Damp Proof Course

blue_lemon

Hi,
Can anyone please give me advice. I found some damp whilst decorating my front room (victorian mid terrace) in one small area I was told I had rising damp & so decided to have a chemical damp proof. I was also told I needed to have all the plaster work hacked off & re-plastered using a special damp proof rending, (for I've had really expensive quotes). However apart from the above patch the rest of plaster work seems fine with no evidence of damp & plaster is not blown, I have removed skirting & again no visible damp. The damp metre readings were high but this room was being used as a storeroom, with intermittent heating & ventilation for the last couple of years. Will the plaster dry out? or do I need to have this work done?

muckybutt

Its normal for the plaster to be hacked off and re rendered with renovation plaster. If you dont hack the plaster off it will most likely blow when the cdpc is done, the dpc will effectively push the water from the wall into the plaster and you will get efflorescence from the salts in the original plaster coming through then.

daveyjp

Far easier to ventilate the room and don't store items close to walls.

blue_lemon

Thanks, I intend to use the room as a lounge now hence the decorating. I have read reports that 'rising damp' is very rare in most cases. The brickwork is exposed where I have removed the skirting & it seems fine, masonry is intact & from what I can see of the joists they also seem also dry?

Dry_Rot

Hi

Re-plastering is essential to end up with a really dry wall, because the rising damp (if that's what it is), deposits ground salts in the plaster.

Where the plaster is visibly stained or salting this is really essential. However, what you could do is leave the sound looking plaster and see if it is still blemish free after the DPC has been in for say 6 to 12 months (if it is a brick wall of average thickness). If it is still good then well it will probably stay good.

However, sometimes the very installation of a DPC will result in a salt bloom as the walls begin to dry out and that may come through the old plaster and destroy it, whereas the new render will be impervious to that.

Dry Rot

Leif

What are the signs of damp?

daveyjp wrote: »

Far easier to ventilate the room and don't store items close to walls.

Indeed. A chest of draws or a cupboard near a wall can lead to reduced air flow and condensation, causing mould, as you are probably suggesting. The fact that the plaster and skirting are fine is consistent with condensation.

AlexMac

I'm in favour of the 'heat and ventilate' solution, and waiting til after the coming summer, as that will show you if the discoloured plaster has really deteriorated to the point that it has become hygroscopic and forever prone to absorb atmospheric moisture. (google it or look at http://www.property-care.org/files/hygroscopic_salts2.pdf )

Victorian buildings are incredibly forgiving. You can get away with 80% fixes and they don't fall down. Their damp courses do tend to break down over time, as they often only consisted of a relatively fragile layer of slate or bitumen a couple of brick courses above soil level- or were sometimes absent. But decent ventilation and heating often compensate for this, and it has to be wet for ages before severe/more expensive problems develop (such as wet rot or dry rot in the wood joists and boards of any suspended timber flooring in contact with very damp brickwork; which is why you have air bricks to ventilate the sub-floor).

In your OP you say " in one small area I was told I had rising damp & so decided to have a chemical damp proof." Assuming you have done this (? ) the installers would then have recommended the (relatively expensive) 110% solution of stripping the internal plaster right back to the brickwork, re-applying a waterproof cement and re-plastering so they could offer a 25 year guarantee against recurrence.

But as the posts above say, even if you didn't have a chemical injection, lesser solutions work. Or a general builder could do it a lot cheaper without a guarantee. Or as Leif sez, there might not have been any rising damp at all- as condensation often lingers -especially in cold unventilated corners, and gives similar symptoms.

One last idea- make sure there's no obvious signs of splashing from overflowing or badly sited outside gutters/downpipes, nor earth piled up outside ground floor walls.

Ninnut85

Rising damp is not only rare, some people believe it's a total myth and does not exist.
Here is the information that was discussed from the QI website

"We're not sure whether or not Rising Damp exists, but there are certainly a lot of people who don't and so we felt duty bound to report the discussion:

Stephen Boniface, former chairman of the construction arm of the Royal Institution of Chartered Surveyors (RICS), has told the institute's 40,000 members that 'true rising damp' is a myth and chemically injected damp-proof courses (DPC) are 'a complete waste of money'.

According to the Independent, Mike Parrett of Lewisham Council in London has investigated over 5000 buildings and has never found a sign of rising damp. TIn 1997 the council offered a £50 reward to anyone who could show them a case of rising damp - none came forward. "

Dry_Rot

Ninnut85 wrote: »

Rising damp is not only rare, some people believe it's a total myth and does not exist.
Here is the information that was discussed from the QI website

"We're not sure whether or not Rising Damp exists, but there are certainly a lot of people who don't and so we felt duty bound to report the discussion:

Stephen Boniface, former chairman of the construction arm of the Royal Institution of Chartered Surveyors (RICS), has told the institute's 40,000 members that 'true rising damp' is a myth and chemically injected damp-proof courses (DPC) are 'a complete waste of money'.

According to the Independent, Mike Parrett of Lewisham Council in London has investigated over 5000 buildings and has never found a sign of rising damp. TIn 1997 the council offered a £50 reward to anyone who could show them a case of rising damp - none came forward. "

The myth of rising damp is just that - even those quoted don't support it and say their comments were quoted out of context.

Rising damp is very common, that is why it's a building regulation for all houses to have a DPC installed when built.

There is a massive amount of independent science papers supporting this and none supporting the rising damp myth mongers.

That said - rising damp is mis-diagnosed by very many untrained and unqualified 'damp specialists' and that is where the problems stems from.

There are very many good qualified guys out there, but sadly it's the cowboys who get the publicity.

For independent damp surveyors, consultants and damp proofing contractors try the property Care Association http://www.property-care.org/

The thing to remember is that those seeking publicity and notoriety tend to make claims which appeal to a cynical mind.. hence the MMR scandle and the new rush for everyone to instal 'green' damp proofing that has no scientific basis behind it - soundbites sell.

best regards

FACTorFICTION?

One last idea- make sure there's no obvious signs of splashing from overflowing or badly sited outside gutters/downpipes, nor earth piled up outside ground floor walls.[/QUOTE]


...wouldnt a good idea be to test if for rising damp in the first place rather than do any work atall?

True analysis with the use of calcium carbide.

To install or carry out ANY work solely on the grounds of a 'damp meter' is actualy fraudulant. Work should be proven to be needed.

cyclonebri1

Ninnut85 wrote: »

Rising damp is not only rare, some people believe it's a total myth and does not exist.
Here is the information that was discussed from the QI website

"We're not sure whether or not Rising Damp exists, but there are certainly a lot of people who don't and so we felt duty bound to report the discussion:

Stephen Boniface, former chairman of the construction arm of the Royal Institution of Chartered Surveyors (RICS), has told the institute's 40,000 members that 'true rising damp' is a myth and chemically injected damp-proof courses (DPC) are 'a complete waste of money'.

According to the Independent, Mike Parrett of Lewisham Council in London has investigated over 5000 buildings and has never found a sign of rising damp. TIn 1997 the council offered a £50 reward to anyone who could show them a case of rising damp - none came forward. "

Amazing, just posted exactly the same coments in the other damp thread without reading this:rotfl::rotfl::rotfl:

The tests I saw actually tried to get damp to rise and couldn't achieve it until it was tested in a vacuum which isn't going to happen on this planet