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How to Plaster a Large Ceiling: Step-By-Step Guide Using Extratime Plaster Retarder

Why let plaster setting times stress you out on large project? Plastering a large ceiling on your own might seem like an impossible task, but with the right guide, and the right tools it should be a doddle.

Ready to master very large ceilings? Let's dive into the process and make your ceiling look great. With patience, technique, and the right tools you'll achieve a smooth, flawless finish every time.

This step-by-step guide will walk you through plastering a large ceiling using Extratime Plaster Retarder.


1. Prepare Your Tools and Materials

Before starting, gather all the necessary plastering tools and materials.

You'll need a handboard/hawk a good quality plastering trowel (Marshall Town or similar), scrim tape, a mixing bucket, a whisk, a trowel/scoop, and hop ups and planks to walk on.  Ensure you have access to fresh, clean water and have enough plaster to do the full job (not having enough to complete the job will cause all sort of problems).  For a stress free experience, make sure you also have a sachet or two of Extratime Plaster Retarder (found here).

Ensure you also have safety gear such as safety glasses/goggles to stop any plaster getting in your eyes, and a dust mask to protect your airways when mixing. 

With all your materials at hand, you can start the plastering job confidently.

TOP TIP: Check the best before date of the plaster before use and make sure it is in date. Using out of date plaster can cause setting problems.


2. Prepare the Ceiling

Preparation is a key element in plastering, and more so when attempting large areas. 

Before starting, make sure you remove any furniture or obstacles that might get in your way and make sure you sheet up and protect all floors and skirting boards.

Make sure the area you are plastering us prepared correctly, any dust, dirt or debris is removed and all plaster board joints are covered with Scrim tape(Eazyscrim). Ensure all big gaps are filled in and if the ceiling is not plaster board make sure to apply two coats of  PVA/SBR.  Try and apply PVA around an hour before you start the job.  Have all your water and buckets ready to go for your second mix 11.5 litre of water per 25kg of plaster (see manufacturer’s instructions).

These preparation steps ensure the plaster adheres properly and the suction of the substrate is controlled to provide an even, smooth, uniform surface.


3. Mix the Plaster

Always use fresh clean drinking water to mix with. 

For a very large ceiling Extratime Plaster Retarder can be added to the water to increase the working time by an hour.  Extratime can be used in both the first coat and also in the second coat (if required) for maximum effect.

Add the Extratime sachet into your water (1 sachet of Extratime for 1 x 25Kg bag of plaster) and whisk into the water to fully dissolve. Start to add your plaster as you whisk and make sure the plaster is the required consistency, not too stiff or too loose.

The retarder will improve the mix as well as giving you extra time to work. This makes the process less stressful, allowing you to take your time to get everything on stressfree.


Once done, clean all tools.


4. Apply the First Coat

Start to apply the first coat of plaster to the ceiling methodically from one end to the other applying around 2-3mm of plaster filling in any gaps where necessary.


5. Flatten the First Coat

Once the first coat has been applied start back at the beginning and flatten off the plaster filling any areas that are hollow and any big gaps that are apparent.


6. Make a Second Mix of Plaster

Make a new plaster mix around 2/3 of the first mix should be enough for the second coat. If it’s a large area and you need even more time add another satchet of Extratime to the gauging water before adding the plaster.

Start at the beginning and apply another coat in the same way as the first covering all areas. Take your time to ensure its smooth and uniform across the whole area.


7. Trowelling Up

 Once the plaster starts to pick up/set give it all a trowel over making sure it is flat and smooth. Repeat this process as the plaster becomes fully set. The Extratime should allow plenty of time to patiently create a smooth flawless finish.

8. Final Trowel

Once the plaster has become unworkable give it a final trowel using a bit of water and let it dry completely.

The drying process might take a few days, depending on the humidity, temperature and substrate that has been plastered. It is essential not to rush this process to prevent issues with the final finish.


9. Clean Up

Finally clean up the tools and working areas ready for the next job. All floors skirting boards etc. must be cleaned off once finished.

Using Extratime
Extratime slowing the setting time on a large ceiling


Additional Ceiling Plastering Tips


As in step 1 preparation is key to plastering. Being one step ahead saves time and stress. If you are new to plastering large areas it is recommended that you build up gradually with the total area you plaster in one hit.

If the plaster starts to dry too quickly while you're working, you can lightly mist the surface with water to keep it workable for a bit longer. This technique helps, especially if you're plastering a larger ceiling and need extra time to smooth everything out.

In some cases, you might find that the plaster isn't adhering well to the ceiling. This is often due to inadequate surface preparation. Ensuring the ceiling is clean, dry, and free of dust or loose materials is crucial for good adhesion.

Additionally, using PVA/SBR can improve the plaster's grip on the ceiling if you are not plastering onto plaster boards.


Mastering How to Plaster a Large Ceiling

Plastering a large ceiling might seem daunting. But with this guide you can achieve professional results stress-free. 

So are you ready to transform your ceiling with ease? Try Extratime Plaster Retarder, which extends plaster setting times by up to 60 minutes, making it perfect for plastering larger areas. It can be used with all finishing plasters; simply add one sachet for every 25 kg of plaster and achieve professional results every time.

Extratime Plaster Retarder is available from Wickes, Travis Perkins, Selco, B&Q, Huws Gray, JT Atkinson, JT Dove, MKM, and online through TW Wholesale and Plasterers 1Stop Shop.

Browse our range of plaster additives and scrim here or contact us today for more information.



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