Ceiling Insulation (foil type)

[4MyEgo]

Hi Guys

 

Its now time that I put ceiling insulation in, already have thermal reflective insulation under the tiles, and am now considering putting insulation above the suspended ceiling, however do not want the traditional batts, and am thinking of a foil type insulation if it works and is available here, also want to know if I should replace the LED downlights to normal ceiling LED lights under the ceiling as they can be as effective. What impact if any, if the foil comes into contact with electrical wires in the ceiling, 99% are in pipes or in coils to stop the occasional rat biting the electrical wire.

 

I am thinking rolls of foil just rolled out for ease in the ceiling, its a single level house of around 300m2 in total area, we do get the occasional mouse playing soccer up there, and the big geco who he passes it to.

 

All advice/options considered, and anything that might be detrimental to the air quality etc etc, slab on floor, and yes, heat rises, and the house does get hot, however I am thinking more so for the A/C's not having to work so hard, as I ma sure the cool air is going straight through the ceiling and into the roofline.

 

Thanks in advance.

[canuckamuck]

You can get foil backed drywall for the ceiling, or foil backed suspended ceiling tiles.

[Denim]

Rolls of foil are available at most large hardware stores.

 

I bought some direct from the factory to save a bit of cash but later found some cheaper at Global.

 

Obviously , the thicker they are the more effective. However we initially went with the cheap 2 inch type and noticed a big difference. I then added another 2 inch layer on top.

 

They are easy to unroll if you have good access.

 

One observation is that they really slow down the build up of heat under the ceiling. However , in the evening, when It can be cool outside, the insulation retains the heat that has built up during the day.

 

To offset this  we have an large extractor fan in the kitchen ( open plan house design ) which we turn on for an hour around nightfall.

[Kwasaki]

Had fibreglass foil type covered insulation in my ceiling for 10 years or more, no problem.

[simoh1490]

Foil, by itself, on the attic floor will not provide any insulation whatsoever, even if you use foam backed foil it still won't insulate.

 

You've already got a radiant barrier in place under the roof tiles, that reflects radiated heat from the roof tile which then turns into convected heat or hot air. The next step, as you've correctly realised, is to prevent the convected air from penetrating the living space through the ceilings. Trying to use foil by itself for this purpose, or even with a bubble wrap backing, won't insulate against convected heat, the R value of that stuff is almost 0, despite some claims to the contrary (lots of good data on this on YouTube).

 

http://www.greenbuildingadvisor.com/blogs/dept/musings/stay-away-foil-faced-bubble-wrap

or:

 

 

You have two choices: either ventilate your gable ends/ridge line and under the eaves so that hot air escapes and is replaced by cooler air at a lower level, and/or, use bat insulation on the attic floor, there really are no other sensible choices that will work - figure on using insulation with an R Value of at least 32.

[Kwasaki]

20 minutes ago, simoh1490 said:

Foil, by itself, on the attic floor will not provide any insulation whatsoever,

Wrapped around fibreglass it does, it works for me with a vented loft area to promote air-flow. ?

[simoh1490]

1 minute ago, Kwasaki said:

Wrapped around fibreglass it does, it works for me with a vented loft area to promote air-flow. ?

Yes of course, but it's important to understand what is doing what and why.

 

The insulation in your example is the fibreglass, the foil that encases it is merely a casing which prevents bugs etc from making nests in it and, in the cases of roofs that don't already have one, the foil acts partially as a radiant barrier - I say partially because a radiant barrier is only effective when installed at 90 degrees to the source of the radiated heat. If you don't think that's true, try removing the fibreglass  and just leave the foil in place and see what happens.

 

FWIW I use similar, foil encased bats on the attic floor and radiant barrier under the roof tiles, my foil eased insulation is now R64 and works really well.

 

[Denim]

2 minutes ago, Kwasaki said:

Wrapped around fibreglass it does, it works for me with a vented loft area to promote air-flow. ?

 

Same here. In fact we have a thick foil directly under the roof tiles plus fibreglass wrapped in foil lying 4 inches deep on top of the ceiling.

In addition , the attic space has vents front , back , and all along the eves to help airflow.

