Damp Proof course

[AndersonC]

it has been surveyed

A ha! That old chestnut eh?? I bet the surveyor even recommended that they get a second opinion from a "damp specialist company", who of course would be totally impartial in their recommendations .

I had a house surveyed and was told there was a rising damp problem in some internal walls. He advised me to get a damp company in for a second opinion (thieir 'unbiased' opinion being that they wanted my money). Lo and behold, they recommended chemical injection (unforunately not into themselves).

As I found out more about damp and ventilation, it turned out that the moisture content 'detected' in the walls was related to the fact that the old biddy who lived there before never opened a window and blocked all the draughts in the place. Oh, and the fact that there was a physical DPC at the foot of the walls as well.

My concern was that it obviously never entered the thoughts of the surveyor to question the levels of ventilation in the property, levels of cavity bridging etc, they seem to be pre-programmed so that when the meter goes beep, the ONLY answer is to get a chemical 'DPC' put in.

 

[anobium]

Whats up Softus, nobody taking the bait these days, you must be a real sad barsteward and have a sad life if this is how you get your kicks.


No problem I will humour you, I have a few minutes to spare before I go out.

Could you please elaborate on your above responses.

 

[Softus]

[Whats up Softus, nobody taking the bait these days, you must be a real sad barsteward and have a sad life if this is how you get your kicks.

If you say so.

No problem I will humour you, I have a few minutes to spare before I go out , could you please elaborate on your above responses.

You know the topic anobium - time might have passed, but nothing has changed. If you yourself have a real-life example, I've yet to hear about it.

 

[davebelushi]

I rarely come on here. But Softus, opinions are like arseh*les! everyones got one. Yours is however, wrong.

Well, could I politely request from you the details of just one real-life example if rising damp, i.e. one that you've seen with your own eyes, and one for which you've seen the cure?

Internal party wall visibly damp to around 350mm. No physical DPC. After salt analysis a heavy presence of Nitrates, Chlorides and Sulphates was found. Ergo, salts have been carried up from the underlying substrate. Unless the salt pixies mined them into the wall! I deduce that the salts were carried via a source of moisture rising from the ground.

Injected a siliconate remedial DPC. Allowed a number of months to dry before replastering with limelite renovating plaster.
I have done this many, many, many times.

 

[AndersonC]

I have some questions Dave:-

Were the salts confirmed only in the plaster (which was then removed) or also in the brickwork?

Was there a physical gap between the plaster and the floor or did the plaster extend all the way to the floor? What was the floor made from?

Where is the evidence that the injected DPC solved the problem? You allowed the walls to dry out for months before re-plastering with fresh, plaster/sand & cement which commonly contains a waterproof additive. Doing this would probably remove the damp symptoms, in the short term, without the DPC having been injected.
What I am trying to point out is that when a walls is diagnosed as having rising damp, the solution rarely involves only injecting a chemical DPC. Therefore how can anyone be certain that these things actually rectify the problem?

I have yet to hear of evidence to show that when the old plaster stays on and the level of ventilation in the house has not changed, the injection of a chemical DPC and nothing else results in the damp problem being resolved.

I am not very likely to see this because the first thing DPC firms do is hack off the plaster to a height of 1m, and replace it after the walls have dried out, with loads of ventilation in the property.

 

[anobium]

I would in the absence of a response from Davebelushi like to reply
1) Were the salts confirmed only in the plaster (which was then removed) or also in the brickwork?

When identifying the cause of damp it is common practice to take samples from both the mortar and the plaster and measure the salt content in both materials.

2) Was there a physical gap between the plaster and the floor or did the plaster extend all the way to the floor? What was the floor made from?
Again anybody who knows what they are doing will include this aspect in their diagnosis, but bear in mind that the plaster can extend down to the floor without any adverse effect on the dpc.
I refer of course to a timber suspended floor
.
3)Where is the evidence that the injected DPC solved the problem? You allowed the walls to dry out for months before re-plastering with fresh, plaster/sand & cement which commonly contains a waterproof additive. Doing this would probably remove the damp symptoms, in the short term, without the DPC having been injected.
What I am trying to point out is that when a walls is diagnosed as having rising damp, the solution rarely involves only injecting a chemical DPC. Therefore how can anyone be certain that these things actually rectify the problem

Quite simple really if you have correctly identified rising damp as due to failure or lack of a dpc and injected a chemical dpc, do not remove the old plaster or replaster for about 6 months.
Return to property after this period and take further tests and compare with initial tests.
Alternatively if wall in question was severely affected with salts the answer will be self evident as the wall dries out the salts will crystallize.

4)I have yet to hear of evidence to show that when the old plaster stays on and the level of ventilation in the house has not changed, the injection of a chemical DPC and nothing else results in the damp problem being resolved

Again if testing for the cause of damp in a property correctly , ie not solely using a damp meter, the results in a case such as you describe will show that only the outer surface of the wall, the plaster is damp.
Lack of ventilation will not affect the moisture content of the bricks or mortar to any great degree.

