Rising Damp fact or fiction?

Post by **ultimatehandyman** » Tue Mar 13, 2007 11:24 am

I have just finished writing a page that I started about 18 months ago and never got around to finishing.

http://www.ultimatehandyman.co.uk/rising_damp.htm

I believe that rising damp does exist as I have had two properties that have been effected. There are a few people now that are saying that rising damp does not exist!

I find this hard to believe and if it did not exist then would all the mortgage companies insist on having a suitable damp proof course?

Opinions please?

jason123 · Post by **jason123** » Tue Mar 13, 2007 5:22 pm

There are alot of factors, some houses foundations are actually lower than the surrounding water table, they if dry are defying the laws of physics and have a good DPC. Moisture testers usually just detect abnormally high levels of moisture in the plaster and as such, poor air circulation/condensation could be the problem and not rising damp. In my opinion rising damp does exist, and the dryer the brick the more inclined will moisture be to rise in it.

dewaltdisney · Post by **dewaltdisney** » Tue Mar 13, 2007 6:44 pm

Of course rising damp exists but it depends on many factors as to how severe it can be. Bricks will suck up water relevant to the density and porosity of the bricks used by capillary action. Older bonded walls without a cavity are more susceptible as there is a greater mass of brickwork to soak up water. Much will depend on the foundations and it is usual to build foundation walls out of very dense engineering bricks through which water cannot easily penetrate.

If the ground is saturated or the water table is high then this constant presence of water will feed the capillary action.

In older properties slate damp courses where used and as time has gone on these crack and allow water through. any breaches can be dealt with chemically quite successfully. If a house has sleeper walls supporting wooden floors on the ground floor then damp can enter these and cause rot in timbers so it is important to ensure that these walls are also dealt with. often the party wall in terraces and semi's did not have DPC's so this is another area to check.

Yes, rising damp does exist.

DWD

owen · Post by **owen** » Tue Mar 13, 2007 8:21 pm

I have looked at/worked in lots of old houses with damp problems, so here is my opinion:

I have had DPCs injected into several houses, all of which prevented further damp, so i am happy that rising damp does exist.

However, in old houses without DPCs there are often numerous other causes of damp, many of which get diagnosed as rising damp by damp proofing companies trying to sell their services. A lot of properties i look at have no central heating and no double glazing, so is likely to suffer from condensation. Many have old guttering and dodgy roofs, again sources of damp. I also did some coucil grant work on a house a few months back, installing an injected DPC to solve supposed rising damp on three walls. However, the damp on one wall i traced to a leaking plumbing fitting in the downstairs bathroom.

tim'll fix it · Post by **tim'll fix it** » Tue Mar 13, 2007 10:24 pm

rising damp is due to air pressure as well isnt it, which is why it only rises so far

I agree with owen you need to understand the source of the damp to solve the problem, also you can only inject brickwork, if you have stone you need a different solution

dewaltdisney · Post by **dewaltdisney** » Wed Mar 14, 2007 9:02 am

I recall somewhere in school science about air pressure pushing water up to 32 feet. I think you needed a vacuum for this though

DWD

tim'll fix it · Post by **tim'll fix it** » Wed Mar 14, 2007 9:04 am

Where is stoday with his encyclopedic knowledge when you need him

marksson · Post by **marksson** » Fri Mar 16, 2007 10:53 pm

I seem to remember that there is some guy who has had various brick/block walls sitting in fish tanks for like 5/10 years with different bricks/mortars etc and the moisture levels will not become significant at 6" or 9" above the water level.
Anyone else remember this or is it some sort of folklore fable?

Post by **ultimatehandyman** » Sat Mar 17, 2007 9:26 am

marksson wrote:I seem to remember that there is some guy who has had various brick/block walls sitting in fish tanks for like 5/10 years with different bricks/mortars etc and the moisture levels will not become significant at 6" or 9" above the water level.
Anyone else remember this or is it some sort of folklore fable?

I have seen two guys on the net that refuse to accept the fact that rising damp exists, one of these went to great lenghts to disprove the fact.

One of these guys also says that if you find proof of woodworm it is not worth treating it with pesticides as the attack could of been 50 years or so ago!

Personally if I have an house then it is a valuable asset and needs looking after, if I find rising damp I get a DPC installed and if I find woodworm holes, I treat it as a precaution! Better safe than sorry!

tim'll fix it · Post by **tim'll fix it** » Sat Mar 17, 2007 9:48 am

woodworm only attack soft timber so If you have an old oak in your house once it is past being green and soft then the worm wont attack it

softwood is another matter

a little knowledge is a dangerous thing

dewaltdisney · Post by **dewaltdisney** » Sat Mar 17, 2007 10:59 am

You never know if the people who make these statements are just doing a wind up. We all accept posters as being credible if it sounds about right and if it all sounds credible then you will start people believing it. Of course rising damp exists. It will not show on individual bricks in a tank as you need mass to cause the capillary action.

I have seem valid arguments for and against global warming so this sort of rubbish happens at the highest levels as well. Personally I think that it is an excuse for more taxation.

DWD

Hinton Heating · Post by **Hinton Heating** » Sat Mar 17, 2007 2:28 pm

Damp definitely rises... I repaired a leak on a cold main, which was buried in the concrete slab this morning.... The water had risen up the internal walls by about 2 ft!

legs_akimbo · Post by **legs_akimbo** » Sun Mar 18, 2007 9:57 am

I have hacked off the perished plaster on an old cottage to a metre in height, then tanked it and replastered it only for it to manifest itself one metre above the floor some weeks later, the lower replastered section was and still is perfect.

tim'll fix it · Post by **tim'll fix it** » Sun Mar 18, 2007 4:20 pm

damps funny stuff

a mate of mine did a barn conversion and has a patch of damp on an internal wall, no pipework nearby, etc in the middle of the wall, dry all around it, it just wouldnt dry

probably salts or something