 

 

[simoh1490]

What you describe Denim is the same thing as I have set out, the radiant barrier (foil under the tiles) neutralises radiant heat from the tiles and the 4 inch insulation on the attic floor insulates against hot air penetration. What the OP is talking about is using a thin layer of foil with a bubble wrap backing on the attic floor and that will not provide any insulation whatsoever.

 

And just to confuse matters further, the extent to which a well vented roof will reduce heat build up can be enormous, even the most heavily insulated roofs will fail eventually without that, given sufficient heat and time.

[Denim]

8 minutes ago, simoh1490 said:

What you describe Denim is the same thing as I have set out, the radiant barrier (foil under the tiles) neutralises radiant heat from the tiles and the 4 inch insulation on the attic floor insulates against hot air penetration. What the OP is talking about is using a thin layer of foil with a bubble wrap backing on the attic floor and that will not provide any insulation whatsoever.

 

And just to confuse matters further, the extent to which a well vented roof will reduce heat build up can be enormous, even the most heavily insulated roofs will fail eventually without that, given sufficient heat and time.

 

Agreed. Its like putting water in a saucepan. If the flame is high it boils quickly. If the flame is low, it still boils but takes that much longer to come up to heat.

 

Another option you can have ( which we don't ) is to have an extractor fan in your roof space that you can turn on 30 minutes before it gets dark to assist in sucking out the built up hot air.

 

Pretty cheap and every little helps.

 

 

[simoh1490]

The risk with extractor fans is that they need a cool air intake from outside and below the eaves, otherwise they risk sucking the aircon cooled air into the attic.

[CGW]

If you do go ahead with the foil you need to cut out above each light to allow cooling!

[simoh1490]

Unless you use LED's

[Kwasaki]

So many different ways to insulated roof / lofts etc go with what your happy with.

[simoh1490]

Insulating a home is 100% physics so the answers should be very straightforward, unfortunately, for many people, marketing gimmicks get in the way and they ignore the physics.

[4MyEgo]

Thanks everyone for the advice, as I have LED lights it shouldn't be a problem putting in batts, personally I did this years ago and didn't like being itchy and hot, add a few decades and weight to that, I will buy the R rated batts, the higher the rating the better, and have someone install them, hopefully I will stop sweating while sitting in my chair...lol

[sometimewoodworker]

21 hours ago, simoh1490 said:

Unless you use LED's

Even if you  use LED's. LED's produce heat, heat kills LED's.

 

Keep them cool or underrate them for long life.

[simoh1490]

1 minute ago, sometimewoodworker said:

Even if you  use LED's. LED's produce heat, heat kills LED's.

 

Keep them cool or underrate them for long life.

Is that not an argument in favour of covering the LED's with insulation, so that they avoid the extreme heat of the attic? We have LED's throughout and when I touch any of the fittings in the attic they are always cold.

[sometimewoodworker]

3 minutes ago, simoh1490 said:

Is that not an argument in favour of covering the LED's with insulation, so that they avoid the extreme heat of the attic? We have LED's throughout and when I touch any of the fittings in the attic they are always cold.

No. It isn't. If your fittings are cold that is an indication that they are being underrun. Of the couple of hundred LED's we have some run cool most are walm and any insulation over them will shorten thier life.

 

It is an argument not to have an extremely hot attic.

 

Foil, by itself, on the attic floor will not provide any insulation whatsoever, even if you use foam backed foil it still won't insulate.

Not true. It will insulate against radiated heat and with foam backing it will help against convected heat. Over the long term its effects will reduce due to dust, so in general foam or bubble backed foil is a poor choice to lay flat.

You've already got a radiant barrier in place under the roof tiles,

True

that reflects radiated heat from the roof tile which then turns into convected heat or hot air. The next step, as you've correctly realised, is to prevent the convected air from penetrating the living space through the ceilings. 

Mostly confused and incorrect.

The foil under the tiles works because it is an extremely poor radiator of heat, any reflective effect is virtually irrelevant 

Trying to use foil by itself for this purpose, or even with a bubble wrap backing, won't insulate against convected heat, the R value of that stuff is almost 0, despite some claims to the contrary (lots of good data on this on YouTube).

You are correct that foil by itself doesn't work against convected heat (it also does not work against conducted heat) it works because it doesn't radiate heat.

