chemical damproofing

[mgdave]

Do the chemical damp proof products advertised actually work ?,I am talking about the ones were you drill holes at intervals along the wall and inject the chemical, if so can anyone recommend a good one ?
Dave

 

[Glassman]

I made a post about this last week.

The Chemical Injection is not a cure to rising damp but merely a way to help reduce it. These companies can charge you hundreds of pounds for something that you can very easily do yourself in my opnion.
You may even find that once you are £500+ out of pocket, the damp is still there.

A quick search on google should provide you with the info to buy the chemical injection yourself.

I paid a cowboy £620 last year for DPC Injection and now I've had to completely remove the plaster from the internal wall in my house because the damp is still there. I'm just waiting for a good downfall so that I can try to trace the source of my damp problem myself.

BE WARNED! - If you should have to make a claim on their warranty they may find some loophole and not pay out. In my case, I used my own plasterer afterwards and although I was issued with a garauntee for the damp-proofing, it was void before they had written it out. They didn't forewarn me of this because they wanted my money.

Dont waste your money before you do a lot of research.

 

[Lower]

i've read lots of stuff on here about how rising damp doesn't exist etc, but in my house i have damp in a couple of internal walls. they are brick built internal walls with foundations and a double line of blue bricks. the walls are plastered, but way above the blue bricks and there is no way for water to contact the plaster from the ground. there is decent ventilation around these walls, yet they are still damp.

So if there is no such thing as rising damp, why is the plaster permenantly slightly damp to about 2 feet above the floor level, 3 feet above ground level?

 

[Softus]

Do the chemical damp proof products advertised actually work ?

No. They don't. Please see the various topics on this forum regarding this question.

So if there is no such thing as rising damp, why is the plaster permenantly slightly damp to about 2 feet above the floor level, 3 feet above ground level?

I don't understand your reasoning - you seem to be challenging the postulate that rising damp doesn't exist, and you can't find it in your property, but are still saying that the damp you're experiencing must be rising?

To me the answer to your question is obvious - the damp is cause by one or more of the following:

1. Condensation;
2. Falling damp;
3. Penetrating damp.

There are other questions to which the answers are not so obvious, viz:

How is the inner wall attached to the outer wall? Is there a cavity? To what height is the cavity backfilled? Are your gutters leaking? Do you have any external rendering? Is the outer wall exposed to driving rain? Where have you looked for the source of the damp so far?

 

[Lower]

the wall in question is a fully internal, single brick thick wall and at the point where the damp is there is no contact with outside walls so can't be leaking downpipe, penetrating damp etc. There's decent ventilation around the wall at this point, and all the flooring around this area of wall is suspended flooring. There is good ventilation under the floor.

I am basically confused as to why there is damp there if there is no such thing as rising damp. It seems to be more than just condensation because the recent skim coat of plaster took much longer than the rest of the room to dry, and never went the same colour as the rest of the plaster. the wall is never wet to the touch, its not that extreme dampness but never the less it is there.

 

[Softus]

the wall in question is a fully internal, single brick thick wall and at the point where the damp is there is no contact with outside walls so can't be leaking downpipe, penetrating damp etc. There's decent ventilation around the wall at this point, and all the flooring around this area of wall is suspended flooring. There is good ventilation under the floor.

I am basically confused as to why there is damp there if there is no such thing as rising damp. It seems to be more than just condensation because the recent skim coat of plaster took much longer than the rest of the room to dry, and never went the same colour as the rest of the plaster. the wall is never wet to the touch, its not that extreme dampness but never the less it is there.

When you report that it's damp, how are you measuring it? A damp meter measurement would be useful. And what type of plaster has been used? Some feel colder than others.

Also, note that bare plaster isn't a common wall finish, and it does absorb moisture from the surrounding air. What kind of rooms are either side of the wall? How many people live in the house? Do you have double glazing with no draughts? Do you have any extractor fans? How many radiators do you have? What is the average room temperature?

 

[masona]

How is the inner wall attached to the outer wall?

Although rare but I have seen sloppy bricklayers dropping mortar in the cavity therefore can transfer damp across and not using batten/rope to collect the mortar dropping. Another one I have seen is a dpc covering the 2 cavity wall together so any mortor dropping will cause damp across

 

[Softus]

How is the inner wall attached to the outer wall?

Although rare but I have seen sloppy bricklayers dropping mortar in the cavity therefore can transfer damp across and not using batten/rope to collect the mortar dropping. Another one I have seen is a dpc covering the 2 cavity wall together so any mortor dropping will cause damp across

masona - he said it has no cavity - it's an internal wall.

 

[Lower]

the damp area is in a corner of a small room that used to be the kitchen until we built an extention on the back of the house. It now forms part of an 'L' shaped kitchen. On the other sides of the wall there is the hall, and the dining room( its a 'T' corner if that makes sense).

When the house was surveyed, the surveyor reported damp readings higher than he would expect, and higher than elsewhere in the house, but not damp enough for him to say it was rising damp. The wall underneath the plaster was originally painted brick which has been plastered with modern plaster (ie plaster rough coat and then skim) within the last 20 years, and then skimed by us 6 months ago again with modern plaster. We painted the plaster with emulsion, but had to use an antidamp paint on the damp area because the colour wouldn't match ( beige paint used which always looked darker on the damp area).

The house is a 1920's house with single glazed sash windows (so well ventilated!) and there is an extractor fan for the kitchen which we do use. We rarely get significant condensation on the inside of the windows. two people live in the house, and the kitchen has 3 radiators in it , sized to be 1.5 times the recommended BTU output for a room of that size.

can you see why i'm confused as to where the damp is coming from!

the wall in question is a fully internal, single brick thick wall and at the point where the damp is there is no contact with outside walls so can't be leaking downpipe, penetrating damp etc. There's decent ventilation around the wall at this point, and all the flooring around this area of wall is suspended flooring. There is good ventilation under the floor.

I am basically confused as to why there is damp there if there is no such thing as rising damp. It seems to be more than just condensation because the recent skim coat of plaster took much longer than the rest of the room to dry, and never went the same colour as the rest of the plaster. the wall is never wet to the touch, its not that extreme dampness but never the less it is there.

When you report that it's damp, how are you measuring it? A damp meter measurement would be useful. And what type of plaster has been used? Some feel colder than others.

Also, note that bare plaster isn't a common wall finish, and it does absorb moisture from the surrounding air. What kind of rooms are either side of the wall? How many people live in the house? Do you have double glazing with no draughts? Do you have any extractor fans? How many radiators do you have? What is the average room temperature?

 

[Lower]

oh, and the average room temp is 19 degrees. the damp area is adjacent to the thermostat in the hall, and there is no door to the kitchen.

Additionaly, there are no central heating, water or waste pipes that run within 10 feet of the damp area.

 

[anobium]

damp meters are not diagnostic, they merely tell you that you have a damp problem. To determine if you have true rising damp would involve destructive tests of the plaster and brickwork using a calcium carbide metre.
However before you go on to that I suggest if the floors in the room were the problem is are solid you do the following.
Remove the skirting board from the wall which is affected and check if the plaster is in contact with the solid floor. Is so cut it back above the dpc level and apply a bitumastic waterproof solution to the exposed brickwork.
On the other hand if the floors are timber suspended , moisture vapours from the subfloor can condense in the void behind the skirtings, you can usually tell if this is so if the back of the skirtings are wet.
What happens in this case is that the moisture in this void is drawn up the wall by the plaster giving the appearence of rising damp
If this is the problem seal the gap between the floorboards and wall using foam or similar
Best of luck