REPAIRING TIMBER STAIRCASES

Faults in a staircase can spoil its appearance or provide a nuisance; some may be serious and endanger the safety of stair users. Whatever the problem, it is worth correcting it at the earliest possible stage to save yourself the expense of more costly repair work later. Problems which can arise in timber staircases will often be the same with both closed and open-riser staircases and frequently repairs can be carried out using the same method for both types of stair.

Identifying problems

Creaking treads, which are a common problem with timber staircases, are caused by the joints opening to allow the parts to move against each other. This is brought about by shrinkage of the timber, due to poor seasoning, or perhaps drying out because central heating has been installed. To stop the creaking, the affected treads should be prevented from moving against adjoining parts. Another problem involves treads and risers which work loose. They are fairly easy to repair if the staircase has cut strings or, in the case of close strings, if the underside is accessible; if it is not accessible, you can still attempt repairs, but you will have to strip off the underside covering and make good afterwards.

Nosings may become worn or damaged, but these are quite straightforward to repair. Where treads have worn they can be resurfaced with plywood – if they are to be covered with carpet. Very badly worn treads, or ones affected by woodworm or rot, will need replacing. Again this is a DIY job. unless there is a carriage beneath the treads.

Loose balusters are another fairly common problem and are quite easy to repair. Handrail repairs, however, can be awkward. It is easy to rcsecurc wall-mounted handrails, if they work loose, or to replace them if this is necessary; but handrails fixed between newels are very difficult to replace because of their mortised and tenoned construction. One method you can use is to remove a handrail by sawing through the tenon and fit a new one by gluing it to the newel and securing it with hardwood dowels.

If a newel has worked loose, you may be able to secure it by lifting the adjacent floorboards and tightening the bolts which fix it to the joists.

Strings rarely give trouble, although a wall string may pull away from the wall and create a gap. In other cases the string may be securely fixed to the wall, but the staircase can move slightly away from the wall string and loosen the treads and risers. You can deal with both these problems yourself; but if the staircase is really rickety it may be best to consider installing a new one.

WARNING

When you are planning to carry out major structural alterations to a staircase, for safety reasons it is best to consult your local building inspector before you begin work to check the alterations comply with Building Regulations.

STOPPING TREADS CREAKING

In closed-riser staircases creaking treads are caused by movement between treads and risers. Often the most simple solution is to drive No 10 screws through the top surface of the tread, just behind the nosing, into the top edge of the riser below. If possible, before fixing the screws prise the tread and riser apart and inject some PVA woodworking adhesive into the gap. Countersink the heads of the screws and fill the depressions with wood filler before replacing the carpet; use matching filler if the stairs are to be left exposed.

If the underside of the staircase is accessible, a neater repair can be made using wood blocks. To make the blocks, saw diagonally through a length of 50mm square timber to form triangular pieces and then cut these into blocks about 75mm long. Alternatively you can make blocks from triangular section timber sold for fencing arris rails. Fix two or three blocks under the creaking tread where it joins the riser below it. Two blocks should be inset about 150mm from the strings on each side and a third block fixed in the centre, if two blocks are not sufficient to cure the creak.

The blocks will tend to split if fixed with nails; drill holes and secure them with two No 10 screws – one into the underside of the tread and the other into the back of the riser. Before fixing the blocks, coat the back of each with PVA woodworking adhesive to reinforce the joint. Treads and risers can otherwise be held firm with metal shelf brackets which you screw in place under the stairs.

In open-riser staircases where treads are fixed into housings or recesses in the strings, creaking may occur because the treads move in their housings. To stop this movement, the treads should be wedged or screwed tightly in place. Since screws should be fixed through the string horizontally into the tread, preventing movement in this way is only possible on the outside string of A conventional staircase – because the inside string will be fixed flush against a wall, preventing access. You can stop treads moving in the housings in the inside strings by inserting wedges. Cut the wedges from hardwood or softwood timber roughly to the shape of the cavity or area in which movement is taking place. Apply woodworking adhesive to the wedges and hammer them tightly into all visible gaps to ensure a permanent fit; allow 24 hours for the adhesive to set before walking on the treads.

CHECKING FOR WOODWORM

When carrying out repair work on staircases, or when moving stair carpet, look out for woodworm holes in the timber. Where woodworm is active, you will see fresh holes with small piles of loose dust beneath them and light-coloured timber on the inside of the holes. You should treat woodworm as described earlier in the Course. If treads are seriously affected by woodworm, they should be replaced; if the attack is really severe, you may have to replace the entire staircase.

SECURING LOOSE TREADS AND RISERS

Treads and risers fixed to cut strings rarely come loose; but if they do, they can be refixed from below by screwing triangular wood blocks beneath the sides of the treads and risers and the cut string. Loose treads in open-riser staircases can be fixed in the same way. If the underside of the staircase is inaccessible, the treads and risers can be screwed down again to the string from above. Countersink the screwheads so they can be filled with wood filler or a wood plug, which you should glue in place and plane Hush with the surface when the adhesive is dry.

It is more likely that treads and risers will come loose with close strings because the wedges which secure them have worked loose and the glued joints have broken. Working from the underside of the staircase, lever out the loose wedges and coat them with PVA adhesive. Reposition the wedge behind the riser, using a mallet or hammer and scrap of wood to drive it into the groove. If the wedge is worn and will not tighten in the groove, replace it with a new wedge cut to shape from 25mm thick softwood. If the wedge protrudes below the bottom edge of the riser, cut it off with a saw so a second wedge can be driven into the horizontal groove below the tread. Secure the tread by inserting two No 10 screws vertically up through the tread into the edge of the riser about 150mm from each side of the tread. The tread can be further secured by screwing triangular wood blocks beneath it where it joins the strings.

