Question about damp course in house (renovation)

Aubrey_Thicket

Hi all

My brothers & I started a small property renovation business a few years ago. We had loads of building contacts etc and over the last 6 years we have purchased 5 small mid terraced houses that were in need of total renovation. When I say 'Total' I mean 'Total'. Every inch of plaster off the walls, every ceiling dropped, full re-wire, new central heating etc. During the course of the works such was the poor condition of these houses that the plaster on the walls literally fell off. The good thing was that you could get a thin paint scraper behind the plaster and great big chunks would fall off. Whilst it was very satisfying (like peeling sun burn or popping those packing balls) it really helped us get the properties right back to the brick. This was also great for the electricians because there was no chasing out for wires etc. Also, brilliant for the plumber because he could just attach his pipes to the brick. Naturally, the whole house would then be dot and dabbed and plastered. So, onto the most recent property...Again, we have just picked up this property very cheaply. We fully expected to do the same again...Ie, rip every inch of plaster off. However, this house is different. The plaster is fixed solid to the wall. In fact, I would go as far as to say it looks like sand & cement. I tried getting a small patch off and it was very difficult. So, whilst thinking what course of action to take we got talking to a local builder who told us we don't need to and should not remove all the solid plaster/cement etc on the walls. So, this is where it gets complicated. In our previous houses we have used the same guy to our damp courses. Basically he does the Chemical damp course first (squirting into the brick) and then he comes inside the house and fixes a membrane to the wall all around the property then it is dot and dabbed over. Now, I have never questioned anything he's done and have accepted everything he told me. So, again, yesterday he told me we need to strip every wall in every room because the house is so damp. However, the builder chap says "The house is bound to be damp. Its been empty for 3 months and there's a huge gap under the back door". In a nut shell, the builder guy says there is no need to go to such extremes and he even told me that the damp guy is making work for himself. Unnecessary work. So my problem is...How do I know whether to believe the builder (who has nothing to gain by telling me this) or do I believe the damp guy who tells me the whole house needs doing. The reason I ask is simply because this plaster - Sand/cement mix is so solid against the walls. If it came away easily I would simply accept what the Damp Guy told me. The ceilings have also previously been changed to plasterboard too.

I am genuinely stuck now. Of course the house is going to be damp. I don't really want to strip all the walls if it is unnecessary.

What do you think guys? Any advice would be appreciated.

Doozergirl

Same position as you when we started. We thought we were doing the right thing having DPCs put in but we learned that your builder is correct. These damp specialists create work for themselves. The first time the penny drops is when you!!!8217;re sold a chemical DPC for a wall that already has one! It sounds like yours may already have been treated by means of rendering.

Genuine damp problems are solved by fixing the source of the problem and allowing it to dry. Old houses have damp proof courses and it is unusual for them to fail. They are usually breached on the outside by high ground levels or there are problems outside with pointing/rendering or failed rainwater goods. I have seen several examples on this board where people have been sold chemical DPCs but where the actual source of the problem is still visible in photos! That hasn!!!8217;t even been fixed but the DPC has been installed - it!!!8217;s the new rendering blocking it from coming through, it isn!!!8217;t solving the initial, usually simple problem.

If you are going back to brick then you should be putting insulated plasterboard on the walls which helps to keep them warm and reduce condensation. Ventilation is important which is why we have always left fireplaces open.

We haven!!!8217;t put a DPC in a house for over a decade and not had a problem come back to us. I have not employed any type of !!!8216;damp specialist!!!8217; either. The only time we resolve to damp proofing measures is in basements. As you grow to understand these houses you will start to have gut feelings and learn to trust them. Fact is, you are taking an old broken house. If you fix it properly, there are no issues left. Of course they will suffer if they have had a lack of maintenance, poor heating or no heating.

There is an entire industry based up around lies and it!!!8217;s perpetuated and supported by surveyors who just don!!!8217;t seem to care when they fill out their survey reports. It!!!8217;s easier to tell people to enploy a damp specialist than it is to look at the symptoms (if there are any genuine ones) and make a proper diagnosis.

