Wall insulating paint

belfastgirl23

I'm looking at getting some repainting done fairly soon. In my little '250 tips for an eco-lifestyle' book they mention wall insulating paint (tip 129 if anyone is interested). I have a painter coming around on Saturday to give me a price. He is a jovial type and I have a feeling he will have a chuckle if I mention this so I'd like some ammo before I broach the subject. Does anyone have any experience of this and if so does it really work? I'm in an old detatched house built 1905 so as you'd imagine any insulation is a big bonus

edit - should have said the walls are solid rather than cavity so no options for cavity wall insulation

economiser

It can't offer much in the way of conventional insulation as it is so thin. It must contain a degree of heat reflective material and act rather like the reflective sheets often mounted behind radiators. I am afraid I have no idea as to its effectiveness but I would expect it to be marginal.

Seakay

I'd never herd of this so I did a quick Google and found this discussion thread. They are initially talking about an additive for paint, but presumably the paint that you mean just has the additive already in it.

http://www.greenbuildingforum.co.uk/forum/index2.php?DATEIN=tpc_ibyajmsjt_1155209638

rustyjemma

http://www.thermilate.co.uk/

Is this the stuff you were thinking of?

economiser

I looked at the Thermalite site and the Salford University test results. They show a 46% increase in the thermal resistance of a layer of 9mm plasterboard when coated with Thermalite giving a total resistance of 0.136 m2 K/W therby contributing about 0.086 m2 K/W. A modern insulated wall would have a resistance of about 4.0 m2 K/W so it would seem that painting a wall with Thermalite would add about 2% to its resistance and save about 2% in heat loss.

belfastgirl23

Thanks for this economiser - any idea what would be the benefit in an old solid (ie not cavity) wall? I think it's been dry lined but nothing else as far as I know.

The painter in fact didn't laugh in the end up - he had checked it out a year or so ago himself but hadn't been able to find a supplier in Ireland...so he's going off to check on it again.

Oh and thanks for the site rustygemma, I hadn't found that one....off to have a proper look.

krishna

Have you ensured that you have draught-proofed? Especially around door and window frames, at any point where pipes etc enter house/rooms, around skirting and under floors. This is the most important thing and will save far more than any special paint. If you can, some proper insulation on the walls would be more useful, even if it was only 10mm. There is something called Sempatap that you can apply like a wallpaper. Even better, of course, is to line walls (inside or out) with more insulation, but that does involve a lot more disruption. We are going to be insulating walls externally, probably next year.

economiser

The thermal resistance of a 12 inch thick solid brick wall would be about 0.6 m2 K/W so with the paint it would be 0.686. An improvement of just under 15%. This would of course only be for heat loss through the wall, not through windows and ventilation etc. which probably make up the majority of your heat loss. As krishna says draught proofing is far and away the most cost effective way of conserving heat. Gaps around windows, doors, skirtings and between floor boards, open chimneys etc. Make sure you allow for enough ventilation though if you have gas appliances in the room. Improving the insulation of solid walls if very difficult, you need thickness to be effective and even good insulating material would need to be15mm at the very least and preferably 50mm to have any real effect, insulating paints and wallpapers have a very limited impact I fear.

belfastgirl23

Thanks for taking the time to reply. The 'room' that I'm thinking of is our hall, stairs and landing. It's an old detatched house so this is basically an expanse of solid outside wall with a large window in it. I have draftproofed the front door etc very recently so have taken care of it from this POV. I don't think I'd bother with a normal room in a way but this is exposed to the full height of the house on an outside wall so it seemed like a good place to experiment with...any thoughts?

I did speak to an academic who knows about renewable technologies a couple of days ago and he said he was pretty sure it wasn't a scam although again didn't exactly know what level of difference it might make...

economiser

I don't think Thermilite is a scam. It's just the most manufacturers like to paint (no pun intended) the best picture for their product. With your large uninsulated outside wall you are getting a big radiant cooling effect making the hallway feel even colder than it really is. I suspect this paint might have more of an effect on this radiation effect than the convective heat loss and I think the effect may be that this paint might make an overall improvement of about 10% in the case you describe. Unless the paint is very expensive I would think it was worth a try. I'll make some enquiries and let you know if I can find anything more.

belfastgirl23

economiser wrote: »

I don't think Thermilite is a scam. It's just the most manufacturers like to paint (no pun intended) the best picture for their product. With your large uninsulated outside wall you are getting a big radiant cooling effect making the hallway feel even colder than it really is. I suspect this paint might have more of an effect on this radiation effect than the convective heat loss and I think the effect may be that this paint might make an overall improvement of about 10% in the case you describe. Unless the paint is very expensive I would think it was worth a try. I'll make some enquiries and let you know if I can find anything more.

Most kind of you, thanks a million