/ Home & Energy

Don’t be a drip! Watch out for dodgy damp advice

Damp companies that offer ‘free surveys’ may seem appealing, but our latest undercover investigation found several companies recommending unnecessary treatment that could cost hundreds of pounds.

Everyone loves a freebie, but if you’re tempted by the ‘free surveys’ on offer from damp-proofing companies, you may end up spending more than you need.

In our snapshot damp investigation, we invited damp-proofing companies to carry out an assessment of our properties’ damp problems. In two thirds of cases they recommended unnecessary or inappropriate treatment, or missed the problem completely. But does that mean you have to pay to get good advice?

All we needed was a plumber

In one case, our property had a leaky toilet – and any damp specialist should have instructed us to get this fixed before the room could even be assessed for other potential damp problems.

There was no evidence here of rising damp, and yet four of the eleven companies told us that we needed to install a chemical damp-proofing course in the walls and re-plaster the room – at a cost of up to £1,440!

That’s not to say all the companies were bad. We did see some good practice, with just over half of the companies that visited this property giving us helpful advice.

How to get good damp advice

Deciding whether to take your chances with a free survey, or shell out hard cash for independent advice is a toughie. Even though I’ve seen these results first-hand I know I’d be tempted to try my luck with the free option first – although I’d make sure to get at least three companies to come round and quote for the work.

Then, if there were inconsistencies in the work recommended or I had any inkling that the work might be unnecessary, I’d definitely consider getting an independent damp specialist round.

If you think you might need to call on a damp company, check our damp advice guide first for info on the different types of damp that can affect your home (if it’s just suffering from condensation you won’t need a specialist).

[This Conversation has been closed and is not open for commenting.]

Heritage House says:
9 October 2013

I’m really struggling to see where the “Outrage”, “Petulant” and “Abusive” comes from – I’m assuming that Dryrot takes offence to very simple, factual comments by others, and becomes outraged, which leads him / her to accuse people of the things stated. Perhaps the mods could comment on this – I think Dryrot is getting rather upset…

Scaremongering – Hmm – this is exactly what is seen on most damp peddlars websites – let me see… “rising damp will cause all sorts of fungal and mildew problems which will see you in hospital – best call a damp man to sort it out “…. and so on…..

Rising damp is common – hmmm.. here we go again – making a statement and expecting the world to take it at face value… I’m sure we’ll see a response quoting some learned document – but in the many years of solving damp issues that I have under my belt, I’ve never once had to inject, smear waterproof compounds on people’s walls, or use ANY of the snake oil remedies offered by damp peddlars.

Usually, a bit more air flow is all that’s needed, sometimes helped by removing the previous damp ‘wally’s’ tanking, plasters, waterproofing etc., to let the poor flippin house walls breathe and dry out.

Readers of this forum just need to look at the Historic Scotland, English Heritage and SPAB guidance notes to realise that the damp industry has VERY little time left in which to sell its snake oil..

As for the comment about RICS – I have it on very good advice from RICS that the chemical industry association, and anything that may be inferred from that, is NOT recommended by RICS. They are preparing a conservation update in which I understand things will be made a little clearer as to where they stand on such practise. Let’s leave it to RICS to state facts.

Perhaps Dryrot will get measels (not sure that’s how it’s spelt mr dryrot) from the stress of my response …


I, among others, have listed links to Heritage Scotland and SPAB publications that deal with damp. I think, as a non-expert, that they seem to give a good introduction to damp causes in old buildings. They allow people with a damp problem to consider possible causes and remedies and have a more informed discussion with any “expert” they might ask for advice. However, rising damp is referred to, so presumably you accept this can occur (even if generally only in the lower 300mm of a wall for example)?
The maintenance of breathability of structures and surfaces is a point well made throughout this conversation, and chemical treatments or materials that destroy this are to be deprecated. No doubt many reading these posts will take this on board.
It would be useful if Which? could extract the facts from this conversation and produce a summary of what people with damp problems should know and do, and what they should avoid. I wonder if that would excite more controversy?


