OK – we have rising damp. I have cleared all the crap that was under the floors in the lounge so that air can circulate properly (vents blocked etc.), but it seems I need to get a DPC re-done too. In the dining room there is also damp, but the floor is tiled, and I cant get access to the underneath without lifting the whole lot. So, should I:

a) Lift the floors, and inject some tubes of damp proof cream (probs about £300 for the cream – anyone ever used this kind of stuff?)
b) Lift the floors and pressure inject liquid (cheaper, but tricker I believe).
c) get someone else in to do it for me.

Obviously, once all thats done, I'll have to get the walls re-plastered, but thats a different step… any advice greatfully received…

STS.

Have you done something recently round the base of the external wall of your house if this has just started happening?

We noticed some damp smells last year, so we lifted floor in lounge and removed loads of loose dirt and crap, unblocking the air bricks at the front of the house. We also put DPC underneath the joists where they meet the wall, as there was no membrane, just slate. We swapped out a few joists that had rotten, and one that had snapped. We've done nothing to the actual walls apart from clear loose debris from their base. Now, damp is rising and discolouring the walls above the skirting, and is making the paint bubble off in a few small places.

Also, this is happening on the tw exterior walls, and in an interior partition wall (supporting wall) and the party wall between us and the neighbours (who haven't got any signs of damp on their side).

Is there a damaged rwp or internal water pipe that's leaking down into the underfloor space? Or a blocked gulley outside?

Have you got any sleeper walls honeycombe & are they clear? You need cross ventilation.
Also what is the wall construction & does your neighbr have the same problem?
How are your drains?

No internal water leaks. Not sure of wall construction, but have ventilated what I can. Neighbour did have the problem a number of years ago, but got it sorted – I think by injecting a new DPC.

On two exterior walls there are plugged injection holes from an old DPC, but I think it has failed (and that company no longer in business). The shared wall has never been DPCd as far as I can tell.

Drains, such as I can see, are OK, but I might have a look under the drain cover in the yard to have a check next time it is raining – just to see that what is coming down the downpipes is actually flowing away, and not into the floor.

In the street the gutter at the edge of the pavement is blocked and frequently ponds (asked for it to be cleared about 2 years ago to no avail). I wondered if that would cause a problem – its about 4 meters away from the lounge wall. However, this problem exists at the dining room, which is at the back of the house and nowhere near the street.

Have you recently paved up to the wall? Do you have vents on 2 or more sides?
Have a quick google for what the rics published recently on rising damp as well.

We have vents on one wall at front (lounge), and one wall at back (dining room). Air can circulate between the two rooms underneath the floor.

Not recently paved anywhere (been here 4 years). There is concrete up to both walls though, but when it rains the drainage works to take surface water away from house.

Teggs Horatio Stegosaur

Wow – fantastic name 🙂

Is there a decent gap between the outside ground level and the DPC ? – I can't remember the min. height but if the DPC is relatively too low water splashup could give the effect of rising damp. Pretty sure that's what some prior numpty in our last place did in the 70's – lobbed in a patio that put it a few inches below the original slate DFC, at some point later a physical DPC was installed, presumably to fix it. Tho' even then there was still a minor issue wrt the rear/party wall we shared with the neighbours.

Doesn't really explain your party wall issue tho' – unless they've previously had problems and plaster on their side's stopping it breathing effectively – eg in the unlikely event the render coat was portland cement, but you'd be more likely to get that in a bathroom.

Regardless of the cause (which hopefully is something you can easily find/fix), if you do decide on some injected treatment I'd get someone else to do it as they will give you a guarantee (last one we did had a 25 year guarantee I think) which is handy to have when you sell and even handier to have if the damp comes back.
Hope you find the problem. Are your gutters working properly?

Edit: when was the dpc last injected? Do you have the guarantee – although they may not be around you may be covered by someone else.