Physics 101. QED

 

 

[simoh1490]

I'm not going there again with you on any of this (or any other topic either) , not given our history, you are of course absolutely correct on every point and aspect!

[4MyEgo]

2 hours ago, sometimewoodworker said:

No. It isn't. If your fittings are cold that is an indication that they are being underrun. Of the couple of hundred LED's we have some run cool most are walm and any insulation over them will shorten thier life.

 

It is an argument not to have an extremely hot attic.

 

 

 

Not true. It will insulate against radiated heat and with foam backing it will help against convected heat. Over the long term its effects will reduce due to dust, so in general foam or bubble backed foil is a poor choice to lay flat.

 

True

 

 

Mostly confused and incorrect.

The foil under the tiles works because it is an extremely poor radiator of heat, any reflective effect is virtually irrelevant 

 

 

You are correct that foil by itself doesn't work against convected heat (it also does not work against conducted heat) it works because it doesn't radiate heat.

Physics 101. QED

 

 

Ok so I see there are two different point of view here and some history between you and Simon1490, that said, what do you recommend.

 

I will reiterate, I have thermal reflective insulation under my concrete roof tiles, which work well, however, as you can appreciate as the day gets hotter, the attic heats up, e.g. prior to the reflective thermal insulation being installed, the house would heat up at about 10am, now it can be between 1pm and 3pm depending on the sun.

 

I am not used to sitting in a house sweating, I have gone to extremes like putting in a few whirly birds which do work, and I know some people will say, yes they spin, that's about it, but I have stood directly under them and felt the heat being sucked up into them and released into the air and some say, you need a breeze to get them going, well our spin 24/7 and I haven't seen any breezes.

 

I have put up steel awnings covering external walls in their entirety to stop the sun penetrating the bricks/windows and coming into the house, it works and has been done in a way that compliments the house as external sitting areas.

 

What I am looking to do is insulate the ceiling so as to stop the heat in the attic coming into the house, and the cool air from the A/C's when on, staying under the ceiling, as opposed to exiting through the ceiling and into the attic space.

 

As far as LED lights being cool, hot, they are not an issue for me, as I can replace them very easily with LED circular lights on the ceiling as we have in other sections of the house, and I do believe that they don't have one of those little attachments next to them, like the old downlights used too have, i.e. transformers like the downlights.

 

I am all ears on what you may recommend as an insulation material to effectively help keep the house cooler inside, considering that heat comes in from the ceiling space, and of course rises, we do have a concrete slab, so I would suggest that the heat is not rising from there.

[simoh1490]

A series of related points whilst I'm waiting for a flight:

 

A useful and simple explanation here of radiant barrier technology:

http://www.radiantbarrier.com/why/how-radiant-barrier-works/

 

Anyone who thinks bubble/foam backed foil insulation that is less than 1 cm thick has any insulating properties whatsoever, needs a serious refresher course on R-values and the physics of insulation.

 

There's a useful thread on replacement roofs which incorporated insulation option quite extensively, the roof in question was moderator Sheryl and is dated last November  - it's 30 or more pages long but incorporates all the aspects discussed here - a PM to Sheryl will yield a link I'm sure.

 

As for having differing points of view, that's really not the case. Sadly we have posters from time to time who operate personal agenda's and like to contradict and disagree with anything certain other posters have to say on almost any subject, regardless of whether they know anything of the subject matter or not.

 

Flying time coming up, back in November, byee.

 

[4MyEgo]

38 minutes ago, simoh1490 said:

A series of related points whilst I'm waiting for a flight:

 

A useful and simple explanation here of radiant barrier technology:

http://www.radiantbarrier.com/why/how-radiant-barrier-works/

 

Anyone who thinks bubble/foam backed foil insulation that is less than 1 cm thick has any insulating properties whatsoever, needs a serious refresher course on R-values and the physics of insulation.

 

There's a useful thread on replacement roofs which incorporated insulation option quite extensively, the roof in question was moderator Sheryl and is dated last November  - it's 30 or more pages long but incorporates all the aspects discussed here - a PM to Sheryl will yield a link I'm sure.

 

As for having differing points of view, that's really not the case. Sadly we have posters from time to time who operate personal agenda's and like to contradict and disagree with anything certain other posters have to say on almost any subject, regardless of whether they know anything of the subject matter or not.

