/ RIsing damp reported in house survay advice wanted

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kipper12 - on 14 Jul 2017
Hi this is one for a surveyor, architect or builder

We are looking at buying a property which is probably 80 or so years old (thought I suspect younger). We have just had the survey back and instances of rising damp have been identified. (I presume by conductivity meter). The property has been redecorated so its not obvious if there is any damp and it certainly doesn't smell damp, We cant see the brickwork as it is rendered and again recently painted. (rental property now refurbished to sell). It is recommended we get it sorted out before we complete.

Now doing some brief reading yesterday it appears that conductivity meters are not reliable for anything other than timber and true rising damp may not even exist. My partner wants to go ahead at the moment. Im reluctant to get a remedial company to have a look as they have a vested interest.

Im not sure where to go next. Any advice would be very welcome.

cheers
jkarran - on 14 Jul 2017
In reply to kipper12:

True rising damp most definitely does exist and it rises further than most people claim (~60cm IIRC). I have a single skin internal wall with damp that had risen at least 1m into the room and there's another meter of it in air but saturated below the floor, no pipes to leak, not condensation as my damp report claimed (you can see the pattern radiating out from the few standard bricks substituting for engineering bricks in the DPC).

I'm not a surveyor, architect or builder but I had a damp survey done on my similarly aged damp house then subsequently pulled the boards up and plaster off to start fixing it. It wasn't worth the paper it was written on. I think only in one location did they actually correctly identify the problem AND the cause. It was little more than a pitch for expensive work that mostly didn't need doing (work was and is needed, just not what they proposed).

Can't really offer much advice but it's a point to haggle over and if you get the remedial work done with a guarantee you can keep calling them back until they actually fix it. You probably won't know for sure for a couple of years either way.
jk
Toerag - on 14 Jul 2017
In reply to kipper12:

a) It's probably been redecorated to hide the damp if it does have it.
b) rendered is good as it prevents penetrating damp
c) it's almost certainly been painted with emulsion which traps damp in the walls.
d) retrospectively curing 'rising' damp is virtually impossible. Electro-osmotic courses don't work (I have one), grout injection is never going to create a completely impermeable barrier, and cutting out and inserting a proper DPC is going to cost mega money.
e) damp isn't the end of the world if your lifestyle / funishing preferences can work with it.

f) unless the advert specifically states it has damp you can now go back to the vendor and say your survey has found damp and they need to reduce the price by the amount it will cost to fix it.
g) is it cavity built?
h) does it have a damp proof course, and if so what is it?
i) does it have solid concrete floors, or suspended timber floors?
j) if the latter can you get into them to see the state of them?
k) a moisture meter is about £80, get one and do your own checks
l) there's lots of stuff about damp online
m) does rising damp exist? Bricks are like sponges, but as anyone knows a sponge can only suck water up a certain distance above the source (damp ground). Capilliary uptake like this is balanced out by evaporation, the faster water can evaporate from the bricks the lower the damp will appear to rise to. Hence why painting everything is bad unless you use permeable paint like Keim paint. The other mechanism believed to be responsible for 'rising' damp is condensation, and this is simply moisture condensing in cold walls near the ground. so, the best thing for rising damp is to lower ground levels where possible, keep the walls warm by insulating outside not inside, and allowing them to breathe.

More to come when I've had some feedback I've an 1895 house with suspended floors, rubble walls and no DPCs which gets a lake forming in the voids under the floors in winter because the water table is so high....
Toccata on 14 Jul 2017
In reply to kipper12:

I bought a house once with rising damp thinking I could manage it (great house and location). Within a year I had developed allergic asthma to the mould in the house and despite significant expenditure the asthma resolved only when we moved out.

As has been pointed out it can be a good negotiation point but personally, having lived in quite a few characterful older houses, I'd run a mile.
gethin_allen on 14 Jul 2017
In reply to kipper12:

Old houses often will have damp relative to modern building standards. They rely on having good ventilation to stay dry and people come along and fill all the gaps and air bricks to stop draughts and/or unscrupulous builders fill the underfloor cavities with rubble to avoid paying for a skip.