This seems to be in danger of turning into a flame war between Heritage House and Dry Rot, something I don’t think is particularly appropriate for this kind of forum.

I agree with you that the publications of HS and SPAB are a good starting point. The former is a government department with more than a passing knowledge of historic structures, including the care of their own estate. We have provided links to their advice and I would very much encourage readers to work their way through such publications before coming to any firm views on the ways of dealing with dampness.

As for rising damp, I do not personally doubt that it exists in both theoretical terms (the Edinburgh paper on the physics of capillary movement, for example) and practical terms. What I would dispute is the presumption that it is endemic to anything like the extent proposed by damp proofing “specialists” or that an injected dpc is necessarily the correct way of dealing with it.

In my experience, many cases of “rising damp” are in fact due to misdiagnosis of penetrating dampness (especially on lime mortared stonemasonry buildings) or have been exacerbated by poor management. I used to smile when I saw someone trying to inject a chemical dpc into a whinstone wall instead of improving the ground drainage, but now I just despair.

The other thing which perplexes me is the public perception that PCA members are seen as the automatic experts in contrast to, say, independent building surveyors (note: I am not an RICS member) or other professions. And yet we hear here stories of differing diagnoses, multiple rounds of failed treatment, and so on.

It’s enough to make you cry!

Dry Rot says:
9 October 2013

I gave some advice and even my DryRot pseudoname was mentioned, as some sort of sign that I have evil intent… I mean… it’s reminiscent of a ruinous rot you know… for Christ’s sake, get a grip!

Now my spelling is worthy of attention… well that’s a sign of rigorous standards; when it comes to consumer advice. This is like Daily Mail journalism… maybe my dad hated Britain too eh?

My advice on salty chimneys is ‘rubbish’ but where are the facts that our clients’ needs addressing? A glib assertion that a bit of lime plaster and brushing off harmless efflorescent salts (leaving the damaging hygroscopic ones behind), will do stinks frankly, and does the client no service at all. As it happens, my advice stands and jolly good it is too (IMHO). I did take the time to explain the why and the how, so the client could better understand the purpose of the recommendation – that’s called treating the client with respect. Slapping on lime and such is a mantra and a dogma which thinly disguises an attitude, which is bereft of any depth and a blinkered approach too, which lacks any flexibility or ability to meet the myriad conditions we find on sites.

It’s very reminicant of the dogma of the old school damp prooing firms rave on about. You know, the ones who just get a high reading on a ‘damp meter’ and put a chemical DPC in? I hate them for that, as I spend half my time apologising for their errors – you lot are peas in a pod.

As for vested interests, mine are with my clients, who pay my wages and that of my staff. My VAT cheque this quarter is £27000 so they also help with the deficit too – so everyone’s a winner, provided that the solutions we offer to for client’s damp problems bring success that is.

Fortunately my unnamed firm is 27 years old this year, so the solutions have been good up to now, or we wouldn’t be around would we?

Robusto says:
9 October 2013

If we are going to get into a debate about which damp book is the best might I suggest the BRE publication “Understanding Dampness” if you are dealing with damp problems in what might be described as “ordinary” houses – i.e. 95% of the housing stock. If you are dealing with the minority of properties that are of special heritage interest then I would suggest that the ICCROM publication “Damp Buildings Old and New” knocks the spots of anything by SPAB.

I certainly don’t agree with everything that is written in either book, but they are both written by authors who have spent a lifetime researching moisture ingress into buildings – or in the case of the father and son team that wrote the ICCROM publication (Massari and Massari) two lifetimes.


Upon reading your post, I turned and picked a slightly dog-eared copy of Massari off the shelf. The Rome 1993 edition, for what it’s worth, which according to the receipt inside cost me £24.50 from Archetype in Fitroy Square back in 1998.

