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Spray on heat insulation under roof tiles - good or...


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Would appreciate some comments from members who are knowledgeable about this method of heat insulation and perhaps opinions re comparisons with other forms of insulation to block heat coming down into the upper level rooms of the house.

 

Thanks.

 

 

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Had this process done almost 5 years ago by a firm that does all the big stores, malls and hotels.  It was 75,000 baht all told and provided both heat and noise insulation with 3 cm of applied substance.  Lohr trade stood behind their work as we did experience leaking after the first application.  There are certainly other ways to achieve lower temperatures such as painting the surface of your roof with reflective white paint or using an attic fan. 

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When we built our house we used Rockwool on top of the ceilings, having worked for Rockwool manufacturing the stuff in the UK I know how good it is. It's manufactured in Map ta Phut Rayong. Link in Thai but but you can change countries to get it in English.

 

http://www.rockwool.co.th/home

 

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We had our house done by Lohr a few years ago with heat insulation. They did a very good job and I have no complaints. What I will say is that the temperature 'drop' is certainly only minimal: at a guess, maybe 2-3 degrees Celsius, at most. Painting the roof white would probably be far better and I know there is (was?) a company selling a special paint designed for the roof in Bangkok, albeit a tin of the stuff was quite expensive, as you might imagine. Hope this helps.

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We went with the tin foil space blanket attached to underside of battens. Easy and cheap to purchase and install. Most new builds use same product. Had a dramatic improvement in reducing heat gain in the house, maybe 5°C or more, especially afternoon sun from the west. I would start with that and see if you need any more. We did not.

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You get the best effect for your home by applying the insulation to the ceiling, not to the roof.  Start with 6" of fiberglass insulation minimum and 12" is better.  The top layer should have the foil pointing up toward the roof.

 

Thai houses lack the louvered vents in the space between the ceiling and the roof that you see in the wall close to the peak of the roof in Western houses.  There is usually plenty of ventilation into the space above the ceiling because the bottom edge of the roof isn't tightly sealed to the walls but no way for the hot air to get out.  One of the spinners on the roof will drop your home temperature as much as a couple of degrees if you don't have an insulated ceiling and help some if it is insulated.  Add a white heat reflective roof paint and you would be amazed at how much cooler a typical Thai house can be.

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12 minutes ago, HarrySeaman said:

Start with 6" of fiberglass insulation minimum and 12" is better. 

I disagree, go with Rockwool as it's fireproof as well. One problem with our ceilings being insulated is that it works both ways, if there's no breeze it will trap heat in the house as well.

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If you are going to do it by yourself :

just measure the area of under the roof and then go to Mega Home (better prices and more products) or Home Pro. Buy a roll or rolls of insulation( padding and aluminum). They come in different thickness. I would go with just average thickness. Not too thick, not too thin. Unless you don't mind the price. 

Just lay it flat over gypsum board of ceiling. No space between and don't miss any area. Glue it to gypsum board if needed (not too much of glue). 

Be pationt, do it right, you don't have to finish it in one day. 

I don't like spray foams for ceiling, could become problem later for ceiling lights or in I case if you need to access any wiring on the ceiling. 

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1 hour ago, williamgeorgeallen said:

i hear of it being sprayed under tiles and it lifting the tiles as it expanded causing leaks. i would just go for a good layer of pink bats ontop of the plasterboard. might even be good to put 2 layers.  only costs about 10 000thb per room so should be a cheaper option as well.

I have 350 sqm of roof, of which the majority has waterproof foil under the tiles, and about 25 sqm has been sprayed.

 

Actually it has been sprayed twice already, and it is still leaking, because as you say it lifts the tiles. With a leak it is also impossible to trace the leak, because the water most probably enters at a completely different location as where it exits.

 

I have no leaks on the remaining 325sqm of roof.

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Thanks to all for your comments and suggestions about types of insulation etc. Much appreciated.

 

A different question. The lining under the eaves of the house has, on all four corners, a simple panel with small holes, to let some air out but too small to allow and vermin etc., to get in.

 

I'm not knowledgeable about this matter but I rather doubt that the holes, which are about half a CM in diameter and the total area of each of the 4 panels is only about 15 to 20 CM square let's much air out at all.

 

Apart from a  spinning turban* thing to get some of the hot air out, are there any other products around to allow / to get the hot air out?

 

(*Which got a strong thumbs down from the family when I suggested it might be worth trying.) 

 

Any suggestions much appreciated.

 

Thanks again. 

Edited by scorecard
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27 minutes ago, scorecard said:

Apart from a  spinning turban* thing to get some of the hot air out, are there any other products around to allow / to get the hot air out?

We've got louvres at both ends of the of the house  and with the prevailing wind blowing mostly off the sea about 700m away it ventilates the roof void and removes any moisture that comes from our bathroom ventilation fans which vent into the roof void.. 

Louvres.jpg

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2 hours ago, Foozool said:

If you are going to do it by yourself :

just measure the area of under the roof and then go to Mega Home (better prices and more products) or Home Pro. Buy a roll or rolls of insulation( padding and aluminum). They come in different thickness. I would go with just average thickness. Not too thick, not too thin. Unless you don't mind the price. 

