Air bricks

[janz70]

hi , just been to look at a house we are thinking of putting an offer on but on leaving I noticed the block paving has been laid almost level with the top of the exterior airbricks - leaving approx only the top inch open

concerned about the DPM being breached and the ingress of water into the open airbrick incorrectly - surely this is has been laid incorrectly

 

[flameport]

surely this is has been laid incorrectly

Certainly has, so some rectification work will be needed.

Whether the DPM has been breached depends on where the DPM is (above or below the airbrick), assuming the property actually has a DPM at all.

 

[gregers]

also be concerend about 'splash'/

 

[janz70]

Im sure the surveyor will pick this up but I'll mention it so its logged in ~ It may be a price bargaining point.

What could be done to remedy this ?

done a little research and there seems a numbers of options

Remove block, dig down and then relay
Remove 2 blocks around house perimeterand, dig trench down below airbrick / DPM and put in a gravel soakaway

If the DPM is above blocks, its still unlikely to be 150mm above ground level (unless its 2 courses above the airbricks) but if it is could an S-type airbrick be used to bring it well above ground level

 

[Mattboyslim]

i'm a builder and have done quite a few block paving drives - personally i would remove a couple bricks from around the house and dig a 200mm trench around the it, then put 50mm of gravel around to tidy it up.

as for a damp proof course is it a brick house? if so then have a look at an external doorway and the dpm should run along the level of the threshold.

 

[^woody^]

You only need a 100mm gap in front of the air bricks, so you can form a trough just in front of each air brick with the soil being retained by some slate or tile and some gravel in the bottom to allow drainage.

These become a leaf and debris trap so you need to clear out regularly, or better sill form a grid-like cover out of some metal or plastic or mesh which sits flush with the paving

I'm not sure what you mean about the "DPM" being breached, but air bricks are normally below the damp-course

 

[noseall]

I'm not sure what you mean about the "DPM" being breached, but air bricks are normally below the damp-course

I think the o.p. was referring to the paving height breaching the dpc.

The o.p. needs to remove all the material surrounding the air brick and create a kind of trough that allows the entire air brick to function. This can be achieved by laying three bricks on edge in front of the air brick.

It will likely attract leaves and rubbish so will need regularly cleaning out.

 

[janz70]

correct - as said the airbricks are 90% covered by the blocks, so even if not technically breaching the DPC ie above, it is to close to ground level so would get splash back etc, so a trench all round house is the easiest option I think, it will certainly be easier than lifting it all, digging down and relaying.