air bricks

[scrapmandave]

Hi my mate has just bought a 1930's house and he were advised to have a few air bricks fitted on the back of the house as there was a bit of damp getting in and there are no air bricks fitted. Where should the air bricks be? Above the damp course or below it? Should it also go straight through the cavity for the joists aswell, thanks for any help given.

 

[gregers]

if there is enough room then put them under the dpc beaware for the splash factor!!!!,if not then put them above.
i would use plastic 9x6 louvered vents as they are approx 65% efficient.
we used to put them approx 1-1.5 m apart,im sure there is a guide somewhere?

 

[scrapmandave]

is it ok to put airbricks in without putting the liners in? just knock a couple of bricks out on the inside so air can get through the airbrick and vent the joists

 

[noseall]

It is irrelevant where your dpc is if you intend venting the floor space.

Look at where the finished floor boards are and work down from this. It is possible to vent the floor space within the thickness of the joists.

Always use a liner to transfer the vent from inner to outer leaves as this is the correct (robust) way, besides you never know you may want to install cavity insulation.

I have seen vents located a differing heights relative to floor level as there are telescopic vent ducts available that allow you to transfer the height of the exhaust vent a fair bit higher or lower than the floor void.