How to repair Lath and Plaster Ceilings

repairing a lath and plaster ceiling with large section missing

This ceiling needs some love after 150 yrs

Uh oh….. you’ve got a period lath and plaster ceiling that needs some ‘love’ hmm? I’ve been working with lath and plaster for more than 25 years so read on and learn what you can do to get years more life out of your plasterwork and what to do if it’s beyond economic repair…..

(p.s. if you want to remove your lath and plaster ceiling, you can head over to the “How to Take Down Lath and Plaster Ceilings” page instead).

Most people agree that traditional lath and plaster ceilings (and walls), really add charm and enhance the feeling of living in a period house. Eventually though, old lath & plaster is prone to cracking, sagging or even falling down. The good news is that it’s often possible to repair lath & plaster ceilings (and walls) and make them last a good while longer (if you like the look and feel). For those that have gone too far and need replacing with something else, we’ll look at the different options open to you.

What you choose depends on the look or feel you’re aiming for, your budget and your ‘tolerance’ of erm…..how can I put it; ‘rustic’ surfaces! It’s also a universal truth that the ‘flatter’ and most ‘long lived’ repairs cost more to carry out and the older your lath and plaster, the more work it’s likely to need.

OK, enough blurb, lets get started……

Here are the Top Ten Eleven Ways to Repair Lath and Plaster ceilings and walls

Pretty much in order of cost/complexity/longevity…….

  1. Re-decorate the plasterwork as it is

    The most minimum work, arguably not even a repair but basic maintenance. Vacuum to remove dust, (wash down, if required) and then re-decorate, preferably with a lime based paint (if the ceiling is completely original) or most likely with suitable water based paint. Not a good repair if the plasterwork has gone beyond the cracking stage, i.e. sagging badly, so this depends on the plasterworks condition.

    • Cost: Very economical and quick.
    • Pros: Period charm in abundance. Ideal for very old cottages that don’t have a straight edge or surface in them. Shows imperfections.
    • Cons: Possibly very short term solution for damaged plasterwork and even potentially dangerous if really bad! Not a ‘flat’ finish. Shows imperfections!

  2. REPAIRING CRACKS IN LATH AND PLASTER (CEILINGS AND WALLS)

    If the plasterwork has cracked or crazed but is still firmly adhered to the laths then you could simply fill the cracks and blemishes and redecorate. First scrape out all cracks and vacuum out loose material. Prime the cracks with a suitable primer like unibond then fill cracks and small blemishes with decorators’ filler using a suitably sized scraper or drywall spreader. Push the filler in at 90 degrees to the crack and then press to flatten out and scrape off excess by running the scraper along the crack. Gently sand the filler flat if necessary (shouldn’t need much) and vacuum all dust away. Fine cracks could be filled with a flexible decorators caulk and smoothed over with a damp flexible scraper. Wash down if required and re-decorate.

    • Cost: Economical repair.
    • Pros: Retains period feel. Looks good initially. Easy and quick repair.
    • Cons: Might only last a few years depending on plasterworks original condition.

  3. Repairing loose and small sections of missing plaster

    Small areas of missing or loose plasterwork can be re-plastered, preferably using similar haired lime based mortars and plasters. If these are not available to you, then areas could be re-plastered using modern lightweight backing plasters and finish plaster (non protected ceilings only). Ensure that loose plaster and dust is removed and damp the area a little before re-plastering. Ask at your local builders merchant for suitable plasters.

    • Cost: Economical to medium repair depending on size of area.
    • Pros: Retains period feel. Fairly quick repair.
    • Cons: Needs reasonable DIY Skills. modern plasters might be too ‘rigid’ alongside your old plaster leading to some cracking. Might only last a few years depending on the surrounding plasterworks condition.

    NOTE: It is popular to see folks recommending to completely ‘re-skim’ old plasterwork with a thin ‘veneer’ of modern gypsum based plaster, say 3 or 4mm thick. Whilst this can tighten up the plasterwork on an old wall, it can cause cracking later due to the relative stiffness of the new plaster in comparison to the underlying lath and plasterwork. Sorry!


