Façade redecoration + Damp

[dal3001]

Hi all,

I bought a Victorian terrace house a year or so ago that was in a pretty poor state and I'm getting some work done to restore the decorate stonework and stone sills. Only the areas that are painted already will be stripped/cleaned and repainted. I've been quoted by a few companies that seem to lean more towards period property restoration and seem fairly reputable (large social media followings, good reviews) and it seems the paint being recommended is Dulux Weathershield. Having had a look at the spec for this, Dulux do claim it's "breathable" but I've seen places online that are sceptical of this... Does anyone envisage this being a huge issue? This property has had low level damp problems in the past and I note that it has a cement plinth/skirt that runs around the base of the house that would be included in the repainting.

I suppose it's likely that this cement plinth isn't actually breathable anyway, so what paint goes on it may not be much of an issue... As far as I can see, most houses on my street (100+) seem to have a similar plinth, so would this have been an original feature that should be painted more sympathetically to breathability? I have a book on Victorian houses and the plinth isn't mentioned as a typical feature, and not much is coming back online. I attached a few pics for reference. I believe this house had DPC injection sometime in the 80s according to some docs I got my hands on, though no physical evidence of this, presumably hidden by fills in the plinth... As you can see, the side plinth looks decidedly worse (and a lot different) to the front one (front has the gas meter box).

Any advice?

Thanks

 

[aockenden]

Generally speaking it matters less to the internal house condition if you put a non-breathable paint onto an already non-breathable external surface, but you might still expect that non-breathable paint to start flaking and peeling off its substrate in the future which looks like trash. I for one don’t trust paints like the one you mentioned and idk if there’s any standard of HOW breathable a paint needs to be for the company to claim its breathable. Breathability is not a binary condition of yes / no. There are degrees which makes scamming consumers much easier!

 

[DaveG]

I know this wasn’t necessarily what you were asking as it was more a question of paints but from your pictures I would say the biggest contributing factor to any low level damp problems inside will be those outside ground levels.
Assuming that subfloor vent shown is the original height, a building survey would suggest a minimum of 75mm clearance between the bottom of that vent and the ground level. There should be at least another 2 courses of brick below that vent. The slabs adjacent to the wall will act like barriers to moisture being able to escape so perhaps not something you want to entertain now but if you do find you’re having problems with damp at the base of your walls I’d be suggesting you look at that. If ground levels were taken down you may then find a “floating” and somewhat superfluous concrete skirt.

 

[jamest]

It's quite common to see the lower part of a wall that abuts a hard surface rendered with cement to produce a skirt. I suspect that this was a misguided way of trying to reduce water penetration in the lower part of the wall due to rainwater splashing up it above the dpc. Assuming this is what's been done in your street, the best thing to do would be to strip off the render skirt and remove the hard surface so there's a gap about 40 or 50 cm between the hard surface and the wall. If needed, you can dig a bit of a trench (if as DaveG says, the levels are a bit high) and backfill it with a bit a gravel or lay a bit of turf to prevent splash, but keep the bricks exposed. If you wanted to retain the look, you could paint the newly exposed bricks (or, if they're damaged by the removal, re-render in lime first). I would use a silicate paint for that or an exterior limewash suitable for plinths (Ingleby paints do one, if I remember correctly)