Blocks Versus Superblocks

[Negita43]

I've read quite a bit about how superblocks are better for building a cooler house BUT I have a question - On average they are 4 times the price of 'ordinary' cinder blocks and I wonder this:

In my country (UK) they reckon that in any uninsulated house the majoritory of heat LOST is through the roof (80%). Well applying that in reverse does it mean in THAILAND the majority of the heat ENTERING the house is through the roof? If so doesn't it make more sense to insulate the roof than to spend a lot of money on making the walls 'cooler'

Just wondering - anybody have any thoughts?

[Morakot]

I say it's not so much a question of providing Thermal insulation for your roof or ceiling but installing reflective foil underneath the roof and providing adequate ventilation of your roof space.

[sezze]

It all depends what you want and what you got .

If you do have aircon , insulate as much as possible . The roof is not the only loss there because hot air rises ( that is why in cold countries , this is the biggest loss ... heating goes away through the roof ) . A reflective screen in a hot country allready helps quite a lot for keeping the heat out , and that is also different then in a cold climate .

If you do have a wall which does have sun on it quite a lot of the day , the sun will heat those walls up and radiate in inside your home . The solution is or a double wall ( best ) or those superblocks or q-con blocks .

In case your house is non airconditioned or has no walls which are facing the sun . Then is does not matter a lot . Then it is the point of keeping the heat out of the attick . Best solution here is a reflective screen under the roof and venting the area as much as possible . When putting in glassfibre insulation , it is best to put it on top of your ceiling . This is to prevent the heat of the attick entering the room and/or preventing cold loss through the ceiling ( if ac is applied ) .

[Negita43]

Thanks seeze

My idea is to put refective foam directly under the roof with vents (maybe powered extractors) in the roof space. I think I will build single skin 7mm basic blocks for walls are shaded and/or don't face the sun and use superblock for the walls that face the sun. I don't think I will use fibreglass above the ceiling as this will prevent the hot air rising into the attic to be axtracted ( I don't think Thais worry about putting in vapour barriers between ceiling and attic like they do in the UK so I assume the hot air from the house will dissapate through the ceilings (maybe I should put some ceiling vents in to help this)?

Mike

[Naam]

I think I will build single skin 7mm basic blocks

7mm?

[sezze]

Thanks seeze

My idea is to put refective foam directly under the roof with vents (maybe powered extractors) in the roof space. I think I will build single skin 7mm basic blocks for walls are shaded and/or don't face the sun and use superblock for the walls that face the sun. I don't think I will use fibreglass above the ceiling as this will prevent the hot air rising into the attic to be axtracted ( I don't think Thais worry about putting in vapour barriers between ceiling and attic like they do in the UK so I assume the hot air from the house will dissapate through the ceilings (maybe I should put some ceiling vents in to help this)?

Mike

As long as the roofspace is ventilated enough , then you would not need extra ceiling fans in the ceiling . If you do have aircon , i would suggest to put fibreglass on top of the ceiling since you will loose your cold there . Outside is warmer then inside with aircon , and you will cool your attick with the aircon . No aircon , indeed forget about the fibreglass , no point at all .

[extexthai]

Heat rises and the coolness of AC falls. Open your refrigerator and you will feel it on your toes before anywhere else. You will not be cooling your attic, ever. It sure doesn't hurt to insulate it, however.

I used both ACC block with a dead air space and then the red bricks brought out flush so we wouldn't have those confounded column offsets along the inside of the wall. The interior of the west wall stays as cool as it is in the morning as it does at 17:00. I wired two rooms for AC and have yet to install it. Having said that, our house is orientated north to south to take advantage of the monsoonal air flow...something to think about. Do not go with a hip roof...it turns you attic into an oven...as does using a dark colored roof. Go with gables and vent the gables at the top and use that vented soffit material all around the overhang. Where are you building your house? ett

[sezze]

Heat rises and the coolness of AC falls. Open your refrigerator and you will feel it on your toes before anywhere else. You will not be cooling your attic, ever. It sure doesn't hurt to insulate it, however.