It's virtually impossible to survey a house thoroughly enough to determine that there are no damp issues as to do so would involve things like lifting floors and peeling back wallpaper and I don't think you'll find anyone willing to let you do this before you make an offer.

I'd say, use the report as ammunition to haggle on the price but expect to find some issue with damp at some point.
I wouldn't be too cynical in thinking that the only reason it's been painted is to hide a damp issue, anyone who wants a quick sale of a property would give the place a quick lick of paint to freshen things up.

Damp is just one of the trials of having an old house, my place is 115 years old and in the process of renovating it I've found dry rot, wet rot, rising damp, penetrating damp, wood worm to the degree that large timers have needed replacing and numerous issues with wiring and plumbing.
Very few of these issues could have been found in a survey unless the surveyor had spent weeks de constructing the building.
kipper12 - on 14 Jul 2017
In reply to Toerag:

Cheers for this, I don't know the answers to the critical questions yet, but I will let you know.

At the moment our thinking is get estimates for remedial work from reputable company, and then go in for some haggling. One of my concerns is that some information on line indicates that a conductivity-based damp meter works for wood but over estimates for other surfaces. So, has the surveyor found something or is the on-line info wrong?
Toerag - on 14 Jul 2017
In reply to kipper12:
Conductivity damp meters work well on wood, but the problem with using them on walls is that any salts left from previous damp episodes will affect the readings whether the damp is current or historic. so they are useful to know if an area has suffered damp at some stage, but don't necessarily tell you if it's still a problem. Only drilling in to see if the mortar is dry and dusty will tell you if it's currently damp. Expect to find 'damp' in alcoves on external walls, chimneys, internal 'dead air' corners, and around doors and windows. Black mould is condensation damp and will occur in the coldest parts of rooms like alcoves and under windows where the walls are thinnest.
Scotch Bingington - on 14 Jul 2017
In reply to kipper12:

I'd get miss Jones onto it, personally.
Yanis Nayu - on 14 Jul 2017
In reply to kipper12:

Those meters can give false positives where previous damp has left salts in the plaster.

I'd be more interested in whether there's a dpc or not.
hang_about - on 14 Jul 2017
In reply to kipper12:

When I was redoing my kitchen in a Victorian terrace I discovered a major damp problem. Wicking up the plaster (not cavity wallled)
Got a good company to fix it. Bubble mesh to form a gap between the wall and new plaster board. Sorted it for a few hundred quid.
His view was that it was impossible to keep out in some buildings but you can adapt techniques to remove the problem.
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kipper12 - on 14 Jul 2017
In reply to Toerag:

The flooring is suspended timber, and the survayors report says it is not possible to establish whether there is a Dec between the walls, though he thinks that it may not be present due to the age of the building
webbo - on 14 Jul 2017
In reply to kipper12:
Several years ago I watched TV programme where a Professor from some University had been trying for years to create rising damp by standing bricks, stone and breeze block in tanks of water. Never happened, his conclusion was there is no such thing, it's always caused by something else.

ian caton on 14 Jul 2017
In reply to kipper12:
The BRE (Buildings Research Establishment) had to abandon a research project into the effectiveness of remedial damp proofing because of a lack of properties. And they were working with one of the largest installers in the south of England.

In an old solid walled house with no insulation it can be condensation.

If the skirting boards aren't showing signs of deterioration it ain't so bad.
Post edited at 20:20
gethin_allen on 14 Jul 2017
In reply to Toerag:
"... Only drilling in to see if the mortar is dry and dusty will tell you if it's currently damp..."