  4. Using a thick lining paper

    A sound (ish!) lath and plaster ceilings appearance can be improved greatly by the use of a good quality, thick lining paper. Lining paper has the benefit of ‘tightening’ everything up and giving the ceiling an uniform look. It can then be decorated however you wish (ironically, some are painted to look ‘distressed’!?!). It can be a good idea to scrape out and fill cracks as No.2 before you glue a thick grade of decorating lining paper over the plasterwork, as lining paper will ‘shrink’ into any cracks and unevenness. Re-decorate as you wish.

    • Cost: Reasonably economical repair.
    • Pros: Retains period feel. Could gain many more years out of reasonable plasterwork.
    • Cons: Relatively difficult on uneven surfaces. Won’t stop further cracking over time if surface is still moving.

  5. Using a ‘glue’ system to fix sagging plasterwork

    Plasterwork can be ‘glued’ back into place by drilling holes in the plasterwork, vacuuming out the dust and injecting a suitable tube type adhesive. The plasterwork is then gently pushed back into place and supported until the adhesive dries. There is even a ‘system’ available in the states called “Big Wallys Plaster Magic“, or you can see an video that explains the principles here:- Gluing lath and plaster. A popular way is to drill 4mm holes, slightly countersink the holes, vacuum then squirt a thin adhesive into the hole followed by the drywall screw. Gently tighten the screw up into the countersunk plaster. Push up and support any sagging plasterwork first onto blanket covered lengths of timber gently wedged up to the ceiling. The guys at ‘Old House Online’ have a great artice that explains how to glue up a sagging ceiling perfectly… How to fix old ceilings with glue.

    • Cost: Medium to high cost, depending on time taken and plasterwork condition.
    • Pros: Medium term effectiveness. Retains period feel.
    • Cons: Arguably a specialised job and may be too fiddly for some DIY repairers.

  6. Removing the whole ceiling and exposing the existing beams

    Completely remove the lath and plaster, de-nail and clear away. Wire brush all plaster marks off the joists. Re-route any wiring, if required and repair any damage, holes in the timberwork etc. Clean up and vacuum all surfaces. Leave as is or decorate with varnish, wood stain, or paint. Often strips of plasterboard are fixed in between the joists on small lathes nailed onto the side of the joists to hide wiring and the underside of the floorboards above. Usually just used on ceilings (walls sometimes in the USA due to better sawn lath).

    • Cost: Economical to medium depending on timberwork condition.
    • Pros: All the old plasterwork is removed and finished with newly decorated surfaces.
    • Cons: Different look and feel, arguably only suited to certain properties and owners. Difficult electrical wiring and limited choice of light fittings.

  7. Over board with plasterboard or sheetrock

    A lath and plaster ceiling can be left in place and ‘over-boarded’ with plasterboard, using long drywall screws through the existing lath and plaster into the joists (not ideal but, quite commonly done). You will hear this option discussed a lot and for many it is considered the ‘only’ option, mostly to avoid the horrible mess created by complete removal!

    • First you need to find what there is to fix your new plasterboards too. Usually ceiling joists or studs in a wall.
    • Find them using the old way of drilling a line of holes 20mm (3/4″) apart where you suspect there is timber. You will feel the resistance when you hit wood, mark it and continue to find the other side of the wood.
    • Now you know how wide the wood is and where it is.
    • Next Mark their position on the wall, about 25mm down from the ceiling.
    • Now you are ready to over-board with plasterboard (sheetrock) using long (60mm to 75mm) drywall screws into the  timberwork where you have marked.
    • Board joints are then taped and filled if tapered edge drywall is used or skimmed with finish plaster if square edged boards are used.

    An even better way to overboard a ceiling or wall is to ‘batten out’ first. Here, appx 25mm x 50mm battens are fixed flat, underneath the existing lath and plasterwork, by screwing through it, into the existing ceiling joists. The battens could also be packed level/flat using thin plastic or timber ‘shims’ as they are screwed tight.
    Plasterboards are then fitted as normal, (often incorporating, new wiring, insulation and a vapour barrier). This becomes a good repair as the battens secure the old plasterwork and the plasterboard gives a ‘new’ finish, plus the convenience of easy cable runs for new lighting.

