Reflective Foil: Quality Comparison?

[Greenside]

OK. I need to buy about 30 rolls of reflective foil to put directly under the roof tiles that they will start to lay towards the end of next week. I thought these were already ordered but seems I was wrong .

On the current house we used the Chang brand which is SCG and was very expensive, but we didn't need many so I wasn't quite as focused as I am this time round! There seems to be a lot of choices but not much help from the retailers as to which one to choose.

Global House in Chiang Mai has the following on the shelves (prices are for a standard size roll of 1.25 x 60m)

Coolguard Double Sided Bt1490

OHO Cool 101 M-2 Bt1550

Space Foil Bt1640

Pro-Tech Bt1750 (This picture was of a smaller roll)

OHO Cool 101 F-2 Bt1750

Does anyone know the differences between this lot, specifically between the two OHO offerings which had identical properties listed on the label - close up above - GH just waffled and it was clear they really had no idea why one would cost 200 baht a roll more than the other? They all seem to claim the same properties so I'm thinking that maybe some are easier to fix than others (although the expensive Chang brand we used before was ripped in numerous places and I had to insist it was fixed before we OK'd the roof).

Obviously I'd like to use the best value foil - your comments appreciated.

Edited June 28, 2013 by Greenside

[jbrain]

Homeworks has a two sided foil that is waterproof. I forget the name ( something with sun in the name), but i have it under my rooftiles and it doesn't rip as it is a kind of plastic, where the Chang is a paperbased foil.

[Greenside]

I think they are all waterproof but I'll see if I can find a sunny sounding one at our Homeworks dealer.

[David48]

Greenside ... great OP.

I don't have an answer, but will read the replies with interest.

.

[Greenside]

By the way, I didn't quantify it in the OP, but the SCG Chang brand is an eye watering 3900 baht per (same size) roll. The brands shown above claim between 95 and 98% reflective surfaces - what on earth could the 2000 baht premium be for?

[IMHO]

By the way, I didn't quantify it in the OP, but the SCG Chang brand is an eye watering 3900 baht per (same size) roll. The brands shown above claim between 95 and 98% reflective surfaces - what on earth could the 2000 baht premium be for?

Something that hasn't degraded into dust within 5 years?

My POV on this one is simple - get the best. The material price of the SCG stuff is nothing compared to the expense of trying to replace cheaper stuff later because it delaminated and fell to pieces.

Edited June 29, 2013 by IMHO

[Greenside]

I agree with you, but have you any experience of this kind of material de-laminating or are you just citing it as an example? Personally, I've never heard of it happening but then my experience is limited.

The extra cost of using SCG over say the OHO upper priced Global House brand is somewhere around 45,000 so while it's not in the same league as replacing it should it fall to bits, it's money I would sooner put towards the 3 phase replacement wiring (see the above thread).

Edited June 29, 2013 by Greenside

[IMHO]

I agree with you, but have you any experience of this kind of material de-laminating or are you just citing it as an example? Personally, I've never heard of it happening but then my experience is limited.

The extra cost of using SCG over say the OHO upper priced Global House brand is somewhere around 45,000 so while it's not in the same league as replacing it should it fall to bits, it's money I would sooner put towards the 3 phase replacement wiring (see the above thread).

Yes, have seen it degraded to the point of being useless - wasn't able to determine the brand though. My family's business has used the SCG stuff for almost 20 years, and never had a complaint from a house owner.

Edited June 29, 2013 by IMHO

[Greenside]

Thank you. That at least gives me an idea of what to focus the comparisons on. Anyone else had (or seen) trouble with lower priced products?

[Thai at Heart]

PU foam sprayed on is a much better bet. By the time this is covered in an inch of dust it's reflective qualities have largely dissipated.

[jbrain]

Thank you. That at least gives me an idea of what to focus the comparisons on. Anyone else had (or seen) trouble with lower priced products?

I'm not gonna dispute anything posted on this thread, but let me give you an idea.

The foil I mentioned is sold by Ceris, which is part of Cpac Monier group under their own brandname at about 3 times the price it is available at Homeworks.

I know because I have the Ceris roof tiles on my house and purchased the first lot of insulation through Ceris.

[Greenside]

I hadn't considered the dust issue. Possibly a good point...

Spraying with PU is way outside my budget, I'm afraid although I've heard it can work well if you have a good contractor to do the application.

