Period Ceiling Suggestions

[Andys]

I seem to have pulled down the artexed plasterboard ceiling in the empty ex-bathroom in the outshot of our C17 timber framed cottage, it was perhaps impulsive but it was the artex, it made me do it.
I'm left with fairly modern 2x4 joists on 450mm spacings. There's a load of noggins flush with the bottom edge where the plasterboard was nailed on and a clearance of at most only 60mm between head height (mine anyway) and the joists, so there's not much room to play with. Our CO isn't too particular about the outshot but I'm inclined to draw the line at asking to put new plasterboard back up.

The question is: what to replace it with? I've been looking into Wood-Wool boards, Claytec boards, reed boards and of course Actual Lath and Plaster. The clay boards and reed boards look to be quite heavy and rigid for a ceiling, wood wool boards looked promising but I handled one today and it's a lot more rigid than I hoped ( in a cracking-round-the-outline kind of way) and the 15mm size I had my eye on doesn't seem to be specified for ceilings, from looking at the data sheet.

I find myself coming back to circling the idea of spending the rest of my natural life putting up split lath, having replaced all the noggins 10mm higher up to allow clearance for the plaster to squeeze through the lath. Maybe it's just the right thing to do and at least it doesn't come in impossibly heavy sheets.

Does anyone have any advice, encouragement, or failing that, anecdotes to offer?
Andy

 

[a twig]

Fermacell? Quite heavy though...

Reed mats (garden centre style) with lime plaster?

 

[Flyfisher]

Are all 'reed boards' similar? I ask because I used some in the roof of an oak-framed 'lean-to' and, to my inexperienced eye, they don't look very well suited for supporting plasterwork as the reeds are pretty tightly bunched together and I can't see how any applied plaster could 'get behind' the reeds to form the 'nibs' necessary for a strong key. I can imagine the boards working when vertical as they certainly have some texture for the plaster to grip, but whether this would be sufficient for a 'hanging' application such as a plaster ceiling I don't know.

Having said that, I know they are sold for such purposes (I bought mine from Mike Wye and they know a thing or two about lime!) so perhaps I'm completely wrong to be concerned. It was not an issue in my case as I had no intention of plastering the reed boards and only used them to hide the waterproof membrane above. Just a thought.

 

[livias]

Are you concerned about weight because it will be too much for you to lift ... in which case use a deadman or a helper

Or because it will be too much weight on the ceiling cos a lath and plaster ceiling is at least as heavy as those you mention. Lime plaster is very heavy it is liquid rock after all

There are other reed mats for plastering on. I think tymawr do one

The non purist option is plasterboard gypsum skim and then limewash several times for the olde effect. I am a purist myself but i don't recommend it !

 

[MikeG]

........The non purist option is plasterboard gypsum skim and then limewash several times for the olde effect. I am a purist myself but i don't recommend it !

Thistle Universal Onecoat plaster (http://www.british-gypsum.com/products/thistle-universal-one-coat) produces a lime-plaster look on plasterboard. It doesn't polish up like the normal pink stuff, and produced a slightly mottled/ grainy surface. You can then paint with either a limewash, or with an acrylic emulsion.

 

[Andys]

Thanks All, the weight issue is just about me not getting squashed by a heavy panel, I think the house can take it.
Hmm, I am drawn to doing it 'properly', I might ruminate for a while and see if it wears off...

 

[MatthewC]

it was the artex, it made me do it.

That would be an interesting defence in a court of law!

Personally, I would vote for lath and plaster (because that's what I did here) but I wonder what the biggest allowable between joists should be for lath? I reckon mine were nearer 300mm rather than the 450 that you have. You would want each lath to be nailed to at least three joists (if not four) for stiffness when plastering...

 

[a twig]

Just to slightly hijack this a little - I'm redoing some ceilings, which will be reed mat and then plastered.

I have just seen a datasheet for a "One Coat Lime Plaster" - Lime Green Solo.
Link to the datasheet:http://www.womersleys.co.uk/techguides/LimeGreenSolo.pdf

No cement additives etc, and looks like it could be a lot quicker - anyone used it or got experience of it?

Also before I embark on the ripping down of old plasterboard and putting up of reed matting, anyone got any tips?

