A quick rising damp question...

[Pecanfan]

Has anyone ever come across rising damp that's so bad that the internal bricks (1-2 bricks above DPC) are literally wet to the touch? (not just damp but literally dripping with water)

Just to give a bit of background, 1930's semi - brick built with cavity and visible DPC. The pointing has seen better days but other than that the gutters are fine, there's no leaky pipes (that I can find!) etc etc. Anyway, could dodgy pointing cause such obvious internal damp problems?

I've had a damp proof 'expert' out who scratched his head for a while then offered to charge me £600 to squirt the wall full of stuff, but he seemed rather confused when looking at it, which didn't fill me with confidence... :-)

?

Andy

[Phil L]

This is a rarity, but I have seen it.

Highly unlikely, unless the rain drives into this one spot more than any others?

When I've come across this in the past, it has been penetrating damp, and strangely enough, it's always been on a cavity wall where the cavity is blocked with mortar / debris / crap ...both walls may have a suitable DPC, which would normally work fine, and probably have worked fine for many decades, but the mortar etc blocking the cavity goes down below the dpc and the water is soaking up this, my advice is to open up the exteriror brickwork, say 2 or 3 bricks and scrape out as much crap as you can - it's often better if you take out the bricks below the DPC if possible, then you are below the blockage pulling down, rather than above it trying to pull it upwards...you need to clear it to 150mm below DPOC, and have some new plastic dpc to hand when bricking up, in case the bitumen off the old one comes apart, which it often does in cold weather....solid 9" walls hardly ever seem to suffer from this, even if they don't have a dpc..

[Cicero]

=============================== Beware of salesmen selling damp proof courses. My local paper ("Express & Star", Wolverhampton) has a report today of a firm, 'Aqualine Damp Systems, Stoke' facing 11 charges of ".....recklessly making a false statement under the Trades Description Act 1968".

Two of their salesman are also accused of "...........persuading people to buy damp proof courses which were not needed."

Most people seem to agree that finding and remedying at source is better than chemical injection.

It's possible that the water is entering via a butterfly wall-tie(s) which is / are collecting condensation. If so, same treatment as suggested by another respondent but you might have a slate DPC in which case try to preserve it unbroken.

Cic.

[The Natural Philosopher]

ABOVE DPC?

Not if you HAVE a DPC, no...

Its far mnore likely if the DPC exists and is sound that the water is coming in from outside, not upwards, and running down..typically a load of earth that bridges the DPC and wet weather will show this effect.

Explain how and why its visible?

If its a cavity wall my best guess is water is running down INSIDE the cavity from somewhere and pooling at the bottom *on top* of the DPC.

I had this with..what was it..ah Busted and rotting barge boards allowing rain to drive into a gable end wall. Used to drip out of the window tops. .. came all down inside the wall.

The pointing has seen better days but other than that the

Might do if there is a direct path for driving rain (and boy we have had some, haven't we?) into the cavity.

Id leave that to one side..and try and find out if

1/. The DPC IS a DPC and if it is actually functional 2/. the outside of that bit of wall shows the DPC well above splash height..i.e has some doozer laid a concrete path up to the outside wall, and rain is splashing off that straight onto the wall above the DPC? 3/. No soil has bridged the DPC. 4/. no airbricks exist to allow rain ingress into te cavity.

My money is on water getting into the cavity..by 1930 they knew how to do a pretty decent DPC. Finding where will be a bugger though.

[The Natural Philosopher]

Thats a scenario I hadn't thought of..we both agree that water is probably getting into the cavity..but you say that its coming upwards..I think downwards..

Surely a proper DPC bridges inner and outer leaves of a wall? I am sure mine did..

Certainly removing a couple of bricks is a darned good idea, and the answer at that point will probably be obvious.

[Pecanfan]

Cheers for the replies guys - as it happens part of one of the walls is coming out soon anyway so hopefully all will be revealled soon! It answer your questions though...

There's a black line going all around the house about 2-3 bricks from ground level - defo a bitumen DPC. No idea what state it's in though.

Around that section it's about 2.5 bricks above a very badly layed concrete patio area (which is currently being ripped up) suppose it could be splash, although it just seems *too* wet for that.

Not externally, although internally it was certainly bridged (see:

- it's not any more though and still damp (new damp, not old damp slowly drying out)

Nope!

Honestly, this poor house has had so many bodges done to it over the years it wouldn't surprise me if the bath drained straight in to the cavity or something. Hopefully it will make a bit more sense when we get one of the walls down. :-)

Andy

[Owain]

That is not unknown, especially with toilet overflows. If it were the bath drain presumably the rising dampness would smell soapy?

