Liquid DPC, Is it a myth?

Hecklar

Hey guys.

I'm tackling a rising damp issue in a 100 year old terraced house with no DPC. The damp is primarily on the exterior walls but some of the internal walls have damp to a lesser extent.

There's a lot of rot damage to the skirting, sub floor and plaster work but that's all due to be replaced when the damp is cured (possibly poured concrete).

So I did a little research on my options and came across liquid DPC and electro osmisis as potential solutions.

I understand how both are supposed to work but I've found claims that both are snake oil and better avoided so I was hoping to ask here for opinions from anyone who has experience with them before I spend on either.

Particularly liquid DPC, anyone have any personal experience with it? Is it an instant solution or does or take time to do it's thing?

As an aside, I have a drain pipe outside that runs onto a pavement that has a little channel to run off into the gulley. I've noticed a bit of moss growing in the general area and this spot corresponds with wettest part of the wall on the inside so I'm suspecting that water is pooling there or getting down a gap between the front wall and the join with the pavement.
Does any of that sound logical?

What would I generally do with this situation, cut out the channel and redo it with fresh concrete/water proofer maybe?

That turned out longer than I intended. All help very much appreciated.

BryanF

Can your pm me the claims that they are 'snake oil' thanks

Hecklar

BryanF wrote: »

Can your pm me the claims that they are 'snake oil' thanks

Hi, I'll have to check back through my history and find it. Some were videos on YouTube from a company who said that instead, a breathable render should have been applied to either side of the wall so it could dry out naturally and not trap water inside the wall, though I'm not sure I like the sound of that if the water is regular enough, surely it'll still be damp?

my3cents

I've seen the Liquid DPC's used on some massive old houses and it works with some caveats. The biggest issue is getting the chemical injected all through the wall. With for example a mix of good facing brick, rubble + air space then inner wall isn't going to work. I know a fiends 16th century red brick manor house was done and it worked except in a couple of problem areas where the walls were extra thick and filled with loose rubble. Edit> Should also add that in that particular house apart from the liquid DPC traditional (breathable) materials were used throughout and they may have also had some effect on the outcome.

Then if you have a good solid cavity wall you may have to have the wall injected from both sides (inside and out) and also any solid brick or stonework inner walls will need doing.

If you can get the "Liquid" into all of the wall and all of the wall is well bonded then I'd be happy enough to say its a good workable fix.

Hecklar

my3cents wrote: »

I've seen the Liquid DPC's used on some massive old houses and it works with some caveats. The biggest issue is getting the chemical injected all through the wall. With for example a mix of good facing brick, rubble + air space then inner wall isn't going to work. I know a fiends 16th century red brick manor house was done and it worked except in a couple of problem areas where the walls were extra thick and filled with loose rubble. Edit> Should also add that in that particular house apart from the liquid DPC traditional (breathable) materials were used throughout and they may have also had some effect on the outcome.

Then if you have a good solid cavity wall you may have to have the wall injected from both sides (inside and out) and also any solid brick or stonework inner walls will need doing.

If you can get the "Liquid" into all of the wall and all of the wall is well bonded then I'd be happy enough to say its a good workable fix.

Hey, Thanks for the info.

My wall is only 2 bricks thick (no cavity) in the main problem area so getting good coverage with the liquid DPC shouldn't be a problem.
I've read that I need to drill 12mm holes 3/4 the way through the wall every 140mm along the top of the first brick (assuming it's above ground level on the outside).

I also have some sort of poorly applied render on the exterior wall that's been painted over a lot. I'm not sure yet what kind of material it is but I suspect it's sealing in any moisture that's coming in through the ground. I'm considering chiseling this off to see what the brickwork is like and either leave it bare or redo it in lime plaster maybe?

Inside there was obviously a damp problem in the past where they had the plaster removed up to about 1.2m and redone in gypsum which I suspect didn't do any favours either, as that was covered in salt and falling off too. I removed much of this and the wall seems to have dried out significantly since then.

Does the liquid DPC start to work relatively quickly, and would it be advisable to wait until the weather is a bit milder before doing it?

Thanks for the help.

my3cents

I'm not 100% sure but I'd have thought it should be done when the wall is as dry as it can be so the chemical can disperse better, but I've seen the work done in the winter.

