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Ceiling plaster patched

How to Plaster Patch a Ceiling

How do i patch a hole in a plaster ceiling? How difficult is it to do and should i call someone to complete the task for me?

These are a few questions you may have when faced with a hole in the ceiling left from the removal of flues, vents or small water damaged areas. Small holes are easily fixed with a few tools, tricks and know-how. When i say small, i mean roughly 300mm or there abouts. For larger holes it may be better getting sheets replaced, but that is a different story and one we are not discussing today.

Now, the tools required for this job are:

  • 100mm paint scraper
  • plasterers trowel 300mm or larger (you can use smaller but larger trowels cover the whole patch area and make it easier to get flat and level)
  • cup to measure and mix plaster
  • hawk (mud board) or something to hold plaster whilst on the ladder. must be easy to get plaster onto trowel.
  • Ladder

Materials required are:

  • 25mm chipboard screws
  • piece of gyprock larger than the hole or piece of timber
  • ceiling repair plaster (quick drying time – 20 min)
  • water

When starting out it is a good idea to put down a drop sheet to avoid splatter on clean surfaces and ensure that the work area is not cluttered where possible. Having a stable ladder in a good position to reach the work area without having to strain is a must. First determine whether the hole needs to be cut nicely before patching (inexperienced patchers may find this easier). It is important to sweep any dust from the area above before you begin.

Measure the hole and cut a piece of gyprock or thin timber about 30mm wider than the hole all round, if you can access the top inside the roof space. If you cannot access the roof space to put the block over the hole, you will need to cut the block as a rectangle and push it up through the hole and then pull it back down. It is ideal to put a screw or nail in the middle of the block to be able to pull it back down before fixing the block with a few screws around the edges, this creates a block to patch up to. Plaster can be put on at different thicknesses, making it easier to get a level finish. There are a few methods to patching, but i find this the quickest and easiest.

Plaster ceiling hole for chimney flue with back block.

Once the hole is blocked, you are ready to mix up some plaster (the above photo has been blocked from the top, which is the best form of block because there are no gaps). You only require a small amount of plaster for this stage. I use a measuring jug of 250ml to add roughly 2-3 cups of plaster and then slowly add water, roughly 1 cup (a stiff mix will set quicker and stick better). Ensure the plaster is mixed thoroughly and wipe the ceiling with a damp cloth to allow good adhesion. Using a paint scraper, apply the plaster in small amounts all the way around the edges of the block, working into the ceiling edges and around the hole until the block is entirely covered in plaster. Drying time should be roughly 15 – 20 minutes depending on the consistency of the mix and the ambient temperature, in cold weather this may take longer. Clean your tools.

At this stage it is not important to get a nice finish, or to make the plaster flush with the ceiling as plaster is filled in stages. The first coat needs to set firmly before re-coating and should not come off on your fingers when touched. Once the ceiling is dry enough, mix another, smaller batch of plaster. You should only require a little amount because the bulk of the area is done and depending on the amount to fill, decide on the consistency of your mix. I will have this near finished on first go and so i would have a slightly runnier mix than before, but if the hole needs more than 2 mm you should make a thicker mix.

This coat is more important and will determine if you require more sanding when finished. The first coat should be lightly sanded around the edges and then wiped with a damp cloth before using your trowel to work the plaster over the hole. I find that an arcing motion works best for me. Fill the hole and any screw holes, chips or dents around the area. now this is where a plasterers trowel works best because they are bigger than about 350mm and therefore can reach either side of the hole and with one pass you should be able to level the hole (don’t worry if it has a few small drag marks, as you will fix this). Try not to spend too much time on this, as you will go over it two more times.

It is important to keep a bit of your plaster for the second coat to touch up any drag marks or low spots, but because the first coat is dryer it should be much easier. If the spare plaster is drying too quick give it a slight wet up with water. Check the first coat and see if it is going tacky, again this should not feel too wet when touched but still be tacky enough to accept another pass. Touch up the area and give the whole area another good going over as now the plaster will be starting to set. It is a good idea to scrape any excess off before it gets too hard and requires sanding. This coat should be near finished and will only require about 5 minutes wait before being able to finish. It you are happy with the finish now, clean your tools or else keep some plaster for the next coat.

When the plaster is fairly dry, give the trowel a wipe with a damp cloth and flick a little water on the plaster to be able to smooth it easier. You should only need to go over it a few times using a bit of pressure to get a nice finish and this will depend on trowel skill or experience. Trowelling is a skill, requiring a slight angle and varying amounts of pressure depending on the plasters softness. A 30 degree angle is ideal for smoothing and applying, whereas a 45 degree angle will strip plaster (everyone is different and will find what is comfortable for themselves.

Now that you have finished the patch, you should wait a few days for the plaster to cure before priming and painting.