Is damp usually condensation?

[George_engineer]

It's worth reading the report carried out by Salford Uni a few years ago. It's goes into detail about how moisture gets through the mortar joints after a number of years. They had the finance to carry out a number of surveys on older, damp properties. Rising damp has always been difficult to reproduce in the lab.
The problem with Peter Ward's site for me is that he makes stupid statements, such as ' rising damp was invented in 1962' and the UK is the only country with a rising damp industry'.
Even Jeff Howell, who wrote the book, has had to come round to the fact he was wrong.

Is that the one where the house had already been treated with a chemical DPC?

That a mockery of the whole study.

 

[stuart45]

There were quite a few houses surveyed in the study, so probably one of them had previously been treated. It was quite an intensive research looking at all the aspects of the rising damp industry. They also worked with surveyors in Venice to look at their issues. Research of Jeff Howell's book was also done in detail, as well as Peter Ward's site.
Whatever study of rising damp is done there will always be someone who disagrees with the results.

 

[mrrusty]

Rising damp has always been difficult to reproduce in the lab.

I'll stick to my opinion, you have every right to have yours.

 

[JohnD]

No not really - I've experimented myself and yes a brick in water gets wet so there is an element of truth, and maybe the next brick up the wall also gets wet through absorption, but to imagine that water creeps up a wall several feet jumping across the mortar layers......

Very difficult to argue it exists through capillary action to the extent that some people suggest it does against this photo

Capillarity causes water to rise by surface tension. The smaller the pores, the further it rises.

It moves from large pores into small. But does not easily move from small pores into large.

Good clean brickwork has courses of bricks separated by beds of mortar. The pore sizes are different. The change in pore size makes it difficult for water to rise in and out for more than a couple of courses. And it evaporates off the exposed surfaces. Hence the canal and bridge photos where there is unlimited water but it does not rise far

When it does rise more than a couple of courses, there is likely to be some other unusual cause, which needs to be investigated, identified and addressed.

 

[stuart45]

The mortar course on new brickwork forms quite an effective barrier against rising damp. That's why Jeff Howell found it wouldn't rise. He only managed to get it to rise a couple of courses by using a special, more clay based mortar.
The sorptivity of the materials means that the moisture will normally evaporate before it rises too far. What the studies have found is that the ground salts over a period of time change the properties of the masonry, especially the mortar, which means that the wall doesn't desorb moisture as well as when first built.
This means it can rise further up the wall.

 

[foxhole]

I'll stick to my opinion, you have every right to have yours.

It’s been impossible to reproduce rising damp in the lab , the lab being a basement which was flooded and had all the main brick types built in small piers ( over 80 ) sitting in the water for over 2years . Zero rising damp was detected using sensor mounted two inches above the water line.

 

[JohnD]

What the studies have found is that the ground salts over a period of time change the properties of the masonry, especially the mortar, which means that the wall doesn't desorb moisture as well as when first built.
This means it can rise further up the wall.

It didn't in my house. The water rises no more than two courses. It doesn't reach the DPC. You can actually see a crust of limescale because the house is built on chalk.

 

[stuart45]

It didn't in my house. The water rises no more than two courses. It doesn't reach the DPC. You can actually see a crust of limescale because the house is built on chalk.

It won't on every house. Chalk is generally a good sub soil for building on and usually drains really well.
It only affects certain properties.

 

[JohnD]

certain properties

I prefer the word "rare."

 

[stuart45]

I prefer the word "rare."

Depends on what your definition of rare is. It's definitely not as common as the damp proofing companies would claim. As most houses built since 1875 have some sort of DPC, those would be excluded. You then need a sub soil containing an abundance of the chlorides and nitrates needed, and masonry units that will absorb moisture. However, as most people don't work in that particular field of the industry, they can only guess at the amount of properties affected.

 

[stuart45]

I'll stick to my opinion, you have every right to have yours.

It's not so much my opinion, it's the opinion of people who have studied it.
I wouldn't have so much faith in a site that claims rising damp was invented in 1962, only the UK has rising damp, and has a picture of a moat that claims proves beyond doubt that it's a myth.

 

[mrrusty]

It's amazing isn't it that there are a zillion threads and articles out there about damp in caravans - very similar issues that people have in their homes - damp walls, damp floors, mould..... - must be jumping damp that leaps across the gap from ground to caravan!

 

[stuart45]

I don't know much about caravans, but would guess they could get serious condensation issues.
If you like, I could probably find the report and email it to you. It's worth reading for an alternative opinion.

 

[mrrusty]

It's worth reading the report carried out by Salford Uni a few years ago

I've read it and it sets out to prove what the writer wanted to prove....except look at this from that report- "rising damp" in an early 20th century house.....around a fire place, that inevitably would have had coal fires burning for several decades. IMHO, (and as found in my own house) damp around the breast is salt contamination caused by reactions of combustion gases, condensation and building materials.

As I said, you have your opinion, I have mine.

 

[stuart45]

Photos on their own never really prove things either way. What happens in one properly can be different to another.