Green Building Forum - Lath and plaster ceiling on 1910s house - replace it with plasterboard? Tue, 19 Dec 2023 08:36:29 +0000 http://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 Lath and plaster ceiling on 1910s house - replace it with plasterboard? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300656#Comment_300656 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300656#Comment_300656 Wed, 08 Mar 2023 22:55:24 +0000 bgasparotto
We recently moved into our 1910 Victorian (Edwardian?) house and are insulating it. The house sits in a conservation area so EWI is not an option, so we are going the breathable IWI route (wood fibre for walls and floors).

Currently we stripped most of the walls from old paint and wallpaper back to the original lime-plaster, so since we already in the mess, we are considering replacing our lath-and-plaster ceilings.

Before we moved, a full buildings survey report noted our ceilings are saggy in places and might need replacing. I am all for keeping the house as original as possible, but since I know lath and plaster decay over time and we will be renovating for 2+ years, I am tempted to take it down and replace it with something else, as I am afraid it might give us headaches in the future after everything is done.

Question: should we take down the ceiling and replace it with something modern such as plasterboard? Or should we patch it and it will last decades still? If replacing it, what exact materials should we use for the new ceiling? By replacing it, are we jeopardising the breathability of the property?]]> Lath and plaster ceiling on 1910s house - replace it with plasterboard? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300657#Comment_300657 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300657#Comment_300657 Thu, 09 Mar 2023 07:47:33 +0000 Peter_in_Hungary Over here the often used practice is to leave the old ceiling in place and fix plasterboard under the old, screwed through the old ceiling into the joists with (lots of) long plasterboard screws.

Removing a lath and plaster ceiling is a lot of work and mess. Once the ceiling has been pulled down all the remaining nails have to be either removed or banged in unless battens are fixed to the joists to carry the new ceiling.

Battening over the existing ceiling is also an option as this can give better support to the old ceiling and the battens can be spaced to match the PB sheets to reduce waste and cutting. (I used 50mm x 50mm battens last time I did this but I have also seen 30mm x 50mm used (AKA roofing tile battens))

A consideration in what ever you decide can be driven by any decorative architrave you may want to keep.

We don't have lath and plaster ceilings here but have reed matting and plaster - same idea though. When I have repaired such I have used normal plaster successfully (a layered build up may be needed). Your picture shows that you might be missing some of the battens, in which case these should be replaced to give a better key for the plaster. Don't be tempted to nail replacement laths, use screws - much gentler on the remaining ceiling than the banging.

Depending upon the amount of ceiling that is sagging it is possible to screw back the laths with large headed screws to refix the laths but you have to ask if the whole ceiling might be going the same way so if more than a couple of places are involved a better overall fix should be undertaken.

Some time back when faced with a ceiling to do I bought a plasterboard hoist. Magic - it makes plasterboarding a ceiling a one man job and allows easy accurate positioning of the boards. Buy new or secondhand and sell on when done.

Plasterboard hoist (they fold up for storage)
https://alinda.hu/gipszkarton-es-osb-emelo-allvany?gclid=EAIaIQobChMIuLiu66XO_QIV-YxoCR2uyQcUEAQYASABEgKH1fD_BwE]]> Lath and plaster ceiling on 1910s house - replace it with plasterboard? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300658#Comment_300658 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300658#Comment_300658 Thu, 09 Mar 2023 08:50:58 +0000 bhommels Also, keep in mind that insulating on the 'dirty' side of the L&P using rigid boards will always leave air gaps in between.]]> Lath and plaster ceiling on 1910s house - replace it with plasterboard? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300659#Comment_300659 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300659#Comment_300659 Thu, 09 Mar 2023 09:39:06 +0000 WillInAberdeen
Depending how big each blown section is, you can cut it back square as far as a joist, and insert a patch of plasterboard with packers to match the level, then tape and skim over.

If you have woodchip wallpaper or swirly artex it is easier to replace the whole lot with plasterboard than to remove the wallpaper!]]> Lath and plaster ceiling on 1910s house - replace it with plasterboard? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300660#Comment_300660 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300660#Comment_300660 Thu, 09 Mar 2023 09:43:01 +0000 philedge Lath and plaster ceiling on 1910s house - replace it with plasterboard? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300663#Comment_300663 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300663#Comment_300663 Thu, 09 Mar 2023 11:30:39 +0000 bgasparotto
The message I am getting is that replacing it with plasterboard is viable (please correct me if I am wrong), but the mess and work for removing it completely might be the problem.

