Ceiling/roof insulation "stay cool"

[Lacessit]

1 hour ago, Naam said:

reading thaivisa threads on airons, insulation and related topics for nearly 15 years is still a neck hair raising experience for a physicist. 

Funny, I get the same feeling when I read engineers trying to explain chemistry.

[Mavideol]

14 hours ago, CharlieH said:

Ok, thanks to those that have contributed so far.

 

Here is the story to date: I was looking for something to assist in cooling the house due to the excessive heat in latter months, more so than previous years, or so it felt. Anyway, I did some research and decided to try this insulation. As a test I did the main bedroom first at 6m x 4m. This room is generally closed up during the day and if entered mid/late afternoon was really hot and uncomfortable, it needed the Air-con opening almost immediately if staying in there for more than a  few minutes.

So, in Homepro I see the above item @425 per roll and bought enough for that room. The result was quite dramatic and saw an immediate drop in temperature during the day of some 4 degrees, and less use of air-con as it achieved set temp quicker and seemed to stay cooler longer.

Having a pleasing result, I then went to Thaiwatsadu who had the same product on sale @ 419 per roll. I then purchased enough to cover the rest of the home. It was easy to lay although really hot up there. It took around 3 hrs to complete the job and total cost for the home around 10k. So far so good.

 

I will now monitor the specific room temp differences / air-con use etc in the coming week and report back on the overall effect this has had for the benefit of those considering a similar project.

glad to know it worked out, does it also buffer rain noise on a metal roofing, kids school have metal roof (cheap stuff) when it rains the noise is so loud that one can not speak to another without raising the voice, which imagine it's not a good environment for teaches neither, was thinking about proposing such type of insulation to reduce the noise levels, would it work?

[poka513]

My Thai step-son (house building/remodel business) and a few of his mates installed insulation in the attic of our Chiang Mai 2 story townhouse in April. Took them 1-2 hours and the material was around 4k Baht (forget exactly). Although, upstairs still gets hot during daytime, seems to have helped. My son said should help reduce heat by 20 percent.

[connda]

CharlieH,  We're currently doing an upgrade on our ceiling which includes adding this type of batting to the interior of the roof.  Does it work?

We did our guest house in April in the middle of the Hot Season in Lamphun.  The internal ceiling temperature was averaging over 45C at mid-day with the aircon running full-blast.
After the addition?  The internal ceiling temperature dropped to about 30C or within 2 degrees of the aircon temperature setting.

Yeah baby! It works.  FYI, the guest house is a recent addition built just before the hot season.  We added a vent window at one end of the roof and an exhaust fan at the other.  I had high hopes - it didn't work worth squat.  We don't use it.

Here's the batting we used which I got a Du-Home.  For the price it was one of the higher insulation coefficients for the price per roll.  This is R-19.  

I do recommend it - insulating that is.  However - with a safety warning.  As part of the ceiling renovation and for safety we completely rewired the house.  Added addition switches/breaker boxes to balance the load between the most heavily used appliances, and to just basically ensure there aren't any overloaded circuits.  So we added spare capacity - plus - we installed new wire encased in plastic conduit to prevent shorts and arcing.   Actually we're still working on it with the guest house finished and about 1/2 of the house completed.  

But absolutely - you'll see an immediate difference.  

[jkcjag]

20 hours ago, Sheryl said:

There is a lot of debate about these things - a lot depends on whether the interior is air conditioned all the time or not. If it, is this will help retain the coolness. But if not, while it may decrease heat transfer down from the ceiling it will also prevent heat from rising up and out which of course is what the heat needs to do.

 

A radiant barrier (tinfoil between the roof and the interior of the ceiling space )is far better IMO as it will prevent heat transfer into the ceiling space. While ideally put in when the house is built, it is possible to retrofit by attaching it to the underside of the roof beams (normally one would have it between the cross cross beams; there has to be a space between the barrier and the roof tiles).

 

Also very important is having adequate cross ventilation in the ceiling space.

 

I did this (retrofitted radiant barrier and increased windows to ventilate the ceiling) a few years ago and it has made a huge difference.

 

they sell the radiant barrier in same area as they sell this fiberglass insulation stuff.