There were markers at two locations:

Page 88, beginning with “capillary interception with resins” (that’s an injected dpc, for any homeowners till reading) moving on to trenches (only if the dampness is due to surface water management) and “worthless pseuodscientific methods”. I especially like the section on Electro-osmosis.

Page 177, “Cooling, not water penetration”, or in other words “check for condensation and dew point”.

I must admit that I don’t agree that all of Massari’swork is relevant to other parts (predominantly northern) of Europe and consideration has to be given to construction techniques. But yes, I read it years ago and would concurr that anyone working in the field should have made themselves familiar with it.

Robusto says:
9 October 2013


For the treatment of rising damp, Massari only really had any faith in physical DPCs – although in fairness it could be argued that other methods have improved since the book was written – e.g. development of injection creams. It should be noted that he wasn’t particularly enthusiastic about land drains either.

You are correct that some relevance is lost due to the emphasis is on large, historic Italian buildings, some of which have very thick walls (which can cause rising damp to be more severe due to the lower surface area restricting evaporation). Nevertheless, it’s still my favourite reference when it comes to dampness in historic buildings. There is still a gap in the market for someone to produce a such a well researched book from a UK perspective.


There’s a reason that we used to use slate DPC in mass masonry construction, at least in areas where we used more porous sandstones (there is obviously little point in granite/whin/greywacke areas), and even if building a new mass stone wall today I would look at incorporating some sort of physical barrier.

I’m always cycnical about the relevance of these very large southern European walls with the salt “tide mark” 1.5m up the outsidfe inasmuch as they are so very different from the kind of constructions we see in most of northern Europe and certainly the UK. Indeed the four key issues in determining the scope of rising damp, where it exists, seem to me to be:

1. Thickness of wall.

2. Construction of wall, i.e. porosity of both the stone and the mortar matrix.

3. Amount of water in the surrounding ground surfaces.

4. Evaporation / Microclimatic issues.

In my personal experience, and I have to say as I was always taught at university, rising damp is rarely (if ever) seen more than 300mm above highest external ground level on a traditional mass masonry wall 450-600mm thick in this country. The highest extent tended to be where the core was an open/rubble/mortar mix – the “sponge” effect, ground water levels were high, and where surrounding surfaces could exacerbate wetting through splashback.

Under those circumstances I have always:

a. Ensured that penetrating dampness on the faces was controlled through a robust programme of hydraulic lime repointing, including core voids, the hydraulicity determined to suit local conditions.

b. Improved ground and surface water drainage at the immediate foot of the wall in order to ensure that water is not tending to pool around the footings, including cutting-back metalled pathways and pavements. I should add that, although a believer in French drains, care has to be taken to ensure an inadvertent reservoir is not created in heavy clay soils.

c. Where a new solid floor is being cast in, turning the DPM up the inner face of the wall 450mm above ground level in order to limit the scope for transference to internal linings. That said, I often use either lath & plaster on studs (for historic work) or gypliner (modern work) rather than plastering on the hard.

Problems I have seen on other projects where injected dpcs are used include the inevitable concentration of salts and dampness within the lower section of the masonry leading to accelerated weathering and spalling of natural stone or softer brick faces.

I should also say that, where I work, lime harls (i.e. hand cast renders) can help in increasing avaporation from the external faces and thus controling rising AND penetrating dampness in a subtle but important way. This does, however, tend to be restricted to historic properties.

As a final shot, I’ve always been a little worried by those who advocate limecrete slabs being laid directly onto hardcore without a DPC on the basis of breathability. This is, of course, only really an issue in the conservation & repair of “properly” historic structures however it seems to me that it only works until you put a moderately impervious tile or floor finish above, at which point the game is a bogey. I wouln’t recommend it.

In summary: it’s very complex and independent, impartial advice is usually a good thing. But said advice has to come from people who have studied and understand the issues.

Heritage House says:
9 October 2013

Perhaps some discussion of why the Dutch don’t even bother to use dpc’s would be interesting – they live with their feet in water – but have long ago stopped using or specifying them. Makes a mockery of everything we do over here – I teach architectural students, and whenever a bunch of Dutch students appear, they fall about laughing when confronted with what they call our ‘Quaint English Custom’ of dpc’s.

