Am I insulating wrongly?

[bonzerpeach]

Have an old house in France, cold stone walls etc. I have put a stud frame on a couple of walls and am covering this with tongue and groove. The space is about 1.5 inches. wall to wood. I bought some insulating material - not a lot of choice in this neck of the woods - which consists of three lays of aluminium/silver foil with very thin synethetic wool in between. It is just about an inch thick so the gaps between it and the wood and the wall is very small or non existent. The instructions (in French) tell me to leave 2 cms either side of the insulation, but I don't have that space. Will the product be effective or should I save it for another job and buy something else? If the latter, what should that something else be? Thanks in advance

 

[Deluks]

Yeh, you are supposed to counterbatten so that their is an airspace both sides of the insulation. See if you can track down some mineral/rockwool slabs, or celotex/kingspan type stuff. You might need a vapour membrane behind the t&g.

Is the space wall to wood (stud) or wall to wood (t&g)

 

[bonzerpeach]

Thanks for response. The 1.5 inches is the wall (stone) to the tongue and groove. I had a separate response from a commercial company selling Low-E insulation which is only 6mm thick and sounds suitable but it is not sold in France.

The area to be insulated is not large and maybe I just have to live with what i have. Is an empty cavity better than a filled one, though? I have put in the foil and it fits OK - just does not leave the desired space either side

 

[Deluks]

Upto you, do you want to be warm or do you want the extra inch of room space?

Full void is much better than empty cavity, but consider how cold it will be in the winter, what the windows are made of, roof insulation and decide from there.

What's this 6mm insulation? It's probably just silvery bubblewrap, not much use other than for sheds really.

Seriously consider adding counterbattens before fixing the cladding.

 

[bonzerpeach]

The extra inch is nothing - but the thick battens are up after much hard work drilling into mortar and concrete and most of the T&G is in place. On this room I cannot go back and it is a question of making the best of a poor initial choice.

The 6mm insulation - see this website www.low-e.co.uk Sounds OK?

 

[Deluks]

The extra inch is nothing - but the thick battens are up after much hard work drilling into mortar and concrete and most of the T&G is in place. On this room I cannot go back and it is a question of making the best of a poor initial choice.

The existing battens can stay. You affix the insulation to the battens with staples and then fix new battens atop the existing. This will give something of an air space both sides and will be closer to the installation guidelines than what you are proposing.

The 6mm insulation - see this website www.low-e.co.uk Sounds OK?

No. Snake oil.

Looks like they are trying to blind potential customers with science.

Here is a quote:

"The primary function of Low-E Insulation is to reduce the transfer of radiant energy."

I seem to remember reading something somewhere many years ago (don't ask for reference!) about those silver survival blankets (like those that they give to marathon runners.)


The manufacturers claimed that they reflect back 90% of body heat lost through radiation. Sounds impressive but the upshot was that only 10% of heat is lost in this way, so in effect they only keep you 9% warmer. The article was about their uses as survival blankets, I'm sure that they still have use to a marathon runner (keep the wind off?)

So the point is that all facts and figures can be manipulated to suits your purpose (just ask our ex- PM) and that this stuff will be a waste of money.