Penetrating or rising damp problem

[anobium]

Gordon B11 wrote

I am in the process of buying the house.

Tell the vendors to sort out the problem or else you won't buy the house.
PS, also tell them you want a written insurance backed guarantee that it will not return for at least 20 years.
If they say no, get several estimates for what ever needs doing and deduct the cost of the most expensive and reliable off the price of the house.
Problem solved.

 

[GordonB11]

Thanks for the suggestions and such clear and useful diagrams - very informative.

In response to the points raised:

Tell the vendors to sort out the problem or else you won't buy the house.

Too late, have now exchanged.

I wonder where your airbricks are

They are in the next but one course above the outer skin dpc - in the photo below, the damp course runs in the mortar course above the cable.

possible, but not easy, to get a lot out with a powerful aquavac

I think, in the first instance, I'll try to access the cavity via 2-3 points on then outside wall in the row below the dpc, and the hole in the inner wall under the floorboards (under the inner dpc).

At each point I'll remove two bricks & see if I can clear out the cavities at the 3 levels of bridging (from my intitial probings): just above the outer dpc & above & below the inner dpc.

Unless anyone knows or can suggest any better solutions: I'm going to try a combination of:
- scraping out using a shave hook or similar
- attaching, somehow, the shave hook to some flexible pipe to get a longer reach - maybe plastic water feed pipe?
-using a hose on a vacuum to aid the above or vice versa. Material maybe a little damp. Any suggestions for suitable 35mm hose?

I agree with Masona that you should really take up the concrete outside and lower the level.

. Yes I should but, as the drive is a fairly poor hotch potch of patches and will need upgrading as a whole. I'd rather do this later when I can afford the do the whole lot. When, not if, I do, I’ll certainly follow Masona's excellent advice.

I'm hoping that clearing the cavities will reduce the damp to acceptable levels until then - if not I'll have to cut in a gravel filled gully as in Masona's diagram (nice diagram M)

Thanks for the help so far - any help or suggestions for the scraping & hosing gratefully received.
G

 

[masona]

More info here which may help

//www.diynot.com/forums/viewtopic.php?p=545263#545263

 

[GordonB11]

Forgot to add:

and it looks like you have a newish joist, so maybe the floor has already suffered from rot

Yes I thought the floorboards and joists looked more like 20 years old (rather than 1930's) and suspicious that not tied into the wall. Now you mention it, it looks that they were replaced; and the hole in the wall under the floorboards is just the right shape to take a timber beam, on top of which would have sat the floor joists (assumimg floorboard levels were kept the same). Take a look at the earlier photo - why else would there be a rectangular hole left in the wall - doh. So yes you were right this problem goes way back and probably affect all outside walls
Ta
G

 

[JohnD]

It would have been very bad practice to put a joist in that, as it is below the dpc. maybe if it was wrapped in lead or something?

you appear to have oversite concrete (it may be loose and soft) so it would have been more usual to build dwarf walls and rest the joists on them... preferably with slate dpc

good point in the link about the gulley may be leaking... in my old London house I found all the gullies had snapped at the bend due to the house settling into the soft clay by an inch ot two since being built (and war movement as well from a Land Mine on the next corner which demolished a bunch of houses)

BTW, GordonB11, haven't you moved to No. 10 now?

 

[GordonB11]

Ha I've been rumbled.
Obviusly one of the previous occupants must have boarded over the problem without tackling the underelying causes.

I'm not pointing the finger (or repointing the house) but here's a clue;
Who does this remind you of:

"I'm going to be tough on damp, and tough on the causes of damp"

GB

 

[foxhole]

Under a bay window you would expect condensation damage from windows, meter used is suitable only for timber, waste of time using it on walls.

 

[Softus]

In response to the points raised:

Tell the vendors to sort out the problem or else you won't buy the house.

Too late, have now exchanged.

If you had a structural survey, then this problem should have been pointed out to you by the surveyor - sue him.

 

[masona]

If you think rising damp is real, go and have a look at one of the canal bridges, made of brick, with some of the bricks standing in the water.

How high does the water rise up the bricks?

There you go from France near Bergerac yesterday