Paint for a damp cellar wall?

We have cellars under our (1920s) house. 3 of ’em.

The one currently used as a bike room/workshop was the previous owners office and he’d had it done up to look reasonably smart. But it turns out very badly.

Plaster straight onto the bricks (well below the DPC) with no membrane and mains volatge, phone nd TV aerial wiring all embedded directly in the plaster with no containment and at all kinds of jaunty angles.

The plaster has been spalling off the brick (which was sopping underneath, but is now fairly dry) ever since we moved in and since tracing some RCD issues to some of the sockets on the external walls being rusty and full of moisture I’ve ended up stripping most of it off and digging out the cables and removing them.

I’d like to tidy it all up some now, so I’m wondering what the best paint type stuff to cover the bricks in that will be suitably breathable to stop the bricks getting damp again and won’t flake off. I’m guessing it might be some kind of old-school limewash?

(we do run a dehumidifier down there, but no heating)

Thanks!

I’m not an expert but think you’ll need to tank it to make it damp proof

Tanking slurry. You need more than you think – 10kg does a surprisingly small area and is a right chew on to apply with a brush. I’d envisage for a basement some sort of truck parked outside with a pipe spraying the stuff on like mr blobby’s goo.

Or hide it with a tanking membrane and put studs up. I’ve done both.

Limewash is the answer. You’ll never stop the damp but limewash will let it pass through and your dehumidifier will reduce it

Very easy to make limewash,  buy some powdered lime from a builders merchant and mix with water to a full fat milk consistency. If they only have nhl lime get the lowest they have eg 2.5 not 5. Lower has better permeability.

Use a fence paint type brush, allow to dry between coats. Each additional coat will make the whole lot translucent until it dries. Minimum 3 coats, more the merrier. Last coat, burnish with a dry brush all over just before it dries, this will stop dusting off.

20 quid will make enough limewash to last you out!

If you want, put some colour pigment in for fun.

You can buy ready made, it’s pricey but good. You’ll probably want to water it down to the right consistency. Too thick tends to crack

To be more clear – I’m not looking to make it living-space style bone dry. The bare bricks being able to breathe is plenty dry enough compared to the sweatiness when they were under plaster. I’m looking to maintain that level, just looking a little smarter.

@Vader that sounds more like the kind of thing I was thinking. When you say “burnish” do you literally mean drybrush it?

Thanks!

Yes, dry brush it. It needs to be damp but not wet to do it, and the brush must be dry

Some areas of the wall may never fully dry especially in winter, but don’t worry. It will make those areas very easy to identify

If you can, get as much old paint off as you can, assuming you haven’t already

Watching with interest.

I have a cellar, I put a dehumidifier down there and it can fill a 70 gallon drum in like a week.  The dehumidifier died and now it’s just wet, which is not great because all my tools (and bikes) are quietly rotting to themselves.  It never occurred to me that I might be able to seal it somehow.

Any chance of ventilation in either cellar?

Only by dint of leaving the cellar door open, which I do whenever practical.

Tanking it would be a better long run plan surely? The electric bill sucking the moisture out the walls will be never ending? I would talk to a local damp company if I were you.

Worked on a job converting cellars into flats.

Due to the room closest to the road outside being below ground, there was no DPC(well there was, but it was above the level of where the flat room would be) .  So we had another builders firm come in who drilled deep holes into the masonry on the inside and outside, then injected some sort of stuff(possibly silicon) – I’ve just looked it up – its called ” wall injection damp proofing ” unsurprisingly, and its done exactly how i remember, series of drilled holes and pumped in.

.

On the inside, they had me paint that internal wall with bitumen, directly onto the brickwork, which we then placed behind stud partitions, with a polythene membrane over the rear to stop any remaining moisture affecting the gyproc that we put onto the partitions. We were on a schedule, so the partitions needed to go up and little chance to allow the wall to dry naturally.

Although ours was done using a big pump thing, seems theres a more basic trade/diy option.

https://www.permagard.co.uk/aida-dpc-injection-cream-pro-pack?mp_feed=MDozOkZlQTNoQnVCa2VQNmQycEpTRnUrU2g5N0YwcFdaTm5leTFaRi90ST0=&gad_source=1&gclid=EAIaIQobChMI7LfChYCxhgMVeppQBh2vfgSTEAQYBCABEgI_9fD_BwE

I would think thats going to give you a more effective and permanent solution than trying to paint something on and having to deal with the likely damp/mould problem thats likely to arise from it being untreated