The site is messy already as I've been using an angle grinder with a stripping disk to remove old paint from the walls which creates tons of dust, so I also bought myself a JSP mask with filters. In this case, I might as well just take it all down so I can install the plasterboard straight onto the joists?

Posted By: philedgeI do regret the bits I left in place. Having said that, it is a *really messy job*.
Also, keep in mind that insulating on the 'dirty' side of the L&P using rigid boards will always leave air gaps in between.

Are those something that can be cleaned with time and patience? I am not in a hurry to get the job completed, so I wouldn't mind going around with a scrapper and pliers to remove nails and scoop out bits of plaster from the joists.

Also, is there a right plasterboard material to use? should ceilings (in between floors and loft) be breathable?]]> Lath and plaster ceiling on 1910s house - replace it with plasterboard? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300665#Comment_300665 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300665#Comment_300665 Thu, 09 Mar 2023 11:47:59 +0000 fostertom Lath and plaster ceiling on 1910s house - replace it with plasterboard? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300666#Comment_300666 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300666#Comment_300666 Thu, 09 Mar 2023 11:48:11 +0000 bhommels Posted By: bgasparotto
Are those something that can be cleaned with time and patience? I am not in a hurry to get the job completed, so I wouldn't mind going around with a scrapper and pliers to remove nails and scoop out bits of plaster from the joists
I was referring to the unfinished side of the L&P where the plaster is protruding from between the lathe strips. This is a feature. When leaving the L&P in place, getting rigid boards to fit to the unfinished side is impossible without leaving air gaps. This was my main reason for removing L&P on my (sloping) ceilings, for example.]]> Lath and plaster ceiling on 1910s house - replace it with plasterboard? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300667#Comment_300667 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300667#Comment_300667 Thu, 09 Mar 2023 12:01:29 +0000 djh Posted By: bgasparottoAlso, is there a right plasterboard material to use? should ceilings (in between floors and loft) be breathable?I don't think there's any particular plasterboard.

Between floors it doesn't matter about breathability but breathable will be normal. What does matter between floors is noise insulation and if you're replacing the ceiling you should be able to improve that. We used acoustic rockwool for noise insulation. We also put resilient bars beneath our joists and haven't seen any sign of cracks. It might also help overcome your old-fashioned joist spacing.

Below the loft you do need to think about airtightness (that's also a bit of an issue between floors because of noise) and about breathability. What you do will depend on your particular situation. A vapour control layer is fairly safe and essential in some circumstances, although some people dislike them.]]> Lath and plaster ceiling on 1910s house - replace it with plasterboard? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300669#Comment_300669 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300669#Comment_300669 Thu, 09 Mar 2023 12:27:45 +0000 bgasparotto Posted By: djhBetween floors it doesn't matter about breathability but breathable will be normal. What does matter between floors is noise insulation and if you're replacing the ceiling you should be able to improve that. We used acoustic rockwool for noise insulation. We also put resilient bars beneath our joists and haven't seen any sign of cracks. It might also help overcome your old-fashioned joist spacing.
Did you use rockwool as thick as the joist height? Mine are pretty tall (150mm) so I am wondering about the weigh it would be adding to the structure. Also, could I also use soft wood-fibre instead since I will be also using it in other places? I read it also has good sound insulation properties given its mass.

Great idea about the resilient bars! I was wondering how I would hold the insulation in place as I will install it from under the ceiling (I don't want to remove the floorboards above as they are the one thing that look nice here), so it seens I can just sit the insulation on top of the resilient bars?]]> Lath and plaster ceiling on 1910s house - replace it with plasterboard? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300672#Comment_300672 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300672#Comment_300672 Thu, 09 Mar 2023 13:41:13 +0000 bhommels Posted By: bgasparotto
Great idea about the resilient bars! I was wondering how I would hold the insulation in place as I will install it from under the ceiling (I don't want to remove the floorboards above as they are the one thing that look nice here), so it seens I can just sit the insulation on top of the resilient bars?
+1 for the resi bars. And yes you can fit the rockwool, mount the resi bars and screw the plasterboard onto the resi bars. Make sure you use the right length plasterboard screws so you don't accidentally screw the resi bar to the joists. Seems obvious, but.....]]> Lath and plaster ceiling on 1910s house - replace it with plasterboard? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300678#Comment_300678 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300678#Comment_300678 Thu, 09 Mar 2023 18:28:07 +0000 revor Posted By: djhWe also put resilient bars beneath our joists and haven't seen any sign of cracks.