Just lay it flat over gypsum board of ceiling. No space between and don't miss any area. Glue it to gypsum board if needed (not too much of glue). 

Be pationt, do it right, you don't have to finish it in one day. 

I don't like spray foams for ceiling, could become problem later for ceiling lights or in I case if you need to access any wiring on the ceiling. 

this is the right way to do it.

The air under the roof is heated up , if no circulation (because you spray something under the tiles) is goes up to 60 cel !

This hot air will heat up your plasterboard-ceiling......and this is the reason your room is so hot.

So any insulation has to be done on top of your ceiling ,not under the roof.

If you choose spraying foam (expensive ) in your ceiling ,it must be at least 20 cm thick ! Not 3 cm as in cold Europe.

The insulation can only keep the heat out a certain amount of time.(R-value) So the longer you need protection ...the thicker (or denser)the insulation needs to be . In Thailand it could mean 24 h in april !!!

Spinners in the roof are helping ,choose the best quality and check the work or you will have leaks. 

 Reflective foil, if installed correctly.....read this good.... and" facing an open air space"..thus not directly under the roof tiles facing the tiles!!!!!!!, can also act as a radiant barrier

All the rest is ............

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13 minutes ago, lucjoker said:

this is the right way to do it.

The air under the roof is heated up , if no circulation (because you spray something under the tiles) is goes up to 60 cel !

This hot air will heat up your plasterboard-ceiling......and this is the reason your room is so hot.

So any insulation has to be done on top of your ceiling ,not under the roof.

If you choose spraying foam (expensive ) in your ceiling ,it must be at least 20 cm thick ! Not 3 cm as in cold Europe.

The insulation can only keep the heat out a certain amount of time.(R-value) So the longer you need protection ...the thicker (or denser)the insulation needs to be . In Thailand it could mean 24 h in april !!!

Spinners in the roof are helping ,choose the best quality and check the work or you will have leaks. 

 Reflective foil, if installed correctly.....read this good.... and" facing an open air space"..thus not directly under the roof tiles facing the tiles!!!!!!!, can also act as a radiant barrier

All the rest is ............

 

Good to know, can you please clarify what you mean by 'spinners'. Thanks.

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3 hours ago, sandrabbit said:

I disagree, go with Rockwool as it's fireproof as well. One problem with our ceilings being insulated is that it works both ways, if there's no breeze it will trap heat in the house as well.

There is no real difference between fibreglass and Rockwool, they are both fireproof. They both work from the air trapped inside the voids of the blanket, so the thickness of the blanket determines how effective the insulation will be.

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2 hours ago, sandrabbit said:

We've got louvres at both ends of the of the house  and with the prevailing wind blowing mostly off the sea about 700m away it ventilates the roof void and removes any moisture that comes from our bathroom ventilation fans which vent into the roof void.. 

Louvres.jpg

I agree this is the right way to do it if possible. Some Thai builders understand the desirability of roof space ventilation, others do not.

I am a bit wary of spinners because (a) they won't work if the rest of the roof space is sealed ( b ) I'm not sure they can withstand monsoon rain.

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8 minutes ago, bazza73 said:

There is no real difference between fibreglass and Rockwool, they are both fireproof. They both work from the air trapped inside the voids of the blanket, so the thickness of the blanket determines how effective the insulation will be.

Sorry wrong, I used to work on maintenance manufacturing Rockwool in the UK. Fibreglass is not fireproof, if I remember correctly Rockwool slab is certified to withstand 800degC for 30 minutes and is an insurance requirement now in UK supermarket roofs as a few Sainsburies went up in flames after fires starting and spreading through the roof void. It even has better insulation properties than fibreglass and is not affected by moisture, I can tell you that's true from lying in line offcuts in the rain outside when a conveyor broke down. It is expensive and that's because it really is stone spun like candyfloss.

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For the money involved in under roof spray on insulation, there's a load of other measures you could take which are equally as effective and have a better pay back. Gable and soffit vents would be my number one, you have to do them together as a pair and they have to sized correctly else they don't work - if you've already got gable vents, get bigger ones!

 

A gable end extractor fan on a therm. switch is my number two, figure 1,500 for the fan and 500 for the switch.

 

Foil encased attic floor insulation is number three, done in combination with a retro fitted radiant barrier they'll improve things enormously. We put down 12 inches of the stuff on the attic floor and it does keep the hot air out of the living space. Retro fitting the radiant barrier can be easy or hard, based on the pitch of your roof, ours is very steep with an eighteen foot drop from ridge to attic floor but we managed it, just.

 

Reflective window screen also works well, most places that instal it on cars also will instal at your home.

 

BTW the rules for this sort of thing are reflect, deflect then insulate, in that order.

