Damp proof course - is it a necessity?

monicamj

This may be a controversial question but is a damp proof course absolutely necessary or is something that will help a house sell more quickly?

I am buying a house that needs pretty much everything doing to it, I'm a complete novice apart from bits of DIY here and there - and mental I know!

It's a brick built terrace around 100 years old with floorboards downstairs. There is no damp that I can see, my mother's house was very similar - it never had a damp proof course and there were no apparent ill effects.

I'm not intending to sell the house for quite a long time, is damp proofing very disruptive?

Thanks for reading - sorry if I sound ignorant (I am;)) any comments most appreciated!

M

wallbash

Boy! are you opening a can of worms with your posting
A number of threads about Damp / Rising Damp / DPC etc recently.

Are you sure you haven't got a DPC.
quote After 1880 early Damp Proof Courses of tar and sand, lead cored felt, dense bricks and slate could be found.

If it aint broke , don't fix it!

monicamj

I thought it might! I don't know what it has currently, I was thinking of checking out the other houses in the street and seeing what they have

David_Aldred

As a direct answer to a direct question resistance to rising dampness must be provided to habitable accomodation under the Housing Act 2004 / public health legislation and Building Regulations to name but a bit of the rules / regs especially if you are renting the property out. Having said that many historic buildings have survived to this day quite happily without such a dpc and it depends what level of dryness you are prepared to put up with / what the risk of true rising dampness is. It may be obvous to state that masonry of foundations in the ground below the dpc survives very well though as moisture evaporates above ground level it leaves behind salts that can be disruptive the wall / plaster / decorations - what I would certainly be more cautious about is leaving timber in contact with dampness as it will inevitably germinate airborne spores of decay that are naturally occurring if the moisture within the wood rises above the threshold of decay (20-22% to sustain and generally about 28% to initiate). These rots especially dry rot can be a nightmare to resolve and the products of mould growth (the latter of which does not usually correlate with rising dampness) can make you very poorly indeed. Agree with previous posting that the house is likely to have a dpc - builders at that time were not dummies and were well aware fo this issue and probably you just cannot see it readily due to it being obscured by mortar / render / paths whatever. Agree also with previous posting in that this is a can of worms and hotly debated subject. Kindest regards to all - David Aldred

macman

The relevant question is not whether there is a DPC, but whether there is any damp. If there isn't, what are you worrying about? Most likely it has the basic slate DPC as described above, that was the standard at the time.
If you are gutting the place anyway then it would probably be worth having a chemical DPC done while the plaster is off the walls, otherwise no.

monicamj

Thanks David, can I ask - how do you know if you have rising damp?

monicamj

sorry macman my last post crossed yours, I see your point. I wasn't planning on stipping the plaster unless I have to.

David_Aldred

If there is true rising dampness then the plaster will be contaminated with salts making it hygroscopic such that it will attract moisture from the air so if you do not remove the contaminated plaster the wall will remain damp even if the new dpc was effective and justified. If the plaster does not have ground salts within it you are unlikely to have rising damp so then you start asking yourself why are you considering putting in a dpc. The modern paste type chemical dpc's are very safe to use and do not require pumps / fear of injecting into the adjoining property and can be hand caulked into wall drillings by any competant DIY person. Remember dpc work to the party wall comes under the Party Wall Act so if you are doing such work you must comply. The only way to prove rising damp is to undertake analysis of wall samples for each and every wall under investigation as set out within Building Research Establishment Digest 245 which is destructive and so expensive to do it requires big budgets and / or its court work for disputes. You can take less expensive measures to give you a bit of a clue such as salt analysis and carbide meters but you really need to know what you are doing if your going to base a decision on anything less than full lab analysis as salt readings can be misleading and carbide tests on site can give very high readings simply from hygroscopic moisture which is nothing to do with rising damp.

Do you want to put a chemical dpc in the wall as a precautionary measure whilst the area is accessible because your after a long term guarantee to show folks assuming the company is still in business later on and / or because you want to rule out any risk at all of rising damp coming to haunt your lovely finished property and here there are two sides to the argument. Why drill holes all over the place (2 to every brick) which with hammer drilling old brickwork can make a fragile old wall even more unstable if rising damp has not been proven and there is a strong liklihood of an existing dpc that is on balance usually working fine, against the argument of well supposing there is rising damp and I cover everything back up, decorate etc and then have to take it all apart again at a later date to insert a dpc. The ideal approach should be to rule out moiture sources that are apparent other than dpc failure and then monitor for drying down. If areas fail to resolve further lab tests for dpc failure may be justified but with a renovation project where you are working to a time frame and one trade is following another you may not have that luxury to wait and see, hence people have quite differing views on the issue. Kindest regards, David Aldred independent dampness and timber surveyor

monicamj

Thank you that is exremely helpful and given me something to think about.

andy69_2

Why don't you..'ask jeff' haha, only jokin! If you don't have any damp their is no need to do anything! Save your money that's what I would do!

monicamj

is ask jeff the guy that claims rising damp is a myth?!? And yes I'd rather not be spending money that I don't need to!