 

[Softus]

1) Were the salts confirmed only in the plaster (which was then removed) or also in the brickwork?

When identifying the cause of damp it is common practice to take samples from both the mortar and the plaster and measure the salt content in both materials.

That's actually the rare practice; the common practice is to recommend injection based on insufficient sampling and an incorrect analysis.

2) Was there a physical gap between the plaster and the floor or did the plaster extend all the way to the floor? What was the floor made from?
Again anybody who knows what they are doing will include this aspect in their diagnosis

By inference, then, people who don't know what they're doing will exclude that aspect. And, by deduction, since there are people out there who don't know what they're doing, it must happen.

...but bear in mind that the plaster can extend down to the floor without any adverse effect on the dpc.
I refer of course to a timber suspended floor

It can do, but doesn't always. And AndersonC already knows that.

3)Where is the evidence that the injected DPC solved the problem? You allowed the walls to dry out for months before re-plastering with fresh, plaster/sand & cement which commonly contains a waterproof additive. Doing this would probably remove the damp symptoms, in the short term, without the DPC having been injected.
What I am trying to point out is that when a walls is diagnosed as having rising damp, the solution rarely involves only injecting a chemical DPC. Therefore how can anyone be certain that these things actually rectify the problem

Quite simple really if you have correctly identified rising damp as due to failure or lack of a dpc

That's a huge "if", because one school of thought is that it's simply impossible to correctly identify rising damp as due to a failed or ommitted DPC.

4)I have yet to hear of evidence to show that when the old plaster stays on and the level of ventilation in the house has not changed, the injection of a chemical DPC and nothing else results in the damp problem being resolved

Again if testing for the cause of damp in a property correctly , ie not solely using a damp meter, the results in a case such as you describe will show that only the outer surface of the wall, the plaster is damp.

Again, your reply to AndersonC's questions are all hypothetical, and have nothing to do with the reality of davebelushi's scenario, which we've yet to hear more about.

Lack of ventilation will not affect the moisture content of the bricks or mortar to any great degree.

So, by inference, it will affect the moisture content to a small degree. In your opinion.

 

[AndersonC]

My word this is becoming an interesting debate again!

Again if testing for the cause of damp in a property correctly , ie not solely using a damp meter, the results in a case such as you describe will show that only the outer surface of the wall, the plaster is damp.

Anobium, I am interested in what techniques there are to test for damp as well as using a conductivity meter, the damp 'tests' that I was conned into believing some years ago were based solely on conductivity meter test results.

Lack of ventilation will not affect the moisture content of the bricks or mortar to any great degree.

So ventilation will only affect moisture levels in the plaster then?

Allowed a number of months to dry....

It's interesting that davebelushi has referred to allowing the wall to dry out - perhaps it wasn't ventilation and air movement around bare bricks and mortar that allowed Dave's wall to dry? How did you allow the walls to dry out over a "number of months" Dave - offer them a towel?

 

[anobium]

Softus before I reply to your recent post, could you please deal with davebelushi's point re the presence of salts in a wall, ie where did they come from.?
It may save us both a lot of time.

 

[davebelushi]

rapid artificial drying was not introduced. as the wall dries out, approx 1 month per inch thickness, the salts migrate to the surface and are brushed off.
tests carried out again.
tests confirmed that the density of salts has reduced to much lower levels. calcium carbide test confirms that moisture within the brick has fallen to below 5%.
tests also taken from below level of chemical dpc where heavy salts and high moisture still present.

 

[anobium]

1) Were the salts confirmed only in the plaster (which was then removed) or also in the brickwork?

When identifying the cause of damp it is common practice to take samples from both the mortar and the plaster and measure the salt content in both materials.

Softus wrote
That's actually the rare practice; the common practice is to recommend injection based on insufficient sampling and an incorrect analysis.

It is common practice to those who know what they are doing and uncommon to those who are ignorant .
Bit like good and bad plumbers and electricians.

2) Was there a physical gap between the plaster and the floor or did the plaster extend all the way to the floor? What was the floor made from?
Again anybody who knows what they are doing will include this aspect in their diagnosis

Softus wrote
By inference, then, people who don't know what they're doing will exclude that aspect. And, by deduction, since there are people out there who don't know what they're doing, it must happen.

you've answered your own question

...but bear in mind that the plaster can extend down to the floor without any adverse effect on the dpc.
I refer of course to a timber suspended floor

Softus wrote
It can do, but doesn't always. And AndersonC already knows that.

3)Where is the evidence that the injected DPC solved the problem? You allowed the walls to dry out for months before re-plastering with fresh, plaster/sand & cement which commonly contains a waterproof additive. Doing this would probably remove the damp symptoms, in the short term, without the DPC having been injected.
What I am trying to point out is that when a walls is diagnosed as having rising damp, the solution rarely involves only injecting a chemical DPC. Therefore how can anyone be certain that these things actually rectify the problem

Quite simple really if you have correctly identified rising damp as due to failure or lack of a dpc

Softus wrote
That's a huge "if", because one school of thought is that it's simply impossible to correctly identify rising damp as due to a failed or omitted DPC.

