How to get Damp reliably fixed? oh and woodworm.

[jazzuk777]

Buying a small victorian terrace in Caister and it's a doer-upper. There's quite bad damp downstairs with re-plastering needing doing in the dining room.

Question is: any tips on getting it fixed reliably? We had a homebuyers survey and then a damp specialist spoken of well by the estate agent came to quote.

The specialist quoted c.twice the cost estimated by the surveyor(and we weren't overly impressed with the surveyor work, including missing a rotten window we knew about in the report). The specialist recommended tanking which seems inappropriate and got quite sneery when I asked him to explain (I had done a little research on tanking before I called him back about it) saying I wouldn't understand.

The specialist says it is damp ground and soft Norfolk brick and the surveyor say it is caused by the render reaching the ground (although the damp is in the dining room which has less contact with the render, specialist thinks front room has been treated) and I think the guttering needs work too.

...So where do we find a real expert to give us an independent cast iron diagnosis of the problem we can 100% rely on and then how do we ensure we find a treatment specialist that is trustworthy to do a good job??!? Tried the local trusted traders scheme and specialists are few and far between it seems, at least on the scheme.

Anyone have any experience of the Property Care Association and what reassurance that gives, or any other body?

Oh and we have woodworm in the rafters to deal with too... Which I understand is common with damp issues.

[Casscat]

I have a deep suspicion of most damp companies as their agenda is generally to hack off plaster and squirt chemicals into your brickwork rather than find the cause of the damp problem and cure it. I Googled 'independent damp consultant Norfolk' and came up with this. Obviously it is not a recommendation as I have no knowledge of this chap, but his web page looks like he is involved in diagnosis rather than flogging chemical based remedies: http://www.dampconsultant.co.uk/

[French Cricket]

I too would run a hundred miles from 'damp experts' who basically haven't a clue (or any interest) in how a period property works. (Nor have most surveyors or estate agents, come to that).

This forum is a good starting point - it's one we used a lot when we owned a listed building in north Norfolk but is equally useful for Victorian property: https://www.periodproperty.co.uk/forum/ ... 9682ac0e2e

[Hells Bells]

We had an extension built in the late 1990's and recently noticed damp patches along what used to be the exterior wall of the house. The new exterior walls were fine, as were the other internal walls. A so-called damp expert from a national company approved by Which magazine declared a failure of the damp proof course and suggested over £1000 worth of remedial work, which involved digging up part of our concrete floor to inspect the membrane. I knew it was there, and I knew it was intact. It had been passed by the building inspector, and I was there when he did it. It was sorted by a friend at a cost of less than £200. Once he'd removed the skirting boards all around the area with the damp patches it became obvious that the stupid plasterer had not left a gap at the bottom of that wall. The plaster in the rest of the extension was fine, so can only assume it had been given to the apprentice to do and not finished off correctly.

[Ecosse]

I can't comment on the damp issue, but woodworm isn't always as bad as you might think. Your expert, even if he's not right on other things, is right about woodworm being common if you have a damp problem... the beetles tend to only attack wood already under stress. If the woodworm is active (look for fresh sawdust and holes, or small cones of sawdust under the affected beam in the Spring, when they're most active) then you'll need to get a pest control company (as well as sorting the damp problem). If they're not active, and the beam is still solid, you don't need to do anything. If it is no longer sound, unfortunately it's a case of replacing the beam.

We had to do this with a floor - the previous owners had installed a very dodgy shower in a bedroom, which leaked for many years and rotted the floor. Coupled with the impressive woodworm, we had no choice but to replace the whole floor. 3 years on and there's no reoccurrence of the problem.

[Norfolk Canary]

I worked for a market leader in the damp/ timber treatment industry a couple of decades ago. From my experience, many so called surveyors had little relevant experience or education on the subject and although usually well intentioned, often made howling errors in diagnosing causes and remedies to damp issues.
Firtsly, if the area where you have damp is above ground I can categorically state that your surveyor is talking b******t.
Tanking is a term used for a method of waterproofing walls where the floor is below external ground level such as basements. It has no place in treating rising damp.
I guess your Victorian property will be solid 9" thick brickwork possibly with a slate DPC. If it is rendered externally right down to the ground then that will be certainly be a problem as it will be bridging any DPC that is present (in the same way that HelenBs internal plaster was doing in the post above). If there is no dpc, or it is thought that it may have failed, then a chemical DPC should be injected. Either way, the render should be removed below the DPC level. Any plaster that has been affected by rising damp will be contaminated with hygroscopic salts and will continue to absorb airborne moisture and consequently appear damp even after the rising damp issue has been addressed therefore it needs to be removed and replaced with a microporous 'waterproof' render, then skim coat.
Your surveyor saying the soil is damp makes no difference. It is the size of the pores that govern how high moisture will climb brickwork. The smaller the pore, the higher it will go. It would not make any difference if the brick was literally sitting in a bowl of water as there is no upward pressure involved, just the surface tension of the water drawing it up the pores.
Certainly many wrong diagnoses for rising damp have been made in instances where it was actually penetrating damp due to faulty or badly maintained rainwater goods, so make sure your gutters, and particularly hopper heads, if you have them, are kept clear. It should be pretty easy to differentiate between rising and penetrating damp by observation, but if in doubt you can take internal plaster samples and have them analysed. The types of chemicals found can prove the source of the damp.
The external ground level should be 150mm below the DPC level.

