I had a phonecall today from a company that applies "insulating cream" to the outside of houses. Now normally I have no truck with cold calls, but I'd never heard of this one. Does anyone know anything about it? Does it work at all?

This is something I've googled, as an example http://www.facadecoating.org.uk/masonry-insulation/

From what ive read they are a waterproofing product which would have a minimal themal insulating which would largely be dependent on if the wall was normally wet, as the moment it was dry any insulating properties would be negated.

I'm pretty sure it was on watchdog this week. Check out series 38 episode 1 on I player.

Complete rubbish if I remember right.

[Edited on 6/7/17 by Andybarbet]

Thanks both. It didn't sound right.

It sounds a bit far fetched to me!

I've fitted rolls loft insulation, which work well (certainly reduced our central heating usage). Our integral garage has just been converted into a bedroom and the ceiling, floor and walls were insulation with Celotex type material (winter will be the real test), but I have far more faith in the material (and the builder) than "cream".

My take on it is that you have to have a relatively thick layer of material, which heat can't easily pass through. In other words trapping the heat in the house rather than losing to the external atmosphere.

Some relatives had insulation injected into their exterior cavity walls. The material injected was similar to polystyrene balls. That seems to work well too - it's certainly reduced their central heating usage.

smart51

Ask them to post you a free sample tube of the material so you can investigate. I'd have thought you could apply it to one side of a small sheet of timber, then position the timber over a heater (radiator). Use a thermometer before and after applying the "cream" to monitor the rate at which the temperature climbs.

Celotex is really good. I lined a wall in our house that suffered from damp due to condensation [no cavity walls] with 25mm celotex and it has made a huge difference in the room and solved the condensation issue.

This stuff presumably works by waterproofing the bricks rather than by it having insulating properties in its own right.

If the bricks are wet then latent heat of evaporation will mean that energy will be removed as the water evaporates and the brick will cool. However, assuming that you have a double skinned wall with a layer of insulation between the two, I cannot see it making much of a difference unless you have a real damp problem. I would imagine that most of the energy to evaporate water from an external brick will come from external heat sources (i.e. sunshine and ambient air temperature).

The people on Watchdog were claiming something like a 30% reduction in heating bills, which is ridiculous.

By the way, my local Wilko sells 5l tins of similar stuff, but I cannot see it on their website.

Thompsons water seal, Wickes equivallent etc. Do the same by waterproofing the brick.

Must be done after a long dry spell when the walls are completely dry otherwise it will trap moisture in.