Where on earth do you get this information from, if you have read the many previous post you will see it is just as easy to identify rising damp as it is to identify all the types of damp that can affect a building
In laymans terms it's simply a process of elimination

4)I have yet to hear of evidence to show that when the old plaster stays on and the level of ventilation in the house has not changed, the injection of a chemical DPC and nothing else results in the damp problem being resolved

Again if testing for the cause of damp in a property correctly , ie not solely using a damp meter, the results in a case such as you describe will show that only the outer surface of the wall, the plaster is damp.

Softus wrote
Again, your reply to AndersonC's questions are all hypothetical, and have nothing to do with the reality of davebelushi's scenario, which we've yet to hear more about.

Again what makes you arrive at that conclusion, do you have information regarding my occupation , qualifications or experience on the subject. ?

Lack of ventilation will not affect the moisture content of the bricks or mortar to any great degree.

Softus wrote
So, by inference, it will affect the moisture content to a small
degree. In your opinion.

Not an opinion but fact, simply based on the results of carbide tests of the wall structure.

 

[Softus]

That's actually the rare practice; the common practice is to recommend injection based on insufficient sampling and an incorrect analysis.

It is common practice to those who know what they are doing and uncommon to those who are ignorant .

I utterly agree. And the industry is dominated by people who don't know what they're doing. Ergo, it's rare.

By inference, then, people who don't know what they're doing will exclude that aspect. And, by deduction, since there are people out there who don't know what they're doing, it must happen.

you've answered your own question

I didn't ask a question, I pointed out the fallacy in your statement.

...but bear in mind that the plaster can extend down to the floor without any adverse effect on the dpc.
I refer of course to a timber suspended floor

It can do, but doesn't always. And AndersonC already knows that.

I don't know what you're confused about.

3)Where is the evidence that the injected DPC solved the problem? You allowed the walls to dry out for months before re-plastering with fresh, plaster/sand & cement which commonly contains a waterproof additive. Doing this would probably remove the damp symptoms, in the short term, without the DPC having been injected.
What I am trying to point out is that when a walls is diagnosed as having rising damp, the solution rarely involves only injecting a chemical DPC. Therefore how can anyone be certain that these things actually rectify the problem
Quite simple really if you have correctly identified rising damp as due to failure or lack of a dpc

That's a huge "if", because one school of thought is that it's simply impossible to correctly identify rising damp as due to a failed or omitted DPC.

Where on earth do you get this information from

It's common knowledge, to the people who know what they're talking about.

4)I have yet to hear of evidence to show that when the old plaster stays on and the level of ventilation in the house has not changed, the injection of a chemical DPC and nothing else results in the damp problem being resolved

Again if testing for the cause of damp in a property correctly , ie not solely using a damp meter, the results in a case such as you describe will show that only the outer surface of the wall, the plaster is damp.

Again, your reply to AndersonC's questions are all hypothetical, and have nothing to do with the reality of davebelushi's scenario, which we've yet to hear more about.

Again what makes you arrive at that conclusion

The fact that you always hypothesise, and never give an example of a real-life, touchy-feely, I've-seen-rising-damp-with-my-own-eyes-and-only-one-thing-was-changed-to-cure-it scenario.

do you have information regarding my occupation , qualifications or experience on the subject. ?

Do you ever post any such information?

Lack of ventilation will not affect the moisture content of the bricks or mortar to any great degree.

So, by inference, it will affect the moisture content to a small
degree. In your opinion.

Not an opinion but fact, simply based on the results of carbide tests of the wall structure.

Which wall?

 

[davebelushi]

rapid artificial drying was not introduced. as the wall dries out, approx 1 month per inch thickness, the salts migrate to the surface and are brushed off.
tests carried out again.
tests confirmed that the density of salts has reduced to much lower levels. calcium carbide test confirms that moisture within the brick has fallen to below 5%.
tests also taken from below level of chemical dpc where heavy salts and high moisture still present.

no comments? interesting.

 

[AndersonC]

Here's an observation though:-

rapid artificial drying was not introduced. as the wall dries out, approx 1 month per inch thickness

So the wall just got dried out by the air around it?

Lack of ventilation will not affect the moisture content of the bricks or mortar to any great degree.

If the lack of ventilation doesn't affect the moisture content of the bricks & mortar, how can the presence of ventilation, i./e. moving air around the wall, affect the moisture content sufficiently to dry it?

Surely if the presence of ventilation affects moisture levels then the lack of it must affect moisture levels .

 

[davebelushi]

Here's an observation though:-

rapid artificial drying was not introduced. as the wall dries out, approx 1 month per inch thickness

So the wall just got dried out by the air around it?

Clearly

Lack of ventilation will not affect the moisture content of the bricks or mortar to any great degree.

If the lack of ventilation doesn't affect the moisture content of the bricks & mortar, how can the presence of ventilation, i./e. moving air around the wall, affect the moisture content sufficiently to dry it?

Surely if the presence of ventilation affects moisture levels then the lack of it must affect moisture levels .

Clearly