Workshop Phase 3.
Installation of a Plasterboard Ceiling.

Ceiling to be constructed first, using the plasterboard.

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I decided that the easiest way to attach the large sheets of plasterboard to the ceiling joists was to construct three temporary joists spanning the whole width of the workshop. This method (which thankfully worked very well!), temporarily supported the plasterboard sheets from underneath whilst they were screwed to the bottom surfaces of the (70mm higher) permanent joists. One temporary joist was constructed from a spare 300mm x 145mm x 45mm timber left over from the construction of the permanent joists. The two other temporary joists utilised 95mm x 70mm timber which was later used in the construction of the workshop stud wall partition. These temporary joists rested on (and were not screwed to) supports, one at each end of the joist, constructed from 70mm x 45mm offcuts left over from construction of the studwork wall lining. Each of the two supports (per temporary joist) were attached by two 90mm long 6mm diameter hexagonal headed coach screws (as used for attaching the wall studwork), fastened with plastic plugs to the brick walls between the studs. The photo shows the temporary joists in place with the first two constructed from 95mm x 70mm timber and the back one from 145mm x 45mm timber.

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After marking out the plasterboard using a pencil and straight edge, it can be fairly easily cut to size using a variety of methods. I found the easiest way was to use a jigsaw with small teeth (as specified for cutting plastic). This ensures that the paper-based backing is not cut jaggedly.

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The first sheet was cut to size and then hoisted into place fairly easily, I found that two people were easily able to manoeuvre the first sheet (white paper side down), through the 70mm gap above the first temporary joist. Care was needed to push and pull the sheet over the other two temporary joists without damaging the fragile paper covering.

Note how the front edge of the positioned plasterboard, is half way across the edge of the overlying permanent joist. Also the use of scrap pieces of wood which can be used between the temporary joists and the plasterboard to bring the boards closer for screwing to the overlying permanent joists.

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The next stage is to use a straight edge to rule pencil lines on the plasterboard corresponding to the overlying mid points of the joists. In the photograph, the overlying joist can be seen on the left, whilst on the right, the mid point has been extrapolated from the pencil line on a previously fixed plasterboard sheet.

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Using a scrap piece of wood 150mm long, as a template to mark off the positions of the drywall screws at 150mm intervals.

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Drilling 2.5mm pilot holes through the plasterboard and into the overlying joist to take the 3.5mm drywall screws. Once each hole is drilled, the drywall screw is placed in position, ready to drive home.

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Driving the drywall screws home. I preferred using a hand screwdriver, as using an electric driver, although faster, increases the risk of overtightening the screw so the head penetrates the paper covering into the underlying plaster of the board!

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Work in progress 1, showing how two sheets of plasterboard abut under a joist. Here the first sheet has been screwed into place on the joist.

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Work in progress 2, showing how two sheets of plasterboard abut under a joist. Here the second sheet has been screwed into place abutting the first one and sharing the same overlying joist.

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First two rows completed, only a narrow strip on the right to do!

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Last piece of plasterboard being fixed!

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Photograph showing all the plasterboards fixed in place and the temporary joists (used to support the boards whilst screwing them to the overlying permanent joists), removed. The Sketchup drawing of the ceiling is also shown for comparison.

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10Kg tub of ready-mixed jointing compound, fibreglass self-adhesive jointing tape, various application tools. The Hawke and Float are essential for minimising mess (The hawke is great for holding the plaster whilst using the other hand for holding the float which can easily scoop the plaster off the hawke and then the hawke is held underneath the area where the plaster is being applied and catches all the drips and spills!)

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The adhesive tape is applied along the joint between two adjacent plasterboards.

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Using the Float, jointing compound is pressed into the joint through the jointing tape. The photograph shows work in progress. Once cured, a second coat of jointing compound is applied and smoothed out over the first, prior to sanding when cured. The Jointing compound is also used to fill the depressions made in the plasterboard by the drywall screw-heads.

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Using a sanding block and 40 grit abrasive paper to sand smooth the jointing compound applied to the joints. If you really want a smooth finish, then follow up with 100 grit abrasive paper.

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Ceiling after sanding with 40 grit abrasive paper. I didn't use any finer abrasive grades for a smoother surface, but I would have done if decorating a room in the house where a smoother finish would be required!

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The ceiling was given two coats of white emulsion applied with a roller. Very quick to do and no brush needed.

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