Owain

[Phil L]

They do, and in 99% of cases, they stay dry because of the cavity inbetween, but if the cavity has later filled with debris both below and above the DPC, the damp can track up this....I've seen cavities filled with mortar snots and bits of broken bricks up to a height of 2 ft above the dpc, but even then it rarely causes damp inside, only if there is sufficient moisture in the footings

When I used to install insulation for many years, we occasionally had an estate where every house had to be cavity cleaned prior to installation to ensure maximum fill, usually just above the DPC, but on a couple of estates above window and door lintels too, it was a very well paid job IIRC, although extremely dusty and hot in summer, and freezing in winter, using compressed air tools didn't help

[Phil L]

I missed something here...do you mean a single DPC bridging both leaves? - I have only seen this once or twice in old buildings, most DPC's are single, IE about 4 inches wide

[The Natural Philosopher]

This is all good stuff mate, keep it coming!

[The Natural Philosopher]

I did..a layer of slate etc laid across both leaves..for example.

I agree that with bituminous cloth etc, its more likely to be separated..and its not uncommon to have the inner DPC lower than the outer..but on a 1930's house I thought it might simply be slates laid across both walls at the same level.

[Ed_Zep]

I hope you get it sorted because it's exactly the same problem I have. I had a plasterer/builder inject a DPC and it's gone quite well. I think the problem in my house is concrete floors pushing moisture out to the walls. Also condensation from a boiler in a cold extension. I was alarmed to see very wet bricks whilst the plasterer was working! I've ruled out leaks, though.

There is still a problem, though, where the DPC wasn't put in behind a kitchen unit. It's moved around the bit he lime plastered.

I've paid to have a proper, independent survey done tomorrow, so will see what happens there.

Ed.

[Phil L]

The DPC behind the cabinet could have been done, and without disturbing any kitchen units too - a reputable firm of DP installers (an oxymoron there?) who I know, get around unmovable obstacles like this every day - not just internal kitchens, bathrooms etc, but also outside structures like concrete coal bunkers and garages which are built close to the exterior walls, the method is simple, and it's approved by the chemical manufacturers who issue the gaurantees.....first off, as with yours, the exterior brickwork is drilled, usually to a depth of 40-50mm, then pumped with injection fluid, if there's a part he can't get to on the inside, he can go outside, drill through the holes of the bricks he's already drilled, with a longer bit obviously, and into the inside brick, he also has extra long wands for the pump, that go through the outer brick, cavity and into the interior brick, he then pumps the DPC fluid in from the back...the method is reversed for walls that have obstructions outside (he does the inside wall 'twice' as mentioned above)

[Pecanfan]

Well, you were 100% correct! Taken down the outer leaf of part of the wall (the bit that's coming out completely) and it's FULL of crap - up to about

2' above the DPC! Managed to get in and scrap most of the rubble out to the left and right of the opening so hopefully the problem will be resolved now. Also gave me a good chance to check out the wall ties (which are notorious for going in this type of house, apparently) and they're absolutely solid, so more good news - woohoo!! £600 saved. :-) Hope this is useful to others considering remedial damp proof injections etc. - in my view a damp proof injection wouldn't have done anything to resolve this problem, at all - and three 'reputable' companies recommended it as the best course of action.

Andy

[The Natural Philosopher]

Yeah..and thee cheers for the man who correctly identified it.

Injection *above* the DPC up to the 2ft level would have fixed it of course..but pulling the bricks out and shoveling up the crap is infinitely more satisfying.

There is nothing more satisfying than getting right to the bottom of a problem and feeling 99.99% sure you have fixed it..

[Ed_Zep]

Ah, this wall is slightly different in that it's internal and on the other side is the boiler. However, with some dexterity I might be able to get under the unit with the drill.

By the way, my understanding is that it's better to get the injection fluid that goes into the mortar course as that's how the damp mostly travels.

Anyway, as mentioned I had the independant survey and he said there was no major problem and not to spend any more money on it; that houses have some damp.

I think I'll just finish under that bit under the unit, though.

[Phil L]

NP, glad to be of help :-)

[meow2222]

Where do you think the water in the cavity would go then? Its still got to come out.

Are you thinking that an injected fluid would soak into all parts of all bricks and all mortar, as opposed to just following the easiest course with half of it weeing into the cavity?

NT

[The Natural Philosopher]

Out through the outer wall.

well if it weed into the cavity that would make the rubbish itself water proof and it wouldn't wick up water would it?

;-)

I had a bad kitchen problem - single brick, and no DPC. I just tanked up to about a meter and a bit with waterproof mortar. Problem solved., The wall was still damp..on the OUTSIDE. And it evaporated away nicely.