How to repair and maintain floorboards

Floorboard repairs are straightforward and require few special tools. But repairs are essential for safety and for preserving the good condition of the joists beneath, and the floor covering above the boards.

Although solid and hardwearing, floorboard timbers are prone to all sorts of minor faults and irritations. For instance, creaks under the carpet are annoying but not dangerous; rotten boards which Collapse underfoot can be dangerous as well as annoying. Even if your floorboarding is in perfect condition, it may still need work to improve draughtproofing—or to get to wiring underneath.

Types of floorboard

Most floorboards are made of softwood, usually pine. In a single-skin floor as used in Britain, the boards are fixed at right-angles to the joists which support them, and may be nailed or screwed in place. The board ends are arranged to coincide with the joists, so that the join lies over the centre of the joist, for maximum support. In a double-skin floor as used in North America, the sub-floor is usually of plywood or wafer board, but the main floorboards are still at right angles to the joists.

Floorboards fall into two basic types: square-edged, and tongue-and-grooved. Tongued-and-grooved boards and their derivatives are designed to eliminate draughty gaps but are more difficult to take up than their square-edged counterparts.

If you are in any doubt which of the two types is used for your flooring, choose two boards with a slight gap between them and slide a knife blade in as far as possible—compacted grime or draughtproofing in the gap may have to be scratched out first. If the blade is stopped, the boards are either tongued or rebated.

Lifting square-edged boards

For your starting point, choose the most convenient free end of the board you wish to lift. If the board extends right across the room and under the skirting on both sides, you have to start lifting it in the middle and work gradually towards the ends. When all the nails are loose, you spring the board free by pulling it upwards into a bow shape.

To lift the board, insert a bolster into the joint gap between it and the board on one side, in line with the nails at the free end. Use a club hammer to drive it home. Then stamp on the bolster to push it down towards the floor. Do the same on the other side of the board.

As the board is levered up, insert the claw of a hammer under the end and continue levering up from here until the board comes completely free of the joist.

To help lift the rest of the board, insert a metal bar, length of stout timber or piping underneath the free end. Use the bolster and hammer to loosen the board at each line of nails, then lever it clear with the metal bar. For safety, immediately remove any exposed nails—particularly those left upright in the joists. A crowbar is much easier than a claw hammer for this job.

If a board proves particularly stub- born, try to free one end and insert a metal bar under it. Using the bar as a levering support, stamp on the free end. After each stamp there should be some ‘give’, so move the support along the board towards the next joist until the nails give way here.

Lifting T&G board

Start by choosing a suitable free end and section of board, well clear of the skirting. To break the tongue, insert a bolster into the join between two adjacent boards at the end of the board you wish to lift. Give the bolster a few sharp taps with a hammer, until you feel or hear the tongue below start to split. Continue until the split extends at least 75mm from the nails, or until you otherwise judge it to be clear of the joist. You can then replace the bolster with a saw, knowing that its blade will escape damage from floorboard nails.

You can use almost any type of saw but a compromise between the awkward length of a panel saw and the short length of usable blade on a tenon saw is a purpose-made flooring saw.

If a power saw is used, set the sawing blade depth to about the thickness of the board to avoid any damage to the sub-floor , or to pipes or wires suspended below the flooring.

Continue cutting between the two boards until you are about 75mm from the next line of nails, and once again use the bolster to break the tongue along the stretch over the joists.

When the tongue is fully severed, use the bolster, claw hammer and metal bar to lever up the board as you would do to lift a square-edged one. In this case, though, concentrate your levering activities at the end and along the severed side of the board at each joist. You should be able to lift the nails and tilt the board enough for the interlocked side to slide free of the adjacent board.

Well – fitted tongued – and – grooved boards may be so tightly cramped together that splitting them apart with a bolster and hammer may not be possible without causing extensive damage to both boards. In this case, the board you wish to remove must be split lengthways at the middle. A power saw is best for this job.

Cutting across floorboards

In a single-skin floor of the sort used in Britain, it is best to cut across a floorboard either over a joist or to the side of one, so that support for the new board ends is readily available. Cutting over a joist is a little more difficult than cutting beside one, but enables you to nail the cut section straight back in place. A double-skin floor can be cut anywhere, but try to avoid having two cut ends side-by-side on the floor.

Cutting on a joist: It is important to make the cut along the centre of the joist, otherwise one or other of the two freshly-made board ends is not going to be supported properly.

The centre line of the joist can be pin-pointed by following on the line of nails of adjacent boards and board ends. Use a try square to pencil a cutting mark on a line joining the farthest possible reference points on each side of the board you are cutting. You can do this by eye or, better, by stretching a piece of string over the distance between the two points. If you are cutting alongside a board with a clearly indicated joist, just continue the line of the board end when marking the cutting line. If the nails are staggered, take a common centre-line from as many boards as possible.