I second that. We put Res bars on all our ceilings and internal studwork as part of sound proofing between rooms. The secondary benefit was no visible cracks in the PB joints.

Posted By: bhommelsMake sure you use the right length plasterboard screws so you don't accidentally screw the resi bar to the joists. Seems obvious, but....


The idea is that you do not transmit sound to the joist via the plasterboard. I found it useful to predrill a 2/2.5mm pilot hole through the plasterboard and res bar as if the screw does not take up on the bar straight away it can push the bar away from the plasterboard and when eventually it takes up the screw is angled and ends up with the head countersinking deeper than desired. The pilot hole in the bar locates the screw. Use the screws designed for the bars. If fitting downlighters you will need top hats to lift the rockwool off the fitting. Ones made by Hellerman Tyton will fit through the light fitting hole and the legs spread out. I am sure other makes exist.]]> Lath and plaster ceiling on 1910s house - replace it with plasterboard? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300680#Comment_300680 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300680#Comment_300680 Thu, 09 Mar 2023 19:16:08 +0000 Gareth J Lath and plaster ceiling on 1910s house - replace it with plasterboard? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300683#Comment_300683 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300683#Comment_300683 Thu, 09 Mar 2023 20:18:53 +0000 djh Posted By: bgasparottoDid you use rockwool as thick as the joist height? Mine are pretty tall (150mm) so I am wondering about the weigh it would be adding to the structure. Also, could I also use soft wood-fibre instead since I will be also using it in other places? I read it also has good sound insulation properties given its massNo we just used the 100 mm required by regs. Our joists are 200 mm+ metal web joists :) Dunno about the woodfibre. It sounds like it ought to work but I'd check the weight is OK and that it's flexible enough to insert easily (the rockwool is bad enough - make sure your clothing is itch-proof).

Great idea about the resilient bars! I was wondering how I would hold the insulation in place as I will install it from under the ceiling (I don't want to remove the floorboards above as they are the one thing that look nice here), so it seens I can just sit the insulation on top of the resilient bars?
We installed from underneath. The insulation just sits on the resilient bars unless its held up by wedging between joists or over pipes, wires and whatnot. We didn't have any downlights so didn't need to get into top hats and suchlike.]]> Lath and plaster ceiling on 1910s house - replace it with plasterboard? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300686#Comment_300686 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300686#Comment_300686 Fri, 10 Mar 2023 09:01:23 +0000 Jonti Lath and plaster ceiling on 1910s house - replace it with plasterboard? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300687#Comment_300687 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300687#Comment_300687 Fri, 10 Mar 2023 10:38:27 +0000 Nick Parsons Lath and plaster ceiling on 1910s house - replace it with plasterboard? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300690#Comment_300690 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300690#Comment_300690 Fri, 10 Mar 2023 11:35:55 +0000 bgasparotto
So it seems we will be taking the L&P ceiling down then, to replace with plasterboard on the resilient bars. I appreciate the few tips for spacing hole/screwing, I am learning that the details are just as important as the big picture for such projects.

Posted By: djhDunno about the woodfibre. It sounds like it ought to work but I'd check the weight is OK

I am right to think this is something I should check with a structural engineer? As I am not sure this is something the manufacturer would be able to answer.

Posted By: Nick ParsonsI have never used flexi WF for any acoustic purpose, so I cannot comment on tat specifically, but in terms of ease of use it is great. Still loads of dust and fluff from cutting, so wear a mask, but really so nice to use and easy to fit. I've used it in retrofit under-floor insulation