WALL STRING MOVEMENT The treads may have come loose because the wall string has settled away from the outer string. If the wall to which the string is fixed is sturdy, it may be possible to drive timber wedges between the string and the wall to force the string, treads and risers back into place. This is a difficult job; if the string will not move, check with a professional who will be able to advise you if it is better to fit new wider treads and risers to bridge the gap between the strings or whether a new staircase is required.

You can try to force the various components together, but you will first have to chip.off the plaster above the string in the afiected area. With a crowbar or other strong lever, case the string away from the wall and drive 250mm long timber wedges coated with PVA adhesive into the gap between the string and the wall. Use as many-wedges as necessary to hold the siring against the steps and drive oval nails through the string into each wedge to make sure they are held firmly. Saw off the top of the wedges flush with the top of the string and replaster the affected area.

RESURFACING WORN TREADS

IF a tread is worn, the nosing will also be worn. Chisel or saw off the nosing flush with the riser and make the tread as flat as possible; you may be able to chisel or plane away the high spots to the level of the hollow, but do not remove more than 6mm of wood. Alternatively fill the hollows with a strong wood filler. Cover the tread with 6mm plywood, glued in place and fixed with panel pins. Replace the nosing as described below.

REPAIRING WORN AND DAMAGED NOSINGS

If the damage extends well beyond the nosings, it is best to replace the entire tread. Replacing just the nosing, if the damage is restricted to this area, is quite an easy job. If there is a moulding beneath the nosing, prise this oil’ and then saw or chisel oil’ the nosing flush with the riser. Cut a new nosing from 38 x 25mm planed softwood; plane the wood to the shape of the other nosings and, if it is to be fixed to a cut string, mitre its end so it fits against the planted nosing at the side. Use PVA adhesive and nails to fix the nosing in place: when the adhesive has set, if necessary plane the top edge of the nosing flush with the tread. If there was a moulding fitted under the tread, glue and pin this back in place.

REPLACING TREADS AND RISERS

This job can be tackled from above or below the stairs, depending on the staircase construction. When there is a cut string on one or both sides of the staircase, the treads can be replaced from above: with close strings they must be replaced from below. Where a carriage is fitted beneath the stairs, you should leave repair work to a professional since access is difficult.

CUT STRINGS Use a chisel or screwdriver to prise off the planted nosings so the balusters can be tapped out of their dovetail housings in the tread. At the top. prise out any filler pieces fitted beneath the handrail and tap the balusters towards the head of the stairs. Prise away any mouldings under the tread nosings. Use a lever to prise up the nose of the tread on the side of the cut string: this should open up the joints, revealing securing nails or screws – which you may be able lo remove with a claw hammer or pliers. If this is impossible, use a hacksaw to cut through the fixings. The riser may be tongued into the tread, in which case you may have to cut through the tongue with a pad saw before the tread can be replaced.

In most cases the material required for the new treads will be ordinary softwood; but it is worth telling your timber supplier what you require the wood for. Choose a piece without knots and well seasoned so it is unlikely to warp later. For a closed-riser staircase, if the old tread is not made from standard softwood, take it to your timber supplier to make sure you buy a good match; the same applies for open-riser staircases. The timber must be cut with the grain running in the direction of the length of the treads so the grain runs between the strings. Measure between the strings, adding on extra for the housing joints, and use the old treads and risers as patterns for cutting the new pieces to size and making grooves where necessary.

You will probably have to mitre the edges of the risers where they fit against the cut strings. Glue and nail the risers and treads in position, working from the bottom to the top of the stairs. If they are a loose fit in the grooves in the wall string, fit glued wedges to hold them firmly.

Because it is impossible to fit a wedge under the last tread to be fitted, use an offcut from the old tread as a filler piece and fit it accurately into the wall string groove before the tread is fitted. Tap the tread into place and secure it with nails before replacing the balusters and fitting the planted nosing to the edge of the tread.

CLOSE STRINGS Prise OUT THE glued wedges from beneath the staircase and also remove the triangular reinforcing blocks. If the treads are screwed to the risers, remove the screws and also any moulding from the nose of the treads. Depending on how the treads and risers are assembled, a tread or a riser should now be free to slide out of its groove. Use a large hammer to help tap it out. placing a block of wood against the tread or riser to protect it against the force of the hammer. If the tread or riser refuses to move, use a pad saw to cut off any tongues holding the risers at the top and bottom. After removing the old treads and risers, cut the new ones to fit between the grooves and fix them with adhesive and wedges – as for securing loose maximum gap. It can, however. make the stairs darker, unless a toughened glass is used for the panelling.

The simplest way to do this job is to use hard-board. plywood or wallboards glued and pinned to each side of the balusters. Use half-round mouldings to cover the joints between the adjacent boards and narrow quadrant or scotia mouldings to give a neat finish round the edges. Other ways of modifying a balustrade include fitting toughened safety glass or wired glass into framing pieces. You can fit wrought iron balusters, or glue and dowel rails between the newels parallel with the strings and handrail. Remember Building Regulations also apply to the gaps in wrought iron panels and between rails.

SECURING LOOSE WALL HANDRAILS

Wall handrails are usually fixed with special brackets screwed lo the wall. If a bracket comes loose, you should fit longer and stouter plugs and screws or pack the holes with a fibre plugging compound to make a secure fixing.

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