thermostat-controlled fan would therefore run, waste energy and of course wear and tear would increase.

if the soffit vents are properly sized they are intakes.

[Naam]

Ceiling insulation/foil wrapped GRP/Batts is inexpensive.

"inexpensive" is a relative expression. the cost for double sided foil backed 15cm/6" insulation was some years ago approximately 90 Baht/m². it's "R-value" is equivalent to 2cm foam insulation if (BIG if!) applied as close and tight as foam, which is impossible due to straps which hold the substructure for the gypsum ceiling boards.

it's all a matter of a little "rithmetic". good and experienced workers might achieve with batted insulation 70% of the 100% which foam yields. foam application, thickness 5cm/2" costs around 400 Baht/m², i.e. the cost foam thickness of 1.5cm is around 120 Baht/m² which, based on the achieved R-value is cheaper.

thanks for not listening!

[Thai at Heart]

Infra red from the tiles itself is far worse than hot air itself.

Foam done properly will reduce the temperature at the ceiling massively. It is the infra red that heats the ceiling not hot air. Turning the air around will help a bit, but keeping the infra red from heating up the ceiling will help a hell of a lot more.

[ClutchClark]

CM,

Power Roof Vents are installed and operated by a thermostat-controlled switch so that the homeowner does not have to attempt to monitor the temperature of the attic space throughout the day...every day.

As for the soffit vents these vents can not replace an intake vent, they can supplement it and improve overall air circulation in the attic which is beneficial to remove moisture.

during "winter" i have read in this forum dozens of complaints from forum members living up north about being too cold and their questions where to buy electric heaters. during this period attic temperature would rise too and a thermostat-controlled fan would therefore run, waste energy and of course wear and tear would increase.

if the soffit vents are properly sized they are intakes.

Naam, from your posts it appears you have no actual personal experience with any of this but are hypothesizing based on your many years of schooling. Is this correct? Or do you actually have knowledge that structures in the north have a problem with fans running when they are not required? I have always enjoyed trouble-shooting design and installation issues so if you have specifics I would be glad to help out.

Also, It would be helpful to me if I know who has practical experience since I don't want to waste time in hypotheticals. Thanks for your understanding.

And since you are going to nitpick, yes, soffit vents are obviously an intake vent when the power fan is operating. The problem with relying on them as "the" source of intake air is that a portion of them will be impeded by attic insulation. Another portion might be impeded by framing and blocking. Over the years some may become obstructed by trees and shrubs or nests. Can anyone tell me the last time they "inspected" their soffit vents? ;-) the answer is probably never. So, from an actual "real world" experience versus a hypothetical equation as you have been kind enough to provide in earlier posts, a powervent or attic fan should have intake vents either in the roofing or the gable ends, locations where the penetrations are less apt to be blocked.

CM, I wish you well and I think you are really on the right track and you will be enjoying the fun projects that always come from a new residence. There have been some excellent, experience-based posts here and there is really nothing further I can add.

The world has all sorts. Its got the guys who have a need to nitpick others and its got the guys who like to listen to Buddy Guy. I used to catch Buddy Guy and Magic Slim and some others in 1970's Chicago.

Cheers to All

Edited June 13, 2014 by ClutchClark

[Dellboy218]

Whirlybird type [rotating] roof vents are very efficient and may be installed below ridge-line so not visible from road. Building supplies on HD/CM Rd just south of airport and on the western side had a stack of them outside yesterday.

Have you tried them lately? I had some fitted by them some years ago but now they appear to have so much business from companies that require large numbers they no longer seem to be interested in customers requiring one or two.

Edited June 13, 2014 by Dellboy218

[noendtoit]

The theory sounds good, but heat rises hence trying to create positive pressure inside the roof void is not likely to force the hot air downwards and out through the soffits, dunno, this sounds like one for Herr Naam. But as you say, if it fails then reverting to the status quo is cheap and easy so you're probably right to give it a shot.