Yea I read a fair bit about WF not itching as much as rockwool, and we will be using it for our underfloor insulation as well so that's another reason we are so keen on it.
Seems like I need to do some research about the sound proofing properties of it compared to rockwool!]]> Lath and plaster ceiling on 1910s house - replace it with plasterboard? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300691#Comment_300691 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300691#Comment_300691 Fri, 10 Mar 2023 11:56:25 +0000 Peter_in_Hungary If you are going to replace all the ceilings with plasterboard then seriously consider a plasterboard lifter to take all the stress and strain out of the job
https://www.ebay.co.uk/b/Plasterboard-Lifter/184199/bn_7023424666?norover=1&mkevt=1&mkrid=710-153696-560033-8&mkcid=2&mkscid=102&keyword=&crlp=355246904622_&MT_ID=&geo_id=&rlsatarget=dsa-764521878696&adpos=&device=c&mktype=&loc=9106041&poi=&abcId=&cmpgn=2033188068&sitelnk=&adgroupid=71572596173&network=g&matchtype=&gclid=EAIaIQobChMIq-T_p6bR_QIV7JBoCR0SMAgzEAAYASAAEgLE_vD_BwE]]> Lath and plaster ceiling on 1910s house - replace it with plasterboard? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300692#Comment_300692 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300692#Comment_300692 Fri, 10 Mar 2023 12:01:09 +0000 Nick Parsons Dunno about the woodfibre. It sounds like it ought to work but I'd check the weight is OK

I am right to think this is something I should check with a structural engineer? As I am not sure this is something the manufacturer would be able to answer.

Flexi WF: 50-55kg/m3. Not itchy at all, to me anyway.

Acoustic Rockwool 60kg/m3. If you're getting the SE to check re weight of WF then you need to do it more so for acoustic RW.]]> Lath and plaster ceiling on 1910s house - replace it with plasterboard? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300694#Comment_300694 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300694#Comment_300694 Fri, 10 Mar 2023 12:09:18 +0000 bgasparotto Posted By: Peter_in_Hungary
If you are going to replace all the ceilings with plasterboard then seriously consider a plasterboard lifter to take all the stress and strain out of the job
Thanks for the suggestion Peter! I am definitely considering it after your first comment (sorry I didn't respond your first comment but I noted it :))
In fact it should be a good idea to get one of these as we will be doing this in the whole property, but I wonder whether it would work in narrow spaces such as hallways? Otherwise it will have to be me and the wife lifting it up :D


Posted By: Nick Parsons

Flexi WF: 50-55kg/m3. Not itchy at all, to me anyway.

Acoustic Rockwool 60kg/m3. If you're getting the SE to check re weight of WF then you need to do it more so for acoustic RW.

Thanks Nick! I was under the false assumption that some "wool" would be inherently lighter than anything else! I will double-check this with the engineer anyway since we will also be adding weight to the bottom floor with the WF + UFH system.]]> Lath and plaster ceiling on 1910s house - replace it with plasterboard? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300700#Comment_300700 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300700#Comment_300700 Fri, 10 Mar 2023 14:17:35 +0000 bgasparotto Posted By: fostertomMy first hands-on householder experience was a 3 storey 1790 Listed terrace house in Bath - @ £12,500 were actually affordable starter-homes in 1974! Middle of night, heavy rain, huge crash from below the 2ndFl bedroom - the entire 1stFl L&P ceiling and a flood of water had collapsed over the room contents. Leaking valley gutter (central, M-shaped roof) had channeled water down thro the 2ndFl partition to collect on the 1stFl ceiling till it all got too heavy.
This will give me nightmares at night!! Hope you managed it OK. Can't imagine how tough of an experience it must have been. Luckily we don't have a M shape roof, but now you scared me off them!]]> Lath and plaster ceiling on 1910s house - replace it with plasterboard? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300701#Comment_300701 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300701#Comment_300701 Fri, 10 Mar 2023 18:20:53 +0000 jamesingram Lath and plaster ceiling on 1910s house - replace it with plasterboard? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300702#Comment_300702 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300702#Comment_300702 Fri, 10 Mar 2023 18:49:59 +0000 revor Posted By: bgasparottoSo it seems we will be taking the L&P ceiling down then, to replace with plasterboard on the resilient bars. I appreciate the few tips for spacing hole/screwing, I am learning that the details are just as important as the big picture for such projects.