Aubrey_Thicket

Wow doozergirl. I was going to claim that your comments surely must be false, controversial and downright wrong. However, I have just spent the last hour reading about the 'damp con' on the Heritage House site. I cannot believe it and I am sat here with mixed feelings of I have previously been conned or did the damp guy genuinely believe his works would have solved all the problems. I was actually going to go out and buy myself a 'damp meter' until after reading the site I discovered that a 'Damp Meter' is a device that measures conductivity not damp. I'm actually stunned now. So, I have paid out over £15,000 over the years on chemical and membrane damp courses that were not required. Don't know wether I feel annoyed, relieved, conned etc???

Thanks Doozergirl for your input.

Doozergirl

Been there, done it, felt it!

I think most of them genuinely think that they are providing a relevant service. It!!!8217;s those of us who own the houses, rip out all the detritus, piece them back together over and again that start to ask the questions.

I have questioned myself before but after one particular experience I will not question myself again. We started work on a very large house that had a pretty clean survey. One wall in the garage (against the house wall) had tide marks appearing through render. There were two injected DPCs visible in the wall and one in the cellar underneath (under the subfloor of the adjacent room but just above ground in the garage).

My client did call out a RICS surveyor as I was scratching my head. He came and advised me to put in a DPC and render again! So I questioned him on why a fourth would work if three DPCs had apparently failed and I then took him and his little damp meter over the house and the meter did help where I knew we had a problem as we then traced it all the way down through the chimney.

It had already transpired when we started and the heating went off that every chimney breast upstairs very quickly had quite serious wet patches appearing on them. It was completely invisible before as it was just evaporating in the nice warm house. We established that the back gutters had broken. There was nithing appearing internally in decorated room so I presumed it was limited to upstairs.

The problem on the wall in the garage was the water coming from the roof and pooling at ground level. Because it was cold in the garage and the chinney had been blocked it was showing there. It was obvious once I had a chance to think about it but this was a big house and the ground was over 10 metres down from the back gutters which were also on the other side of the chimney breast. All the DPCs were just a red herring. In fact, they were holding that damp above the ground.

There is always an answer to any visible damp. That garage is now a playroom and there have been no issues in the 30 odd months it has been there. If I had trusted that opinion we would have wasted money. That time served surveyor, a lot older than me, did not even think about it before making a recommendation. The only reason he had been called was because I was looking at the DPCs and wondering why they were failing. I thought he might know something I did not.

Aubrey_Thicket

I am very impressed with your knowledge. Can I tell you something? Of all the previous Damp Courses we've had done by said Damp Guy they all seemed to have worked brilliant! Ie... No damp. However, I am now of the opinion that there may never have been any damp in the first place. I just believed what he told me at the start and I was pretty happy with myself for hiring him. If you don't mind me going off subject for a second please allow me to ask you to look at another post I have just made on here. It is titled 'So what does cause plaster to fail in old houses if its not damp?'. I hope you will give me your opinions there on that post.

Thank you...

Doozergirl

Yeah, there was no damp. Unless you were seeing it and smelling it, they were just crusty old houses.

FreeBear

Doozergirl wrote: »

Genuine damp problems are solved by fixing the source of the problem and allowing it to dry. Old houses have damp proof courses and it is unusual for them to fail. They are usually breached on the outside by high ground levels or there are problems outside with pointing/rendering or failed rainwater goods.

My house is a late 1920s build with cavity wall on the ground floor, and solid brick for the top half - Fairly typical of a lot of properties built between the wars. And like many properties, it has had an extension stuck on the side in later years.

There is an ongoing problem with damp in the kitchen - Two sources here..
1) In heavy rain, water is (was) being driven through cracks in the render and down behind the felt on the flat roof of the extension. This has been cured by installing a lead flashing strip and patching the render.
2) One external wall in the kitchen is suffering from rising damp due to the cavity being filled with rubble and crap from when the extension was built. Much of that work was a bodge job even by 1970s standards. The extent of the damp was only revealed recently during a refit of the kitchen. Once the weather has improved, bricks will be removed externally so that the cavity can be cleaned out. Fortunately, much of the mortar is old lime based, so will be easy to rake out.

Upstairs, another damp problem has surfaced whilst having some guests staying over - One external wall in the bedroom is dripping wet !
Heating in that room is barely adequate, and the guests sleep with the door firmly closed. The end result is massive condensation that no amount of chemical DPC or waterproof plaster will cure.

Long term fix is to insulate the wall internally, fix the heating, and encourage occupants to leave the door open as much as possible.