From DIYinfo.org
Where space limitations are such that a hinged door cannot reasonably operate, sliding doors are used. They are easy to install and generally work quite well. However, being mounted on the wall surface, they are difficult to insulate and can be the cause of irritating draughts.
An alternative to the surface mounted sliding door is known as a cavity or slide in door. It consists of a housing frame and a number of fittings with which it is assembled. Any standard door will fit into it.
To install the housing frame, a section of the original wall must be removed. The area removed must allow for the width of the door when closed and the space the housing frame will occupy within the wall itself. The area will double if double slide in doors are to be installed.
Ensure that the new header beam is sufficiently strong to bear the weight. As the housing frame cannot be altered, be sure that all adjustments to the existing walls and the header beam are made before attempting to fit the frame. Once the frame has been fitted the wall lining is replaced.
You will need
Tools
Steel measuring tape; spirit level with horizontal and vertical vials; pencil; adjustment square; screwdriver; adjustable spanner; hammer; nail punch. Possibly also wood saw; hacksaw; wood chisel.
Materials
Cavity door kit; 50mm and 75mm bullet head nails; 45mm raised head screws; hardboard packing pieces; 15mm flat head nails.
Method
1 Door widths vary so it is essential to check that the wall opening is the correct width. Check the height to the underside of the header beam.
2 Check that the wall is vertical and that the header is horizontal. Cut and fix packing pieces to compensate for any deviation from the true levels.
3 For a single door opening, fit the door track to the housing frame. To do this, align the dowels at the end of the track with the holes in the metal bracket and snap the track into place. ALTERNATIVELY, for double doors, cut equal amounts from the door heads and tracks so that the tracks form one continuous length.
4 If the track is a very tight fit, use a block of wood to protect the end of the track and tap it firmly into place.
5 Place the housing frame in the opening. For single doors, it can go the wrong way around. Make sure the opening is where you intend it to be. Use your spirit level to position the housing frame vertically, then fix it, about 100mm from the top, with a 75mm bullet head nail. Do not drive the nail right in, you might have to adjust the frame.
6 Line up the door head with the header beam. Fix through the pre-drilled hole in the track and door head timber into the header beam with a 45mm raised head screw.
7 Go back to the upright which is temporarily fixed in place. If one edge of the housing frame has pulled away from the house wall, use packers to fill the gap. Re-check for vertical and adjust if necessary. Then fix the housing frame firmly into place using three more 75mm bullet head nails spaced at equal intervals.
8 Re-check the door head. Loosen and adjust the screw if necessary. Then fix the head firmly in place with another 45mm screw.
9 Use two or three 50mm bullet head nails to fix the base plate to the floor.
10 Punch all nail heads below the surface. Test the housing frame for stability by shaking it (not too hard) back and forth. If necessary, add a few more nails.
Fitting The Door
If you are buying a secondhand door, check that the top rail, by which the door hangs, is in good condition.
You might prefer to do most of the painting or staining before the door is fitted. When sliding doors are in place it is often difficult to keep them steady when painting. However, if you have already put on the finish coat, there is always a risk that you might damage the surface when attaching the fittings.
1 Plastic strips are supplied with the cavity door kit to make the door slide more easily. Cut the strips to suit the width of your door and nail them to the bottom of the door with 15mm flat head nails.
2 On the top rail of the door, measure 95mm in from each edge. ALTERNATIVELY use one of the sliders as a gauge. Align the edge of the slider with the edge of the door and mark off. Position the outside end of a slider on the line and trace the position of the fixing slots.
3 Fix the slider retaining screws in a line which is approximately the middle of the door thickness. Leave the screw heads about 5mm above the door rail. The door can now be hung.
4 Place the sliders in the door track. Position the door so that the slots in the sliders pass under the heads of the retaining screws. Place packing pieces under the door to keep it steady.
5 Tighten the hexagonal head screws with a spanner. Remove the packing pieces and test the door for fit.
6 If the door binds inside the frame, you will see where the problem is. Slacken the slider retaining screws a little and twist the door into line. The walls can now be finished. Perhaps leave the final coat of paint until you are painting the rest of the woodwork around the door.
7 The housing frame is designed for lining in the same way as regular timber framing. However, care must be taken not to drive nails into the void between the uprights or the door will not operate.
Any of the standard lining materials can be used.
8 When the lining is done, trim around the frame with architraves or cover strips, depending on the lining material. Punch in all nail heads and fill the holes.
