Rising Damp - Fact or Fiction?

[opps]

I have worked in loads of houses where the ground floor walls have been damp from floor level up and above the skirting. The clients have got someone in to drill and inject the walls. When the walls have dried out, the damp has not returned. No other remedial work was undertaken.

If DPCs don't do anything, why didn't the damp return?

 

[Harry Bloomfield]

I've read claims that there is no such thing as "Rising Damp" and that there's much disinformation surrounding this topic. Could someone with real world building experience please explain the true fundamental with regards to this.

In my opinion - Not all damp is of the rising variety, though many so called 'experts', with a damp curing business will say it it is. Most damp problems, are due to moisture condensing on a cooler surface.

 

[stuart45]

Blimey you've been busy getting indoctrinated by Peter Ward.

He says they don't have DPC's in the Netherlands ... that is a big fat lie.

I think the reason that people claim this about Holland is that Jeff Howell wrote about it in his book, based on a weekend in Amsterdam.
I have worked with Dutch bricklayers in Belgium years ago and DPC was used there. Also Holland does appear to have some problems.

European attack on rising damp in buildings (tudelft.nl)

 

[Captain Nemesis]

Blimey you've been busy getting indoctrinated by Peter Ward..

Ive never heard of him

 

[kettlemanjim]

"Damp/rising damp/condensation/water ingress" can be one of the most difficult problems to sort out

 

[ShowerWoe]

Rising damp is a myth, says former RICS chief

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’.

www.architectsjournal.co.uk

 

[ShowerWoe]

I have worked in loads of houses where the ground floor walls have been damp from floor level up and above the skirting. The clients have got someone in to drill and inject the walls. When the walls have dried out, the damp has not returned. No other remedial work was undertaken.

If DPCs don't do anything, why didn't the damp return?

The plaster they use stops any damp coming through

 

[opps]

The plaster they use stops any damp coming through

Well that doesn't make any sense. In the vast majority of cases the plaster wasn't removed. All that was done was drill and inject.

The only time I have seen the plaster removed and replaced with a cement based product was where dry rot was spotted.

 

[opps]

Rising damp is a myth, says former RICS chief

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’.

www.architectsjournal.co.uk

He claims that if you put a brick pillar in a bucket of water, there will be no capillary action past the last brick in the water.

How is that in houses with rising damp, the screws holding the electrical metal back boxes in place are often rusty whereas the screws in the back boxes on the floor above are not?

 

[George_engineer]

From my own experience inspecting houses and from renovating a 1880s house, I fully agree with Peter Ward that the mechanisms sold to us by damp companies are nonsense. I cannot see how capillary action could possibly go from a brick, through mortar and back into the next brick. The solutions are pretty tenuous as they all aim to put in a DPC when it is not necessarily required. Lime plaster, ventilation and heating should solve it.

On my house at one point a damp 'specialist' quoted £6k to inject gunk into the wall just above the perfectly serviceable slate DPC. In the end, damp was solved by removing cement tanking and gypsum plaster and replacing it with lime plaster, heating the house and improving ventilation. No chemicals needed.

What you need to remember is that old houses were built with multiple fireplaces which drag huge quantities of fresh air into them and kicked out lot of heat. They never had damp issues. Sealing them up and using central heating just won't cut it - old houses are best off with mechanical ventilation. (Also, showers and steamy cooking which also weren't around back when)

Causes of damp
95% damp is caused by penetrating damp (broken gutters, high external ground levels, hardstanding causing rain to splash against the wall etc), or by condensation, caused by a lack of heating and/or lack of ventilation.

I think the reason 'rising damp' exists as a concept is because the base of walls near the ground are cooler (heat risings and the earth is a massive heat sink, often just below the dew point). This means condensation will form there first. Once the plaster and the wall get wet, the conduction of heat to the ground is more rapid, allowing the dew point to creep upwards in the wall.

