Normal for external air/vent grille to be below ground?

diymonkey

Hi everyone,

With the last few days of relentless downpours of rain, we got minor flooding in our recently moved home basement. I have been trying to suss out where this water has come from, including checking drains with camera, colour dye etc, but no explanation.

But it's only today I've noticed that from all air/vent grilles going around the house, one is half buried under the ground. I'm pretty sure they should be totally above ground and my suspicion is that previous owner has built a flagstone patio, not thinking that by burying bottom half of the grille may cause flooding.

Is this normal? Any advice would be greatly appreciated.

Ruski

Hmm.. will water pour though an open vent below ground level....

I suspect that you didn't really need to ask this question

Russ

diymonkey

Thanks ruski. Sorry I wasn't clear in my previous question. What I was trying to ask was whether it's normal to have an air grille half in ground and half out.

Also what do you suggest to fix this issue?

Annie1960

French drain? Easy to do.

diymonkey

Thanks Annie. How would a french drain that's higher than the air grille stop water getting through the grille?

FreeBear

diymonkey wrote: »

What I was trying to ask was whether it's normal to have an air grille half in ground and half out.

No it is not normal - You will have to dig out the ground around the vent, aiming for a minimum of 50mm clearance (150mm would be better).

Whilst a french drain would help (it is basically a channel dug around the house and filled with gravel), it still needs to be below the level of the vent.

diymonkey

Thanks freebear. This is what the current one looks like:

.

As you can see from the photo, the previous owner has built a flagged patio covering half of the air grille. My suspicion is that rain water will be getting inside the house and into the cellar.

The rest are above ground by about 5cm.

silvercar

Do you need that grill? If not seal it off.

Annie1960

silvercar wrote: »

Do you need that grill? If not seal it off.

Or seal off the bottom half of the grille and leave the rest. There must be a good reason for the grille to be there, so try to keep at least some of it.

diymonkey

The house has got something like 8--10 grilles and I'm not sure how many are required. Chances are though it's not required. If I could seal it, what's the best way?

Davesnave

Are you sure the water came through the grille?

It would be unusual for a patio to slope towards the house and a grille in that position would normally be in quite a dry position. Which way does the patio slope?

Basements typically flood through the floors in extreme weather.