To make the cut, you can leave the board in place and use a padsaw, compass saw or power jig saw. But if the board is long enough, it is easier to lift it up into a ‘hump’ and cut with a tenon saw or flooring saw. To do this, you lever the board upwards with the bolster and then support it with two offcuts of timber wedged beneath it. Cutting beside a joist: First locate the side of the joist. You may be able to do this by inserting a knife or metal rule into the gap between the floorboards, sliding it along until it hits the joist. Mark the board at this point, and use a try square to complete the cutting line. Alternatively, and if there is a gap between the floorboards on the other side, repeat probing and simply join up the two points marked on the board.

Drill an 8mm hole up against and at one end of the cutting line then use a padsaw or power jig saw to cut next to, and along, the cutting line. The padsaw can be replaced with a handsaw or circular-blade power saw when convenient, and re-used if necessary at the end of the cut.

Fitting an extra bearer

If you have removed a section of floorboard by cutting along the side of a joist, you must fit an extra bit of timber to the joist, in order to provide support for the new board end.

Make this bearer from an offcut of softwood, whose minimum dimensions ought to be no less than 38mm by 50mm. Cut it to length, slightly longer than the width of floorboarding removed and use either nails or screws for fixing it in place. If you choose nails, use two or three about 75mm long for each floorboard width, and hammer these partially into the broader side before positioning the bearer. If you use screws, two for each board width are enough, but drill pilot holes before fitting them.

Position the bearer against the joist and make sure that the top edges of both pieces of timber are exactly flush. Pull the bearer upwards, tightly against the floorboards on either side, while you hammer or screw it securely in place.

Replacing square-edged boards

There are few problems in replacing square-edged boards. New ones of the same thickness are cut to length and— in the case of non-standard sizes—to width. If part of the board has to be tapered or otherwise shaped to fit, use the discarded board as a template when you saw to shape the new one.

If a single board is to be replaced simply slot it into place and nail down. A number of boards covering a large area are best fitted individually—if possible in the same flooring ‘pattern’ as originally. No two board ends should lie side by side on the same joist.

When fitting a number of boards, do a ‘dry run’ first to check the width fit, and whether tight butting of the boards is possible. Where the boards are to remain visible, keep to the original spacings for the sake of appearance.

If a complete floor area is being replaced, make a point of butting all boards as tightly as possible before fixing. This is done with a floor cramp —available frtjm hire shops—and substantially improves underfloor draught-proofing.

If part of the original floorboarding is to be replaced, cut off any wood which is badly split where nails were removed. Do not re-use old nail holes. These, and new holes along the length of the board, should be made good with a filler paste.

Replacing T&G boards

Replacing tongued-and-grooved boards is not quite so straightforward. If you are re-using the old board, this can be replaced by fitting the remaining tongued or grooved side into the adjacent board. A small gap will remain on the other side—this must be plugged for complete draught-proofing. To fit a new tongued and grooved board, you may have to plane off its tongue to get it to fit, but leave its grooved side intact.

If a number of adjacent boards have been removed, any necessary combination of used and new boards may be used when reflooring. The technique is to loosely fit these together over the floor area to be covered, in the process forming a low arch by making the boards slightly over-sized. Lay a spare plank over this, and press or stamp the boards down: the tongues and grooves knit together in the process. The flattened boards can then be fixed in place. Alternatively, you can use an off-cut and mallet.

Replacing short sections

If you are cutting out and replacing a short section of floorboard you may want to use up a spare piece of timber lying about the house. Alternatively, you may have difficulty getting a re- placement board which exactly matches the thickness of your existing ones. Either way, the new board will be better too thick than too thin.

Having cut your new section to length, lay it beside the gap in the floor and mark off on the underside where it is to pass over a joist. Chisel out rough rebates between the marks, to the same depth as the board is oversize.

When you lay the board, the rebates should fit over the joists and allow it to rest flush with the others.

Dealing with creaking boards

Loose and creaking floorboards may be caused by incorrect nailing, by the joists below them settling, or by warping and shrinkage. It is usually possible to cure a loose board simply by re-nailing or screwing it back in place.

But before you do this, check that the loose joint coincides with the centre of the joist below, taking the board up if necessary. If it does not, widen the joist with a new bearer , or replace the whole board.

To nail floorboards, use 50mm lost-head nails or flooring nails. Position them next to, and about 12mm away from, the existing nails. When you have finished, drive all the nail heads well below the surface of the board with a nail punch.

To secure floorboards with screws, use 40mm countersunk steel screws. Drill pilot holes for them 12mm from each existing nail, taking care that the holes go no deeper than the thickness of the board. When all the screws are in place, make sure that none of them protrudes above the surface.

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