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Replacing Lath and Plaster with Plasterboard


lord_seagrave
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Morning all,

New Seagrave Towers mkVI (or possibly mkVII, I’ve sort of lost count) is an 1830s property with a Grade II listing (which references the external appearance only).

Anyway, there is a pretty grotty top floor spare bedroom, which has saggy pitched ceilings and is cold and miserable.
 

Setting aside any listing hoops I might have to jump through, what sort of practical  problems at I going to encounter if I attempt to replace the lath and plaster with plasterboard?

What are my insulation options as I do?

Im reasonably handy - is it even  DIYable?

Are there any reasons for repairing/restoring the lath and plaster, rather than replacing it?

Cheers, as ever,

LS

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Hello,  depends on how much of the ceiling that needs to be repaired, also how do the the ceiling joists look if you did decide to take down the old lath and plaster, theres no going back once you start hacking off , if there is to much sagging and dislodged area it might be the case taking off and replace with modern materials eg plasterboard, with insulation between the joists, it's likely  the joists will not be level to put plasterboard straight on so you will need to use timber strips the same width as the joists each cut the depth required, once done then insulation material can be put in between joist and plasterboard over, depending on finish required,  tape and paint or a nice skim finish, how big is the area of ceiling ? renewing like the original lath and plaster would be expensive and not really a DIY moment, also the hire of platforms rather than a few pairs of steps and scaffold boards, 

Edited by oldypigeonpopper
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18 minutes ago, oldypigeonpopper said:

Hello,  depends on how much of the ceiling that needs to be repaired, also how do the the ceiling joists look if you did decide to take down the old lath and plaster, theres no going back once you start hacking off , if there is to much sagging and dislodged area it might be the case taking off and replace with modern materials eg plasterboard, with insulation between the joists, it's likely  the joists will not be level to put plasterboard straight on so you will need to use timber strips the same width as the joists each cut the depth required, once done then insulation material can be put in between joist and plasterboard over, depending on finish required,  tape and paint or a nice skim finish, how big is the area of ceiling ? renewing like the original lath and plaster would be expensive and not really a DIY moment, also the hire of platforms rather than a few pairs of steps and scaffold boards, 

Sound advice , I have cut corners and used treated battens nailed over the old ceiling to save a lot of mess , these were put the opposite way to how the joists ran and then plasterboard nailed to them , with then two coats of finish plaster .

On the old cottages we looked after we would often take the whole ceiling down , this would be a dirty job with the amount of dust lying in between joists , more so if the roof was thatched , very often the joists were replaced because the old ones were full of wood worm and started life as timber on a ship. so what turned out as a few hair line cracks in the old plaster ended up as a complete new ceiling .:good:

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If its reasonably flat and the joists are sound, board straight over it using longer screws than usual to fix them. Get some adjustable plasterboard props which will let you crank any sagging areas back up as you fix the boards. Then get it skimmed. I did this several times in my last house with no issues. (I also tore down lath and plaster ceilings in my previous house, and its not a pleasant job). As you are essentially adding to the mass of the ceiling you also get more sound insulation. Heat insulation should be done above the existing ceiling in the loft space.

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5 hours ago, lord_seagrave said:

which references the external appearance only)

The entire building and its curtilage is listed, so any structure affixed to it is listed. You require Listed Building Consent for the works. 

The “listing only references x part so only these parts are listed” is a commonly held / repeated fallacy. 

It should be straightforward to secure Listed Building Consent, applications can be made free of charge via the planning portal. 

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8 hours ago, samboy said:

If you do take the lath and plaster down make sure you have overalls and a face mask on. Filthy job. I've done it.

The worst ones to take down are reed and plaster , with the plaster having horse hair mixed in the lime , this make your eyes sting a bit as well as making your mouth dry . 

I have plastered on top of lathe and it is not that hard with the modern bonding coat , and the trick is to make sure the lathe is damp before you start .

Plastering on top of reed is a different kettle of fish , the flatter you get the reed the better , give it a base coat and scratch it before you give it a second coat , you then might have to repeat it to give a finishing coat .

The old tradesmen were certainly good at what they do .

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Got any photos?  That would help a lot.

Presuming you do end up going down the route of ripping it down......