    • Cost: Medium to high.
    • Pros: Effectively a brand new surface is created out of plasterboard/sheetrock.
    • Cons: Potential problems with adding additional weight or levels if there is a cornice. Loss of ceiling height. Loses that period feel.

  8. Replacing the plaster and lath with plasterboard

    Completely remove the lath and plasterwork and replace with plasterboards / sheetrock. Once the existing ceiling is down and cleared away, mark the positions of all joists and timbers onto the walls. Then fix 12.5mm plasterboards to the underside of the original joists using 38mm drywall screws as normal. Use the marks on the walls to snap a chalk line onto the plasterboards, showing you where to place the screws. Board joints are then taped and filled if tapered edge boards are used, or skimmed with finish plaster if square edged boards are used.

    • Cost: High. Removal of old material, new boards and finishing makes this one of the most expensive options.
    • Pros: Plasterboards/sheetrock are stable and very flat. A permanent repair.
    • Cons: Loses the period feel.

  9. RE-PLASTERING WITH TRADITIONAL LIME MORTAR AND PLASTER

    A rarer alternative to complete removal, is the removal of the sagging and broken plasterwork, repairing the existing laths (or replacing them) and re-plastering with a suitable two coat haired lime mortar and a third coat of lime finish plaster. You may need access to the top of the laths to clear away the ‘keys’ or mortar ‘snots’ that were pushed through the gaps in the lath the first time.

    • Cost: High, due to special skills and materials needed.
    • Pros: Good as new finish, that also matches the surrounding period work. Long term repair.
    • Cons: Arguably not a DIY proposition due to work involving lime plasterwork.

  10. FULLY REPAIRING A ‘PROTECTED’ LATH AND PLASTER CEILING

    Given enough time and money even the worst ceilings can be rescued, as you would  have to do to satisfy the authorities if your ceilings were historically valuable.
    Briefly, fully support the plasterwork from underneath on blanket covered timber on props or staging. Working from above, gently remove all the accumulated dust, debris and old loose keys or nibs that build up over the decades or even centuries (dust masks essential!)
    Repairs can then be carried out using one of the various lath and plaster repair systems available. Often using stabilizing chemicals, wire mesh and adhesives or plasters, with the aim of reattaching the plasterwork below.
    For example; one system involves fixing a wire mesh to the inside edges of the joists just above the plasterwork and then applying adhesive to the plasterwork embedding it into the mesh.

    • Cost: Expensive due to extreme care needed and labour involved.
    • Pros: Retains all original period features. Usually only used on plasterwork of significant historical interest.
    • Cons: Complicated, expensive, and sometimes beyond even the average builder. Arguably not a DIY proposition due to care needed to preserve original features without damage.

  11. And that just leaves….buy a newer house.

    Maybe you are just not cut out for living in a period house and would be better suited to a mimimalistic pad with the latest in smooooth technology…. *laughing*.

    • Cost: Horribly expensive, removal companies, estate agents, lawyers etc.
    • Pros: No lath and plaster to repair.
    • Cons: Everything is very, very flat, smooth and arguably…..boring.

Need More Information or Help?

Urban legend has it that you only need to read six books on a subject to be classed as an ‘expert’. So, here are some books I found interesting which will be useful to get you started! Or drop me a comment and ask a question.

All available from amazon.co.uk, (or here at amazon.com for the rest of the world), just follow the links to have a peek!

    1. old house handbook

      Not destined for the coffee table……..

      Old House HandbookA Practical Guide to Care and Repair, by Roger Hunt and Marianne Suhr. Hardback.

      Don’t be deceived, this book may be at home on the coffee table, but it packs a lot of really useful information into its 208 pages. Passed and approved by my favorite ‘Institute’, the guys at SPAB, the Society for the Protection of Ancient Buildings.

      The book teaches you to work with your house, not fight it. Repair not restore or renovate. If you are into minimalistic, white flat surfaces and recessed downlights, this book may be a shock for you, as it educates us to live with a buildings character, not destroy it.