While doing some further research I came across these articles which explain the way the radiant barrier material functions.

http://energy.gov/articles/radiant-barriers

http://en.wikipedia.org/wiki/Radiant_barrier

Both say that to be effective, they should be free of dust but most importantly that the reflective surface must face an air space or a vacuum to work effectively. I'll have to go up to our attic tomorrow to check, but I believe the tiles are pretty much on top of the foil - I don't recall an air space worthy of the name.

Edited June 29, 2013 by Greenside

[jbrain]

PU foam sprayed on is a much better bet. By the time this is covered in an inch of dust it's reflective qualities have largely dissipated.

I have PU foam sprayed on a small part of my roof.The problem with PU foam is that it expands, and keeps expanding for a long time, and lifts the rooftiles.

[Greenside]

That sounds tedious. The downside I heard about was the difficulty of replacing tiles with the foam in place.

[jbrain]

That sounds tedious. The downside I heard about was the difficulty of replacing tiles with the foam in place.

Indeed it sticks very strong to the tiles, which sometimes is considered an advantage against burglars, but it really push the tiles upwards as it creeps in the smallest crevice whem sprayed and then expands.

[Ackybang]

Hi Greenside,

30 rolls seems like an awful lot, mate - your roof must be huge ! How many square meters are you talking about ? My house is 200 square, and has a very complicated roof, not sure how big, but I know I used around 3,800 cpac tiles, and I think I used around 6 rolls ?

Myself, I went through exactly the same as yourself, and the retailers generally try to sell you whatever they make the most commission on. I would also believe - many of them don't actually know, or have any experience of using foil - it's not a thing your average Thai would bother using. My roof is entirely cpac - even down to the screws, and the cpac reps tried to deter me from using other brands, and naturally tried to sell me cpac foil, and of course it was the best, for sure, and blah blah blah. All unbelievable advertising spiel.

In the end, I went to every retailer I could find, and actually opened every type of foil I could find, and tested the strength in a small corner of the foil. Some of the makes have leaflets, with samples in them, so you can see for yourself, without having to resort to such measures. All of the paper based stuff ripped easily, burned easily, and pushed through easily with just a very small amount of water applied. I couldn't see any of it lasting long if you had a leak in the roof, or a fire. Once you compromise the fabric of these materials with screws, I'm not sure how they would hold up if your roof is breathable, with vented ridges, and the constant airflow / humidity.

In the end, I was lucky, and found some rolls in stock clearance, that should have been around 4,000 baht - reduced to 1,900 baht. The stuff I ended up with was made in New Zealand, (Harvi foil) and was actually listed as agricultural foil (which cpac said was not good to use) - guaranteed for 10 Years against chemical sprays and water, and presumably animals pissing on it - which means in real terms it will last for an age. Very strong - you can't rip it manually, I believe you could actually swing off it if you wanted to. I tried burning it, and it just shrivels up. Retrospectively, this was a good move in a number of ways. Some of the longest horizontal runs on my roof are around 20 meters long, and when I had it installed, if you can imagine one guy at either end of a long run of this stuff, quite a few meters off the ground, trying to pull it tight to screw it down, before applying the tile batons, with the wind getting behind it like a sail, and nearly pulling the poor fellows to their demise - I'm fairly sure the expensive paper based stuff would have ripped to pieces easily.

For all of the claims of other brands, on a very hot day, my house is a good deal cooler than outside, and I haven't rendered, or fitted uv reflective windows yet - the foil works a treat (although my roof is a breathable design). I've used an extra roll I bought for two shelters on my farms, and a rabbit hutch - all corrugated iron roofs, and in direct, blazing hot sun, the heat does not radiate through the foil. It is important to have the air gap between the roof and the foil. The cpac alloy batons allow around 5cm from the foil to the inside apex of the ridge of the tile, if I remember correctly.

I would ignore the manufacturer's claims, and have a look at finding the physically strongest double sided foil you can find - invariably, this will be plastic based sandwiching a woven aluminium reflective surface. Have a look at good quality agricultural stuff, man. In my experience - highly reflective, durable - acts like a secondary roof / water barrier, and much better against the elements. Make sure it's applied horzontally, under the tile batons (or under the joists if your batons are welded steel), with a good overlap from the next piece above (around 20 cm). You don't need to join the edges with foil tape either with this overlap, regardless of what the suppliers / builders say - expensive, and so ridiculously thin / fiddly to use, not durable for sure. If you have breathable vented ridges and soffits the foil wants to start about 50 - 60 cm in from the extremeties of your roof, (usually the second baton up) - convection does the rest.

