Plastering over existing plaster

[chriselevate]

Hi,

I've tried to plaster a ceiling of mine and to be honest it's turned out to be a bit of a disaster due to the uneveness of the boards up on the ceiling! Grrrr!

Having said that, the multi finish I've used has taken out a lot of discrepancies but I'll need to re-skim it tomorrow for a good finish.

How can I now plaster over the existing multi finish I applied?

Thanks

 

[SUPERSLASHER]

Give it a couple of coats of pva and when the second coat is still tacky lay on your plaster. S/S

 

[roy c]

I would roller the first coat of PVA over the ceiling and leave it for 24 hours, then before you skim it roller another coat on and mix up your muck then skim... Mix your pva 3-1(PVA/water) or 4-1..

 

[chriselevate]

Brilliant. Sounds great!

Thanks for those tips.

What would you do to take out the discrepancies in the ceiling? I mean yesterday I as trying to plaster the ceiling but as previously explained... it just wasn't working due to the fact that there were too many low spots in the ceiling.

The problem then came that I was trying to load lots of gear up onto my marshal town towel in order to get rid of low spots. The only problem with this was that most of the gear was landing on me and my head because there was too much on the trowel.

I'm asking what the best thing to do is due to the fact that i've got a much bigger ceiling to plaster in the same condition later in the week. I guess one solution is to plasterboard over the ceiling and then skim the new surface. What about other ways/ideas?

Cheers

 

[Richard C]

What would you do to take out the discrepancies in the ceiling? I mean yesterday I as trying to plaster the ceiling but as previously explained... it just wasn't working due to the fact that there were too many low spots in the ceiling.

Just how low are the low spots? Is it free of cracks? If it’s that bad, an initial coat of Bonding plaster would even it up followed as soon as it’s set by Multifinish; this works well over heavy pattern Artex but if the ceiling is that bad, you may need some remedial work first. Overboarding & a re-skim is sometimes quicker & better but if the origianl boards are really uneven then it won't help.

The problem then came that I was trying to load lots of gear up onto my marshal town towel in order to get rid of low spots. The only problem with this was that most of the gear was landing on me and my head because there was too much on the trowel. I'm asking what the best thing to do is due to the fact that i've got a much bigger ceiling to plaster in the same condition later in the week.

Is this the same ceiling you posted about back in July? A good choice of trowel & no offense intended but a “MarshallTown” won’t help you make fewer mistakes & turn you into a competent plasterer. I’m all for having a go but it takes a lot of skill & practice, walls can be bad enough for the inexperienced but ceilings are 3x more difficult & not for the feint hearted; I still let out a groan under my breath just before I start one. Try to tackle one too large before your ready & it will go off on you way before you’ve finished getting it up there let alone start troweling up & the larger the ceiling the more problems your going to have.

 

[roy c]

If it is coming off your trowel and you are having problems with it ,it may be you are not ready to tackle a "Problem " ceiling. It may be wise to get a plasterer in and get him to do it and watch and learn and pick his brains for next time.. No offence intended

 

[chriselevate]

Hi,

Yeah it's the same ceiling I talked about in a previous post.

It seems that the problem is that there are a serous of low spots aligned with the joists in the loft. In other words... where the joists run the boards seem to have dropped a little bit caused them to have a rippled sag effect across the ceiling.

The ceiling I was first mentioning above is technically the same ceiling but it's 1/6th of the ceiling split off into the en-suite (which you've probably heard all about!!!!)

You mention remedial work - by this do you mean work such as.... bringing down the existing ceiling and starting again with 12.5mm PB?

I think part of the problem is that I'm having to use hop ups which are getting me near the ceiling but there's a still a stretch for the last bit.

Is it feasible to set myself a smaller target with the big ceiling and plaster half of it in one go rather than attempting the whole lot? How would you break it up? Will I be able to lose the join line or isn't this worth thinking about?

Thanks for your help guys.

I'd like to give it try based on help and advice given on here.

Cheers.

 

[Richard C]

It seems that the problem is that there are a serous of low spots aligned with the joists in the loft. In other words... where the joists run the boards seem to have dropped a little bit caused them to have a rippled sag effect across the ceiling.

Are you sure it’s PB & not lathe & plaster? It’s not normal for PB to warp like this unless it’s been flooded at some time or has been exposed to damp; if so, has the original cause/problem now been cured?

You mention remedial work - by this do you mean work such as.... bringing down the existing ceiling and starting again with 12.5mm PB?

That may be the best option, it depends how much has it sagged, can you post some pics? If it’s dropped between every joist across the whole ceiling, I’d probably start again. Even a pro will have difficulty leveling a ceiling with extensive rippling so it looks any good, let alone the additional time/effort involved. Just overboading may not be suitable either if it’s dropped significantly, you may just end up with a slightly less rippled look; you could batten down but that's also quiet a lot of work. Whats the overall condition of the ceiling like? are the boards well fixed? do they move at all when you push on them between the joists? Replastering alone will not cure such problems.

