Wall cavity.

millerman said:

Thanks guys, the idea of debris bridging the cavity sounds like a possibility. Mold was at skirting level raising up about 8 - 10 inches, in the hallway it was behind a shoe cupboard, in the lounge/diner it was near patio doors. Cant show you the mold because we have cleaned up the walls with a bleach solution.

Click to expand...

That could be condensation, any house with humans in it will generate water, if you don't have enough ventilation, for example behind furniture, in the corners of rooms or areas that are lightly heated, you can get enough condensation to allow mould (British spelling for the win) to grow.

As part of a cavity wall survey they will check the cavity to see if they're clear or not, so getting someone around to quote might be a two for one. On the other hand I wouldn't get the CWI installed until you were sure you were sorted on any damp first.

ted456 said:

Interstitial Condensation explanation: warm air moves from inside the house into the cavity, where it can reach Dew Point, and Condense to form Water.

Click to expand...

out of interest, where is the warm air or vapour getting through -is it through the inner skin, ie unplastered blockwork behind baths, in between floor joists or through an open loft cavity.

My understanding for insulated lofts at floor level was that the insulation runs across the floor, finishing at wall plate on inner skin -so that eves ventilation remains open for cross ventilation of the loft void.

I'm not sure what happens if you get a frosty morning with full sunshine -that could create a warm loft that could circulate into the cavity and meet cold brickwork perhaps.

f k

Notch7, im unsure where the damp is getting thru, when i say mold is on outside walls i mean the inside wall of the cavity if that makes sense. I posted some pics of the outside of the house as req by JohnD.