Indy Total Construction

Staircases are often taken for granted yet they are complex pieces of carpentry which give many years of trouble-free use. They rarely need replacing: just as well, since they are often tailor-made to fit. Even so you can buy ready made versions, which cater for common storey heights and these can often be easily adapted to fit exactly.

A staircase comprises a number of steps fixed between two long boards which are fixed to the joists of the floors they connect. These boards are called strings, the horizontal surfaces of the steps are called treads and sometimes they have vertical boards between them known as risers.

Strings can be in two forms: closed and cut. With the former the ends of the treads and risers are housed in shallow slots cut in the face of the string and held there by wedges driven in from behind and below. The risers are fixed to the treads below with housing joints or screws, and to the treads above by triangular blocks glued and nailed in place. The top edge of a cut string is shaped to provide horizontal ledges to which the treads are fixed. Sometimes both foul’s of string will be used in the same staircase, the closed string being fixed against a wall with the cut string on the outside.

Further support for the steps can be provided by a beam that runs below the treads and risers parallel to the strings. This is known as a carriage.

There are two basic types of staircase: the closed tread and open tread. Of the two, the former is most common, having treads and risers in a boxed-in construction. The underside of the strings are usually clad with lath and plaster or gypsum board or there may be a closet below the stairs. The latter is preferable since it allows easy inspection and repair. The open tread staircase has no risers and is completely exposed.

In a closed tread staircase the treads are about lin thick and will overhang the risers by a similar amount, their leading edges or noses being rounded off. A decorative molding is often fitted below the nose. An open tread staircase will tend to have thicker treads because they are not supported by risers, although sometimes a batten will be set on edge immediately below them to stiffen the tread.

All staircases must have at least one handrail and if wide they must have one on each side, depending on the requirements of your local code. The handrail forms part of the balustrade, the other parts of which are the newel posts and balusters.

The newel posts fit at each end of the stairs with the handrail running between them. Not only do they support the handrail but often the strings as well which will be slotted into them and fixed with wooden dowels. Further support for the handrail is provided by the balusters which fit between it and the strings.

Though straight staircases are common, where space is limited it is often necessary for the stairs to change direction on the way up. A small quarter landing is used to provide a 90° change of direction and a half landing will turn the stairs back on themselves.

If there is not room for a half or quarter landing a turn can be put into the stairs by inserting triangular treads called winders. Winders are also used in spiral staircases which can be great space savers. Unfortunately they are not very practical since carrying furniture and other bulky items up them is difficult.

Actual physical damage to stair treads is rare and will probably be limited purely to split or broken nosings. These can be repaired by cutting them off flush with the riser below, using a chisel, and pinning on a new molding.

A much more common problem, particularly in older houses, is creaking as a result of the treads becoming loose. The ease with which this can be fixed depends very much on whether you can get to the underside of the stairs or not. If you can, simply pin and glue 2 x 2in triangular blocks of wood between the treads and risers below, and drive screws up through the tread into the riser above. This is the only way you can fix a staircase with closed strings.

If the staircase has one or two cut strings, you can make the repair from above. First prise off the molding from below the tread nose and the molding holding the foot of the baluster in place, using an old chisel. Run a hacksaw blade along the gap between the back of the tread and upper riser. cutting through any fixings. Alternatively, cut through the riser itself with a backsaw. Drive a chisel blade between the tread nose and riser and lever it free. Then you can remove the risers if damaged.

If necessary. cut a new tread and riser from wood of the same size as the originals.

If one of the strings is closed, glue and pin supporting blocks to it for the ends of the riser and tread. Use offcuts of the tread and riser wood as positioning guides to ensure a tight fit. Then glue and pin the riser in place.

Pin and glue more blocks to the top of the lower riser and then glue the tread on top, strengthening the bond by driving screws or nails down through the ends into the cut string or strings. Do not drive any screws or nails through the leading edge of the tread as they may become exposed as the tread wears.

Refit the baluster, pinning it to the handrail and then pin the retaining molding to the end of the tread. Finally, refit the molding beneath the tread nose.

If you can reach the underside of a closed string staircase, you can replace treads or risers by removing their retaining wedges with a chisel and sliding the damaged parts out. Slot the new pieces in and fit new wedges. If a carriage runs down the centre of the stairs, however, the work is best left to a joiner or builder.