We also put DPC underneath the joists where they meet the wall, as there was no membrane, just slate

Actually I think slate IS a DPC in that situation, but putting a modern DPC under as well certainly isn't going to do any harm.

as there was no membrane, just slate.

It was my understanding that slate was much better if in a good state of repair?

I ended up selling my last house because I was sick of the damp. Silly sod that bought it didn't even have a survey done so it was never spotted either (although I would have been prepared to knock something off the asking price to repair it).

It was my understanding that slate was much better if in a good state of repair?

Not sure about it being better but it was the best they had at the time and is probably still acceptable if in good nick. Seems like an injected dpc is required if rotting joists have been found. Also sounds like the joists may be a bit undersized if one had snapped unless full of woodworm.

Fair enough – just my layman's thoughts.

Slate's the traditional material (and works well) – tho' we've got an outbuilding in the garden that was built in the 70's and even that's got a slate DPC.
(I just wish they'd put in more than what appears to be a few inches or foundations :o)

A physical DPC is a better fix than injectable stuff, but you'd need your neighbours to cooperate, and it's more expensive (tho' by how much I dunno)

A few points of note in here:
http://www.cat.org.uk/information/pdf/DampProofCourses.pdf
and the articles/forums here may be worth a read:
http://www.periodproperty.co.uk/ppuk_discovering_articles.shtml

One other issue that can arise is the wall's been repointed with portland cement mortar – a lot of builders will try an use it for repointing, but a) it doesn't allow for brick movement and b) it doesn't breathe as well as the original lime mortar
(even more of a problem where stonework's been repointed with cememnt mortar, 'cos that's the only way the wall can breathe)

Talk to Jeff, he knows about these things.

>Seems like an injected dpc is required if rotting joists have been found

Not necessarily that an *injected* dpc is needed, it just illustrates the wall's been quite wet for a long time when it (presumably) shouldn't be. We had to have one end of a joist in a bathroom replaced because previous owners had let the water p*ss off the corner of the bath though the floor, eventually the joist started rotting – dunno how long it'd been going one for.

jonb – good idea – I'll ask jeff. I wont be out tonight though – not feeling well at the moment. But might post on the other forum.

The slates that were the DPC for the joists were kept, but we also put dpc membrane under the joists as a double check. We put new joists in where the old ones were knackered (due to damp at ends where slate DPC failed). So the woodwork will now be fine.

The level of the old injected DPC outside is high enough to avoid any wash up. It was done some time ago, but the company who did it has gone bust, and therefore any guarantee is gone too (solicitor tried to trace that for us).

So in summary, we DEFINITELY need to inject a DPC, its just back to the original question – should I do it, or should I get someone in? The idea of getting someone in and therefore having a guarantee is perhaps good.

re the drains away from the house – drains to where ?
(has it been windy and reversed the drain flow)

Only asking as my parents house had damp mould on inside of various outer walls till we discovered that the twatt who laid the gravel had used plastic as suppressor membrane and that was funneling water to the house – which had gravel and 'debris' against the walls.

sorry – meant to add could lying/draining snow have anything to do with it

therefore having a guarantee

In my experience, a damp-proofing guarantee is a quite worthless piece of paper – I have never known anyone get work redone under the guarantee (me included) as they *always* find a reason why the damp came back, like 'ahh, you put that plant pot too near the wall' or 'your neighbour opened their window'…

Of course I am about to be proved wrong.

Google dryzone. I use it all the time, brilliant stuff and really works. Doesn't cost the earth either. I wouldn't use anything else now, used to use sovreign injection previously.
I get mine from a lad local to me, he sells through ebay too. Think his user name is stopdamp

gusamc – we had the start of the problem last year, but I suspect it has been exacerbated by the snow. I still think the problem is that the DPC has failed as apposed to ingress through another route.

Funky – I had heard about the dryzone stuff – that was what we would go for if we end up doing it ourselves. At least it doesnt need much expertise to do…