Loft insulation problem

[cath1602]

We have recently insulated our under eaves storage area. We put blanket insulation in the gaps between the roof beams, up against the roof tiles, and it is held in place with plastic sheeting.

Having (belatedly) done a bit of research, it appears that this was not the correct thing to do, and we should have used a more rigid type of insulation and left an air gap between the insulation and the roof tiles. And we should have used netting instead of plastic to hold it in place.

The area now seems very humid. Is there anything we can do to repair what we have done, or do we need to rip the whole lot out and start again?

Catherine

[Julian Ashcroft]

Start again. If you leave it like it is you will get damp problems. There should be a gap between the insulation and the tiles or felt. The insulation should be able to 'breath hence the reason for using netting (or string) to keep the insulation in place rather than plastic sheeting.

Julian Ashcroft

[David]

Rip it out and start again

While you are at it check that the ventilation in your eaves and at the ridge are adequate.

It could be worse, by the sound of it the polythene is acting as a vapour barrier, things could be far worse if it wasn't there, in which case the warm humid air would penetrate the insulation and then condense on the indside of the roof, with the problem being hidden by the insulation. This could well still be a problem and I'd advise you to get the current insulation down ASAP.

With good ventialation and a 50mm gap between the insulation and cold roof this sort of problem should be avoided.

cheers

David

[Richard Sterry]

I can understand why you should use netting not plastic, but why the air gap? The timbers are exposed on the inside, well the edges of them anyway, so they should be able to breath - why should the felting and tiles need to breath?

The problem with leaving an air gap is that if the timbers are fairly small, the inclusion of an air gap doesn't leave much depth for the insulation.

I realise that this is a requirement, and there must be a reason for it, but...?

Rick

[Rick Dipper]

I used celuotex on my sloping celilings which you cut to fit, and jam in the spaces.

its easy to leave the air gaps, its also easy to work with

Rick