I think part of the problem is that I'm having to use hop ups which are getting me near the ceiling but there's a still a stretch for the last bit.

If you’re over stretching, you won’t achieve a good finish. You need to set yourself at the correct working height & to repeat another’s advice; put the tip of your thumb on your head & outstretch your fingers & the tip of your little finger should just about touch the ceiling, or thereabouts. As I stated on your previous post; amongst other things, I use a couple of sets of steel kitchen steps & a suitable length scaffold plank spanning between the treads to set various heights. Don’t be tempted to use blocks/bricks, they topple too easily & you could end up breaking your ankle as I very nearly did once. I don’t think stilts will be an option for you IMO as they will take too long to get used to unless you spend days just walking about on them!

Is it feasible to set myself a smaller target with the big ceiling and plaster half of it in one go rather than attempting the whole lot? How would you break it up? Will I be able to lose the join line or isn't this worth thinking about?

It can be done in several ways & my comments to your original post are still valid;

//www.diynot.com/forums/viewtopic.php?p=1288360#1288360

 

[chriselevate]

Hi Richard,

Thanks for your reply, really appreciate it.

Right here's the ceiling I've got to deal with:



It's not plasterboard or plaster and lathe. The house is 1960 built and the ceiling upstairs is made of like a papery sort of stuff. It's like.... the think hardboard sheet in consistancy and about 12-15 mm's thick.

As you can see in the photo I've had to rip down and replace (with a couple of sheets of PB) the bit at the far end where the fire wall has been leaking and cause the ceiling to sag and become damaged.

The stains and marks on the ceiling you can see I assume were from when the slate roof was on (now it's a concrete roof). And they've used some sort of plaster to even it out before they wall papered it. I've got most of the wall paper off.... that was a tough job!

You can also see I've got a an angle to plaster as it dips towards the windows on the from of the the house. Do I treat the whole thing as one surface or is it worth plastering that small strip seperately.

I can't say the ceiling is sound in all aras. If I stand under it in certain places I can push the ceiling up and down (only slightly) where it's sagged.

Cheers

 

[Richard C]

It's not plasterboard or plaster and lathe. The house is 1960 built and the ceiling upstairs is made of like a papery sort of stuff. It's like.... the think hardboard sheet in consistancy and about 12-15 mm's thick.

You’ve got me there Chris; I’ve no idea what that could be. I’m not an expert on varying methods of ceiling construction in the 60’s but I've worked on many from the same era & both the houses I’ve owned from then, including the one I have now, were conventional plasterboard. I'm wondering exactly what it is you have up there, if it's original or someone’s bodge job; is it currently plastered or does it just have paper stuck over it? Are you sure it's not just totally rotted out plasterboard.

As you can see in the photo I've had to rip down and replace (with a couple of sheets of PB) the bit at the far end where the fire wall has been leaking and cause the ceiling to sag and become damaged.

That probably what’s caused the problem across the whole ceiling but was maybe far worse at that end; what do you mean by “fire wall leaking”; can you explain?

The stains and marks on the ceiling you can see I assume were from when the slate roof was on (now it's a concrete roof).

Can’t really work out what sort of roof you have, "slate to concrete" is it a flat roof? What’s above the ceiling boards?

And they've used some sort of plaster to even it out before they wall papered it. I've got most of the wall paper off.... that was a tough job!

If you stick with re-plastering over what you’ve got, you must get ALL the paper off. You can’t plaster over paper, it will in all probability delaminate & even the smallest bits can cause blister problems in the finish. The brown staining will also have to be sealed or that could cause problems as well; apply a liberal sealer/bonding coat PVA/water (2:1 or 3:1) 24 hours before & let it dry thoroughly, then apply a weaker (1:3) PVA mix just before & plaster when tacky; use a roller not a brush.

You can also see I've got a an angle to plaster as it dips towards the windows on the from of the the house. Do I treat the whole thing as one surface or is it worth plastering that small strip seperately.

I always do the angles at the same time; takes practice but it’s the only way to do it.

I can't say the ceiling is sound in all aras. If I stand under it in certain places I can push the ceiling up and down (only slightly) where it's sagged.

Thanks for going to the trouble of posting the pics. but they don’t really show how much the ceiling is sagging between the joists. Now looking at the overall picture; the fact you say it’s not totally sound, the stains, the paper & that you can deflect parts of it with your fingers, I wouldn’t be messing about with it to be honest, I think it’s shot & I’d rip it down & start again. Whatever you put over the existing, re-skim or new boards, is only going to provide as good a base as what’s there already & it may not last; you need to do it properly or you may well end up having to do it all again in the not too distant future.

