New build house - air bricks placed incorrectly?

pinkcloud17

I am about to move into a new build Barratt home and became concerned when I noticed that the front garden slopes towards my house in 2 directions. This in itself is a concern because I feel the grass could become waterlogged.

I looked back at previous photos to check if I could see if Barratt had put in anything to help with drainage before the turf was laid. This brought my attention to the fact there are two air bricks, one of which has now been completely submerged by the turf and the other one is partially submerged. 

Checked NHBC and it states that air bricks should preferably be at least 75mm above ground level, between ground level and 75mm above if there is suitable drainage and a slope running away from them, or a continuous strip of lowered ground 600mm between the air bricks which is drained.
It is therefore not only concerning to me that the bricks are buried below ground level, but there is a slope in the ground running towards them! I can see that, before the turf was laid, there was a gap between the wall and the soil, and this has been filled with stones. But the turf has now been placed on top of that so there is no ventilation.

My house is timber framed with concrete bricks and it has concrete floors on the ground level which I believe are suspended. I don't know what the purpose of the air bricks is, if they are covered up. I've read that cavity walls should not have air bricks because they are designed to be water tight and moisture should not enter them. I've looked at other Barratt houses the same design on other developments and can't see air bricks anywhere. Now I'm wondering if they should even be there at all.

Just feel really confused on this because I have no idea about building. Wondering if anyone could give me advice on if the air bricks have been placed in the wrong position, if the slope in the garden needs to be changed, or if the air bricks shouldn't be there at all.

Thank you.

stuart45

If you have a suspended concrete floor it should have air bricks for ventilation, although it's not quite as important as with a timber suspended floor. With a timber framed house you need a certain amount of ventilation in the cavity, which is normally supplied by weep vents at DPC level, and above the frames.

pinkcloud17

stuart45 said:

If you have a suspended concrete floor it should have air bricks for ventilation, although it's not quite as important as with a timber suspended floor. With a timber framed house you need a certain amount of ventilation in the cavity, which is normally supplied by weep vents at DPC level, and above the frames.

Thanks. Hopefully the problem is then not quite as serious as if I had a timber floor, but the way they are positioned looks like water will definitely enter the air bricks and I'm assuming this will cause problems?

weeg

Even though it's a suspended concrete floor, there won't actually be a void underneath, so doesn't need any ventilation. It's suspended inasmuch as it's designed to span between the foundations, and the foundations are designed for the load. In practical terms though, they are (with rare exceptions) cast on to either natural ground, or on to fill, because it's cheap and easy.
That said, query the site about the air bricks.

stuart45

There's a void in the ones built in England. Every one I've worked on had a void and air bricks.
Building Regulations: Flooring | Extensions | Planning Portal
Suspended Floors - All You Need To Know - Thermohouse

pinkcloud17

weeg said:

Even though it's a suspended concrete floor, there won't actually be a void underneath, so doesn't need any ventilation. It's suspended inasmuch as it's designed to span between the foundations, and the foundations are designed for the load. In practical terms though, they are (with rare exceptions) cast on to either natural ground, or on to fill, because it's cheap and easy.
That said, query the site about the air bricks.

Thank you. I take it that no underfloor void means water entering them doesn't increase risk of flooding but it could still increase risk of damp? I've emailed the development to ask about them. I don't understand what their purpose is if there is no underfloor void? Would they be to insulate the walls? 

pinkcloud17

stuart45 said:

There's a void in the ones built in England. Every one I've worked on had a void and air bricks.
Building Regulations: Flooring | Extensions | Planning Portal
Suspended Floors - All You Need To Know - Thermohouse

Thanks. I'm referring to a Barratt house in Scotland if that helps?

stuart45

Not sure of the Regs in Scotland. The idea of a 150mm Min void is to allow for ventilation to stop any condensation forming  on the underside of the floor, or the any possible build of gases under the floor.

Ajmason42

if you are meaning the one at the end of the low wall in the middle picture my guess is they have just used bricks with holes and not finished it off properly ie filled the holes with mortar be very strange to have a tunnel of air bricks that long

stuart45

I don't think he means that brick, which is a Brick on edge finish to the top of the dwarf retaining wall.

tonyh66

Seeing you haven't had a proper answer yet,(Stuart45 was closest) the airbricks are there to provide air flow into your underfloor void. This stops the floor timbers from rotting and prevents condensation. The floor timbers sit on the internal wall and dwarf walls all above DPC level (generally 2 bricks above ground). What you have is that the gardeners have put the topsoil and turf down and ignored the level of the DPC covering the airbricks (they are in the right place BTW). You need to get onto the developers and tell them that their landscapers have bridged the DPC (assuming you paid the developers to do the garden) the level of the garden at the wall needs to come down.

Personally I wouldn't have turf right up to the edge of the house, a small gravelled area can be beneficial to drain excess water.

Having reread your OP your floor is concrete beam and block, the airbricks still should be open, from the photos you posted (now gone..) the garden is definitely bridging DPC.