Patio and air brick height

[LR90]

I recently moved into a newish house built in 2020. The patio is at the same level as the DPC which I believe is fine as there’s a French drain and a plastic channel between the house and the patio (I believe this is fairly common on newer houses).

One thing which was flagged on the survey and which I mentioned to a builder friend of mine (who said it was not ideal but wouldn't cause any problems) was the level of their air bricks. As you can see, the gravel has been raked away to preserve the air flow to the bricks, but the gaps are filling with leaves at the moment.

Obviously I’m clearing the leaves out, but is this something I need to resolve in time? We don’t have any damp that I’m aware of, but an ounce of prevention is worth a pound of cure, as they say.

It’s a bit annoying because I believe they should have fitted telescopic underfloor vents, but obviously I’d want to try and avoid retrofitting these. I’m guessing our NHBC wouldn’t cover this?

[Zetec-S]

That looks pretty similar to ours (in fact ours had more gravel in front of one of the air bricks). We've been here 10 years and not had any problems.

(although usual caveats apply to random internet comments, so hopefully someone with more knowledge of this sort of thing will be along )

[POIDH]

I have 1970's house with 1990's extensions.
Someone had done similar on ours, and within first winter we had damp coming in the area.
I dug out all gravel, lifted the 'french drain' pipe to nowhere and dug down another couple of cm, sloped away from the building.
I added drain channel tops at slab height, resting on some metal supports of galvanised u-chanel.
It now gets breeze through it, sun into it for half the year and very little leaf debris.
Most importantly all vents are very clear of obstruction and all damp gone.

[Peanut Gallery]

All the air bricks at the back of my house are a good 3 inches below the brick layer, there is a galvanised metal surround that has been made that stops gravel falling in. I try clear it out every year, but this turns into every 2 or 3 years. No problems *..

Kinda like this, but with metal, not brick https://dampandtimbertech.co.uk/index.php/2022/04/...
Trying to just post the pic -

• - I say no problems, small human managed to get the hose-pipe in there, thought it was a drain, I found it the next day when I heard running water. I have not been brave enough to go under the house yet, but it should have dried out by now!

[bigothunter]

Path around my house flooded in 2023 for the first time in over 30 years. Water ingressed via airbricks into the underfloor cavity. Airbricks are about half-brick height above ground level. Damage was extensive necessitating refurbishment of dining room, kitchen, utility room and pantry. Floor distortion cracked many tiles in three rooms forcing replacement of all tiles. Incident occurred in February and took until August to complete repairs.

Insurance company budgeted £31,000 to cover loss. My house insurance premium has tripled. We cancelled our holiday to accommodate activities.

I have arranged installation of telescopic airbricks which raise the external ports by at least 75mm. Work is scheduled for next week.

Must avoid this nightmare happening again

[LR90]

bigothunter said:

Path around my house flooded in 2023 for the first time in over 30 years. Water ingressed via airbricks into the underfloor cavity. Airbricks are about half-brick height above ground level. Damage was extensive necessitating refurbishment of dining room, kitchen, utility room and pantry. Floor distortion cracked many tiles in three rooms forcing replacement of all tiles. Incident occurred in February and took until August to complete repairs.

Insurance company budgeted £31,000 to cover loss. My house insurance premium has tripled. We cancelled our holiday to accommodate activities.

I have arranged installation of telescopic airbricks which raise the external ports by at least 75mm. Work is scheduled for next week.

Must avoid this nightmare happening again

Ouch. You have my sympathies. That sounds awful but glad you've got it all sorted and the insurance paid out. Was that with a timber suspended floor or a concrete one?

And, if you don't mind my asking, roughly how much is the installation of the telescopic airbricks costing you? It probably wouldn't be worth us doing as I can't see us being flooded here, but it's worth knowing.

[bigothunter]

LR90 said:

Ouch. You have my sympathies. That sounds awful but glad you've got it all sorted and the insurance paid out. Was that with a timber suspended floor or a concrete one?

And, if you don't mind my asking, roughly how much is the installation of the telescopic airbricks costing you? It probably wouldn't be worth us doing as I can't see us being flooded here, but it's worth knowing.

Ground level is floor boards suspended on joists with cavity beneath. House was built in 1959.

There are 13 airbricks around the periphery. Estimate for telescopic airbrick purchase/installation is £720 which is very reasonable.

The house is rated as Very Low Flood Risk in all aspects on the government website. Regardless without remedial action, I could find myself with an uninsurable and unsaleable property after the underfloor flooding incident.

[Glosphil]

In the late 1980s our 1970s house flooded under its floor via the air bricks when the drainage on the sloping games field behind was blocked. We suffered no damp & the 6" of water under the suspended chipboard floor disappeared in just over a week - I've no idea how.

[LR90]

bigothunter said:

Ground level is floor boards suspended on joists with cavity beneath. House was built in 1959.

There are 13 airbricks around the periphery. Estimate for telescopic airbrick purchase/installation is £720 which is very reasonable.

The house is rated as Very Low Flood Risk in all aspects on the government website. Regardless without remedial action, I could find myself with an uninsurable and unsaleable property after the underfloor flooding incident.

Thanks. That does seem very reasonable, I must say.

[LR90]

Glosphil said:

In the late 1980s our 1970s house flooded under its floor via the air bricks when the drainage on the sloping games field behind was blocked. We suffered no damp & the 6" of water under the suspended chipboard floor disappeared in just over a week - I've no idea how.

That's pretty amazing!

We've got a concrete suspended floor, so I suspect any flooding (which I think would be very, very unlikely for us anyway) would have less of an effect.