damp underfloor space

[spope1]

Hi,

Ive been doing some work under my ground floor (is suspended floor on wooden joists), is a typical 1920's semi with exposed wall whcih has been rendered.

I've noticed that in one area under the stairs the walls down there are visibly wet and moist, the woods appears all fine no rot or condensation, but i'm worried that it could lead to this if i'm not careful.

The wall in question is outside wall on the side of the house, it has two air bricks which appear unblocked at ground level. The damp looks like its coming from the ground upwards and is most noticable in one corner.

The drains for the house run along this wall also (I presume, as there all on this side). Could it be broken drains? Just typical damp issues down here? Should it be bone dry down there?

Any help would be good.

Cheers,

Simon

 

[regsmyth]

I'm assuming you mean the dampness is below floor level, and that you wouldn't normally realise it's there.

Are there signs of dampness above the floor?

You should be able to assess if the vents are clear or not, and if not, clear them.

Dig a thin screwdriver into the timber to check structural integrity, particularly timbers that are built into the wall - any softness will indicate a problem that needs sorting.

The problem could just be a local effect of the normal (relatively high) house humidity condensing in a cool and unventilated spot. When the floor goes back down, the condensation may well disappear over time.

If there is a damp proof course in your wall, it would be at about floor level, so you would expect some dampness in the walls below this if you live in a damp area.

 

[spope1]

Think the end of the two of floor joists have rotten, have a look at the pics, are these treatable as they are? or do i need these replacing?

I know i'll need to sort out the ventilation problems, more airbricks, cross flow etc.

Thanks for advice.


http://imageshack.us/photo/my-images/651/img0202zl.jpg/

http://imageshack.us/photo/my-images/62/img0201cy.jpg/

http://imageshack.us/photo/my-images/835/img0199wn.jpg/

 

[regsmyth]

Difficult to tell from the photos. I can't quite tell if the joist goes into the wall or if it's sitting on the jutting brick.

If it's sitting on a jutting brick and the end of the joist is clear of the wall and dry, and only the bottom bit is soft, you could carefully cut away the bad bit, and replace with a suitably preserved packer, with some dpm underneath it.

If it goes into the wall, any softness in the timber within the wall will result in the joist gradually sinking, so the floor will become bouncy.
Treatment not likely to be successful, as you can't stop the wood getting damp from the wall. You can saturate it in a suitable wood preserver, but you'll only delay the problem, not eliminate it.
A cure is to cut off the rotted end, and splice a new end on, wrapped in polythene so it won't get damp from the wall. There are other ways too, but none of them very straightforward.

You might have to try digging away the mortar from around the joist to have a better look.

 

[spope1]

Yeah its sitting on jutted bricks.

Thanks for the info, i've got rentokil coming in next week to have a look.

If they said replace the joists would that be unreasonable? Or is a repair job?

Also this can be done without pulling up the floor above? Ive got wooden floors laid etc wouldn't be ideal.

Many thanks.

 

[regsmyth]

If it's only as bad as it appears, I reckon it can be done with just a few boards lifted. If you were to take up the whole floor it can make the levelling exercise a bit more awkward.