Also, am wondering if anyone has tried spray on foam to the underside of the roof, the theory being that it prevents/reduces heat transfer from the CPAC into the roof void. That's another one where the theory sounds good but at 500 baht a square metre it needs to be proven before actually doing it.

I have both turbine vents and PU foam spray under the tiles. The PU foam spray under the tiles is GREAT and, for this climate, far, far better than insulation over the ceiling. If you would like to know more, PM me. I will surely get flamed on this forum for saying PU foam is better that ceiling insulation, so I am finished here.

[chiang mai]

You get no flame from me on that point, I would guess that you've got a winning combination although one probably wont work well without the other.

[chiang mai]

Anyone seen anything like this for sale in Thailand, if so where?

[kaptainrob]

Available in Aus > http://solatube.com.au/roof-ventilation/ - might look at bringing some over.

[Dellboy218]

The theory sounds good, but heat rises hence trying to create positive pressure inside the roof void is not likely to force the hot air downwards and out through the soffits, dunno, this sounds like one for Herr Naam. But as you say, if it fails then reverting to the status quo is cheap and easy so you're probably right to give it a shot.

Also, am wondering if anyone has tried spray on foam to the underside of the roof, the theory being that it prevents/reduces heat transfer from the CPAC into the roof void. That's another one where the theory sounds good but at 500 baht a square metre it needs to be proven before actually doing it.

I have both turbine vents and PU foam spray under the tiles. The PU foam spray under the tiles is GREAT and, for this climate, far, far better than insulation over the ceiling. If you would like to know more, PM me. I will surely get flamed on this forum for saying PU foam is better that ceiling insulation, so I am finished here.

Just as a matter of interest what was the rough cost of the foam? I looked at this about10 years ago and a very nice chap came to the house to give me a quote. I politely declined after picking myself up off the floor. If the price has reduced it may be worth doing.

[Naam]

The theory sounds good, but heat rises hence trying to create positive pressure inside the roof void is not likely to force the hot air downwards and out through the soffits, dunno, this sounds like one for Herr Naam. But as you say, if it fails then reverting to the status quo is cheap and easy so you're probably right to give it a shot.

Also, am wondering if anyone has tried spray on foam to the underside of the roof, the theory being that it prevents/reduces heat transfer from the CPAC into the roof void. That's another one where the theory sounds good but at 500 baht a square metre it needs to be proven before actually doing it.

I have both turbine vents and PU foam spray under the tiles. The PU foam spray under the tiles is GREAT and, for this climate, far, far better than insulation over the ceiling. If you would like to know more, PM me. I will surely get flamed on this forum for saying PU foam is better that ceiling insulation, so I am finished here.

no flame for you, just pity

[Naam]

Clutch

Naam, from your posts it appears you have no actual personal experience with any of this but are hypothesizing based on your many years of schooling. Is this correct? Or do you actually have knowledge that structures in the north have a problem with fans running when they are not required? I have always enjoyed trouble-shooting design and installation issues so if you have specifics I would be glad to help out.

i lived 15 years in Central Florida, built there 2 homes for myself and two homes for friends all techs designed by my [not so] humble self.

my experience is not based on "schooling" (although "schooling" helped a lot) but also on nearly 20 years living and working exclusively in tropical countries. the climate in Central Florida may-sep is nearly identical to most parts of Thailand whereas we quite often experienced temperatures around or below freezing points in january and february (rarely in december).

my last Florida home was heated in winter (during day time only) by "reverse" using attic air and my preference for attic ventilation you will realise when you count the 8 attic exhaust fans of my home looking at this satellite picture.

[chiang mai]

I have both turbine vents and PU foam spray under the tiles. The PU foam spray under the tiles is GREAT and, for this climate, far, far better than insulation over the ceiling. If you would like to know more, PM me. I will surely get flamed on this forum for saying PU foam is better that ceiling insulation, so I am finished here.

The theory sounds good, but heat rises hence trying to create positive pressure inside the roof void is not likely to force the hot air downwards and out through the soffits, dunno, this sounds like one for Herr Naam. But as you say, if it fails then reverting to the status quo is cheap and easy so you're probably right to give it a shot.

