Vents in attic

Colm R

After insulating attic - and ensuring a gap between the top of the walls and roof allowing air up from the eaves, I have noticed that there is a very light layer of condensation on the underside of the felt for the past few nights. Its very slight and not hugely concerning.

Its the old style non-breathable felt. The house is south facing (30 years old) It only appears on the North Side of the roof. The gable walls accessible at both ends. I plan to put vents in at either end to help the circulation of air. Although I am getting conflicting advice about where to put them.

Some say both high up near the top of the roof. Some say one low, and one high, and others say both low.

Any suggestions?

MicktheMan

High up or low down, it make no odds really once they're there and cross ventilation is possible.


Other things to consider are how is the main house ventilated and is it easy for moisture laden air to make its way into the attic from inside the house through gaps and holes in the ceiling (think recessed lights, attic access hatch, cable/pipe penetrations).

Colm R

MicktheMan wrote: »

High up or low down, it make no odds really once they're there and cross ventilation is possible.


Other things to consider are how is the main house ventilated and is it easy for moisture laden air to make its way into the attic from inside the house through gaps and holes in the ceiling (think recessed lights, attic access hatch, cable/pipe penetrations).

Oh I have loads of those things to sort out alright - lots of work still going on in my house which we are living in. Not least ventilating the house directly to outside and closing up so many gaps - so many tradesmen doing work still so its hard to keep on top of the battle, sorry, I mean renovation.

fg10291

High up and lowdown together work best , avoids pockets of stagnant air, cross glow is all well and good but if you only have it low down, the moist air which is warmer will rise to the apex have nowhere to go and will condensate