Damp treatment for *severe* penetrating damp

[justcalledfubar]

Just buying a house at the moment that has had years of neglect. One of the problems is a broken guttering pipe (in fact it is just loose, but has been loose for about 15 years). This has led to water getting through the brickwork on both levels and causing really severe penetrating damp. One wall (upstairs) has been replastered in the last few years and the plaster is totally gone in the corner. The downstairs is not as bad but could still do with replastering.

The mortgage valuer has mentioned that the plaster needs to be removed and the penetrating damp treated "by a company that can offer guarantees for such work". What kind of treatment can you do to this? Is it a matter of knocking off the plaster to the brick wall, repointing outside and waiting a sufficient lenght of time for it to dry out before replastering?

Or can we just repoint, knock off and replaster with waterproofer added to the plaster mix?

Any help given gratefully received!

Not too worried about a guarantee for the work but need to know if we are missing anything here!!!

[Richard Faulkner]

In message , [e-mail] writes

ISTR my builder suggesting this for a flat I was refurbishing - there was no rush to replaster, so I think it got about 3 months before plastering.

[Owain]

Damp treatment company bollockry

Basically, yes. Ventilation / dehumidifier as appopriate will help speed drying somewhat.

I think that runs the risk of trapping dampness in the wall.

Owain

[meow2222]

Fix gutter pipe, repoint outside, remove plaster, wait ages for it to all dry and replaster. Dont use waterproofers, they only retard evaporation, which is what you want.

Stay away from damp treatment cons, er I mean companies.

I dare say a builder could give you a paper guarantee for =A350, but really a gtee is worthless in this case. I'd just shrug and say that the paper's needed to get the mortgage, easy money for someone.

PS brickwork does take a long time to dry, months. So the builder job could exclude replastering, that would get done later in the year.

NT

[Peter Andrews]

I don't think that you need do anything special about the penetrating damp - as long as the cause of the problem has been sorted, i.e. the loose down pipe, certainly not a 'specialist company'! I had a damp patch when I moved in and that was a cast iron pipe with a split down the back, replaced with plastic and six months later the wall (north facing) had dried out, 25 years further on still OK.

Peter

[Chris Bacon]

The cure is simple, stop the water pssing all over the wall, let it all dry out, and re-plaster. No special work needed.

That's about it.

Is it an old house (how old?) or new?

[justcalledfubar]

Victorian terrace (liverpool). Needs fair amount of work doing to it (lateral restraints, full gable, outrigger and rear elevation repoint, DG, window lintel to replace, through lounge lintel to replace, most of downstairs to replaster.

Apart from that, quite tidy :;)

[The Natural Philosopher]

Just do it. With the guttering fixed, the damp will subside. Don't even think about replastering until its all dried out.

[Chris Bacon]

Make sure that whoever re-points uses either lime mortar (unlikely for most builders as it's a PITA for them) or

1:1:6, which is much more likely and OK for builders - not straight cement:sand, even "with a plasticiser, mate, so it's OK" (because it's not OK). Just a small point :)

[justcalledfubar]

Whats the 1:1:6 mix of? Also what would be the implication of using normal sand/cement mix (with plasticiser)?

Thanks.

[Chris Bacon]

1:1:6 is cement:lime:sand by volume. It's not as hard as cement mortar. If you use cement:sand, it's effing hard. The mortar used originally was soft lime mortar. Plasticiser in cement mortar is for workability, it doesn't change the hardness. Under some circumstances, if you use a hard mortar, it can lead to the stuff being slowly ejected, or, much worse, damaging the brick faces:

@@@@@@@@@ @@@@@@@@@ Brick X-> @@@@@@@@@ Y-> ##::::::: ## = hard mortar, ::: = soft mortar (original lime). X-> @@@@@@@@@ @@@@@@@@@ Brick @@@@@@@@@

Large force transmitted at X possibly leading to flaking. The hard mortar at Y may be ejected due to small movements of the structure, potential water ingress and frost damage.

1:1:6 will also match in much better with the rest of the buildings. You can use white cement, the results can be a bit too white though! It's worth being a little careful with mortar colour, to avoid eyesores.

[Christian McArdle]

Your wall will be utterly ruined as the mortar spalls all the brick faces, costing tens of thousands of pounds to repair.

Christian.

[Richard Conway]

Would placing a dehumidifier in the room help with the drying out from the inside?

[meow2222]

if the interior is damp, then yes, it would reduce RH and thus speed drying. If its not, because its just a small damp patch, then not really.

NT

[justcalledfubar]

Thats interesting - never occurred to me to use a dehumidifier. The interior is not particularly damp, IIRC, so may not make a difference.

[Stuart Noble]

All sounds a bit complicated to me. Sort the downpipe out and you may not need to do anything else.

[justcalledfubar]

Thanks - I think it will need repointing at the front (at least partly) and anyway all the front paint needs stripped/sanded as it is in a state anyway.

Thanks for all the advice from the other posters, too.

[meow2222]

do you mean the brickwork is painted? If so that wont help any.

NT

[Chris Bacon]

I hope he's just talking about the timber... also, if it's the brick, "sanding" isn't necessarily a great idea.

[justcalledfubar]

I think I used the wrong word!!! it needs some scraping as the some of the paint is coming off.