      1. book about the maintenance of historic buildings

        maintenance of historic buildings

        Maintenance of Historic Buildings, A practical Handbookby Jurgen Klemisch.A practical, hands-on guide to the maintenance of your older house. Based on many years of experience, this book teaches you the current best practices related to maintenance and is presented using a straightforward logical format.

        In two sections the book deals with maintenance for use by owners and how to conduct condition surveys  The book makes extensive use of helpful checklists, work cards detailing routine cleaning, deep cleaning, inspection, servicing and redecoration; and even spreadsheets to help plan your maintenance.
        Following the books recommendations would also (over time) build a useful record about your house, which will be helpful when deciding the timing of future repairs and allow you to assess costs accurately.


        1. damp houses a guide to the causes and treatment of dampness

          A damp house is a dying house……

          The Damp House: A Guide to the Causes and Treatment of Dampness. By Jonathan Hetreed. Hardback.

          I thought that I would include this book because as the owner of an older property you will soon come to learn that water or damp is the mortal enemy of your house!

          Managing the moisture and water, on, in and around your home is vital in the battle to preserve and protect it.

          From the patio to the ridge, water is trying to get into your house and cause damage! Read Jonathan’s insights and learn how to keep it at bay.


          1. haynes Victorian house book image

            The Victorian House manual from Haynes

            The Victorian House Manual By Haynes
            A no nonsense book that even Conservation Officers like and use! This book covers some of the most common problems found in houses built in this era, along with some of the more common misconceptions about some of the repairs commonly touted as being able to “cure all ills”.As you would expect from Haynes these books have great photos and easy to understand and follow instructions. A hard to beat primer for anyone owning or thinking of buying a Victorian (or Edwardian for that matter) house.


          1. A step by step guide to using natural finishes in your old house

            Guide to using natural finishes

            Using Natural Finishes: Lime and Clay Based Plasters, Renders and Paints – A Step-by-step Guide By Adam Weismann

            Adam Weismann’s book is more specialized than those above and would suit the hard core enthusiast who wants to have a go at repairing their old walls and ceilings themselves.

            Kevin McCloud from Grand Designs comments that it is “A splendid book. A real addition to what’s out there and very complementary to the Society for the Protection of Ancient Buildings’ new technical manual on Old Building Repairs”.

          Endnote….

          Lath and plaster carpet

          lath and plaster carpet from bev hisey

          Carpet inspired by lath and plaster walling

          Bev Hisey was so inspired by the look and feel of the lath and plaster when renovating her home that she has dedicated a brand new carpet design to it! Click the image to see more…

          The Handy Crowd

          12 thoughts on “How to repair Lath and Plaster Ceilings

          1. Hi Ian

            This is a very good article on plaster repairs.
            I found it whilst trying to find out how old my plaster ceiling is.
            Its lath and plaster, but does that necessarily mean it’s lime plaster?

            The surface plaster is white and the plaster underneath is very dark grey.

            The building is grade II listed, built late 1700′s. Its a townhouse on a terrace; the house has ben converted into flats many years ago. So it may have been replastered when it was converted.

            Norway is a cool place. We have been skiing in Geilo several times over the years. Very expensive for food and eating out though!

            How much ?? :)

            • Hi Bee,
              Yup, Norway certainly is expensive, especially in the ski resorts!

              Hmm, white and grey plaster is ringing a bell somewhere deep in my mind, just can’t quite remember where I’ve seen it! Certainly there are regional differences between lime plasters used that lead to colour and texture differences. I’ve also seen good existing laths re-plastered with modern or lightweight plasters several times hence it being in my top ten list. The colours you describe do sound like it’s been re-plastered sometime. If you have access to the plaster above (in the loft for example) you might be able to see more, if there is hair in the backing coat for example. Hair should mean that its lime based.

              Usually you can tell if it is lime based by how it is ‘wearing’, if there are random cracks on the surface it’s unlikely to be a modern plaster which tends to crack in straighter lines, but even that is not terribly conclusive.