I used both ACC block with a dead air space and then the red bricks brought out flush so we wouldn't have those confounded column offsets along the inside of the wall. The interior of the west wall stays as cool as it is in the morning as it does at 17:00. I wired two rooms for AC and have yet to install it. Having said that, our house is orientated north to south to take advantage of the monsoonal air flow...something to think about. Do not go with a hip roof...it turns you attic into an oven...as does using a dark colored roof. Go with gables and vent the gables at the top and use that vented soffit material all around the overhang. Where are you building your house? ett

You are right , cool air goes down ... hot air rises . I told that also . Now , you are saying that you are not cooling your attick i do agree on certain terms . non isolating your ceiling will certainly increase your elec bill when using aircon . That is a fact . if your room is let's say 25°c and your attick is 40°c , you will loose you cold air in your room , and your aircon needs to work harder . Since the whole room is cooler then the surrounding area , the heat will transfer down and the cold will move up also . Otherwise , why not put a aircon in a open shed ... no roof . optimal venting , and the cold will stay inside because it is colder then the surrounding space . It doesn't work like that . The differences are minimal and any aircirculation will move the cold air again the hot air . This makes the hot air colder ( aka cooling your attick ) and the cold air warmer . basic heat exchange ( hot too cold ) .

[Naam]

Thanks seeze

My idea is to put refective foam directly under the roof with vents (maybe powered extractors) in the roof space. I think I will build single skin 7mm basic blocks for walls are shaded and/or don't face the sun and use superblock for the walls that face the sun. I don't think I will use fibreglass above the ceiling as this will prevent the hot air rising into the attic to be axtracted ( I don't think Thais worry about putting in vapour barriers between ceiling and attic like they do in the UK so I assume the hot air from the house will dissapate through the ceilings (maybe I should put some ceiling vents in to help this)?

Mike

thermo physics and living experience in a tropical country are things you seem to lack. no offence meant, but whatever you wrote is

[oxymoron]

Having built using the Thai 400x200x60 blocks 20 years ago I can tell you from experience "do not do it" our walls constantly get cracks through the first web, the centre cavity of the block is cement filled. All external walls are double block with 60mm cavity,internal walls single block, thermally the house is good visually the patched cracks are annoying. There is a reason Thai's go for the small "cooked bricks" but being a "cheap charley" I ignored their advice and have been sorry ever since. (no superblocks in my day)

The Thai blocks are not the same as Ozzie or European "Besser" blocks, they have very little cement and no structural load bearing strength.

That is why you need a concrete "ring beam" at the top of the wall to support the roof structure and similarly at all window and door openings.

The auto-claved Superblock looks good but in Australia our biggest builder lost about $10,000,000 dollars on them in warranty claims as no one could successfully render them. The float and set just kept falling off after one or two years.

Naam's the man on the subject of rendering "superblocks" he has a beautiful house done in them, and I bet he would not put up with poor quality render.

[Negita43]

extexthai and sezze thanks a lot for your help. I am building in Korat and the house faces nearly east to west (unavoidable due to land constraints) BUT the design is U shaped and the major walls are also aligned that way so direct sun goes only onto a very limited amount of wall. Any suggestions as to the best make of material to use in the roof to stop the heat entering?

Thanks again for the serious and helpful replies

[Morakot]

Another very important factor are your windows. Will you have adequate roof overhang, combined with glass coating etc. ?

[sezze]

extexthai and sezze thanks a lot for your help. I am building in Korat and the house faces nearly east to west (unavoidable due to land constraints) BUT the design is U shaped and the major walls are also aligned that way so direct sun goes only onto a very limited amount of wall. Any suggestions as to the best make of material to use in the roof to stop the heat entering?

Thanks again for the serious and helpful replies

Do you have large overhangs ? What material is the roof made of ? Do you have gables or not ? all important things to consider .

