Airbricks and DPC

[pcsparky]

I have just had a quote for a resin bound drive and path. I am happy with the quote and the explanation of how this is done.

The surface will be 14mm thick and laid on top of existing concrete. The image below shows my current path level and one of 4 airbricks along this path. After adding 14mm the bottom of the lowest openings of the airbrick would be just 18mm from the surface.

I have no problem that the new surface will be 13.6mm or thereabouts below the DPC but I would like opinions regarding the air brick arrangement.

The photo below shows the other airbricks. The contractor said that if I wanted they could replace them with single airbricks, so the bottom of the brick would be obviously further from the surface.

Would this restrict air too much? (There are four other air bricks around the corner and more on the opposite side of the bungalow).

If left as they are, would it be a problem with the risk of some water being able to get inside the air brick with a very heavy deluge of rain?

 

[Blagard]

You should not reduce the size of the airbrick.

The falls on the paving are the real issue. So long as surface water drains away from the airbrick wall I don't see why you should need to worry about anything.

 

[Nige F]

True - but a plastic airbrick half the depth will pass more air than that teracotta one , though look a bit naff

 

[tim00]

In a suspended floor(s), which you appear to have, the airbrick should sit on the DPC and locate between the joist tails. Your path appears to have been installed too high. You have a slight oversail in the brick work above the vent so it's doubtful that the DPC was mis -installed there.
You should locate the position of your DPC. If your DPC is not located directly below the airbrick then the path is too high and the joist tails are possibly exposed to fungal damage.
Check all four elevations for the DPC height vs ground levels.

 

[Blagard]

tim00,

The DPC can be seen running over the top of the airbricks, which is fine as it puts it two courses of brick high.

The manner in which the floor joists have been installed is something that is quite independant of the external DPC. Also, whilst it is common for airbricks to be installed between joists, they can be installed lower.

 

[pcsparky]

I'm taking the advice in, thanks guys. I can confirm that the DPC is definitely at the top of those air bricks.

I'm not too worried about standing water getting in to them, as I'll be getting some drainage channels installed and the slope is away from the house. I was concerned about rain bouncing in off of the surface though, would this be negligable?

 

[tim00]

Blagard, thank you, i stand corrected, i was wrong. My mind was set on a solid wall, i didn't see the DPC ( bad position for an oversail ) i merely assumed.

I should be interested to know where the joists do sit in relation to the airbricks?