The definitive method I think involves collecting a specified amount of material drilled from a test area and reacting it in a pressure container with calcium carbide and measuring the pressure increase.

gethin_allen on 14 Jul 2017
In reply to webbo:

I'm pretty sure I watched the same program and was pretty convinced until last year when I had my own experience with rising damp.
The outside wall is rendered and watertight and there was a damp proof membrane on insulation fitted to the inside of the wall yet the wall behind was wet and damp was rising up the wall.
I took a brick with some mortar on it and sat it in a bowl of water and you could see that there was moisture soaking into it.
My conclusion is that not all bricks are equal and the bloke in the show hasn't designed his experiments very well to reflect real life conditions.
Frank the Husky - on 14 Jul 2017
In reply to kipper12:

Rising damp is a con and, despite various posters being convinced they have it, they have not. There is a paper on the website of the RICS that describes rising damp as a myth.

Damp/moisture meters pick up high (50%+) levels of damp in bone dry wood and bricks and are not to be trusted.

You mention using a reliable company to quote for the work. Essentially this means asking a company that specializes in "rising damp" to give you a quote to fix a mythical problem and then to perform work which I can be certain will not improve the situation.

Send me a PM and I'll go through the options. If you're relatively nearby I'm happy to come out and cast my eye over it FOC.

A final & relevant question:- What sort of mortar has been used for the external walls?

Frank the Husky - on 14 Jul 2017
In reply to Toerag:

When you say "bricks are like sponges" what evidence can you show to support that?

SenzuBean - on 15 Jul 2017
In reply to gethin_allen:

> I'm pretty sure I watched the same program and was pretty convinced until last year when I had my own experience with rising damp.

> The outside wall is rendered and watertight and there was a damp proof membrane on insulation fitted to the inside of the wall yet the wall behind was wet and damp was rising up the wall.

> I took a brick with some mortar on it and sat it in a bowl of water and you could see that there was moisture soaking into it.

> My conclusion is that not all bricks are equal and the bloke in the show hasn't designed his experiments very well to reflect real life conditions.

Bricks definitely do soak up water: https://en.wikipedia.org/wiki/Capillary_action#Liquid_transport_in_porous_media

The damp proofing and membranes are exactly what make this wicking go further up. I didn't watch the show, but if the chappy didn't waterproof his bricks then it wasn't a proper experiment at all.
ian caton on 15 Jul 2017
In reply to Frank the Husky:
"Rising damp is a con".

So would you build a house without a DPC ?
Post edited at 07:46
bedspring on 15 Jul 2017
In reply to Frank the Husky:

> Rising damp is a con

Maybe it is, maybe it isn't, but surveyors and building societies seem to buy into it, so would you invest your life savings in something on the say so of some guy off the internet called Frank the Husky or go with the prevailing view of the industry?
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Frank the Husky - on 15 Jul 2017
In reply to bedspring:

I certainly wouldn't take my word for it, but (as I said) the RICS say the exact same thing.

Would I go with the prevailing view of the damp proof course/injection industry? You mean the industry that has a vested interest in promoting rising damp? I'll let you decide!
Frank the Husky - on 15 Jul 2017
In reply to ian caton:

Rising damp is a con but damp proof courses are a different thing. For example - my house was built around 1820. It was built with an integral damp proof course. House builders back then knew what they were doing. I had what was described as rising damp by the surveyors before I moved in. They told me that stone soaks up water like a sponge when it's over 150 years old - think about the stupidity of that statement for a second.

I got a quote for £4500 to inject and do all that stuff, got that deducted from the price of the house and then never went ahead with the DPC & injection nonsense.

The simple solution was to remove all the cement mortar that had been strap pointed over 100% of the existing but very old lime mortar, rake out the old stuff to a depth of about an inch and then remortar the house with 3.5 NH Lime.

Six months later the surveyors came back, believing I'd had the rising damp treatment and they gave me the all clear.

I did a few other simple things and that was all that was required. £250 of mortar, £150 for tools and a very steep learning curve.