[Norfolk Canary]

I forgot the woodworm bit.
As mentioned previously, any active infestation will be quite evident from fresh 'dust' beneath holes in the timber. If there is none then there is no active woodworm. Try explaining that to a mortgage lender though!
There are several types of woodworm and most do prefer damp timber. I guess it is like comparing a Yorkshire pud with or without gravy.
In a Victorian property thta has no evidence of being treated it would be prudent to have it treated anyway. Obviously all insulation etc would have to be completely removed.

[Norfolk Canary]

I worked for a market leader in the damp/ timber treatment industry a couple of decades ago. From my experience, many so called surveyors had little relevant experience or education on the subject and although usually well intentioned, often made howling errors in diagnosing causes and remedies to damp issues.
Firtsly, if the area where you have damp is above ground I can categorically state that your surveyor is talking b******t.
Tanking is a term used for a method of waterproofing walls where the floor is below external ground level such as basements. It has no place in treating rising damp.
I guess your Victorian property will be solid 9" thick brickwork possibly with a slate DPC. If it is rendered externally right down to the ground then that will be certainly be a problem as it will be bridging any DPC that is present (in the same way that HelenBs internal plaster was doing in the post above). If there is no dpc, or it is thought that it may have failed, then a chemical DPC should be injected. Either way, the render should be removed below the DPC level. Any plaster that has been affected by rising damp will be contaminated with hygroscopic salts and will continue to absorb airborne moisture and consequently appear damp even after the rising damp issue has been addressed therefore it needs to be removed and replaced with a microporous 'waterproof' render, then skim coat.
Your surveyor saying the soil is damp makes no difference. It is the size of the pores that govern how high moisture will climb brickwork. The smaller the pore, the higher it will go. It would not make any difference if the brick was literally sitting in a bowl of water as there is no upward pressure involved, just the surface tension of the water drawing it up the pores.
Certainly many wrong diagnoses for rising damp have been made in instances where it was actually penetrating damp due to faulty or badly maintained rainwater goods, so make sure your gutters, and particularly hopper heads, if you have them, are kept clear. It should be pretty easy to differentiate between rising and penetrating damp by observation, but if in doubt you can take internal plaster samples and have them analysed. The types of chemicals found can prove the source of the damp.
The external ground level should be 150mm below the DPC level.

[jazzuk777]

I worked for a market leader in the damp/ timber treatment industry a couple of decades ago. From my experience, many so called surveyors had little relevant experience or education on the subject and although usually well intentioned, often made howling errors in diagnosing causes and remedies to damp issues.
Firtsly, if the area where you have damp is above ground I can categorically state that your surveyor is talking b******t.
Tanking is a term used for a method of waterproofing walls where the floor is below external ground level such as basements. It has no place in treating rising damp.
I guess your Victorian property will be solid 9" thick brickwork possibly with a slate DPC. If it is rendered externally right down to the ground then that will be certainly be a problem as it will be bridging any DPC that is present (in the same way that HelenBs internal plaster was doing in the post above). If there is no dpc, or it is thought that it may have failed, then a chemical DPC should be injected. Either way, the render should be removed below the DPC level. Any plaster that has been affected by rising damp will be contaminated with hygroscopic salts and will continue to absorb airborne moisture and consequently appear damp even after the rising damp issue has been addressed therefore it needs to be removed and replaced with a microporous 'waterproof' render, then skim coat.
Your surveyor saying the soil is damp makes no difference. It is the size of the pores that govern how high moisture will climb brickwork. The smaller the pore, the higher it will go. It would not make any difference if the brick was literally sitting in a bowl of water as there is no upward pressure involved, just the surface tension of the water drawing it up the pores.
Certainly many wrong diagnoses for rising damp have been made in instances where it was actually penetrating damp due to faulty or badly maintained rainwater goods, so make sure your gutters, and particularly hopper heads, if you have them, are kept clear. It should be pretty easy to differentiate between rising and penetrating damp by observation, but if in doubt you can take internal plaster samples and have them analysed. The types of chemicals found can prove the source of the damp.
The external ground level should be 150mm below the DPC level.

Thanks (and everyone else) for your answers. It was the damp treatment company recommended by the estate agent as not making up extra work for themselves that said we needed tanking. The surveyor disagreed but as I say our faith him was a little dampened (pun intended!) by him missing out a rotting window we knew what there already, not to mention his general efficicency.

The bit that confuses me as to the real cause is that the dining room is partly an internal room with little direct contact with a rendered wall and the damp is present on both sides, one where there is an extension, and the other where there is a sunroom, so I'm wondering how the damp is getting from the rendered walls without affecting the other rooms although as I say the damp specialist thought the front room had been treated.