Also, am wondering if anyone has tried spray on foam to the underside of the roof, the theory being that it prevents/reduces heat transfer from the CPAC into the roof void. That's another one where the theory sounds good but at 500 baht a square metre it needs to be proven before actually doing it.

Just as a matter of interest what was the rough cost of the foam? I looked at this about10 years ago and a very nice chap came to the house to give me a quote. I politely declined after picking myself up off the floor. If the price has reduced it may be worth doing.

I'm sure that poster will reply, in the meantime, the costs I have seen from two companies recently in northern Thailand are between THB 500 and THB 700 a square metre.

[chiang mai]

Available in Aus > http://solatube.com.au/roof-ventilation/ - might look at bringing some over.

Rob, have you seen anything similar for sale in Thailand, I'm going to start doing some serious looking so if you spot any, please shout.

[songhklasid]

MY house outside of sankhaemphang is brick/ cement render/ tiles, steel roof frame, I got 2 industrial size whirlybirds on the roof, my idea is to install ceiling vents in living /kitchen room ceiling, thus sucking hot air from living areas, as my house in australia is set up, vents are available @ home-pro.

regards S.S.

[chiang mai]

Are you sure that's a good idea, the air inside the house on the lower floors is likely to be the coolest air of any and as your vent removes it, it will be replaced with warmer air from outside? That method also precludes the use of aircon in the living rooms.

[BShifty]

If your looking for low profile ventilation. Check these roof vents.

By putting half the vents low on one side of the roof and the other vents high on the other side, air is drawn thru the roof.

http://www.universaltileventilators.com.au/index.php/products/tile-ventilator

Sent from my iPhone using Thaivisa Connect Thailand mobile app

[chiang mai]

Wow, there's some great products in that catalog, question is are they available in Thailand.

[Naam]

Are you sure that's a good idea, the air inside the house on the lower floors is likely to be the coolest air of any and as your vent removes it, it will be replaced with warmer air from outside? That method also precludes the use of aircon in the living rooms.

[chiang mai]

By way of an update:

I found out that the roof in question is MAGMA and not CPAC, it turns out that MAGMA makes a tile based hot air venting product called MAGMA Flow which when installed in pairs across a roof will provide passive venting, their web site is here, cost is circa THB 1,500 a pair and about five pairs are needed in my case:

http://www.mahaphant.com/en/our-products/product-hahaung-detail-accessories.jsp?prdid=24

An inexpensive solution perhaps before trying more pricey alternatives.

[evenstevens]

u have indicated that your roof is CPAC tiles

the sucessful inexpensive route which i took is as follows

bought cpac cut out tiles for ventilation stacks to be made and fitted

went to a local engineering shop and had small stainless steel ventilation stacks made (they have a little cap that fits on top to stop anything from entering)

they are in no way a ugly sight, in fact fit snugly into the pitch of the roof, those hopeless ugly whirly birds etc etc are for factory bldings etc etc

u are always welcome to drop in,to have a bow peep just p.m

c/mai ,nice to see that u have taken my cue,^^^^^ but just a different model and brand to suit your needs,

as i said in another post on this thread, the KISS rule applys big time here

KEEP IT SIMPLE STUPID

and your plan has accomplished this, a very nice afternoon to all

[chiang mai]

Some interesting trivia:

It seems that the major roof tile suppliers such as CPAC and MAGMA all make a purpose designed vent tile that will allow for passive venting, they all show a similarly designed tile in their catalogs. But if you talk to them and try to buy that product you are told that they don't make it any more, nobody bought any so they stopped offering it and then stopped manufacturing it!

So there was a cheap and effective way to remove the hot air from roof voids but people either didn't know what it was for or thought it was too expensive (700 baht per tile), sad really. And it's amazing how many people still believe that vented soffits are designed to allow hot air to escape, even CPAC told me this was their preferred solution.

So, whilst we might like to try and keep it simple, it looks like we probably can't.

Edited June 27, 2014 by chiang mai