Educational innit.
tripehound - on 15 Jul 2017
In reply to kipper12:

Extractor fans are now available with heat exchangers, so you can properly ventilate a building without losing heat at the same time. Any damp will be helped by proper ventilation, especially in kitchens and bathrooms. I would go for the above and get a chemical damp proof course installed as well.

We had damp diagnosed in a survey, we lived in the house for years, there was no smell or visible evidence of damp in that time. Surveyors come up with all sorts of crap to cover their backs, making their surveys virtually worthless as you cannot tell the real problems from the surveyors "just in case" issues.
Fraser on 15 Jul 2017
In reply to Frank the Husky:

> Rising damp is a con but damp proof courses are a different thing.

> Educational innit.

I think you're wrong about rising damp being 'a con', and your experience says more about your surveyor than the existence or not of the condition! Stone, and brick, have different degrees of porosity: the more porous they are, the more moisture they can suck up when left in wet conditions. Engineering bricks for example have a very low porosity and that's why they are used below ground level, same reason slate was historically used as an early type of dpc.

It's also why you shouldn't climb on recently soaked sandstone as it will be retaining that moisture, so will be softer and more prone to damage.

I also think people further up the thread are confusing damp proof membranes (usually laid on the flat on ground bearing concrete floors) with vapour barriers and breather membranes.

webbo - on 15 Jul 2017
In reply to kipper12:
I lived in a house built around 1670 and hadn't been lived in for 50 years. It had no damproof course and was built of porous Lincolnshire limestone and ironstone, it also had no footings and seemed to built just on to top of the clay and chalk ground. When we had it surveyed it was recommended we had a chemical damproof course installed until it was pointed out the foot thick wall were in filled with field rubble.
So we did nothing and we never had a problem with damp.

Frank the Husky - on 16 Jul 2017
In reply to Fraser: Indeed - porosity of stone is an interesting and sometimes complex subject. This is why I defer to the RICS. When I describe "rising damp" as a con, I am paraphrasing the result of some detailed & scientific research by Jeff Howells. It's worth reading his book and reaching your won conclusions.

To quote Francis Wheen (author of "How Mumbo Jumbo Conquered the World"):- 'If rising damp exists, then so does the tooth fairy. Jeff Howell has conclusively debunked a multi-million pound myth.'

Fraser on 16 Jul 2017
In reply to Frank the Husky:

Yes, I've seen the Howell research, at least in part, but have also read some of the responses relating to his earlier studies. I don't think he has debunked the myth in everyone's eyes, particularly as it doesn't appear to have been as 'scientific' as you suggest. Where I think we probably do agree is the field of treatment of said condition. That I do think is a scam, for the vast majority of providers.
Oliver Houston - on 17 Jul 2017
In reply to kipper12:

IMO (been dealing with damp in an 1899 Sheffield terrace for 5 years - no cavity wall, original black brick DPC), old houses get damp. Heat and ventilation is the best cure. We had a DPC injected by Peter Cox and I'm not sure it helped much, they failed to identify the rotten mortar that was the worst culprit of our penetrating damp problem.

So, repointing, digging a trench in the concrete by the back wall, "watersealing" and persuading the neighbours to get new gutters later, we still have a couple of issues, but they're not horrendous. By all means, try and get a discount, try and get a lot of opinions, but if the damp is not visible now, it might not be a problem. Saying that, it's been a dry spring, the vendors might have covered up something that will turn horrendous in winter.

Is there a cellar? can you look at the wall below? Can you see anything else that could be causing damp (a leaking gutter/drain can cause issues).
alan rosier - on 21 Jul 2017
In reply to kipper12:

Cured blown plaster on walls by making sure the dpc was not breached. In my case it was due to a combination of ash mortar filling the cavities and a synthetic wool type cavity wall insulation holding moisture. Cured it by taking out bricks and cleaning out the cavity. I pushed up strips of wire mesh to keep insulation from dropping down again. When windows came out i put a long hoover pipe in the cavities. Used air bricks in some of the repairs to aid drying. Time consuming unskilled labour but worked a treat. Good luck.

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