DPC and air brick levels

iamlucky18

Hey guys,

I know that the DPC layer should be a couple of bricks above ground level. Should the air bricks be lying on this layer, or a course below it (i.e. the top of the air brick at the DPC level).

The side of the house the air bricks are at ground level, which in my opinion isn't good practice. Should I get the ground level lowered? I'm getting paving done so this would be an opportunity if required.

Cheers.

Furts

There is no set rule and it varies. The air brick is to get ventilation under the floor so logically it will be set below the dpc level. On modern houses it can be higher.

iamlucky18

Thanks for the swift reply furts.

I know for a fact that the joists in the front living room are at air brick level. My concern is that if the DPC is at the top edge of the air brick, rising damp can eventually lead to rot. I had a quick look underneath the floor boards and I can see some white substance on a joist where it meets the brick. It doesn't look like fungal growth/rot, plus there's some of the white substance on neighboring brickwork. Efflorescence may be?

Furts

It can vary - one reason being if you have cavity walls or solid walls. But in principle joists would be laid on a dpc, or on a slate course, or on a wall that is not going to get wet. If they get damp then the air bricks provide the ventilation to keep them dry.

Even if your joists are on a damp wall bear in mind that old engineering brick walls are barely porous, old timber was better quality than today and the joists ends may have been brushed, or soaked, in preservative like creosote. Hence the joists last for generations.