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Dry Lining and Plastering Walls and Ceilings

The plasterers are in today so there will be quite a transformation over the next couple of days. In the new downstairs room, there’s a fair mixture of surfaces to deal with. The original room has a ceiling in reasonable condition that will just need skimming. Some of the walls aren’t in such good shape what with a new window opening cut in the side wall and the old chimney breast having been taken out, so these ones will be refaced with plaster board and skimmed out. Other walls aren’t too bad, and they can simply be sealed with PVA and skimmed. The walls in the new part are bare brickwork so these will have a couple of coats of sand and cement followed by two top coats. The ceiling in the new part will be boarded out and skimmed.

Dilute pva in bucket with roller Mixing the bonding plaster

The first job in the old part is to coat the old ceiling and the walls with a diluted PVA solution. This will even out the porosity of the different parts and ensure that the plaster will stick properly. The PVA is mixed up in a bucket and applied with a roller. This is a pretty quick job and once it’s dry the bonding plaster is mixed. This is done in a large bucket part filled with water. The dry plaster is poured into the water and mixed with a power mixer, which looks somewhat like a giant food mixer. Once the correct consistency is achieved, the bonding is emptied out onto the spot board.

Low areas being bonded Low area bonded out

The plasterers scoop up the bonding onto their hawks with a trowel and set to with evening out the low spots on the uneven walls. Although the walls are going to be dry lined with plasterboard a little later, the surfaces need to be reasonably flat and even beforehand. Bonding plaster contains vermiculite which makes it quite bulky but lightweight, so it can be applied in reasonably thick layers. In no time, the bare brick work where the chimney was taken out, and the other ‘low’ areas have been made up and the walls are all pretty even. The bonding is allowed to set up for a while.

Spots of plaster for fixing plasterboard Area dry lined with plasterboard

As noted earlier, some walls are to be dry lined and these are now faced with plasterboard. Spots of plaster are trowelled onto the wall at regular intervals and the sheets are simply ‘stuck’ to these. Each sheet is squeezed back onto the plaster spots to ensure that it’s fully secured and levelled. The plasterboard sheets are cut to suit as they go round the walls and it’s not long before these walls are lined.

Angle bead fixed to external corners Self adhesive joint tape]

Plasterboard angle beads are cut to length to suit each of the external angles and fixed with staples. Once these are all in place in this end of the room, the joints of the plasterboard are taped. A self adhesive tape is used nowadays for taping up the joints. It’s a lot easier and quicker than the old scrim that used to be used and had to be set in a bed of plaster.

Mixing finish plaster Finish plaster poured onto spot board

This end of the room is now ready for skimming. This will be done in two layers which results in a better finish than using just a single coat. The dry finish plaster is poured into a half full bucket of water and thoroughly mixed with the power mixer. The consistency for finish plaster is surprisingly thin. It’s a common mistake for DIYers to mix finish plaster way too thick and then struggle when trying to apply it to the wall. The plaster is poured out onto a clean spot board and the plasterers wet up their tools. Scooping up some plaster onto the hawk they’re ready to start. One plasterer starts work on the ceiling while the other starts on the walls. The plaster is loaded onto the trowel in a quick flip of wrist. That’s another classic for DIYers where they don’t coordinate this motion quite right and end up dropping the lot on the floor. The plaster is trowelled onto the surface in one long sweeping motion, laid off lightly by running the trowel back across the surface, and then smoothed once more in the original direction. The trowel is loaded again and the process repeated next to the first ’sweep’.

Appling finish plaster

It’s surprising how quickly the plasterers can do this. These guys are certainly very experienced and it’s not long before they have the ceiling and all the walls first coated. All the tools are thoroughly cleaned and rinsed off including the mixer and mixing bucket. As one of the plasterers explains, dirty tools or using dirty water can both cause problems. If you use water which has old plaster in it, this affects the new mix and will cause it to set up far too fast to be workable. If you use tools or a spot board which has bits of old plaster on, then these are going to get transferred to the new work and make a mess of the finish. The first coat is left to harden up a little before mixing up plaster for the second coat.

First area of room completed

The second coat is applied in much the same way as the first. However, once it has started to harden off, it gets polished up. Using a trowel which is kept damp by regularly brushing with water, the surface is re trowelled to remove any small tram lines and unevenness. This art of polishing up the surface makes that final difference and it’s soon apparent what a good job they’ve done as the walls and ceilings look great. This half of the room is finished and can be left to dry out.

Prop to support ceiling plasterboard Screw fixing ceiling plasterboard

The ceiling of the new part of the room now needs to be boarded out. The first sheet of plasterboard is lifted up and positioned against the ceiling joists. Although plasterboard is not particularly heavy, it can be a bit awkward. These guys have an extendible prop which, once the board has been aligned, is used to hold it in place while it is fixed. They use an auto feed power screwdriver to fix the boards. This has a ‘belt’ of screws which get automatically fed to driver allowing the work to be done very quickly and accurately. The head of the driver even has an auto alignment mechanism meaning the screws will all get driven straight.

Where cut boards are required, measurements are taken and marked out on a new board. The lines are scored with a knife, and the boards simply snapped back on themselves making a clean fast cut. Once all the boards have been fixed, the joints are taped up and the angle beads set with a power stapler. The ceiling in this part of the room is not straightforward. There are two recessed areas which go up to the underside of the sloping roof on the back and side elevations. There is also a sky light to be worked around as well as a boxed in steel beam.

Render mixed ready for application Applying render

Rendered and scratched wall Close up of scratched render

Sand and cement is mixed up for the walls and this is applied with a trowel. The method looks quite similar to plastering although each sweep of render is somewhat shorter than with finish coat plaster. Working across the walls, each sweep of render abuts the previous one and the surface smoothed as they go. The wall is gradually covered and the surface left flat and smooth although, as you’d expect, with quite a gritty finish. It is then scratched up using special tool something like a long toothed comb with widely spaced teeth. This is drawn over the surface in a wavy horizontal pattern then the wall is allowed to dry and harden up for a while. Scratching up the surface like this provides a mechanical key between the layers ensuring that they bond fully with one another. A second coat of sand and cement is then applied in much the same manner as before and lightly scratched up with a random pattern before being allowed to dry off overnight.

Applying finish over render Close up applying finish to render

Applying finish coat to plasterboard ceiling Applying finish coat to plasterboard ceiling

All that’s left to do the following day is to apply two coats of finish plaster to all the surfaces in the new part of the room. Finish plaster is mixed up to a creamy consistency with the power mixer before being poured out onto the freshly cleaned and wetted spot board. The plasterers wet up their hawks and trowels and scoop up the first load of plaster ready to start. One guy sets to on the ceiling and the other starts the walls. As before, plaster is applied in long sweeping motions, laid off and finally smoothed before loading the trowel and applying another sweep. The walls and ceilings are covered very quickly and left flat and smooth. The detail around the raised ceiling areas, boxed in beam, and skylight are quite awkward and comprise several small areas, which obviously slows things down a bit.

Finished walls Finished ceiling

Once the first coat has set up, the second finish coat of plaster is applied and when this has begun to harden, it is polished up with a dampened trowel to give a top quality smooth finish to the walls and ceilings. It’s been fascinating to watch the plastering being done. It’s one of those very watchable trades where they make it look so easy …. If only !

If you live in the Hertfordshire area and are looking for a professional building contractor, you can get in touch with G L Smith and Sons via their website: http://www.glsmithandsons.co.uk/

G L Smith and Sons