 

Flying time coming up, back in November, byee.

 

Good read, I am sure the reflective thermal insulation that I have under my roof tiles is effective enough to reduce the heat coming in for some hours during the day, however I am assuming that batts with a high R value will assist in the heat heading down and through the gyprock ceilings and into the living and other areas, with the heat remaining in the attic to filter out through the whirlybirds, under the eaves and the gables where there are vents, front and back ?

[sometimewoodworker]

8 hours ago, 4MyEgo said:

I will reiterate, I have thermal reflective insulation under my concrete roof tiles, which work well

It isn't clear exactly what you have.  

If it has a shiny silver side facing down (if it has foam on the other side it helps but may not be so important) then you are good to go as far as a radiant barrier is concerned. It's main function is as a very poor radiator of heat.

 

8 hours ago, 4MyEgo said:

What I am looking to do is insulate the ceiling so as to stop the heat in the attic coming into the house, and the cool air from the A/C's when on, staying under the ceiling, as opposed to exiting through the ceiling and into the attic space.

For that purpose the thick rolls of insulation on top of the ceiling are effective specially if you have a reasonably sealed ceiling (plaster board rather than removable squares. The thicker the roll the better. The rolls are usually covered with the, radiant barrier, silver foil. It does no harm, can help a little and protects the insulation a bit, it also makes it easier to put down.

 

Its not very expensive, our living area of about 100sqm cost around 12,000 Baht.

 

if you have any light fittings that penetrate the ceiling make sure that there is some free space above them, as most of that kind of fitting need some air circulation.

9 hours ago, 4MyEgo said:

I have put up steel awnings covering external walls in their entirety to stop the sun penetrating the bricks/windows and coming into the house, it works and has been done in a way that compliments the house as external sitting areas.

Another good idea, as long as you have a radiant barrier on the side facing the walls. The thin foam with foil on it on the underside will probably be enough.

 

White paint on any surface that gets radiant heat (sunshine or hot concrete) will also help quite a lot.

 

A point that is often forgotten is the area next to the walls. Often there will be a concrete walkway there. This usually gets full sun on it which it will happily radiate on to the walls. Night storage heaters are big blocks of concrete! It is better to have grass as close as you can

9 hours ago, 4MyEgo said:

we do have a concrete slab, so I would suggest that the heat is not rising from there.

Assuming that it is directly on the ground I would think you are correct.

[sometimewoodworker]

1 hour ago, 4MyEgo said:

Good read,

While most  of the information on the linked website is good unfortunately whoever wrote it didn't quite complete physics 101 or didn't understand it fully, the "physics-of-foil" page on the subject of floors and crawl spaces needs correcting 

 

The "how-radiant-barrier-works/" page, has quite a bit of correct information but again needs rewriting by someone who really understands the way the radiant barrier works and doesn't confuse the properties of reflection and Emissivity and how these effect hot climate living.

 

The site seem confused about hot and cold climate uses and how the foil helps in the two very different cases. 

[4MyEgo]

8 hours ago, sometimewoodworker said:

It isn't clear exactly what you have.  

If it has a shiny silver side facing down (if it has foam on the other side it helps but may not be so important) then you are good to go as far as a radiant barrier is concerned. It's main function is as a very poor radiator of heat.

http://www.polynum-insulation.com/index.php?page_id=36 

Cost 60,000 baht to cover 230m2

 

8 hours ago, sometimewoodworker said:

 

For that purpose the thick rolls of insulation on top of the ceiling are effective specially if you have a reasonably sealed ceiling (plaster board rather than removable squares. The thicker the roll the better. The rolls are usually covered with the, radiant barrier, silver foil. It does no harm, can help a little and protects the insulation a bit, it also makes it easier to put down. Its not very expensive, our living area of about 100sqm cost around 12,000 Baht.

 

We have gyprock sheets 2400 x 1200 if memory serves me correctly, no squares. 

 

8 hours ago, sometimewoodworker said:

if you have any light fittings that penetrate the ceiling make sure that there is some free space above them, as most of that kind of fitting need some air circulation.

I think we will disconnect the LED downlights, however leave them in the ceiling, and put the large LED lights, one per room in the middle, so that we can cover all ceiling areas as opposed to leaving gaps, otherwise there will be a few gaps, and I want it to be as effective as it can be.