Give me some links to technical and/or academic papers and I’ll happily read them, as long as they’re not in Dutch!

Presumably poor soil conditions in the Netherlands would tend to countenance against creating slip planes using dpcs, but I’d be intrigued as to how they control dampness.

It would be interesting to know which northern european countries use dpcs, and which don’t. Other than Holland, which has been cited before, do you know of others?

Hi. I know my question is not damp related….but can anyone tell me what ‘dynamic failure’ really means in building terms pertaining to subsidence and if it is unsafe or potentially dangerous?! Thank you so much.

Failure due to movement of the substrate (i.e. bearing surfaces) or masonry structure. How serious it is depends upon a range of factors, not least whether it is ongoing or historic.

If in doubt then construct a structural engineer.

Buie says:
10 October 2013

Hi-I wonder if you can help me. I own a small sandstone end cottage (built about 1850) with 2 rooms downstairs and 2 bedrooms/bathroom upstairs. When I bought it 5 years ago it had rising damp in the lower walls. The damp specialist tanked the lower walls (1.2m) using the Hey’di Tanking System. I am now trying to sell the house and my recent survey has given a Level 3 damp reading for the walls. There is dampness in the lower walls and above the 1.2m level. I got the same specialist back to see what had gone wrong. This time I have been advised it is penetrating damp and that the downstairs walls need to be stripped to ceiling height (and in the case of the gable wall-strip the whole thing vertically bottom and top floor) and tanked (using the Hey’di system).

What I am wondering is:
1)shouldn’t we be trying to find out where the penetrative damp is coming from
2) does the above recommendation sound like a good plan
3) would getting the heating on in the house (its been empty for about a year) on help

Any advice would be great. Many thanks in advance.


Your suggestion is correct: find the source of the pentrating dampness. Treat the cause, not the symptom. The Historic Scotland guides I linked to earlier would be a useful starting point.

Ian MacQueen says:
13 October 2013

Hi I bought a house (built circa 1930) this time last year and have been renovating it since. I have recently started on the front bedroom and after removing the old wall paper and applying a base coat of paint I noticed some damp patches on the roof and at the top of the chimney breast. I have been up in the loft and could not find any leaks. Most of the air vents in the eves were blocked with cavity wall insulation so I have hovered these out. I suspect this was not the cause of dampness and infact the cause may be hygroscopic salts in the plaster (I note that patches of the wall have been plastered with what looks like cement in the past so wonder if this is not a new problem). I also noted that the chimney pot has been removed in the past so this isn’t a concern, but what does concern me is that the builder has laid slates with cement across the top of the old chimney – could this act as a path for damp to travel from the outside bricks to the internal bricks or is this normal practice to seal off the chimney like this? If you believe this is hygroscopic salts do I need to remove the affected plaster and get someone in to replaster or could I use some form of sealer and simply paint over the affected areas? I am keen to do the job right but also on a short timescale as we have a baby about to arrive. Thanks in advance for your advice. Ian p.s I have had a demudifier running in the room, after about 4 days the roof did start to dry out but as soon as I turned the dehum off the damp patches seemed to reappear.

Fran says:
19 October 2013


I would be very grateful for help with these problems.
I have wet carpet on the floor in an alcove next to the fireplace on an adjoining wall in the living room, the floor and gripper rods are wet but the wall and skirting board are not. I don’t think there are pipes in this area but not sure. The wall was damp proofed against rising damp 7 years ago. I also have damp in the kitchen, again an adjoining wall but on the other side of the property, I think there are pipes running along this wall. The house is a terraced house built 1890s.

Many thanks

hughes999, Heritage Scotland and SPAB both acknowledge rising damp as a phenomenon in their publications. Are they mistaken?
What other northern european countries apart from Holland don’t use damp-proofing courses in their cavity wall constructions?

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