Large overhangs are a very good way to keep the sun out of your walls . only early morning and late evening the sun shines on , and the walls will not heat up . Side advantages are the venting options you have underneath the overhang . Like many people stated before , you cannot have enough venting .

Material of the roof . Cement and clay are a loved option by Thais and farangs , but this is mainly due to the fact that they are more expensive , and so give a house a more luxury look ( gives face ) and for the farangs because it is a material they well know . In fact in a hot country it is not a good material at all . Let me explain . It is a very heat absorbing material . This means that it heats up during the day and will give of it's heat all night ( far beyond the sun has gone down ) . A better material here is steel sheets ( like colorbond and others ) . It heats up also , but as soon as the sun is out , it cools down rapidly .

The gables . If you do have them , it is very easy to vent as there are louvre style venting board available everywhere , made for this purpose in every size you want . If you do have gables ... use them . If not , find out other ways to vent the attick .

Now on the insulation .

The best is glassfoam underneath the roof and underneath that a reflective foil . Do not underestimate the reflective foil for heat purpose insulation . There have been many test which you will find that it does not work and many people will tell you also . However these are test for cold climate keeping the heat inside and the cold out . Also the people who say it doesn't work also come from cold countries where they are 100% right . But also for the cold countries they do have the foils as a reflective material to put behind the radiator , bouncing the heat inside the room . Also the reflective foil blanket which ambulances use are for this purpose . And if you look at people who go close to vulcanoes or work in iron furnaces all have suits made out of reflective material . It does work bouncing the heat away ( or not radiating in inside ) . Glass foam works different , it does let heat pass very very slowly . The thicker the layer , the longer it takes . Downside is that the material itself heat up so it releases it slowly .

The primary naterial to look at is the reflective foil , so if you have to choose , put in the reflective material and if you want full option , put the glass foam insulation in also . For aircon , like stated before , it is a question on retaing your cold air inside , as much as possible and as close to where you want it cool as possible . If you have a airconned bedroom , put glassfoam insulation on top of the ceiling and reflective foil under the roof .

The are different types of insulation , but these are the 2 most used . Another thing is the spray on type . It is not cheap , but can be done when and where you want . I heard extremely good results and people who are not happy with it . The main reason of people not happy with it is when they have a leak somewhere and the companies promise that this will solve the leak . This has very mixed results , but as part of the insulating properties , it is extremely good .

[Negita43]

Thanks again sezze My over hangs will be 1 meter and one side of the U is completely shaded by my neighbours trees - good for keeping cool but bad for leaves on the roof (and guttering) - but you cant win them all! I will have 4 gables and plan to vent on each one. The roof I expect will be elephant brand composite material (I say composite but i'm not sure if its not just plain old and dangerous asbestos)- have to say I am not keen on metal because of the noise when it rains! Today I was in Global House and they have on offer a woven aluminium foil price at 990 baht for a 60 meter by 1.2 meter roll - its' called cold guard and it describes itself as double sided foil woven cloth - any knowledge of this product?

Mike

[Negita43]

Thanks Moracot - yes you cant get double glazing out here so I thought I would try to get a car window film company to come and put some film on you have any other ideas?

[Morakot]

Thanks Moracot - yes you cant get double glazing out here so I thought I would try to get a car window film company to come and put some film on you have any other ideas?

Alternatively just buy the ones which already have coating rather than adding some film later.

[TS79]

Thanks Moracot - yes you cant get double glazing out here so I thought I would try to get a car window film company to come and put some film on you have any other ideas?

There are plenty of double glazing firms in Thailand who will travel to install. I had a firm in BKK install ours in the South.

[Negita43]

Thanks ts79 any chance of a phone number for the company

Tks

Mike

[ilyushin]

Click Thaivisa thread on the topic. Interesting SmartBlocks too! Two weeks ago I recall a thread about insulation and roofing. Good posts. Very good details.