 

[Andys]

Hi a twig, feel free to hijack away, it's all useful stuff.
I notice the data sheet recommends only two coats of one-coat plaster with insulation boards, plus mesh to bridge joins - out of curiosity, what approach are you thinking of with reed mat?

 

[Zebra]

I used 15mm wood wool on ceilings, with home-mixed putty-based lime plaster. It's fine. Upstairs where it's 17th century timber frame, it has cracked along the join where ceiling meets wall, but it probably would crack there no matter what I used.
Downstairs where it's modern joists, it hasn't cracked at all. In both cases, I used oversize plastic washers to fix them, and glued the edges of each board together with gripfill.
I had heard that you shouldn't use 15mm on ceilings. I just decided it was fine, and to ignore that.

 

[a twig]

Hi a twig, feel free to hijack away, it's all useful stuff.
I notice the data sheet recommends only two coats of one-coat plaster with insulation boards, plus mesh to bridge joins - out of curiosity, what approach are you thinking of with reed mat?

Ta! I was just going to whack up one coat and see what it does to be honest - I'm not too worried about getting a super smooth finish or whatever, and figured that the reeds should provide a pretty good key. In my experience the thinner and fewer coats used, the more flexible it seems to be. I might do a tester

My main motivation is that my tame lime plasterer was talking about a scratch coat with horsehair, and then a top coat of fat putty, which would be lovely but leaves me with a lot of damping/spraying to do, plus a 3 month wait before painting. The main advantage seems to me of this stuff is that you can just whack it on with less faff, it dries pretty rapidly and requires less aftercare. We have my entire family descending for Christmas and I rather need the spare bedroom back in action before then!

 

[JanJonWestWales]

We opted for 3mm ply boards and planking to generate a "panelled" look, still awaiting its first coat of paint, but should look nice
J&J

http://blaencwmbychan.blogspot.co.uk/

 

[a twig]

An update on my progress, in case it helps anyone else:

I was quoted £3k to do this room, once I picked myself up off the floor, I decided to do it myself.

I was strongly advised that my ceiling plaster should be haired as it is going onto reed, so I plumped for Ty-Mawr Haired Lime Basecoat Plaster for Scratch and Float Coat - available here: https://www.lime.org.uk/lime-base-coat-plaster-for-scratch-and-float-coats.html

After talking to my plasterer friend, I strengthened my reed mats with lath to ensure it stayed attached - apparently ceilings that are just reed mats stapled to the joists have a habit of failing. I also discussed whether I could get away with just doing one coat of plaster, and then applying a slightly thicker limewash to smooth it out, he seemed to think that might work, so a plan of action was laid!

11 tubs arrived on a pallet a few days later, and I got stuck in. One tub does roughly 1 m2 - as per this image:

I still had a fair way to go:

8 hours later, with several huge blisters on my hands, which popped and promptly got lime in, I stopped, as I had run out of plaster, and had this:

Which looks ok, if it's dark enough, and the lights are down low enough, and you stand far enough away... The "thick limewash" will have a lot to do

So, it turns out, I calculated my coverage based on the 20l tubs of hydraulic lime rather than fat lime, which obviously you add water to. Therefore, I had exactly half the amount of fat lime plaster I needed.

I next have a clear day on Wednesday, so 12 more tubs have been ordered, along with some leather "weight lifting" gloves to try and protect my soft weedy hands.

Some learning points to take away:

1) If doing reed mats again for a ceiling, I would double up the matting. There is a lot of give in a single layer of reed mat, despite me pulling it tight and it being clamped with the lath. This made getting good adhesion difficult at times. The section of the ceiling where my two rolls overlapped, and effectively doubled up, were a lot stiffer, and I was able to make much quicker progress. To be honest, the time I saved doing the mats instead of lath, I probably lost when it came to plastering, suspect it will be lath for me next time.

2) Edges (between joists and walls) are the bane of my existence - the 2 or 3" of unsupported reed had me swearing and throwing tools around at times, as there was so much flex, getting the plaster to "grip" was a nightmare. I ended up leaving bits of the edges for after I have done the walls, in the hope that the gap will be closed and there will be a bit more support.