Have a good look if you have the time, mate - it will pay off in the end.

I wouldn't go with foam, unless insulating a colour bond roof - expensive, and makes it very difficult to trace leaks if you have any.

Good luck.

Edited June 30, 2013 by Ackybang

[Greenside]

Thank you very much for taking the time to write all that! I was mistaken about the quantity - read the wrong column in the BOQ! We have a large (and quite complicated) roof area which is going to consume almost 10,000 CPAC Elebana tiles so the requirement is going to be about 17 rolls - still quite an expense but only about half as grim as I had braced myself for!

Here's the building today. It has a deep verandah running round a central pool and two projecting rooms at the back all of which add to the roof space.

It really looks as if durability is the main issue and once bought how well it is fitted. You were lucky to find the agricultural stuff discounted - the amount of building here in Chiang Mai is insane and serious discounts like that are very thin on the ground. In light of what you have told me and some of the other advice here I'm probably going to end up with the Chang (if I draw a blank on the agricultural stuff) but I will question the contract carefully to see that it gets fitted with the proper air space etc.

[David48]

Please tell me you are doing a building thread!!!

If so ... what is the link?

(I'm also a member over at CoolThaiHouse)

[Greenside]

It's called Building A House in Chiang Mai At The Worst Possible Time.

[David48]

It's called Building A House in Chiang Mai At The Worst Possible Time.

COOL ... just finished watching 'Bucket with a view' ...

[Thai at Heart]

PU foam sprayed on is a much better bet. By the time this is covered in an inch of dust it's reflective qualities have largely dissipated.

I have PU foam sprayed on a small part of my roof.The problem with PU foam is that it expands, and keeps expanding for a long time, and lifts the rooftiles.

Just needs to be done properly.

Did it in my place and it reduced the bedrooms by about 3c on the measured temp on the air conditioners.

Well worth it

[Greenside]

I just ventured up into our loft to put some stuff away and thought I'd snag a sample of the Chang foil to make me feel better about paying all that extra. Having read that foil must be separated from the tiles by an air gap I was depressed to see that actually they had simply laid the foil down on the purlines and placed the tiles on top, pushing the wire through the foil to secure them to the roof. This makes me suspect that it's not being very effective as the only air barrier that could possibly be there would be in the curved part of the tile - pretty insignificant, I'd say.

Anyone had this applied in a way that is in line with the advice given in the radiant barrier links I posted above (ie an air gap between tiles and foil)?

By the way, just below the white boards on at the bottom of the steeper pitch, there is an air gap with netting to keep the birds out which serves to let cooler air in and provide some flow through the two louvres.

[Greenside]

I posted the same request for feedback in several other places and after some more research my conclusion and advice for anyone else doing a new build is (in simple terms):

• Double sided reflective material is an essential component of a good insulation strategy
  
  It acts in two ways: (1) the side facing the roof reflects a proportion of the heat that builds up in your roof material and (2) the side that faces into the roof space emits less radiant heat because it is shiny.
  
  In order to work properly, there must be an air gap between the tiles and the reflective material. Where the hot tile touches the foil, heat is simply conducted and the benefit of the reflective surface is lost although it will still emit less than the tile would alone.

The last point is the tricky one, given Thai building techniques, and my guess is that the vast majority of installations get much less value for their spend on this material than if the contractors, owners and architects really knew the principles of radiant barriers (that's the thing to Google, btw). I have spent much of the last couple of days trying to devise a workable way to apply the material to the underside of either the purlines or the rafters (preferable) but so far without success. I can figure out how you could do it on a simple roof but ours is complex and I don't see the contractor's people being able to cope.

SCG has tackled this issue in two ways. Firstly, if you buy their expensive but attractive galvenised bolt together roofing system, the foil is placed over the rafters and the purlines bolted on top, leaving a very nice gap of about two inches. True, the part where the purline touches the foil will be ineffective as far as reflecting the radiant heat goes but then the rafter is directly below so it's really out of the running anyway. If you want to see this, go to your local HomeExpert branch and take a look at the mock up of their fancy roofing system. The second way is something I've not actually seen but I understand they have launched a foil product which is shaped so that it hangs down between the purlines in a controlled way, rather than just being fitted with a sag to try to create the air gap. I'm told this is even more expensive that the Chang brand reflective foil - more of this below.