 

 

 

 

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16 minutes ago, sandrabbit said:

Sorry wrong, I used to work on maintenance manufacturing Rockwool in the UK. Fibreglass is not fireproof, if I remember correctly Rockwool slab is certified to withstand 800degC for 30 minutes and is an insurance requirement now in UK supermarket roofs as a few Sainsburies went up in flames after fires starting and spreading through the roof void. It even has better insulation properties than fibreglass and is not affected by moisture, I can tell you that's true from lying in line offcuts in the rain outside when a conveyor broke down. It is expensive and that's because it really is stone spun like candyfloss.

Be careful who you call wrong. I was the Chief Chemist of ACI Fibreglass in Australia for 4 years.. Rockwool was the competition, produced by CSR. Did a lot of comparison testing.

As you say, Rockwool is stone spun like candyfloss. Fibreglass is melted glass spun like candyfloss. More energy required to produce Rockwool. Fibreglass has a melting point of about 1250 C.

Fibreglass is bonded with phenolic resin. The amount used to achieve bonding is so small that fibreglass gets the same fire rating as Rockwool. In Australia, that is.

Our testing showed for equivalent thicknesses of Rockwool and fibreglass produced at equivalent bulk densities, there was no difference in insulation properties. From memory, Rockwool fibres were considered to be more hazardous for installers because they did not dissolve in body fluids like fibreglass fibres did. That's probably academic now with aluminium foil encapsulation.

 

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9 minutes ago, bazza73 said:

From memory, Rockwool fibres were considered to be more hazardous for installers because they did not dissolve in body fluids like fibreglass fibres did.

We were told, and it was approved by the unions, that Rockwool did dissolve and it came out in urine. What did change in the 90's was a couple of minerals were substituted as the EU considered them to be possibly carcinogenic  which would have required the packaging to be labeled accordingly. Rockwool before it is cured in an oven could cause skin irritation due to the binder fluid but even the finished product used to make me itch, it took 4 years of working there before I stopped itching.

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5 minutes ago, sandrabbit said:

We were told, and it was approved by the unions, that Rockwool did dissolve and it came out in urine. What did change in the 90's was a couple of minerals were substituted as the EU considered them to be possibly carcinogenic  which would have required the packaging to be labeled accordingly. Rockwool before it is cured in an oven could cause skin irritation due to the binder fluid but even the finished product used to make me itch, it took 4 years of working there before I stopped itching.

I can remember the itching with fibreglass too. Took about two weeks to get it out of my system after an exposure.

 

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A Wodan Tile roof   does not absorb heat like clay tiles  or tin 

it looses its heat very quickley  not like concrete or stone that keeps the heat and is stifeling

 

We have a teak wood house with a big Thai up roof with ventilation louvers like mentioned before    no concrete except the base of the house  we have wood shutters instead of glass with bug screens   all let the air in

have an airco but dont use    when sun is down cool  during the day just a   fan  

Teakwood house fantastic

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Agreed, concrete roof tiles are the worst thing possible for heat storage, I read that steel  roofs painted white  are the best because they reflect heat and stored heat dissipates quickly, needs some insulation on the underside though.

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Sealing the underside of roof times is a really bad idea.  Your attic space needs to breath - that's what keeps moisture from building up inside the house.  If you wish additional insulation in your Thai-built home, fiberglass insulation between the ceiling joists.  Do NOT seal under the tiles - the moisture problems you will encounter will be horrendous.

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ive had 2 houses spray with that foam bad idea, its expensive and when they quote you they tell you they put on something like 50mm or more all over,

before i payed the balance owing i went up and put a knife in many areas all over the roof it was about 25mm also when i had a leak in my roof could not find the leak and was very had to remove tiles.

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1 hour ago, bazza73 said:

I can remember the itching with fibreglass too. Took about two weeks to get it out of my system after an exposure.

 

And how long afterwards were you breathing fiberglass particles in your house?  Still?

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3 minutes ago, Dante99 said:

And how long afterwards were you breathing fiberglass particles in your house?  Still?

It's in the roof, with a ceiling separating it from the internal space.

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Moved into a house near Pattaya better part of 20 yrs ago. 10 - 11 am in summer, house got too hot, had to go out & sit under the mango tree. Had some experience with insulation in the Australian desert. Landlord (friend) agreed to take off the roofing, I bought enough reflective for 2 layers double sided. He had a roofing gang come and do the work. 

We put the 2 layers in, lower one loose, upper one tight, to create an air gap between. As continuous as possible (tape joins the adjacent layers). Roofing back on. 

 

After this, under the mango tree was too hot - had to go inside! Veeery effective - (I knew it would be)

Fitted an air con at the same time, - only turned it on once, to check it was working.

Best bang for the buck for insulation in the tropics is reflective. You don't need to insulate against cold here, (bulk insulation), just put a sweater on. The reflective also helps to keep the house warm in winter by stopping house heat from radiating off to space. You just control temps by opening the windows etc in summer, closing in winter, as necessary.

 

But you should use it in the eaves as well.

 

Chok dee.

 

P.S. to test; get a small piece, say 1 m sq, put it on top of the roof at sunup, & hold it with bricks. Test the ceiling temp below near midday, vs ceiling w no insulation.

Edited by Stuart21
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