Building Standards: Roof Insulation & Ceilings

[HIDDEN]

I've posted (Building Standards: Roof Tiles and Insulation) about the really thin aluminium foil used, sometimes, under roof tiles.

In my view this is pretty much useless for thermal insulation. Usually immediately under roof tiles there's a waterproof layer (in the UK it's known as building paper) which is there to collect and channel-away any water that gets blow-up between the tiles. Here that job is done by the aluminium sheet (if it's laid properly) so this sheet does have a purpose although it's not the one it seems to be.

I've checked through the thermal resistivities and other dull specifications for materials and it doesn't have a lot of real-life impact. So last year I did an experiment, totally unscientific but probably very valid.

I took various insulating materials and exposed them in the same enclosed space over a period of days, and at the same time each day checked the heat penetration by touching the area with my palm. 

Material                                                         

1). Aluminium foil (as used in roofs). Result = useless
2). Aluminium foil with 8mm foam backing. Result = useless
3). 25mm waterproof rubber foam. Result = really useless                       
4). 50mm glassfibre quilt. Result = very noticeably cooler
5). 50mm rigid urethane foam sheet. Result = noticeably cooler
6). 50mm ordinary white styrofoam. Result = very noticeably cooler
7). 50mm flexible rockwool. Result = very noticeably cooler

The last 4 were all pretty good, except that styrofoam gives off thick black toxic smoke when lit, and urethane foam burns pretty easily. The rockwool is fire-resistant but it soaks up water and if it gets too wet will disintegrate.

So, for me I'd go for the quilt but it's a really unpleasant material to handle unless the rolls are sheathed in plastic. Otherwise the fibres get into your hands and itch. The quilt is also fireproof. And if you laid the quilt 100mm thick that would do it very nicely.

All the above materials are readily available in Malaysia.

regards, Scott

[HIDDEN]

Many of the houses that I see being built nearby, here in Perak, have asbestos cement ceilings. This is common even in higher priced (above RM250,000) properties. Usually the board forms a suspended ceiling over the car porch/entrance area.

In lower priced properties, the asbestos cement board is used for kitchens and bathrooms. Apart from the asbestos content, this type of board is very brittle and, when wet, it behaves just like wet cardboard. So it pretty much disintegrates and releases asbestos fibres.

This board is a relatively cheap building material, hence its widespread use. If I were buying a property, I'd refuse to have this board anywhere on or near the place. Most countries simply ban all asbestos-based materials from residential construction.

Here's what it looks like. Click to enlarge, then click to reduce back.

[HIDDEN]

Hi Scott:

I think that if aluminium foil is properly installed, it should work as a reflective screen, reflecting away part of the heat... It is widely used in saunas for that purpose here. And with foam backing it should be not too bad thermal insulation - at least its appearance in cold climate is quite good. But of course between the insulating material and the nearby construction elements there must be an air layer.
We use all the materials that you have mentioned, save for rubber foam, and the only set-back is that rockwool and glassfibre could make the construction too heavy, if the space to be insulated is large. Aluminium foil is used only in combination with other insulation materials.

BR,
Sergey.

[HIDDEN]

Scott, I also refused to let the builders use asbestos sheets in the construction of this bungalow............they then imported from KL which delayed progress slightly & also increased the costs slightly, but i am happier knowing there is no asbsestos in the bungalow. (that i am aware of)
John.

[HIDDEN]

hi, John,

That's a good move. The cement boards that I've seen in the local supply yard look too much like asbestos cement.  I don't know for sure that they contain asbestos (wouldn't it be nice to have a CSI back-up lab) but the supplier said yes.

Anyway, these boards are used as ceilings under roofs and if the roof leaks they'll disintegrate as they are not stable.

The aluminium foil generally used in Malaysia is the low-cost, low-quality type. It's better to try and upgrade the specification. For the low-quality stuff there's no foam layer and the reinforcing cross wires are string rather than metal. That's why it gets kicked-in by the tilers. If it's laid properly then, yes, it does reflect some heat.

Rockwool and glassfibre are lightweight and with 50mm it's very effective. Given a choice I'd use both (glassfibre + aluminium "sistalation" foil) with the aluminium acting primarily as a water-proof layer under the tiles.

If you're getting a property built then it's worthwhile to get a higher specification as you've done. If you're buying developers' build then putting in some glassfibre, and replacing cement boards, can easily be done with the general upgrading work prior to moving in.

Alternatively, and this works really well although it's a bit of a hassle. Tell the builder or developer that you don't want any external ceiling boards. Ask him to use roof timbers that have been planed smooth. This is extra work (i.e. extra cost) but it's not much and there's a trade-off with the boards. You can then stain/seal the exposed timbers and you'll also get the effect of extra volume.

regards, Scott

[HIDDEN]

We're buying a new build and horrified to hear from the developer yesterday that some developers (not our one) are still using asbestos for ceilings... and according to this article here http://www.mmail.com.my/content/46271-asbestos-hazard-slow-silent-death quite common in older buildings.  We shall make sure that our renovator is well briefed.

However.... looking at that pic that Scott posted above in 2007.... that is just like the bathroom ceilings in our current rental flat  and we have a surprisingly high dust content in one of the bathrooms.  Thank god we'll only be in this unit for a few more months.  We had no idea about the asbestos.  We presume that these false ceilings were put in by the Landlord's renovator and not the developer.

The article above mentions that they are perfectly okay if not disturbed, but there's renovation vibrations in this condo it seems every few weeks 

[HIDDEN]

hi,

Asbestos boards for ceilings are very common. They are usually 2 feet x 2 feet and the edges of each board covered in a thin wood strip to give a panelled effect.

It's breathing-in the fibres that do you in. I think that you have to work in the asbestos mines and factories to croak early though.   

And it's when the board get soaked, dry off, and start to fall apart.

You need to have a look at the end of the board. If it is fibrous and brittle then it's probably asbestos-based. If it is chalky and crumbly then it's some form of plasterboard sheet.

[HIDDEN]

hi,

Asbestos boards for ceilings are very common. They are usually 2 feet x 2 feet and the edges of each board covered in a thin wood strip to give a panelled effect.

It's breathing-in the fibres that do you in. I think that you have to work in the asbestos mines and factories to croak early though.   

And it's when the board get soaked, dry off, and start to fall apart.

You need to have a look at the end of the board. If it is fibrous and brittle then it's probably asbestos-based. If it is chalky and crumbly then it's some form of plasterboard sheet.

The big boys in the asbestos cement sheeting market got out of asbestos initially in the 70's and out of developing country markets in the 90's, because of all the litigation.

It is extremely difficult to tell the difference between the old asbestos cement sheets and the new fibre-cement sheets (using inert fibres of cellulose etc). In Indonesia where I did the research the local manufacturers said "we only use asbestos to client specification" as it is apparently stronger (or Clients think so) but more expensive. I suspect local asbestos-cement sheet here may not actually contain asbestos; the name is now a generic for "thin white sheets we use for ceilings". I've just had some renovation done and accepted the builder's proposal to use "asbestos-cement" in the store room ceiling.

This white asbestos (as opposed to the blue asbestos used in ships and stuff for insulation) is relatively benign, and as Scott said the danger comes when the fibres are released by demolition work or deterioration. But one large manufacturer told me his workers used to finish their night shift and go to sleep on top of the asbestos in the silo, as it was nice and warm. They only ever had one death from asbestos related disease, and that was their accountant! Good story. True? who knows.

The majority of white asbestos comes from Canada and Russia.