 

[opps]

What you need to remember is that old houses were built with multiple fireplaces which drag huge quantities of fresh air into them and kicked out lot of heat. They never had damp issues. Sealing them up and using central heating just won't cut it - old houses are best off with mechanical ventilation. (Also, showers and steamy cooking which also weren't around back when)

The TV programme Rising Damp was first aired in 1974, but the concept of rising damp clearly existed long before then. How many people in the 50s or 60s had central heating and cooked pasta. If it is simply down to condensation, why is it more noticeable in ground floor rooms where people tend not to sleep?

The following suggests that rising damp is real, but suggests that it is soil evaporation rather than capillary action. Nevertheless, it concludes that rising damp is real.

 

[George_engineer]

I wasn't around but I understand central heating became more widespread by the 1970s.

 

[Deleted member 174758]

If DPCs don't do anything, why didn't the damp return?

The plaster they use stops any damp coming through

And what kind of plaster would that be? Please don't confuse plaster with waterproof render which is often used to make a building more flood-proof in the future (render dries out a lot faster than plaster after a flood)

A large percentage of the housing stock in my area is Victorian, stone or stone and brick built, so pyramid-form masonry foundations and no DPC. Some even older properties have rubble infill stone walls, again with no foundations, although the walls taper from the ground level upwards. The local stone is sandstone, both bedock and for building. Sandstone is most certainly not impervious to water.

I've lived in both types of houses - and they all seem to suffer from a form of "rising damp" in addition to condensation problems when you centrally heat them. At certain times of the year when rainfall is very high the water table gets very near to the ground surface level - near enough to soak into the brick or stone foundations. All the houses I've lived in have been on the valley sides - too great a risk of flooding in houses built on the flood plains in the valley bottoms for my liking - but one thing which is consistent is that damp measured in the masonry using a Tramex meter is always further up the walls on the uphill side than the downhill side in autumn and winter and the water seems to get drawn up into the sandstone masonry, although normally only a few feet above ground level. Put in an injection DPM and it stops a large percentage of that happening, but as said so many times in so many places, there is also a need to ventilate well, especially if you have double glazing and loft insulation

One of our houses was a stone-walled/rubble-infill house where damp inside the back (uphill) wall got to nearly 5ft above the floor level. This was not condensation. The "cure", used a lot locally, was to strip back the (lime) plaster to ceiling level and injection DPC the walls, which dried the wall out nicely. After 6 months I rendered the wall with a thin skim of waterproof rendering then I skim plastered over that. Before doing the DPC we'd endured two damp, miserable winters in this house (no CH downstairs, we had a wood burner in the living room, which itself requires a lot of air flow/ventilation, and a solid fuel Rayburn in the kitchen). The "non-essential" injection DPC cured the back wall's tendency to turn into a really cold, damp area in the winter.

I agree that firms selling injection DPC are often trying to sell a simple solution, but this type of product shouldn't just be written off. It has its' uses.

BTW, that comment about Dutch houses not having a DPM is a red herring (of een rode haring in Nederlands). The Dutch tend to build on a different foundation, which is several layers of different types of compacted gravel and sand which to the untutored eye looks like no foundations, but the masonry which goes on top in a modern building has to have a DPM. I built two houses for myself over there in the 1980s, a conventional timber frame and a SIPS panel respectively and both houses were built onto a concrete raft which had a conventional DPM

 

[Deleted member 174758]

I wasn't around but I understand central heating became more widespread by the 1970s.

I was, and yes it did, together with double glazing - all sans decent ventilation. I feel a lot of houses with damp, especially newer ones, could benefit from a some ductwork and something like a PIV unit in the attic, and better trickle vents

 

[George_engineer]

That's an interesting case because you can absolutely understand why a wall that is in a wet climate, shaded and facing uphill would benefit from a waterproofing system. But that is essentially a different form of penetrating damp (ie the wall is constantly being saturated and has no chance to dry out). It doesn't really have much to do with capillary action in bricks.

I've got nothing against the technology of damp proofing - but often it was designed for basements and it gets misapplied at great expense to the homeowner.