[Ben McNevis]

Just 2 things to add to what Norfolk has said:

Where apparent rising damp is localised (i.e. just along one wall or in one corner) it's worth taking up a floorboard or two to check the state of the ground below. If it's soaking, you've probably got leaky plumbing below the floor. This is particularly something to look out for if any plumbing work was done on the house in the early '80s when far-eastern copper pipes with soluble impurities were frequently used.

Second, if the house is occupied and part is heated more than another part, then warm damp air will condense on the coldest walls and the amounts of water involved can be much more than you might imagine (think of your ice-cold beer glass when you're on a Mediterranean holiday).

[JaneTwo]

I agree with the others about 'damp specialists' - I think chemical damp-proof courses etc. do more harm than good in period buildings. A damp wall in my last house was fixed by just taking off the skirting boards and raking out the rubble that had built up behind them over the last 100 years or so (old mortar etc. falling down inside the wall and bridging the gap between outer stone wall and inner timber lining). High damp readings low on the walls are often caused by this, apparently, and not 'rising damp'.

If you don't have to get a damp 'specialist' in to satisfy a mortgage provider, I would suggest you get a recommendation for a good builder to have a look and suggest solutions. They are often quite simple and easy (and cheap!).

Good luck with it!

[Norfolk Canary]

Chemical DPCs can't do harm in brick buildings. They can do harm in certain old forms of construction that rely on a degree of moisture to remain stable, such as clunch for instance.

[JaneTwo]

I may well be wrong, but I have been told by various people involved in conservation of old buildings that damp-proof courses are generally bad news. There seems to be doubt whether they work at all, even in modern buildings:

http://www.heritage-house.org/managing- ... dings.html

[Norfolk Canary]

I may well be wrong, but I have been told by various people involved in conservation of old buildings that damp-proof courses are generally bad news. There seems to be doubt whether they work at all, even in modern buildings:

http://www.heritage-house.org/managing- ... dings.html

This sums up my opinion......
I posted this onmy blog earlier in the week. May have a bearing...


Rising damp is a myth, some say. Not many really think so; that would be stupid, but those who believe this nonsense seem to have the ear of the press and the ear of RIBA and RICS too.
So instead of being drowned out by howls of derision from the those who really know about these things, they gain publicity and even a bit of notoriety too.
Yet every day – yes every day, rising damp causes damage to our housing stock. It causes salting of brickwork, wet rot in floor joists bearing into affected walls, perishing plaster surfaces and even increases heat loss at the base of walls.


Now then, you may disagree with me. Perhaps I’m just spouting an opinion too, like the ‘myth pushers’, but no, I state facts, facts proven time and again by me and importantly, by people who have really studied the phenomena scientifically.
The internet is full of papers which detail various trials and careful studies done, in an effort to quantify the nature of the problem and analyse the effectiveness of treatments. They are being ignored.
Who cares? Well we all should be worried, because when people read something in the papers they tend to believe it. If building preservation ‘experts’ generally agree on something and one or two of them suddenly start babbling an unsupported view, with no proper evidence, the papers like to publish it; conspiracy and corporate culpability sells so well.
Unfortunately the readers get the information in an unbalanced way. They then become prey for all sorts of crackpot ways of dealing with their ‘mythical’ rising damp problems.
As a result, I see people turning away from proven chemical damp-proof courses, just at the point when the technology of these systems has begun to deliver much better results. You see, chemical DPC’s have a bad press, because too many were installed improperly, by badly trained and sometimes quite iffy installers. Often no plastering was done, so the nitrate and chloride contaminated plaster just sat there; soaking up more humidity and the walls never dried out. Many DPC’s were installed for the wrong reasons; they can’t eliminate condensation or penetrating damp, or rising damp; if the cavity is blocked. This is not the fault of the material or proof that rising damp does not exist – it is the fault of the installer or the surveyor involved – or both.
Now that we have better training and the advent of DryZone DPC injection cream, standards and success rates are far higher. This is good – but because of the bad and completely unjustified attacks on the whole premise that damp rises – customers are being bamboozled into trying unproven, unreliable and generally more expensive ‘cures’.
So this is where the MMR scandal link is. The scandal was caused by poor and unproven opinion being disseminated as science fact. Before long, others jumped on the bandwagon and thousands of parents (many of the them middle class Sunday paper readers), decided that young Rupert and Felicity shouldn’t have the nasty jab. This directly caused the severe illness of many other children and eventually those who had promoted this were shown for what they were – the main doctor was struck off the medical register.
In my opinion RIBA and RICS members who seem to support this current ‘myth’ nonsense should have a read of some proper evidence. As professionals we have a responsibility to give good advice to clients; advice based on facts; advice based on knowledge.
Opinion is no substitute for fact; experience is no substitute for knowledge.


Dry Rot.

[JaneTwo]

Thanks Norfolk Canary - that's very interesting. I obviously need to revise my views on DPCs!

I would still say that, in my experience, most damp problems can be sorted out by doing simple things - e.g. raking out debris from walls or lowering the ground level to below the level of the floor. Maybe my experience isn't relevant in this case though, as here in Scotland most old buildings are stone, not brick - less porous.