My MD had his house flooded to about a meter 3 years back and is looking at ways of preventing it happening again. He has come across external doors that claim a waterproof seal to prevent water entering the house. I am not so sure that this is a good idea due to the damage the weight of water could do to the structure of his house. Do any of you have experience of this type of flood protection?
Mike
Don't forget all the other ways water can get in:
Air bricks. Cavity vents. Conduits for services (power, gas, phone etc). Drains.
No, but how do you stop the drains backing up?
We have some but have not used them yet. I was told by the salesman that they are the height they are and no more is because above that height the pressure of the water could structurally damage many buildings. It was reckoned to be better to have the building flooded if the water came above the height of the flood doors.
Jonathan
I forgot to add you also need barriers for air bricks and downstairs plumbing if appropriate.
Jonathan
We did have a house with flood boards fitted, but the water never got deeper than a couple of layers of sandbags could cope with. However, there are other things you need to consider:
Airbricks - Best option is to replace with flood-proof airbricks or to fit an automatic cover, but a few sandbags work perfectly well, if you are there to put them in place when needed. (You can never have too many sandbags, but empty them after use, dry them and store them carefully away from sunlight)
Downstairs WC - If the water outside gets higher than the rim, it will overflow through backflow up the drains. You need to fit a reflux valve in the sewer to prevent this. Make sure it is between the WC and the first manhole cover or blind entry shared sewer. However, reflux valves can increase the risk of the drains blocking. It will also protect an upstairs WC, but you do have to hope the water won't get that high.
If the water get high enough to start coming through the kitchen sink or handbasins, you are probably getting to the point when you want the water inside, to balance the pressure of water outside, but the can be fitted with anti-backflow valves too.
Older properties may not have over site concrete, so water coming up through the ground under the floor is a possibility in some cases.
I also found it useful to fit a float switch outside, connected to a battery operated door bell, so we could get up and worry if, as usually seemed to happen, the flood came at night.
Of course the ultimate flood protection, provided you protect the drains, is to build a high bank around the entire house and garden, as it was reported that a farmer did a few years ago.
Colin Bignell
Dave Liquorice wrote on 15/02/2011 :
And through the masonary itself. I suspect you could only do any good, if the flooding was limited to a few hours only. Over a more prolonged period the water will find other ways in.
A better way, if it can possibly be done (garden etc.), is a barrier around the entire boundary, then what does get through that can be pumped out.
I've seen this, in an inadequately waterproofed built-on-the- side-of-a-hill data-centre when the water table got 'a bit high' on the uphill side.
First, a small jet of water issuing from a crack in the interior render.
Second, a large, expanding bulge spreading across/up the wall.
Third, several bucketloads of render spread across the carpet-tiles as an area of about a square yard 'blew'.
Fourth, several inches of water in the floor-void, and an emergency shutdown of the facility.
Fifth, some interesting activity by lawyers.
----- Original Message ----- From: "Harry Bloomfield" Newsgroups: uk.d-i-y
any good,
prolonged
only sane solution.
That's how they drain the Fens..
But as peepul have menshunned that's only as good as the drains are..
Nothing like watching other peepul's turds invading over the downstairs loo rim.
Is it permitted to create a (say) one-storey high mound and build the house on top of that?
downstairs=20
Surely floating houses on rafts are the way to go? ;-)
Tim2
Apart from the obvious entry points - doors, air bricks etc many of the estate houses in our village were flooded in 2007 through the damp proof course not being a watertight seal to horizontal water pressure. That effectively knackered all the panic response prevention measures such as clay over the airbricks and boards across the door bottoms.
if planning says so,yes. yu sane way to build on flod plains. make your roads a storey high, and your houses have no habitable ground floor spaces. Just garages etc.
So all bogs above flood level and all gardens surrounded by levees.
That won't help when the next mile-diameter asteroid hits mid-atlantic. Look forward to a 3000-ft wave sweeping right across the whole country.
The best way is not to build where there is a risk of regular(*) flooding.
If you have a pump of suffcient capacity to cope with the seepage and/or over topping rate.
(*) "Regular" being any frequency greater than about once very ten years but even that is a bit too often really. I wouldn't contemplate a property less than 15 vertical feet above *any* water course or 50 vertical feet above a major river. Getting flooded is not fun.
It happens that Dave Liquorice formulated :
We are on a local high spot and some 130 feet above the river level - I did used to suffer a garage flood in bad weather, now sorted. That was annoying enough, but pales in comparison to the house flooding.
When my sister lived on Canvey Island they had a floating patio - just in case. It was anchored with a few fathoms of stout chain to the foundations of the garage, IIRC.
Build on stilts. In the dry season, you can park your car underneath.
It might not need that much. New houses built around here, next to a river, simply have the ground floor raised by about a metre. The road is above the 50 year flood risk level and, when it has flooded, I've not seen more than about 200mm of water.
Colin Bignell
In my working life I worked at many hilltop sites. One got flooded in about
1972 it was just a few feet down from the top.Another site was flooded in the late 90s. The PTB said it was a one off. No steps were made (apart from cleaning out a drain) to mitigate the problem (site again slightly below the summit, U shaped building with the U pointing uphill, French drain originally protected, but filled in as part of building work by those not knowing its significance). After I retired the same thing (as I predicted) happened again. I think it was then fixed properly.
Neither site was above /any/ normal watercourse, but storm water finds its own course.
I think I'm reasonably safe here, 100' above the river.
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