I think a "radiant" barrier is just that. It does little to stop heat conduction...it's too thin...most of any reduction in heat penetration through the ceiling would have ben because of the ventilation of the roof void. I noticed in HomePro once they set up a test for the radiant barrier, with an infrared light. Of course it will reflect the light and the temperature on the other side of the barrier would be cooler, but there is no radiation under the tiles in a roof, unless the tiles are transparent. Most of the heat penetrating the ceiling under a roof void is via conduction from the air temperature in the roof void. The rays from the sun do not get that far..

[sandrabbit]

1 hour ago, chilly07 said:

Always check the fire resistance of any insulation! We had a neighbours house burn out when the insulation caught fire. Failing all else put a lighter to it!

which is why I have rockwool in our ceiling void, it is made from spun melted stone. it's manufactured in Rayong but it is more expensive than fiberglass.

 

 https://www.rockwool.com/learning/fire-safety/

 

[Lacessit]

20 minutes ago, sandrabbit said:

which is why I have rockwool in our ceiling void, it is made from spun melted stone. it's manufactured in Rayong but it is more expensive than fiberglass.

 

 https://www.rockwool.com/learning/fire-safety/

 

There is no significant difference between rockwool and fiberglass, in terms of fire risk. The ones to watch out for are the foamed polymers such as polystyrene and polyurethane, or blown paper fluff insulation.

Paper fluff usually has boric acid added as a fire retardant. However, over a period of years the boric acid is lost, and one ends up with a ceiling full of flammable paper.

Putting a blowtorch to rockwool and fiberglass proves nothing except rockwool has a higher melting point. There is no difference in flammability. Usually, the wool from both types is bound with a minimal quantity of phenol-formaldehyde or urea formaldehyde polymer, which may give the impression of burning. There is not enough to sustain a fire.

[rodpav]

Was going to do this but not good idea in humid climates  it can trap heat in the house, best thing to do is to have the hot air in the roof space extracted get those electronic wringing things theres one on the market that's solar powered and it says it's as good as having 15 wirlygigs installed a company in Uzbek has this product and costs 30 k bhat just cant remember the name of the product

[Kwasaki]

Good for an air-con room cuts outside noise too. 

[bankruatsteve]

3 hours ago, Laza 45 said:

Interesting.. I have foil/foam insulation attached to aluminium roofing.. above ceiling similar ..reflective foil and foam backing.. from what you are saying it wouldn't make much difference if I were to put  insulation batts above the ceiling insulation.. I have been thinking of doing this as I want to put air con in the room.. 

It's not clear to me what you have now and what you might be planning.  If you currently have a reflective radiant barrier under your roof then additional insulation above the ceiling is, IMO, superfluous. 

[connda]

16 hours ago, Thainesss said:

 

 

Spending 20-30k to put insulation in your roof is beneficial even if you don’t use aircon, and even more beneficial if you do. 

 

 

We also live in the mountains of Lamphun province.  And we have had some brutally cold years.  I have space heaters but without insulation you're just warning a place close to you.  With the entire roof insulated I should be able to get the bedrooms and living room (or kitchen depending where we're hanging out) rather toasty after the remodel.  So the insulation make a radiant barrier during the hotter seasons to keep hot air out and a radiant barrier to keep hot air in during the cold season.  We still don't use a fraction of the electricity I used in the USA.  In the US - central air, water heaters that crank out heat whether you use them or not, heat or cool entire 2000 SqFt homes where you use only 10% of the space.  Insulated modular design is the way to go. 

[Thainesss]

13 minutes ago, bankruatsteve said:

It's not clear to me what you have now and what you might be planning.  If you currently have a reflective radiant barrier under your roof then additional insulation above the ceiling is, IMO, superfluous. 

 

Disagree, but the only way to know for sure is to put a temp probe up there and see how hot it gets over a few days. I’d wager it’s still approximately hote-as-balls. 

[sometimewoodworker]

2 hours ago, Lacessit said:

That expanding poly foam chemical is a potential death trap. If there is a short in any of the wiring running through the ceiling, it's a major fire hazard. 

As long as you don't try to cheep out you are wrong. The PU foam is self extinguishing due to the fire retardants incorporated. The wiring should not be attached to the roof but on the walls or ceiling so will net be encapsulated by the PU foam.

