Damp and Mould under floorboards

[awood86]

First post, but always read on here. Looking for a bit of information.
100+ year house, always had a bit of a damp smell in the living/dining area. Bought a dehumidifier which helped, but smell kept re-appearing so took the punt and lifted some floorboards at the weekend.
Found a lot of damp, which I kind of expected as drainage isn't great by the back door and the condenser pipe just drips onto the floor (will be getting sorted asap)
I've attached a few photos, will get some more. Should I take up all the floorboards and clean, as well as the concrete/dirt floor?

 

[awood86]

Forgot to say, I've cleaned the air bricks at the back of spiderwebs and general dirt left behind from builders and pipes from the back appear to be dry, with a bit of condensation

 

[awood86]

Some more photos

 

[JohnD]

after you have cured the sources of water, monitor it for a bit and see if it dries out.

You have some unlagged pipes under the floor, they are wasting heat and may freeze.

I'm a great believer in cleaning out subfloor voids, but it's an effort. See how much you can achieve with a powerful builder's canister vac with long tube.

BTW boiler condensate attacks concrete and turns it to sand and dust.

 

[awood86]

after you have cured the sources of water, monitor it for a bit and see if it dries out.

You have some unlagged pipes under the floor, they are wasting heat and may freeze.

I'm a great believer in cleaning out subfloor voids, but it's an effort. See how much you can achieve with a powerful builder's canister vac with long tube.

BTW boiler condensate attacks concrete and turns it to sand and dust.

Thanks for the above appreciate the info, think i'm going to pull up the boards to clean it further as I noticed this last night (photo attached), do you think I'll need the external re-pointing too for the condensate that's attacked the concrete?

 

[JohnD]

I can't see damaged pointing. If you have any, clean it away with a brush and hosepipe to sound material before repairing. If there's a lot, you can get a pointing gun, IMO they are very good.

In an older house, the oversite concrete is mostly to stop weeds growing under the floorboards, though it can slow the entry of damp a bit. It's possible to screed over it, or lay polythene sheet (and gravel to weigh it down) but in most cases, good ventilation will keep the void sufficiently dry. If not, look for sources of water such as plumbing leaks (esp the water supply pipe, and drain gullies) or building defects, such as post-build paving encouraging water to lie round the house.

BTW, if you are going to the effort of lifting the floor, add or renew any cables or pipes you might want, lag the pipes, and I'd lay Mineral Wool quilt (as used in lofts) between the joists, especially round the edges of the room, but not obstructing free air movement in the void. It's quite cheap and not much extra work. Foamed plastic slabs are good insulators, but more difficult to pack tight enough to prevent draughts. Since Grenfell, I wouldn't have them inside my house.

 

[bobasd]

awood86 i think youve got a dry rot condition or conditions in more than one place.could be caused by poor through ventilation and high grond levels.
the thin rootlike strands you can see in the photos look like dry rot hyphae and mycelium strands.
major cause might be lack of strong through ventilation.the air brick you show is not clean or big enoughand strands are all around it.
you should replace all airbricks with 9" x 6" or 9" x 9" plastic air bricks front and back.
a photo or two of the house at outside ground level will show more.show bad drainage yard.


jab the joists with a small screwdriver to see if they are soft or rotten especialy where they sit on the outside walls.

the salts you see on the soil are harmless ignore them dont go doin some nonsense vacuming the soil business.

the pipes have to come off the deck and be clipped to the joists and insulated.

whats the black membrane doing,why is it there?
laying a membrane on the soil willhelp prevent damp air rising.

condensate pipe has nothin to do with any of this but neds insulating an directing to a gulley.

what do you mean youve found a lot of damp? where? show photos