[Closed] talk to me about DIY damp proofing

first: establish why it's damp.

Oh I know why, solid wall with no dpc and chemical injection I had done has obviously failed.

Check all tiling,flashing ,rendering & guttering above and adjacent to damp .
Stand outside when it's persisting down and see where the water goes off your roof.

Fire fitting chap says its rising, rubble/dirt under the old hearth is damp for sure. He's going to fit a membrane before the new hearth goes in but I need to proof the walls around the fireplace before he finishes the job.

Just used some sika liquid dpm on an extension floor of unknown origin. 2 coats done and dried in 2 hours.

Also, has it dried now it's exposed? We had moisture trapped in under the old flooring of the extension.

Its almost certainly due to water from above somewhere (or external ground level being slightly higher), rising damp doesn't really exist, unless you have internal grade plasterboard linings sitting in a stream.

Fireplace has just been opened this morning. Plan is to board and replaster before fitting a stove. Apparently it needs proofing before boarding otherwise it will all eventually fall off. Trying to figure out best way forward.

Further investigation reveals that whilst the back wall (gable end) of the fireplace is damp, the brickwork of the two wings of the fireplace are dry. The previously fitted gas fire wasn't vented properly so any condensation had nowhere to go. I'm a bit hazy on that point tbh.
Just for the purposes of getting the installation finished, would painting the brickwork with that dpc coating mentioned above sort out the fireplace? I know it won't solve any other potential problem.

There was a thread on here a few days ago with loads of advice and links and things on.

My thought on damp proofing was always that all these fixes make it worse. I'd be leaving it and letting it dry out for some time first if there was no obvious damp causing issues.

Wood burner will dry it out pretty quick.

The fire fitting chap is coming back in two weeks to do the next phase - board & plaster, fit the hearth & line the chimney. I've got that time to decide what to do, just not sure what!

Big fan heater onto wall with an open window for condensation?
See if it drys out after a week?

Last weeks thread: http://singletrackworld.com/forum/topic/damp-proofing-advice
You know the search on here doesn't work when searching for damp proofing advice doesn't bring that up... 😕

Leave it alone for the next week or so. Get a meter if you don't have one and test the moisture content now and in a weeks' time. You'll get a good idea as to what is happening.

It may well dry out now the brickwork is exposed and allowed to breathe, in which case, crack on with leaving it alone.

As mentioned above, the stove will keep it dry anyway.

Well, currently there's a whopping great hole right above the damp area - its the open flue. Hopefully the rising warmth will take the moisture up the flue.

The plan was to recover the exposed brickwork with fresh plaster, the bricks are a bit too 'rustic' for my liking!
I've been looking up damp on the net & one thing has struck me, whilst I've got plaster damage on the gable end wall the skirting boards are all still solid - surely if I had rising damp the skirting boards would be rotten?

Give it a couple of days, then see what happens.

im glad the fire fitting guy is a damp expert - oh he was wrong yeah funny that. Also rain coming down the chimney can cause damp if the unused flue isn't vented. I'd let it dry it a bit and if necessary tell the fire guy to wait a bit. I won't paint on any damp proofing unless it's ok for use in that sort of area.

I've been reading the link on the other thread, some interesting stuff there. My house is pre 1900 and yes, it has a cement render on it.
I'm now tempted to leave the brickwork exposed and let the wall breathe with the new fire drying it out.

I'm a big fan of the sovereign damp proof system. Their K11 mixed with SBR bonding agent work's well and can be applied with a pasting brush so no skill is involved. Also, I wouldn't recommend using plasterboard and skim to line a fireplace. Hardibacker cement board's are a better option.

Well, as far as I'm aware he was going to use cement boards. Can you tell me more about this K11 stuff.

K11 comes in powder form which you mix with water (SBR added) to form a slurry. That's then painted onto the brickwork to form a barrier which stops the damp coming through. You can then plaster over it .

Cheers will look it up. Wish I could post a pic of the brickwork to see what others can recommend - whether its good enough to reveal etc.

But surely if you just whack a sealer onto the wall like k11 you just make the problem worse? The bricks need to breathe, and you're slapping on a barrier to that causing more problems, just hidden at the moment? That's my understanding of it anyway.

The bricks need to breathe, and you're slapping on a barrier to that causing more problems

Bingo.

If you trap moisture or try to block it's progress it will just find a new route and being trapped will lead to stuff breaking down.

Chemical injection is a load of rubbish.

First find out where it is getting into the wall. If anyone suggests rising damp and chemical injection then show them the door. Fix/divert the source away from the wall in the first place. Then, as your wall isnt waterpoof so small amounts will still get in use a covering that can breath. Eg a paint on breathable membrane (vapour permeable) and then a breathable plaster. If it's an old building I would always use lime. Expensive but worth it, especially in problem areas.

OP,

noooooooooooooooooo.

But you've already had plenty of good advice. I have nothing to add except

+1

to basically all of the above.

I'm also a big fan of DIY if you have the time. Getting to know your own building and how to fix simple problems is very much more effective than having to find/book a competent builder. Eg doing some (lime) pointing and fixing your own gutters, which probably addresses 90% of problems for most old houses.

Definitely now leaning towards leaving the brickwork exposed and breathing rather than covering it up again.
Cheers all, plenty to think about here.