 

 

[4MyEgo]

7 hours ago, sometimewoodworker said:

While most  of the information on the linked website is good unfortunately whoever wrote it didn't quite complete physics 101 or didn't understand it fully, the "physics-of-foil" page on the subject of floors and crawl spaces needs correcting 

 

The "how-radiant-barrier-works/" page, has quite a bit of correct information but again needs rewriting by someone who really understands the way the radiant barrier works and doesn't confuse the properties of reflection and Emissivity and how these effect hot climate living.

 

The site seem confused about hot and cold climate uses and how the foil helps in the two very different cases. 

I think once I purchase and have someone put in the batts with a high R rating, we should be good to go

[Kwasaki]

12 hours ago, simoh1490 said:

As for having differing points of view, that's really not the case. Sadly we have posters from time to time who operate personal agenda's and like to contradict and disagree with anything certain other posters have to say on almost any subject, regardless of whether they know anything of the subject matter or not.

You'd make a good salesman ? If people have credible knowledge whether they know anything of the subject matter or not.as you say but have experienced affects of other products being useful they should contradict and disagree with you or anyone, that's what forums are for.

 

There many ways to insulate existing roof builds, costs or practicability of the work method has to be taken on in certain cases. 

Different designs of building dictate that, someone selling a product with an honest figure about different products in field of measuring temperatures would be hard to believe. 

 

A well designed ventilated roof with just insulated ceilings will work. 

Many modern house roof designs being built today will benefit from your recommendations.

[Denim]

21 hours ago, 4MyEgo said:

 

we do have a concrete slab, so I would suggest that the heat is not rising from there.

 

Actually , with respect ( not looking for an argument with anyone )

in my experience of having several houses in Thailand , it is better if the concrete slab is not in direct contact with the ground.

 

The ground all around your house can get heated up by the sun

( unless it is well shaded by trees ), and this heat can transfer to the ground under your slab and slowly heat it up through the day.

 

My sister in law next door has her house on a slab on the ground. Our slab is elevated on 80 cm stilts /posts. If I put a temperature gauge on her floor and repeat on our floor , ours is always cooler. This I believe is because any heat rising up through the ground does not come through the slab but escapes from under the house.

 

In Bangkok, I have several times seen houses with no surrounding shade have the ceramic tiles on the ground floor buckle and break because of heat expansion coming through the floor.

 

To avoid this , builders sometimes put a thin strip of polystyrene in the middle of a poured cement floor to act as en expansion gap.

 

As for your ceiling, just lay down rolls of insulation on top of it and it will stop any heat from the attic coming down to your living area. The thicker the better.

 

 

[4MyEgo]

2 minutes ago, Denim said:

 

Actually , with respect ( not looking for an argument with anyone )

in my experience of having several houses in Thailand , it is better if the concrete slab is not in direct contact with the ground.

 

The ground all around your house can get heated up by the sun

( unless it is well shaded by trees ), and this heat can transfer to the ground under your slab and slowly heat it up through the day.

 

My sister in law next door has her house on a slab on the ground. Our slab is elevated on 80 cm stilts /posts. If I put a temperature gauge on her floor and repeat on our floor , ours is always cooler. This I believe is because any heat rising up through the ground does not come through the slab but escapes from under the house.

 

In Bangkok, I have several times seen houses with no surrounding shade have the ceramic tiles on the ground floor buckle and break because of heat expansion coming through the floor.

 

To avoid this , builders sometimes put a thin strip of polystyrene in the middle of a poured cement floor to act as en expansion gap.

 

As for your ceiling, just lay down rolls of insulation on top of it and it will stop any heat from the attic coming down to your living area. The thicker the better.

 

 

Good advice, and no arguments here.

 

We have no cement around the house, except the front for the driveway, sides walls do not get direct sunlight on them, (covered by awnings), mostly blue metal/stone, or grass runs along the side of the house.

 

Going out shortly to check out the batts, their ratings and price, the area I have is about 300m2, so will more than likely be in the vicinity of about 60,000-90,000 baht installed, I would imagine, that said, I am good at squeezing blood out of a stone, so will see what we can come up with.