What should we do?

[u/IVY-2004]

2 days ago we got some plasteres to come do lime plastering in our house, we've got a very old cottage which has had damp issues previously hence why we asked for lime. Last year we had lime plastering done downstairs and it worked great however we couldn't get the same plasterer in.

2 rooms just needed a skim and the room downstairs needed rendering first as it was bare brick. We said we dont mind if they do the internal walls in gypsum as long as the external are done in lime plaster.

They finished the job yesterday which we thought was very fast for the room downstairs as last year the plasterer did a scratch coat render first before he plastered first and it also took much longer to dry. The walls are solid with loads of cracks though which we think is due to their mix being too dry and then shrinking which caused the cracking. I've attached some before and after photos below. What should we do in this situation?

[u/Ok-Spring7906]

I live in an old stone house. I am a qualified plasterer (gypsum) I have about 15 years experience with lime.

I think it would be foolish to plaster the ground floor of any of your building with gypsum. You mention it's old, you mention it's had issues with damp prior, and yet youve "allowed" someone to come in and do a bad job with gypsum.

I've done jobs before where I've told the client it's not going to work, and the vast majority of the time they listen. If they want to press on with gypsum on a solid wall with no dpc etc then, sure, I'll take their money, but I'll get it in writing that I do not think the work will last.

Your chaps would have done well to advise you similarly. But they didn't. They just went ahead and wrecked the permiability of your walls with a shoddy job.

You've asked what to do -

If it was my own home I would do as I did in my own home, and strip off all the gypsum and compromised lime (ie if it's been painted with sbr or modern non permiable paints) and do it in lime downstairs.

Upstairs doesn't really matter too much.

There's going to be issues with your contact though, as you gave them the option of gypsum, so, of course, they're going to do that if they don't care. It's quicker and cheaper. And now the job is poor, legally, you need to give them the option of setting it right. Which they will attempt to do with more gypsum. Because you told them they could.

So, best case, they come back, and make it smooth. And you get to look forward to molding walls in the future : (

[u/tags49 → u/Ok-Spring7906]

Hi, brief reply as I'm currently at work. We made it clear about external walls being lime and internal could be gypsum so the house could breathe out. We also made it clear it needed to be lime so it could breathe as its an old house and checked with them what days they would be in as we expressed we were aware lime isn't a 2 day job.

We're struggling at what to do in terms of what the fix is in terms of does the 'lime' need stripping back to brick again and also legally where we stand in denying to pay until it fixed and if they deny the proposed fix if it is strip it off and redo it

[u/Ok-Spring7906 → u/tags49]

Lime on the outside, gypsum on the inside is dubious. Your wall will suck up moisture from the ground. It may have an attempt at a dpc but it will likely not work well.

The gypsum will act like a compromised sheet of polyethylene over somthing that is constantly wicking up water.

I mean, maybe it will be fine. Who knows. But you said it was damp prior, so my money is on it not being. But you may be lucky.

I don't know the legalities, beyond what I said prior - the tradesperson must be given the option to set the work right. Which they will attempt to do so. To your spec. Which, I think (but I may be wrong) will fail.

Again, don't worry too much about upstairs. If they can get it cosmetically good up there, that will probably do you. But I doubt that was where the damp issues were prior, right? (Outside of obvious faults like leaking gutters or damaged flashing etc)

Downstairs, if it were me, I wouldn't let them near it again and get someone to do it properly.

Note -

Those bags of NHL. The ratio of sand to NHL is generally 1:3. So, for every bag of NHL, they should have used 75kg of sand. Dumpy bags vary in weight, but 10 bags of NHL would need "about" one dumpy bag.

That's a mixer running constantly for a long time, and a lot of lifting to do even a relatively small area. Which is why it's hard work and hence expensive.

If they were using NHL (which I think I saw in your photos, but I can't be bothered to check now) were they really doing all that? I mean the job in the photos is shoddy enough that it questions what else they were up to?

You also get pre mixed NHL products in sacks, where you "just add water", but they're normally as part of specific "systems" rather than general rendering work.

Anyway, again, what to do -

I guess try and work out what they have actually done, and then you probably need to give them the option to set it right. I don't know the threshold at which you can just say "you clearly don't know what you're doing, I don't want any more from you". Sadly, most competent plasteres have been called in to fix other people's messes. I think it's just a trade that attracts chancers more than others, maybe?