 

I have some pieces of the foam and it's impossible to get them to burn without a constant flame on them, even the thinnest, and even then they don't burn at all well.

[Thainesss]

11 minutes ago, connda said:

We also live in the mountains of Lamphun province.  And we have had some brutally cold years.  I have space heaters but without insulation you're just warning a place close to you.  With the entire roof insulated I should be able to get the bedrooms and living room (or kitchen depending where we're hanging out) rather toasty after the remodel.  So the insulation make a radiant barrier during the hotter seasons to keep hot air out and a radiant barrier to keep hot air in during the cold season.  We still don't use a fraction of the electricity I used in the USA.  In the US - central air, water heaters that crank out heat whether you use them or not, heat or cool entire 2000 SqFt homes where you use only 10% of the space.  Insulated modular design is the way to go. 

 

Honestly it was cheaper for me to keep an entire house (2016 building codes) cool in Florida with central air in the summer than it is to keep 3 rooms in my Thai home cool (about half the operational time too) in the summer. Which says ALOT about modern building codes, insulation, and proper windows & doors in the west. 

 

Most Thai homes are sweat boxes built with zero thought going into not being sweat boxes. 

[Old Croc]

I am a little bemused by posters who say this type of insulation acts as a barrier to stop hot air escaping from the house.

No doubt they are right, but the major source of heat inside the house comes from above - the sun. This barrier prevents the very hot air in the roof space from radiating through the ceiling and heating up the house.  Heat entering this way is vastly greater than any heat generated inside, so the net result is a cooler house. 

[bankruatsteve]

11 minutes ago, Thainesss said:

 

Disagree, but the only way to know for sure is to put a temp probe up there and see how hot it gets over a few days. I’d wager it’s still approximately hote-as-balls. 

I'd wager that it's not much off ambient and no where close to balls.  (?)  In my case, the roof didn't have a barrier installed at construction and the gypsum ceiling would radiate heat.  After putting in 2" reflective bats, the ceiling felt nothing and I could give a crap how hot the attic gets.

[royalmice]

My problem is the wiring that is laying on-top of the ceiling and also the ceiling has all these aluminium wires hanging from the roof beams, looks like it is for ceiling support . 

The wires are for the lights, ceiling fans, these are in the centre of the rooms below the ceiling the other wires for plugs and light switches also criss cross around the ceiling.

 

Do you just lay this insulation on-top of the wires or how do u handle it.

 

If anyone have a before and after picture of their roof interior that would be great.

 

I have around 154 SQM of ceiling to cover.

 

[CGW]

54 minutes ago, bankruatsteve said:

It's not clear to me what you have now and what you might be planning.  If you currently have a reflective radiant barrier under your roof then additional insulation above the ceiling is, IMO, superfluous. 

Not if you run AC!

[bankruatsteve]

14 minutes ago, CGW said:

Not if you run AC!

OK I'll bite.  Are you saying extra insulation keeps the AC cold air from escaping through the ceiling?  Interesting.  And guessing difficult to corroborate.

[natway09]

Make sure the insulation (whatever the kind) is at least 40 KG M3

I have worked in the thermal & acoustic insulation business for 35 years

[CGW]

12 minutes ago, bankruatsteve said:

OK I'll bite.  Are you saying extra insulation keeps the AC cold air from escaping through the ceiling?  Interesting.  And guessing difficult to corroborate.

OK I'll bite, are you stating it doesn't?

[bankruatsteve]

41 minutes ago, royalmice said:

My problem is the wiring that is laying on-top of the ceiling and also the ceiling has all these aluminium wires hanging from the roof beams, looks like it is for ceiling support . 

The wires are for the lights, ceiling fans, these are in the centre of the rooms below the ceiling the other wires for plugs and light switches also criss cross around the ceiling.

 

Do you just lay this insulation on-top of the wires or how do u handle it.

Ideally the wires are inside conduit, in which case just lay the bats over.

 

If they are at least in PVC I would worry more about mice than reflective bats.  I think AU codes don't allow although I'm not sure what the potential hazard would be.

 

[bankruatsteve]

2 minutes ago, CGW said:

OK I'll bite, are you stating it doesn't?

