Lath and plaster work is a means of finishing the internal surfaces of a home and was very common until the introduction of gypsum board (plaster in the US) in the 1950s.

This method of internal finishing consists of thin strips of wood, called laths that have been sawn or split (split along the grain), which are nailed crosswise into the wood frame of the house about 1/4″ or so apart. 6mm batten is then covered with a plaster, usually a two coat lime mortar mix and leveled.

Many clapboard and plaster walls and ceilings lasted over a hundred years before requiring repairs in addition to normal decoration. Some clapboard and plaster ceilings have been in place for several hundred years, especially in the UK.

A crucial element of this construction is the 6mm gap between the battens, as it provides a ‘key’ for the plaster as it is pushed in and slightly protrudes out the back of the batten. This crucial plaster key is also the source of most plaster failures; as the keys gradually come off due to the normal movement of houses over long periods of time.

Once a significant amount of the keys have dislodged from the plaster, the plaster begins to crack and may separate from the laths, slumping or sagging.

There are many ways to repair fallen lath and plaster, but due to financial reasons, they are often removed and replaced with modern materials like sheetrock (gypsum board). This method at least makes it possible to use much better insulation material, thus saving energy and heating costs in the future life of the house.

My Top Ten Ways to Repair Lath and Drywall

Here’s a quick rundown of all the ways you can repair lath and drywall in your home, depending on the look you want to achieve, the time you want to spend on it, and of course, your budget.

1. redecorate as is. Vacuum to remove dust (wash, if necessary) then redecorate with suitable water-based paint. It is not a good repair if the plaster has passed the cracking stage, that is, it is deeply sunken. It depends on the state of the original plaster.
   • cost: Very cheap and fast.
   • Advantages: Period charm galore. Ideal for very old cabins that do not have a straight edge or surface. It shows spots.
   • cons: Potentially dangerous and possibly very short-term fix for damaged plasterwork. It is not a ‘flat’ finish. Show imperfections!
2. Fill in cracks and blemishes.. Scrape all cracks and vacuum up any loose material. Fill cracks and small blemishes with decorator filler using an appropriately sized scraper or drywall spreader. Lightly sand the filler and vacuum up all dust. Wash if necessary and redecorate.
   • cost: Economic repair.
   • advantages: Retains the vintage feel. It looks good initially. Easy and fast repair.
   • cons: It may only last a few years depending on the original condition of the plasterwork.
3. Use thick liner paper. Scrape and fill cracks as in #2. Glue a thick layer of decorative liner paper to the plaster. Renew.
   • cost: Reasonably inexpensive repair.
   • advantages: Retains the vintage feel. Could gain many more years with reasonable plasterwork.
   • cons: Relatively difficult on uneven surfaces. It will not stop further cracking over time if the surface is still moving.
4. Stick the fallen plaster in place. Plaster can be “glued” in place by drilling holes in the plaster, vacuuming up the dust, and injecting a suitable adhesive. The plaster is then gently pushed back into place and clamped until the adhesive dries.
   • Cost: Medium to high cost, depending on the execution time and the state of the plasterwork.
   • Advantages: Medium-term effectiveness. Retains the vintage feel.
   • Cons: It is arguably a specialized job and may be too difficult for an effective DIY repair.
5. expose the beams. Completely remove lath and plaster, remove nails and clean. Wire brush all drywall marks from joists. Reroute any wiring, if necessary, and repair any damage, holes in wood framing, etc. Clean and vacuum all surfaces. Leave it as is, or decorate it with varnish, wood stain, or paint. It is usually only used on roofs.
   • Cost: Inexpensive to medium depending on the condition of the wood.
   • Advantages: All the old plasterwork is removed and finished with newly decorated walls.
   • Cons: Different look and feel, possibly only suitable for certain properties and owners. Difficult electrical wiring and limited selection of lighting fixtures.
6. On board with plasterboard or drywall. Find the framing or ceiling joists, mark their position on the wall and then cover with sheetrock or sheetrock using long (60mm to 75mm) drywall screws into the original wood framing. The board joints are then taped and filled if taper-edged gypsum boards are used or capped with finishing plaster if square-edged boards are used. One of the most common methods to ‘repair’ a lath and plaster.
   • Cost: medium to high
   • Advantages: Effectively, a new surface is created from plasterboard or plasterboard.
   • Cons: Potential issues with adding extra weight or levels if there is a ledge. Lose that vintage feeling.

   This is not strictly a lath and drywall repair as it gets rid of it! But I’m including it, as this is a VERY common fix for lath and plaster ceilings that have failed and badly fallen.

7. Completely remove the plaster and the lath.Replace with sheetrock/gypsum board. Mark the positions of all joists and studs, then attach 12.5mm sheetrock to the bottom of the original studs with 38mm drywall screws. The board joints are then taped and filled if tapered-edged boards are used, or polished with finishing plaster if square-edged boards are used.
   • Cost: High. Removal of old material, new boards, and finishes make this one of the more expensive options.
   • Advantages: Gypsum boards/gypsum sheets are stable and very flat. A permanent repair.
   • Cons: Lose the feeling of the period.
8. Render keeping the original strips. Completely remove the existing render and if the lattice is firm, reapply the render with three coats, two base coats and a thin finish coat.
   • Cost: High, due to the special skills and materials required.
   • Advantages: Good like new finish, also matching the surrounding period work. Long-term repair.
   • Cons: Arguably not a do-it-yourself proposition due to the work involved in lime plastering.
9. Heritage quality. Fully support render from below on wood covered with blanket on props or stage. Working from above, carefully remove all loose debris, old keys or nibs, and dust. Use one of several available systems, for example, attach wire mesh to the inside edges of the joists just above the render, then apply adhesive to the render by embed it in the mesh.
   • Cost: Expensive due to the extreme care needed and labor involved.
   • Advantages: It retains all the original features of the time. It is generally only used in plasterwork of great historical interest.
   • Cons: Arguably not a DIY proposition due to the care required to preserve the original features without damaging them.
10. Buy a newer house. Sorry I couldn’t make 19 ways to fix lath and plaster just didn’t sound right. Any idea for number ten is welcome…
    • Cost: Horribly expensive, moving companies, real estate agents, lawyers, etc.
    • Advantages: There is no lath or plaster to repair.
    • Cons: It’s all very, very flat, fluid and possibly… boring.

The list above is roughly in order of cost to carry out, although some aspects are moving to specialist crafts where costs could increase. It could be argued that the two most common solutions are to either cover the ceiling with boards or remove it entirely and replace it with sheetrock or sheetrock.

It should be noted that complete removal Building a clapboard and plaster ceiling involves a significant amount of mess, particularly large amounts of dust and debris that take a lot of time and effort to contain and remove.

Appropriate safety equipment should be used when working with old lath and plaster.