Waters are rising by my house, time to block some airbricks.
Problem is that some have difficult access being blocked by gas pipes and downpipes (stupidly installed by previous owners).
As an adhoc blocker, I'm thinking of getting plastic bags and filling them with expanding foam, held against the airbrick.
Any comments?
Any problems later trying to clean up?
Thanks
build a small wall around the air brick to make a sump, drop pump in hole to keep the water below the air brick and to get rid of ground water that will come out of air brick from the underfloor cavity.
On Thursday 13 February 2014 07:40 WeeBob wrote in uk.d-i-y:
What's the wall finish?
My inclination, if waters are rising is to screw a piece of ply over the airbrick with a big bead of mastic around it. Or cover it in expanding foam and stick it straight over the vent. And worry about removing the residue afterwards.
On one news proggy last night one poor chap had done this, only to find that the water was coming through the ground like a spring under his house in any case. Brian
Yes often as a friend found out. Holes exist in terraced houses between premises, so if they get an underfloor leak, you get their water as well! Brian
If you need to go and buy the mastic/silicone/whatever, choose a brick coloured one if there's any choice. Lessen the cleanup burden.
Thick draft-proofing rubber P-strip would be another option, if there's a good enough surface around the air brick.
Also check all around for pipe and cable entries which need sealing.
For doors, if you have time, make up a separate flood barrier with thick ply, rather than relying on the doors and sandbags.
You will probably need a sump pump too, as you won't be able to seal completely. Drop it blow the floorboards. Don't run any petrol engine indoors.
Also, plan to be able to disconnect all the circuits below the level of your main fuse/fusebox/meter, whichever is lowest, so that you can keep your power on if the street supply remains on.
Depending where your phone line enters and the height of the first cable join, you might again plan to have a working phone upstairs even if the downstairs wiring has to be disconnected because it's submerged.
The foam won't go off inside a plastic bag. Use bits of ply and silicon. Or us the foam alone.
In message , Brian_Gaff writes
Which is why you really need a sump pump as well, to pump out water that comes up under the floor. A big part of flood protection is getting rid of the water that will make it's way in, so as to keep things at bay until the flooding recedes.
Visions of canute here I'm afraid.
Jim K
I've thinking about this. Would a big sticky wodge of clay work? No idea where you would get some if you don't happen to have a clay subsoil.
At least it would be easy to mould around pipes/wires etc passing through airbricks and easy to remove afterwards. Maybe a builders merchant could suggest some sort of non-drying, non-soluble calking stuff?
As others have said though, you'll really want a sump pump to stop the water rising though the floor after you've blocked the air bricks. Submersible electric (with generator back-up) would be the simplest option.
Good luck!
Tim
Both sand and clay are easily washed away.
Sand would certainly be washed away, but a thick wodge of plastic clay is remarkably sticky and resistant to being washed away. I have some sacks of same (I do a bit of studio pottery), and if I were in a flooding area, I'd stuff up all the air bricks and seal around all the doors with sausages of the stuff, rammed well home, possibly with a few sandbags in front to divert any flowing water away and stop scouring.
Wouldn't stop ground-water coming up through the floor though, or water coming up through the sewers and overflowing the toilet.
A bund all round the garden, or a well-made 4 ft. brick wall with deep foundations, gravel-filled drainage channels across the garden (they could double as paths) leading to a sump and a pump in a shed to cope with anything that leaked through. You'd have to do something about the driveway and car access though, but I guess a temporary barrier could be devised.
This must depend what your subsoil is. If you are on clay, say, you have some reasonable hope of keeping the water at bay, provided you can find all the holes in the building. If you are on sand, the water table will simply rise up inside your building. I am not convinced that you can pump it fast enough. (of course, this depends on you having a void under the house and not a concrete slab, but as you mentioned an air vent I assume you do have a void.)
Do not forget to block the downstairs loo!!
If you use silicone for mastic, it pulls off masonry relatively easily afterwards.
Expanding foam tends to expand with great force, beware.
NT
Yes it will! So long as there is sufficient wetness inside.
I discovered that last summer. The solution was simple though - a light spray of water into the plastic bag.
Can't help thinking that a bag of expanding foam would be likely to float away, however...
Sorry I was not explicit enough. My air-bricks are actually below ground level, but with a brick surround which you could simply fill with "raw" sand. For a more normal above-ground air brick I would suggest either a timber or plywood retainer, or just sandbags. It makes a difference of course whether you have a flowing river down the side of the house, or just a lake which gradually encroaches on you as the level rises.
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