Which type of foil got my vote? I took samples of the SCG Chang foil from our loft and and noted in passing that the bags that StayCool fibre looks like the same foil but single sided so cut a sample of that too. I bought a roll of OHO Cool 101 F-2 and a roll of Cool Guard Woven Cloth from for 1750 and 2250 baht respectively. The latter didn't figure in my earlier post because first time round I missed the significance of the woven bit - on a second visit, someone had kindly ripped open one of the packs and I was super impressed to find that it wouldn't tear without real effort and given how easily the regular foil is damaged it leapt into the lead.



We examined, tore, ripped, stretched and burned the samples from Chang and OHO and could detect no difference at all between them other than the 2000 baht price. They really do look as if they came off exactly the same production line and I can't think of any way to justify buying the more expensive of the two.

The Cool Guard was so much stronger and easier to handle that it was the clear winner so that's one we're going with, although I think we will end up fitting it over the purlines and letting it sag between them as much as is practical to provide the air gap.

The excellent diagram below is how I would like to have arranged it but it will have to wait for the next project!

Thanks for the help and advice on this thread, particularly Ackybang's input.

Edited July 5, 2013 by Greenside

[David48]

Great post and I, for one, really appreciate you coming back and telling us your findings.

Thanks ...

.

[muratremix]

Great topic. I wonder if it will help to place roof insulation on top of ceiling, but no under roof tiles (Like laying a big carpet).

[scooterboy]

Just read this thread....some great info, here, too.

Thanks (especially) to Greenside for his appraisal of different foils.

Unless anyone has any better or newer info, I think we'll try to go with the Cool Guard Woven Cloth rolls, which Greenside recommends.

Cheers

[eyecatcher]

Great topic. I wonder if it will help to place roof insulation on top of ceiling, but no under roof tiles (Like laying a big carpet).

I came to find this forum only recently, great thread Grenade.

To answer this question which he has been waiting a years for a reply..

Yes ceiling insulation is much easier and more effective and allows you to put it in as thick as you need.

Last month was the hottest we have seem but the month of may is even worse because the humidity increases as well.

I am about to insulate the ceiling of our business , I researched the cost to cover a room of 25m2.

A layer of 50mm foil backed quilt and overlay at 90degrees with 75mm quilt would have been 2000bt.

The cost of a new air con unit of 18k btu was circa 25k bt, and a temporary cooler unit was 6k bt.

Insulating the underside of a pitched roof is better when you need to live in the roof space otherwise ceiling every time. the roof space acts as the air space, if its well ventilated and keeps your rooms isolated to a certain extent.

The downside is you need to mess about protecting all the ceiling spotlights they like to do here. Insulation and spots are a fire risk.

[IMHO]

Great topic. I wonder if it will help to place roof insulation on top of ceiling, but no under roof tiles (Like laying a big carpet).

I came to find this forum only recently, great thread Grenade.

To answer this question which he has been waiting a years for a reply..

Yes ceiling insulation is much easier and more effective and allows you to put it in as thick as you need.

Last month was the hottest we have seem but the month of may is even worse because the humidity increases as well.

I am about to insulate the ceiling of our business , I researched the cost to cover a room of 25m2.

A layer of 50mm foil backed quilt and overlay at 90degrees with 75mm quilt would have been 2000bt.

1399792239376.jpg

The cost of a new air con unit of 18k btu was circa 25k bt, and a temporary cooler unit was 6k bt.

Insulating the underside of a pitched roof is better when you need to live in the roof space otherwise ceiling every time. the roof space acts as the air space, if its well ventilated and keeps your rooms isolated to a certain extent.

The downside is you need to mess about protecting all the ceiling spotlights they like to do here. Insulation and spots are a fire risk.

Not worried all that cosy insulation will become a nest?

[Issangeorge]

Would it be worthwhile to put the foil down flat against the dropped ceiling.

Sent from my i-mobile IQ 6 using Thaivisa Connect Thailand mobile app

[bankruatsteve]

Just thinking... it seems to me that any insulation would be pointless in the attic area here in LOS. Reflective foil with/without insulation would seem to be the best way to reflect heat radiation. I wonder if just laying down Al foil - shiny side up - would be a good idea?