Yup.

[spidermike007]

One question about attic fans for all of you experts. I see mixd reviews about attic fans. For a home here in Thailand, what makes the most sense? I am planning on 2" insulation above the ceiling. I am also told exhaust fans are beneficial to get rid of the hot air. Is this the case? If so, how many fans are needed, for a home of about 1800sf, or 180 meters of floor space? 

 

Are there humidity issues with exhaust fans, to take into account? Also, I hear they end up sucking alot of the cool air from below, within the air conditioned home, unless the ceiling is well sealed, which I doubt it is. 

[CGW]

19 minutes ago, bankruatsteve said:

Yup.

Nonsense! guess you believe insulated walls are not thermal barriers either!

[bankruatsteve]

6 minutes ago, spidermike007 said:

One question about attic fans for all of you experts. I see mixd reviews about attic fans. For a home here in Thailand, what makes the most sense? I am planning on 2" insulation above the ceiling. I am also told exhaust fans are beneficial to get rid of the hot air. Is this the case? If so, how many fans are needed, for a home of about 1800sf, or 180 meters of floor space? 

 

Are there humidity issues with exhaust fans, to take into account? Also, I hear they end up sucking alot of the cool air from below, within the air conditioned home, unless the ceiling is well sealed, which I doubt it is. 

My not so popular opinion is that attic fans are not cost effective in this climate.  Especially if there is thermal retardants to keep the heat from going into the rooms below.  Then, why care how hot the attic gets?  The other thing is, I don't get why it is "better" to replace 50C heat with 40C. via extract fan  Ventilation is important and, as you observe, most homes are not sealed.

[Chazar]

On 6/30/2019 at 4:22 PM, Andrew Dwyer said:

I don’t, but I’m interested in it .

What’s the ideal thickness ( the thicker the better I suppose ? ) .

Waste of  money over 2 -4 inches, diminishing returns

 

On 6/30/2019 at 4:32 PM, bankruatsteve said:

In cold places thicker is better because it reduces heat conduction (out).  Here the radiant heat reflection is what we want.  Once the heat is reflected, there's not much left to conduct (through the ceiling) so thickness becomes insignificant.  But, for those thicker-is-better folks - go for it.

 

[The Theory]

16 minutes ago, spidermike007 said:

they end up sucking alot of the cool air from below, within the air conditioned home, unless the ceiling is well sealed, which I doubt it is. 

It’s true, if there are light holes through ceiling. 

Exhaust fans are great if your house lighting system is different. 

You better not using exhaust fans unless you cover and seal the top of light fixtures by buckets and replace  bulbs with LED bulbs (to reduce heat). It might become a complicated process. 

[Chazar]

1 hour ago, royalmice said:

My problem is the wiring that is laying on-top of the ceiling and also the ceiling has all these aluminium wires hanging from the roof beams, looks like it is for ceiling support . 

The wires are for the lights, ceiling fans, these are in the centre of the rooms below the ceiling the other wires for plugs and light switches also criss cross around the ceiling.

 

Do you just lay this insulation on-top of the wires or how do u handle it.

 

If anyone have a before and after picture of their roof interior that would be great.

 

I have around 154 SQM of ceiling to cover.

 

your  wish, do everything myself, no problems EVER.

Anyone who thinks insulation does nothing is  nuts, this  building 50m2 double  block wall with air gap between walls, roof insulated with two inch maybe 4  inch thick cant remember now one 9000 btu keeps it  cool even in 40+c  heat, bills with it on permanently 1000bht cool season 1600 hot  season, set at 26c forever ie 24/7 windows doors  sealed air  tight.

[CharlieH]

1 minute ago, Chazar said:

your  wish, do everything myself, no problems EVER.

Anyone who thinks insulation does nothing is  nuts, this  building 50m2 double  block wall with air gap between walls, roof insulated with two inch maybe 4  inch thick cant remember now one 9000 btu keeps it  cool even in 40+c  heat, bills with it on permanently 1000bht cool season 1600 hot  season, set at 26c forever ie 24/7 windows doors  sealed air  tight.

Nice Job !! But the last image, it would seem the insulation you used is 4 inch (100mm) so your comment above regarding "over 2 inches" is off. (just saying ).????