I assume you are going to have the liquid injected? I know you used to be able to hire the machine to do the work yourself assume they are still available.

afaik it starts to work straight away but obviously if there is a lot to dry out then its not going to look like much has changed for a while.

Dudda

Liquid DPC all depends on the wall. Take one brick from your wall and drill a small hole in it. Mix water with food colouring and inject it into the brick. Leave for a week and then cut the brick in half. In some bricks I've seen the colouring through the whole brick which are good for liquid DPC but in others the brick is too dense and the colouring only travels an inch from the drilled hole.
If you have an internal wall you intend on knocking I would do the coloured water test on it. It's a great way of telling how well it will work and if you need to increase our decrease the spacing of the drilled holes.

Hecklar

Dudda wrote: »

Liquid DPC all depends on the wall. Take one brick from your wall and drill a small hole in it. Mix water with food colouring and inject it into the brick. Leave for a week and then cut the brick in half. In some bricks I've seen the colouring through the whole brick which are good for liquid DPC but in others the brick is too dense and the colouring only travels an inch from the drilled hole.
If you have an internal wall you intend on knocking I would do the coloured water test on it. It's a great way of telling how well it will work and if you need to increase our decrease the spacing of the drilled holes.

Thanks for the reply.
I have a few bricks removed already from clearing out the vented brick and they were saturated at the time. Going by how quickly they dried after being pulled out, I'd imagine they are quite porous and would soak up the dpc no problem but I'll give it a go and see.

JonathonS

I had what I thought was a rising damp problem, but on researching solutions I found many articles from reputable sources that advised not only to avoid liquid DPC , but to question whether the problem was really rising damp (it wasn't).

For example:
"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’. In response, the RICS has put the term ‘rising damp’ in inverted commas in its latest factsheet – according to Boniface, as a ‘non-subtle hint’ to its members."

Full article:http://www.architectsjournal.co.uk/home/-rising-damp-is-a-myth-says-former-rics-chief/5204095.fullarticle

Hecklar

JonathonS wrote: »

I had what I thought was a rising damp problem, but on researching solutions I found many articles from reputable sources that advised not only to avoid liquid DPC , but to question whether the problem was really rising damp (it wasn't).

For example:
"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’. In response, the RICS has put the term ‘rising damp’ in inverted commas in its latest factsheet – according to Boniface, as a ‘non-subtle hint’ to its members."

Full article:http://www.architectsjournal.co.uk/home/-rising-damp-is-a-myth-says-former-rics-chief/5204095.fullarticle

That's very interesting, thanks for the link.
Just out of interest, what did your issue turn out to be?

JonathonS

Hecklar wrote: »

That's very interesting, thanks for the link.
Just out of interest, what did your issue turn out to be?

I had a damp patch in the corner of a living room, stretching for .5m up from the floor near but not quite underneath a window. It was eventually diagnosed as caused by rain penetration at the window, and was solved when we replaced the window, and removed a mound of cement from the bottom of the cavity.

JonathonS

Hecklar wrote: »

As an aside, I have a drain pipe outside that runs onto a pavement that has a little channel to run off into the gulley. I've noticed a bit of moss growing in the general area and this spot corresponds with wettest part of the wall on the inside so I'm suspecting that water is pooling there or getting down a gap between the front wall and the join with the pavement.

OP, you should investigate this further. Similar example in this video (up to 8:48, after that he gets on his hobby horse about rising damp fraud).

https://www.youtube.com/watch?v=XORucdJ5zQw

Hecklar

JonathonS wrote: »

OP, you should investigate this further. Similar example in this video (up to 8:48, after that he gets on his hobby horse about rising damp fraud).

https://www.youtube.com/watch?v=XORucdJ5zQw

Thanks for the reply.

That looks like it could be very similar to the situation I'm dealing with. I haven't had a lot of time to inspect it but I noticed the other night that the neighbours guttering is missing an end cap just after the downpipe. The pipe runs down onto a fairly flat pavement with what appears to be an inadequate channel running it towards the road.

Right at the join of the pavement and the property itself I've noticed a separation that I suspect is allowing much of the pooling water from the gutter to seep into the sub floor and cause the damp issues I'm seeing inside.

The pavement outside is council property so I'll have to look into what can be done about that. In the meantime I think we'll have to get cracking on undoing all the shoddy plasterwork that was presumably meant to cure the problem in the past.