Pulling it down & starting again may seem drastic & a real pain but, as inexperienced as you obviously are, I think it will ultimately make things far easier for you to tackle & ultimately lead to a better job; depends what your after really. Come back if you need more.

 

[chriselevate]

Thanks for your reply.

It's not rotted out PB it's a really strange cardboard like material tbh! Not to worry though.

So you'd suggest bringing the boards down and putting new ones up or would I get away with fixing new boards to the joists with long PB screws? Most of my walls in that room have now been skimmed so taking down the current boards would mess up the finish at the top of the walls wouldn't it?

What thickness boards would you use?

The far end of photo one shows the wall connected to next doors house (we are the end of terrace) so the firewall between us was letting in water before a builder came and fixed it. HE made it better but in the recent rain fall it's not completely water tight yet!!! Very annoying!!!

We have a pitched roof on that part of the house and the tiles are concrete.

Don't worry I wouldn't dream of plastering over paper... I know that's a bit no no! lol

Cheers

 

[marshman]

The ceiling is fibre board and I wouldn't plaster on to that it will most likely sag as it gets damp from the plaster.
if you can't take it down then over board it with 12.5 mm plaster board.

back to you rich'.

 

[Richard C]

So you'd suggest bringing the boards down and putting new ones up or would I get away with fixing new boards to the joists with long PB screws? Most of my walls in that room have now been skimmed so taking down the current boards would mess up the finish at the top of the walls wouldn't it?

Without physically seeing the ceiling & poking it around a bit, it’s a difficult call; it may well accept over boarding but, to be honest, ripping it down & replacing is only marginally more work/expense &, from the photos/info you’ve given, it’s probably an easier & better bet for you; just rather more messy

What thickness boards would you use?

You could use 9.5mm but I always prefer to use 12.5mm; rather heavier & more difficult to put up but hardly any difference in price; & if there is any chance of damp from above, Duplex (foil back) boards will give you an even better chance for just a little extra outlay.

The far end of photo one shows the wall connected to next doors house (we are the end of terrace) so the firewall between us was letting in water before a builder came and fixed it. HE made it better but in the recent rain fall it's not completely water tight yet!!! Very annoying!!!

You need to get it totally water tight before you do anything more, otherwise your just wasting your time &, more important, you hard earned cash.

We have a pitched roof on that part of the house and the tiles are concrete.

Ahh; the penny’s dropped, I guess your talking replacement tiles.

 

[chriselevate]

Brilliant.... thanks for your help guys.

All makes sense and I'm guess the only thing I'm left to do is.... making the decision as to overboarding or ripping down!

Do I want to do it properly.... or do I wan't to do the least messy way?

I guess ripping down the boards will cause the insulation in my loft and any electrics resting on the boards to come down too? Do you think they'll be be a messy join where the walls meed the ceiling if I rip them down? I really don't fancy re-plasting my walls which I've managed to get a good finish on?!?

Taking down the old board will ensure the job is done well and will make sure that the new board are screwed well to the joists I guess. If I overboard it'll be hard to find the joists and get board to lay flush with the existing boards - in other defeating the point in doing it.

Thanks again for your help.

Really appreciate the time and effort you've put into this thread.

 

[Richard C]

I guess ripping down the boards will cause the insulation in my loft and any electrics resting on the boards to come down too?

Electrics should be OK as cables are usually run above the joists; insulation depends on how it’s been done & the condition; what happened when you took the other boards down? I have actually added new insulation between the joists in a flat roof from below when re-boarding.

Do you think they'll be be a messy join where the walls meed the ceiling if I rip them down? I really don't fancy re-plasting my walls which I've managed to get a good finish on?!?

Keep the boards as tight as you can to the walls & it should be OK. The plaster skim will take it up but you may need some minor filling; you won’t be able to tape the corners unless you remove 40-50mm of plaster from the walls but caulking any subsequent cracks should be OK & you may not even get any.

Taking down the old board will ensure the job is done well and will make sure that the new board are screwed well to the joists I guess. If I overboard it'll be hard to find the joists and get board to lay flush with the existing boards - in other defeating the point in doing it.

If you don’t fancy the mess, providing the existing boards are sound over the joists & the joists themselves are sound, you could batten with timber strips over each joist as I said previously. Batten thickness needs to be enough to come below the lowest sag & you must fix through the lot into the joists above. Finding the joists is relatively easy, you can tap with a screw driver, use a bradawl or even make holes in the ceiling with a hammer; once you’ve found 2 of them the rest should be at the same pitch which is usually 400mm, just check in each case & mark the position on the two opposing walls.