Loft Insulation Overlay - is it worth doing?

[kent]

Hi Like many people, with soaring energy bills, I'm wondering whether to incre ase the amount of insulation in our loft. At first sight, this seems to be a no-brainer, but I've read about this causing condensation problems which might be expensive (or even impossible) to solve. At the moment we have insulation up to the top of the joists and have never had any condensation problems and I don't know what to do! I suppose I could buy 1 roll at a time, monitor the condensation situation, and stop if it starts to occur! I'd be grateful for advice from anyone with experience of this. Many thanks.

[Martin Brown]

Best value for money is to make the insulation thicker over the parts of the house that are the warmest. I have double the nominal 12" thickness over the region nearest to the fireplace. Radiospares sell/sold (slightly expensive) LCD thermometer telltales that you can use to figure out where are the warm and cold spots.

And usual rules of not covering mains cables etc apply.

The main thing seems to be not to block off the ventilation and make sure that there are no exposed pipes that can freeze if as a result of decreased heat leakgage the roofspace suffers an internal frost.

[Nightjar]

Sign outside a local army surplus store:

Beat the energy costs Thermal underwear now in stock.

Colin Bignell

[Nick]

Now sold out.

[Weatherlawyer]

I just bought a sleeping bag to put around my legs so I can enjoy sitting at the desk till all hours of the night without worrying about the cold or the bill.

Warm as toast. (Small pleasures take some of the sting out of getting old.)

[Brian Gaff]

Just do it. I did and have seen no increase in the condensation at all. I think the key is that you need to have other good insuulation too, and some ventilation. The bigger the difference on the next coldest place will get the condensation. In my house its a few older double glazed ally windows with no break between inner and outer frames, but its a relatively easy thing to just wipe them over on very cold days. A lot of people also have issues with heat loss and drafts through the floorboards under the house, and I'm surprised no enterprising company has not set up to fix this also by now!

Brian

[kent]

Hi Brian Apparently the condensation can occur in the loft itself, in the long term leading to rotting joists etc.

[Martin Brown]

Only if you have a leak of warm damp air into the loft and ninadequate ventilation. If the air flow is adequate there shouldn't be a problem.

The only time I have seen loft condensation problems was when someone had blocked up all vents at the eaves and the woodwork was dripping.

[John Rumm]

Ideally you want to prevent moisture from the house making it into the loft. So nice well sealed loft hatch, seal up gaps round pipes etc. Then ensure the loft itself has adequate eves ventilation.

Look at the type of underfelt used under the tiles. If its not a breathable one, then you could also cut away a strip a few inched high near the ridge to allow some extra ventilation there.

[RJH]

I'd guess my house was a victim of some loft insulation scheme - fibreglass fairly stuffed between wall, ceiling and roof tiles. Effectively stopping any flow of air between the eaves and the roof void.