3) I'm not sure what is up with Ty Mawr's quality control, the lime mortar was all over the place. All the tubs were dated the same date, yet some were almost dry, others very sloppy. In some the hair was evenly spread, in others I had 2" furballs. So there was a fair amount of faffing required each time to get a usable plaster. That said, still knocked the socks off working alone, and having to stop mix my own each time, just cracking off a lid and carrying on was great.

4) Plastering a ceiling in lime is exhausting - I see why so many prefer plasterboard and a quick skim. I was ruined, my shoulders were so sore I required painkillers to be able to get to sleep.

So, there we go, hope that is of interest/help to someone.

 

[Zebra]

Which looks ok, if it's dark enough, and the lights are down low enough, and you stand far enough away... The "thick limewash" will have a lot to do

Ha ha, likewise! But well done a twig! An exhausting job but I hope it was a satisfying too, perhaps now that the blisters have calmed down. Can you lift your arms yet? Can you lift them enough to take a photo of the finished job and upload it so we can see?

 

[a twig]

An exhausting job but I hope it was a satisfying too, perhaps now that the blisters have calmed down. Can you lift your arms yet? Can you lift them enough to take a photo of the finished job and upload it so we can see?

So I have finally finished the second half of the ceiling (yes I am writing this at 5:45am, I really do need to go to bed). Given that I started this yesterday afternoon, and the second (slightly smaller) "half" of the ceiling has taken me almost eleven hours (allowing for 20 minutes for dinner and two 15 minute breaks) I'm sure you are wondering why...

So it turns out on the reed mat, there was a section of it where there was maybe 15 reeds of wildly differing sizes, some over 1cm thick, others barely 2mm. The 2mm ones moved all over the place, creating a see saw effect, as you pushed the plaster in on one section, the reed would rise at the other end, pushing off a great clod of your recently applied plaster onto the floor.

The large reeds then prevented me from being able to screw in the laths tighter in order to pin the smaller reeds...

This was the final straw (ha ha) for me, I am never doing reed again, there is nothing more dispiriting than seeing (and hearing) hand sized chunks of plaster thwacking to the floor from the previous section as you are working on the next. At one point, I had an Incredible Hulk moment, throwing one of my trowels into the bucket so hard that the handle snapped off! Yet another reason not to buy a cheap Wickes trowel...

So, terrified of pushing on wobbly reeds I have left it as it is, there is still an edge to do, and there has been no trowelling it smooth done at all. Once it gets to midweek, and the plaster has started to go off, the small reeds should be held in position, and I will use the old very-dilute-plaster-and-a-paintbrush trick to get some sort of a finish on it.

Will be up again in around 3 hours time to do the walls, at least these are in hydraulic lime and hemp, so should be a joy in comparison. Huzzah. You might get a photo by about Friday, when hopefully it may look a little less like downtown Fallujah...

P.S. If you ever need to fuel a 12 hour plastering stint, I can recomend the effectiveness of caffeine pills, prosecco, nicotine gum and pizza :shock:

 

[malcolm]

You have done well. I resolved to never ever plaster a ceiling again after my first 1m2. I did find the second time I tried to plaster the same little bit of ceiling that woodwool board is very much easier to plaster onto than lath.

Walls are a joy - I like plastering walls. Plaster rarely falls on the floor unless the mix is wrong, and I find lime much easier than modern stuff. With lime you can normally get angry and throw the tools across the room, then go to bed and then straighten out what went wrong the next morning.

 

[Zebra]

If you ever need to fuel a 12 hour plastering stint, I can recomend the effectiveness of caffeine pills, prosecco, nicotine gum and pizza :shock:

A good tip there. I lime plastered my kitchen ceiling on New Years Eve, while Radio 4 were doing a 10-hour serialisation of War and Peace.

 

[JoceAndChris]

:lol: love it!

 

[a twig]

I found out today from a conservation plastering friend, that lime plastering on uneven stone/cob walls is much easier if one uses a venetian trowel (rounded corners and chamfered edges)...

I will purchase one and report back once I have done my next stint.

 

[paulc]

Mike Wye stock the Pavan trowels at a reasonable price, but you probably don't want the 816 as the blade is very thin and flexible. Venetian trowels are quite small in comparison to the typical plastering trowels - The blades are also quite a bit more springy. I have three that I'll be using over the next few weeks to put the finishing touches to a ceiling

Another alternative would be to take a standard (and cheap) trowel and round the corners off with a grinder.