The absolute best bit of advice has already been given but I'm going to reinforce it - if you do rip the ceiling down, you absolutely MUST buy yourself a very good quality respirator.  Don't be mistaken that those paper masks will protect you, they are only for very brief exposure to minimal amounts of dust.  Your lungs will thank you for taking care of them, but more's the point they might never forgive you if you neglect them 👍

Plasterboard doesn't like going on going on wonky things but it will forgive a tiny bit, if the "rustic" look suits the character of the room and building.  As with most other things that need to look presentable when finished, it all goes back to the prep work and the foundation it's built off so you have to bear that in mind.  The plasterer can only apply his work to what's there already and if it starts off like a donkey's dongler it'll end up that way!

If you want it all flat, clean and crisp with straight abutments you'll probably have to make adjustments to the rafters.  Lots of work with a string line, straight edge and measuring tape needed to set out before you board.  I'd be calling on a carpenter for such a job if you're not too handy in that area.

The way I'd do it is to strap new rafters to the existing rafters, protruding out from the original edge the laths were nailed to.  Temporarily tack one on each end and make sure they're levelled and aligned before finally screwing them up permanently.  Then fit all the intermediate rafters, chuck in whatever thickness of polystyrene you can fit in there then board it.  It's a hell of a faff though!  I'd only be doing that if there was no possibility of over-boarding the existing.

To make the wall abutment a nice clean line you may have to dry-line the wall with plasterboard too if it's wonky.

Have fun, would be interesting to see pics before/after, I like building renovation :)

P.S. Bar clamps are an absolute godsend for jobs like this ;)

P.P.S If you do go about levelling up the ceiling you might then realise how out of level the floor is! 😂

 

image.png.8b48350c50c3db6ddeec8f43e0255100.png

Edited by Jim Neal
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On 12/02/2022 at 09:39, MirokuMK70 said:

If its reasonably flat and the joists are sound, board straight over it using longer screws than usual to fix them. Get some adjustable plasterboard props which will let you crank any sagging areas back up as you fix the boards. Then get it skimmed. I did this several times in my last house with no issues. (I also tore down lath and plaster ceilings in my previous house, and its not a pleasant job). As you are essentially adding to the mass of the ceiling you also get more sound insulation. Heat insulation should be done above the existing ceiling in the loft space.

Done many a ceiling like this with 65mm screws and plasterboard.Check the joists,it's quite common to find that they have dropped out of any fixing they had to rafters and the whole lot could come down.

If you decide to take it all down then use a water most system to drop the dust.

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If you take the old stuff down, be aware that it can come down in very big slabs.  The 'keys' (plaster mushroomed behind the laths) holding the plaster in place often break over time and you removing/disturbing one part of a ceiling can cause great big chunks to clatter down with a big old bang so do take the time to have a good check before starting.

Edit - sorry I didn't read Vampires post properly - apologies for basically repeating what he already said.

Edited by Jonty
numptiness
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Awful job taking lath and plaster ceilings down. I did 3 rooms in our current house and it was a nasty job especially the lounge as that was a big room. When it came to the upstairs hall I gave in and put a new slightly lower ceiling in because the old ceiling was up and down like a fiddlers elbow, I had put loads of insulation in the loft and didnt fancy taking it out again and there was a metric *$%£ ton of muck between the joists. Well i call them joists but more like matches. Anyone ever tells me that victorian houses are well made will get a strong talking to.....

party wall in the house is one brick thick, a long drill bit and you are in next door,

they had no concept of a right angle. Do not try to level stuff up it will be quicker to knock it down and start again.

foundations HAHAHAHA who need them just put a few bricks down on their side. When clay ground dries in summer you get cracks and when it gets wet in winter the porch door wont stay shut. If you ever look at a period property with no cracks then they have just been covered, they will be back.

lime morter is great for letting moisture pass through but it does fall off the bricks. Does the wall sound hollow when tapped? Then the plaster has blown. It would have been nice if they had mixed the horse hair into the mix rather than just dorpping the whole horse into the mix.

High ceilings are great but guess where all you heat ends up. You will discover this when up the ladder sweaing like a pig because you have found all your heat.  And you will need a set of house ladders because everything needs ladders to get to.

And last but not least you have 100+ years of PO bodges. The electrics were the best how the house never went up in flames!

We couldn't even say the period features were nice because they had ALL been ripped out and I mean evrything, no fireplaces, coving, skirting, doors etc. We must have spent a fortune replacing stuff as we went.

On the plus side they are nice and big compared to modern boxes.

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