Airbricks/Damp Proof Course/Pathway - Advice wanted

Qualitee

Hi,

I would appreciate any qualified opinions please as to what level I should lay my paving slabs at the front of my house which is a 3 bed semi.

Our valuation survey states that the damp proof course has been bridged.

Having taken up the floorboards we have found absolutely rotten joists which we will be replacing along with floorboards.

I have removed all the front path/'patio' which was just 6/7" concrete and rubble. However, after doing that we finally found the space for the airbrick under the rendering. It had been filled with a piece of stone and then filled with expanding foam. We have now placed an airbrick in the space. The airbrick is in the void of the front room.

My first question is where do you think the dpc will be?

Is it supposed to be 2 bricks above the airbrick (at this moment in time we cannot find any trace of it if it is 2 bricks below the airbrick.

My second question is where should my pathway be from the airbrick?
I am thinking from all the research I have carried out and continuously looking at my neighbour's frontage that it should also be 2 bricks below the airbrick.

I have moved the soil away from the bricks (2 bricks deep - well actually it is stone). In between the stones is filled with soil. We are looking at having the front re-rendered with a kick plinth and galvanised drainage and put in a slabbed path which will slope/low step down to meet with the pathway at the side of the house. We are on a slight slope in the street.

Any opinions/advice please?

Thanks.

Furts

A typical detail would be a path set at least 150mm below a dpc, with a margin of pipe bedding, or pea gravel, with a width of around 100mm set against the home.

The air bricks need to get air so these have to be above ground level, so this will be your guide on levels.

A typical dpc level will run under your front and back door cills. The builder will have sat the frames on the dpc when brickwork was started.

Older houses could have a bitumen dpc, or slates, or no dpc at all - semi engineering bricks are very water resistant and this type of brick may have been used beneath the ground.

Be careful with re-rendering. A typical detail is to stop the render at dpc with a bellcast bead. This gives 150mm distance to the ground to prevent splash back from falling rain, plus stopping rising damp damaging the render.

Hope this helps - best of luck with your work.

Davesnave

The other thing to think about is whether other air bricks have been similarly compromised.

One air brick isn't enough and a through flow of air is desirable. From memory, we had about 4 or 5 altogether on our old semi-dee.

Furts

Davesnave is spot on. Realistically one needs to think of the wind direction, and cross flow of air. So ask yourself which elevations are best for air bricks? Typical centres would be 1800mm for these.

Qualitee

Hi,

Thank you for your reply and sorry for delay in returning.

After taking up the pathway and digging down a long way we have found where the airbrick should be. Obviously from the outside it was covered over by the raised soil and concrete. Having taken up the floorboards also we have removed the brick and filler that was used to fill it in.

We have now replaced all this with an airbrick and vent.

Has taken a long while but got there in the end.

Thank you again.

Qualitee

At the front of the house it really does look like there was originally only one airbrick. The house is 1920's. It is dry stone in the void and up to the airbrick.

From inside the void the side wall where I am assuming other airbricks should be to allow free flow are in fact red brick so I am thinking we should remove a brick from each alcove in the room and replace with an airbrick.

Having said that, behind the skirting board there is a gap in the plaster where I think a (the internal ) vent should be (probably was originally) to allow the air to flow through to the living room to ensure free flow of air and to ensure the room is freezing cold in winter LOL!

The chimney stack has been removed and the fireplace blocked in. We have put a vent in the blocked in fireplace but I am wondering if that is as much use as a chocolate teapot as the stack has been removed!?