On 13/02/14 12:52, Janet wrote:
In article , says...

"Martin" wrote in message

If you do use sandbags put them on a plastic membrane with the rest of the
plastic on the side facing the flood.

If your flood is from a river that's broken its banks, the force of
fast-flowing water current (and debris it carries) can tear dislodge
or wash away any plastic sheets laid that way. When we lived in a flood
area in Hereford we always laid the sandbags as the outer defence to
protect the waterproof plastic sheet, while pressing it as tight as
possible against the building fabric to protect the points where water
(and suspended mud) could enter.

Place the plastic with a flat strip on the ground (will be pinned
down by sandbag weight), rising up folded into an L against the outer
wall of the building. Build a wall against it with sandbags, kicking
them in hard so they compress the plastic tight against the building to
block the airbrick holes, door frames etc.

People could do worse than look at how the "professional" flood
barriers are constructed, e.g.
http://www.bristolpost.co.uk/picture...ictures.html#2
http://www.bristolpost.co.uk/picture...ctures.html#26
http://www.bristolpost.co.uk/picture...ctures.html#29
http://www.bristolpost.co.uk/picture...ctures.html#43
http://www.bristolpost.co.uk/picture...ctures.html#50

I suspect that if agencies gave "too precise" instructions then
some people might have a claim against them if other forms of
damage occurred.

One thing that springs to mind is that if
an outer leaf is used to hold back a flood, then if the water
is too deep it will simply be pushed inwards causing significant
structural failure. If, OTOH, the water had not been kept out
of the house, there would be not pressure differential and no
collapse.

No, I don't know what "too deep" means, and undoubtedly it
varies between properties.