              If you are searching, does the ceiling have a problem or are you just curious?
              Thanks for the comment!
              Cheers
              Ian

          2. Hi – I’ve read your article with great interest..
            We have a Victorian country / farm labourers house made from Clay Bat and has Lath and Plaster ceiling..
            All ceilings have been overboarded and re-skimmed with great success – since the laths were secure to joists and plaster heavily cracked.
            All the ceilings in the house are very low 7′ 6″.
            Problem was the bedroom ceiling which I have been avoiding – laths separated from joists and sagging up to 30mm partially …… when I stripped the walls of paper use steamer the ceiling got worse and my idea to overbooard was looking very doubtful.
            I read your article about battening to hold laths up to joists ….. great idea ….. but needed something thin dceiling due to low height …. also batten shims seemed to make the job difficult.
            What we did we used galvanised steel “bulders band”. This allowed us to screw up and all laths were secureed back to joist … really easy …. one man job. Ceiling now secure and solid. Then we overboard with 9mm thick plasterboard. We will skim it tomorrow.
            At the moment very happy – builders band cheap at £7.00 per 10m roll – so total cost £28 to scure laths.
            I am sure it will skim up ok. So thanks to your article we came up with this further idea.
            Cheers – Tom

            • And me too Tom! Great and innovative idea to use the builders band, I’m interested in how many times you hit the band whilst screwing up the plasterboards though?!

              Yes, I agree that it will do the job admirably, it’s nice when you read something and it sends you off down another road to the same destination isn’t it?
              Good luck with the skimming tomorrow, it’s been a while since I’ve seen proper plastering, it’s all tape and fill over here.

              Glad to have helped, albeit very indirectly!
              Stay well
              Ian

          3. Just bought a lower conversion dated 1860. Quite severe cracks in ceiling and cornice work in front lounge. This information looks invaluable. Looking forward to using this site for the many jobs that will arise. Several cracks elsewhere but the Home Report provided (Scottish requirement) states this is due to “settlement” and not a major issue.

            • Hey Billy,
              Sounds like a lot of character! Looks like you need to get up there and see how solid it all feels. Hopefully everything is still firm and the cracks are like you say, just a result of the old girl moving about over the years. Then its a case of filling and a few coats of paint. Time will then tell you what you need to do come decorating time again.

              Good luck with the new home and thanks for stopping by :)
              Cheers
              Ian

          4. Ian,

            I need to get a ceiling repaired in a 1930s house. The ceiling is upstairs with access to the attic above. As well as the usual cornicing around the ceiling perimeter there is also decorative plaster “mouldings” on the ceiling itself. Several cracks on the ceiling and from above I can see that the plaster nibs have come away from the lathing in places. I have read that it is possible to push the ceiling back up from below, support it and pour finishing plaster over the laths from above. Do you think this is a viable solution?

            • Hi Michael,
              I wouldn’t recommend using finish plaster, but it was a common solution back in the day, even if not very successful! The problem is that it’s difficult to get the surface clean enough for the new plaster to stick well enough. Plus, although plaster is sticky, it’s not technically very sticky, I mean sticky like a proper adhesive. Sure, plaster sticks to the wall, but then it has huge area on its side, use plaster to try and hold something when it’s only 1/4 wide is asking a lot.

              Your options are to use a wire mesh and resin system, where the resin will grab a hold of the plasterwork below and is reinforced by a layer of thin wire mesh fixed to the side of the joists.

              The alternative that is gaining a lot of favour nowadays is to inject an adhesive into small holes and gently push the plasterwork back up into place and support it on blanket covered timbers and quick grip props. Old house online has a great description here http://www.oldhouseonline.com/how-to-fix-plaster-ceilings/ which will give you an idea of whats involved. This can be done from above through the lath (more tricky to stop the drill before it goes through the plaster!) or from underneath where you drill through the plaster and stop at the underside of the lath. Squirt in your adhesive, gently push up into place and support till dry. It’s a fair repair and although on a typical ceiling you’re looking at many hundreds of holes, they only take a few seconds each. This would be my best bet and certainly it’s better than using plaster.

