Hi
I've recently bought a house in Cumbria, and have been doing some renovations. I have removed the carpet from one room and want to sand down the floor boards and have a wood floor. I was worried about it being cold, so I decided to insulate under the floor. So far so good. I lifted a few boards to have a look and fit some heating pipes for a new radiator and everything looked fine and dry underneath.
In the last week or so there's been quite a lot of rain (remind me again why I moved to the North..?) and part of the ground beneath the floor has got a bit damp - mostly it seems where rain has come in through the air bricks, but in other patches near the walls too. Practically overnight, quite a few patches of efflorescence have sprung up on (the inside of) the external walls. These patches are all beneath the floor and below the damp-proof course, and I only noticed because the floor was up.
There's nothing obvious outside the walls causing water to stay against the walls, the outside being rendered and painted and a concrete-slab path being immediately outside.
Is this something to worry about, or does the fact it's beneath the DPC mean it's not a problem?
Cheers
--Gavin