It will be worthwhile if a bit time consuming if you survey the "flatness" (will call it that rather than level) of your ceiling joist using very tight string lines or laser level. Find the most protruding point and make that your reference point (Zero) From there work out using lines to find the mm out other fixing points are and fasten a plastic spacer of appropriate thickness at the fixing point of the RB. The RB are usually very straight as long as not damaged so you may able to use the lengths as straight edges to work out the amount of packing thickness instead of using lines. If you do not pack out gaps, when you screw the RB in place, you will distort it. Where the plasterboard end meet you need a support cross member you have to be accurate with the position as there is not much bearing surface once you allow for the 12mm from edge screw fixing. Hopefully you get the drift.]]> Lath and plaster ceiling on 1910s house - replace it with plasterboard? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300706#Comment_300706 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300706#Comment_300706 Fri, 10 Mar 2023 20:39:56 +0000 djh Posted By: bgasparottoI read a fair bit about WF not itching as much as rockwool, and we will be using it for our underfloor insulation as wellIs the stuff you're using underfloor flexible as well? I'd have thought you wanted something that was load-bearing to some extent.]]> Lath and plaster ceiling on 1910s house - replace it with plasterboard? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300709#Comment_300709 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300709#Comment_300709 Sat, 11 Mar 2023 10:19:37 +0000 Peter_in_Hungary Posted By: bgasparotto
Posted By: Peter_in_Hungary
If you are going to replace all the ceilings with plasterboard then seriously consider a plasterboard lifter to take all the stress and strain out of the job

but I wonder whether it would work in narrow spaces such as hallways?
Mine (which seems to be fairly standard on the market place) has a base of 106 cm and the minimum board support of 90 cm.

The base could be reduced a bit by not unfolding it fully and redrilling the locating hole but the more it is reduced the more stability would suffer.]]> Lath and plaster ceiling on 1910s house - replace it with plasterboard? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300711#Comment_300711 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300711#Comment_300711 Sat, 11 Mar 2023 11:24:43 +0000 WillInAberdeen
Like Peter said, make full use of the tools that are available, sell on afterwards if you want. If you are doing a whole house then look at buying a collated-screw driver, you can put screws in one handed while holding the pb with the other. Get a couple of step-up platforms the right height to reach your ceiling from comfortably.]]> Lath and plaster ceiling on 1910s house - replace it with plasterboard? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300713#Comment_300713 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300713#Comment_300713 Sat, 11 Mar 2023 15:45:10 +0000 Jonti ]]> Lath and plaster ceiling on 1910s house - replace it with plasterboard? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300714#Comment_300714 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300714#Comment_300714 Sat, 11 Mar 2023 17:33:02 +0000 revor Lath and plaster ceiling on 1910s house - replace it with plasterboard? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300715#Comment_300715 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300715#Comment_300715 Sun, 12 Mar 2023 09:48:44 +0000 Artiglio Reislient bars and largest sheets you can handlle, unlikely you’ll need to go smaller than 1800 x 900. If using smaller sheets a board lifter won’t save much time.
I’ve used Steicoflex , nice to handle and put in place , but a bit of a bugger to cut and messy ( i ended up doing it on the table saw in workshop, the extraction kept everything clean) but best of all didn’t make me itch at all.]]> Lath and plaster ceiling on 1910s house - replace it with plasterboard? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300717#Comment_300717 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17772&Focus=300717#Comment_300717 Sun, 12 Mar 2023 13:39:27 +0000 bgasparotto Posted By: revorIt will be worthwhile if a bit time consuming if you survey the "flatness" (will call it that rather than level) of your ceiling joist using very tight string lines or laser level. Find the most protruding point and make that your reference point (Zero) From there work out using lines to find the mm out other fixing points are and fasten a plastic spacer of appropriate thickness at the fixing point of the RB. The RB are usually very straight as long as not damaged so you may able to use the lengths as straight edges to work out the amount of packing thickness instead of using lines. If you do not pack out gaps, when you screw the RB in place, you will distort it. Where the plasterboard end meet you need a support cross member you have to be accurate with the position as there is not much bearing surface once you allow for the 12mm from edge screw fixing. Hopefully you get the drift.
I think got the idea, thanks! Interesting how the prep work seems to be as important as the finishing itself for us to achieve the end result we are expecting :)

Posted By: djhIs the stuff you're using underfloor flexible as well? I'd have thought you wanted something that was load-bearing to some extent.

It is soft, yea. I am planning to install a breathable membrane around the joists so the insulation can sit on and where the top of the WF is flush with the top of the joists. For structure, we are planning to get UFH boards with channels, cover the pipes (perhaps MDF? still unsure) then install our own flooring on top (mix of tiles and wooden floor reclaimed from the underfloor we are replacing for UFH).]]>