              Let me know how you get on or even ping me some photos and we can pop them on here to help someone else.
              Thanks and good luck Michael!
              Stay well
              Ian

          5. Hi Ian interesting article…. I have an old (1600s) house in Gloucestershire and I have made use of a few of the tecniques listed above in various rooms. I’ve just finished replacing part of the ceiling in what will be the bathroom where an area of lath and plaster was coming down. I used new lath and hemp / lime plaster as a scratch coat over this area. I also screwed plastic washers into the joists along the whole length of the joists (even the areas of the ceiling which were OK) and then scored the old ceiling with a stanley knife and skimmed the whole lot with lime finish coat plaster with some fibre added to cover the plaster washers and give a uniform appearance.
            I can’t manage polished smooth plaster so I then floated it up with a sponge float. Pretty happy. Builders quote – £3500. My costs – £75 + time.

            • Sounds like an interesting house Toby, seriously old! Nice to get a comment from someone not asking about plasterboards too. Sounds like you managed a sympathetic repair on your old lath and plaster, I wish more folks would give some of these old materials a go.

              I actually think that lime finish plaster is more forgiving that the modern stuff which you have to get just right before you can trowel it up and with a bit of breeze can set in a jiffy on occasion. Have you tried running over the plaster after you’ve floated up withe the sponge? Just thinking that the sponge will level out some of the highs and low spots and the metal trowel might just ‘seal’ the texture front the sponge. Having said that, if you’re getting a finish you’re happy with what more is there to do :-)

              Oh, What type of plastic washers did you use, one designed for holding plaster or something you found locally? Be nice to have a link for those too.
              Thanks for taking the time to leave a comment Toby, it’s always nice to hear about real world projects that are successful.
              Stay well
              Ian
              p.s. If you have any photos, I’d be delighted to write them into an article here as an example of what’s possible.

              • Thanks Ian

                Our house is listed, so I was told I can do “like for like” repairs only without going through the listed building consent process. Whilst I wish the application process was easier in some ways the house being listed has been a blessing as it has made me take the time to learn about my house before just ripping things out and replacing.

                I got the washers and the hemp lime from Ty Mawr http://www.lime.org.uk I think the washers are intended for fixing wood wool boards, which have a bit of flex in them so the can be pulled flush with the rest of the surface. They are maybe 2mm thick but are dimpled and holed to carry plaster. It meant I had to apply a thick skim coat of about 5mm to cover it all up, which meant I had to put quite a bit of fibre in the skim coat – I used very fine poly prop fibres intended for use in concrete reinforcement….. Not entirely in keeping with old buildings, but a small concession – horse hair would have shown through I think.

                I haven’t tried lime / aggregate backing coats onto lath but was really happy with how the lime hemp went up, very sticky and light. When it sets (which is about 3 weeks) it is rock hard too. I’ll post some pics after Christmas when it is all finished!

                • Sounds like quite an innovative mixture of new and old technology Toby! Totally agree about learning a little about the house first, knowing how the house goes together and using matching materials will mean fewer problems in decades to come. I feel quite embarrassed at some of the work I did decades ago (along with everyone else at that time), using cement for re-pointing etc on many a terraced house. But the knowledge ‘on the street’ so to speak, just wasn’t there in those days (outside of the heritage world), plus folks were always looking for the cheapest quote.

                  Even now, the world of heritage repairs (like wine and art) tries to retain this mystical air and aloofness that really needs to be knocked down in order for the techniques to become ‘demystified’ and widespread. So many bricklayers I know won’t touch real lime mortar because they are terrified of it’s ‘complexity’. As you and I know, using lime utilizes so many of the same techniques and skills many of us already have. A little new knowledge about the material is all that’s needed (just like employing many of the new things that come to market).

                  At least now you know your ceiling is quite secure and any minor cracking that occurs as a result of the old girl ‘wiggling her bottom’, is just cosmetic and nothing to worry about.

                  Would really appreciate looking at the pics Toby, thanks again for talking through what you did, appreciate it.
                  Merry Christmas!
                  Ian

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