Indy Total Construction

Finishing an Imperial ceiling with a coat of plaster is carried out in a similar manner to finishing off a drywall partition. However, when working above your head (which often presents difficulties of its own) it is best to apply small amounts of plaster at a time to avoid tiring your arms.

Deal with the joints first, spreading a thin layer of plaster down the center of each one and pressing lengths of 2in wide nylon mesh or paper tape into the wet plaster with your trowel. Lightly trowel over the tape then apply another thin layer of plaster on top.

Divide into handy bays; fill in each bay with a thin layer of plaster, but not over the joints. Hold the trowel blade at 30° to the surface of the ceiling; the back edge about 1/Gin clear of the board to provide an even layer. Reduce the blade angle as the plaster spreads and pinch the back edge in as you complete the stroke to stop the plaster falling off. Work away from you to avoid flicking plaster into your face.

When you have filled in all the bays, go over the entire ceiling with another thin layer of plaster. Rule it off with a long metal straightedge to remove the high patches and show up the low spots, which should be filled with a thin coat of plaster.

How you treat the angle between the ceiling and walls depends on whether you are replastering the walls at the same time or not. If not, simply run the corner of the trowel blade along the angle from the ceiling and wall sides to cut out the angle neatly. If you are replastering the wall as well, lay on the floating coat then tape the joint between the wall and ceiling before applying the finish coats. Finish the corner as normal.

Finally, polish the hardened plaster with a clean, wetted trowel blade.

If you intend papering or painting directly over the drywall, the joints must first be made to “disappear”. For this you will need drywall joint compound, paper jointing tape and joint finish (see below).

First spread a layer of compound down the seam and, with a taping knife, press the tape into it. Apply another layer of compound over the top, feathering the edges by going over them with a damp sponge.

When the compound has dried, apply a finishing layer, feathering its edges in the same way. Treat the nail head depressions with compound and finish in the same manner.

At the angles between wall and ceiling, fill large gaps with compound; then apply compound to both wall and ceiling and press a creased length of tape into it. Apply two more layers of compound to wall and ceiling, feathering the edges of each one.

As with all jobs of this type, making a new doorway requires careful planning. You should also check the requirements of your local building code.

A lintel must be chosen to match the type of wall being cut into and you must select a position for the door that, if possible, will not interfere with existing cable and pipe runs and which should be at least 18in from any corner.

It is possible to buy doors and ready-made frames in a range of standard sizes, and unless you are making the frame, it is best to buy the door and frame first, making the opening to fit it. Make sure its height leaves enough of the wall above the opening for fitting the lintel and the temporary wood supports.

With a masonry wall, you must provide temporary support for the wall above the opening and the load it carries while you cut out a slot for the lintel. If the wall supports the joists of the ceiling above, you must also make sure you support the ceiling on both sides of the wall as well.

Support the wall with 6ft lengths of 2 x 4in wood called “needles” — on top of adjustable metal props, which work like an automobile jack (you can rent these), spaced at 3ft intervals. With a normal sized doorway, you would need only one set centrally above the opening.

To support the ceiling, lengths of 4 x 12in wood are used across the tops of more props. None of the props should be more than 2ft from the wall, and if they are to stand on a wood floor, the feet should be placed on another length of 2 x 4in wood to spread the load.

Before marking out the doorway on the wall, use a bricklayer’s chisel and hammer to remove patches of plaster roughly where the edges and top of the opening will be. This will allow you to adjust fairly accurately the position of the opening to coincide with the mortar joints, in order to reduce the number of bricks you have to cut through.

Measure up the door frame, adding 2in to its width and lin to its height to allow for positioning. Using these dimensions, draw an outline of the opening on the wall. Then measure up the lintel — which should be at least l ft wider than the opening — and add a further 2in to its width for fitting. Draw the outline of the lintel on the wall above the door opening.

Finally, draw the outline of the wood needle centrally above the needle outline. Repeat the outlines on the other side of the wall.

Cut the hole for the needle with a hammer and bricklayer’s chisel. Slide the needle through so it protrudes equally on both sides of the wall and fit the props beneath it, tightening them to take the load. Both props must be adjusted simultaneously to ensure even support. Then fit the ceiling supports.