First-time house renovation

TomsMom

Beth wrote

andrew-b - why shouldn't I PVA the walls?! (worried now!)

Sam asked

The whole PVA thing scares me. I don't know whats right and wrong.

Sarah said

I always thought it was the right thing to PVA walls before painting, when it's fresh plaster. That's what several builders have told me to do... didn't do my guest room any harm!

I knew I'd read about it but couldn't remember the technicalities of why not to use PVA. Read this from the DIYnot forum. The second post answers the question.

Also, I'll try and find one of Misgrace's posts which explains it even more.

Found this and this for anyone who is tiling.

At last, found a post by Misgrace which explains, #3 in the thread.

BB1984

Thanks TomsMom, although now I'm a bit stumped as to what to do with the walls I've already PVA-d....! I guess maybe we should rub them back down again and start afresh with a miscoat of watered-down emulsion.
Although I just started a conversation on this topic with the guys at work and several of them do advise using a PVA mixture.....seems to be a contraversial topic!!

BB

helping_hubby

What if I'm going for a darker colour on the 'feature' wall? It's not dark, but it's actually quite a light feature wall and I dont want it lighter than it is. So will thinning it make it lighter?

I'm using Crown paint by the way.

andrew-b

Sorry i should have explained why..

As TomsMom found in misgrace's thread. If anyone knows misgrace will as she is our forum-resident professional decorator.

New plaster needs to thoroughly dry out. If it was just a skim coat of plaster it can take a couple of weeks to dry out (though this time of year and without any heat in your house yet it could take longer). If there was a coat of backing plaster too (bonding/browning) it could take maybe 6 weeks to dry out fully.

By painting over with PVA any moisture in the wall will get sealed in and has got nowhere to go. If you brush water onto a part of wall you've pva'ed you'll notice it doesn't get absorbed, whereas where there's no PVA it will get sucked into the plaster. Emulsion paint is a water-based paint so just like with plain water the wall won't suck it up and the bond of the paint to the wall won't be as good. If there is still moisture trapped it could later start bubbling and peeling off. On the other hand it may be fine and i bet there'll be a few saying "I pva'ed my walls and no probs"

I'm not sure the best thing to do now you've pva'ed it but i wouldn't paint them until you've found out.. If you send misgrace a private message to draw her attention to this thread she may be willing to offer some advice of what to do next

Andy

sarahs999

The builder who told me to do it said that because any water trapped in the wall wouldn't be able to come out, it would work its way out through the outside wall (maybe this is only a good thing to do on outside walls then?).

helping_hubby

ok, so if it's so vague as to when plaster will dry, how do you know for definite that it's dry?

We've just had our walls and ceiling skimmed. The plasterer reckoned a week would be enough to wait. But we were going to wait till a week Saturday. Already above the radiators it's going much lighter in colour. So is it when everything turns this colour that it's dry?

TomsMom

helping_hubby wrote: »

What if I'm going for a darker colour on the 'feature' wall? It's not dark, but it's actually quite a light feature wall and I dont want it lighter than it is. So will thinning it make it lighter?

I'm using Crown paint by the way.

OH said watering down will not make it lighter,adding white paint would do that, water will just make it thinner. I think it should be a couple of coats watered down quite a bit (60/40 or 70/30 paint/water) and the final coat about 90/10. I think this is what I've read in other threads, probably by Misgrace who I don't think can be looking at this thread or would have replied to some of the questions by now. You could always start another thread with that question and I'm sure one of the painting experts will come along.

By the way Sam, I've just seen your updated pictures and your taps are virtually the same as the one we've got for the downstairs WC basin. Great minds think alike! Tiling isn't being done until the end of the month so no photos yet.

andrew-b

helping_hubby wrote: »

ok, so if it's so vague as to when plaster will dry, how do you know for definite that it's dry?

We've just had our walls and ceiling skimmed. The plasterer reckoned a week would be enough to wait. But we were going to wait till a week Saturday. Already above the radiators it's going much lighter in colour. So is it when everything turns this colour that it's dry?

Prod it with a protimeter (damp meter usually used to test for dampness) would be the ultimate test i suppose...though not really worth buying for one off usage.

Yes it appears darker when it's damp. I'd probably give it a week or two past the colour change just to be sure.

Rome wasn't built in a day ...so don't rush it!

Andy

BB1984

Cool, thanks for the advice peeps. We've only PVA-d one-and-a-half rooms so far - one of the bedrooms (this was old plaster, not new, so I'm thinking it'll prob be ok), and the half-room was the kitchen, around where we're soon to put units on the wall. This part of the wall was skim plaster only, over either old plaster, or plasterboard. I HOPE that as it was only a skim layer, it will have sufficiently dried out to be ok...I may give this wall a bit of a rub-down before painting a second (watered down) coat.

This decorating malarkey is a right old minefield, isn't it?!

TomsMom

When I'm bored and have nothing else to do :rotfl: I hop across to http://www.diynot.com which (amongst other things) has a forum with several useful sections, decorating, tiling, etc. I have a look through the thread titles and read any that jump out at me. I've found it quite useful. It may also help answer some questions that haven't been answered on here.