Further suspended floor insulation thoughts

[visionset]

I am concerned about condensation is this rational? Simplest solution (since these are bare board floors and draught is the primary symptom) is to use plastic sheeting stapled to the joists. At the other end of the scale is fibreglass rolls and something like that black garden matting to keep it up, keep it out of my hair when I'm under there and hopefully futher draught exclude whilst leaving it breathable. Cheapest breathable sheet solution anyone and supplier? (EG garden centres == £££)

-- Mike W

[Andy]

I used rocwool roll held up by wires stretched between nails hammered into the joists. It worked but I wouldn't recommend it. You might consider plastic mesh on a roll, that's pretty breathable. You'll still need long gloves, goggles, boiler suit, hat ( or use a disposable boiler suit with a hood ), mask and a scarf to seal your neck if you're handling rockwool from underneath.

Andy.

[Phil L]

Cavity batts would probably be easier to handle and they give off less dust...either way, you are going to end up cutting it/them to fit between the joists, but cavity batts are more rigid and you could do the whole lot before aplying the netting,(this is available in metre wide rolls) another choice here would be breathable sarking (roof felt) but it's quite expensive...an added bonus with sarking is that the insulation is 'sealed' and not going to cover you with dust each time you go down there (assuming it's a cellar?)

[Pete C]

Hi,

I'd look at a foil radiant heat barrier. Breathable ones are available, or ones including a layer of bubblewrap.

They work best where the heat flow is down, so should work quite well as underfloor insulation.

Because the foil surface radiates very little heat and so stays warmer, there is less risk of condensation. The layer of bubble wrap would help too.

cheers, Pete.