There is something quietly satisfying about an old floorboard. It has seen decades of boots, dogs, dropped crockery and Christmas trees, and it still holds the room together. Restoring it is one of the few jobs in a period property where the effort is visible within a week. But floorboards are also tired, uneven and full of gaps, and treating them badly does more harm than leaving them alone. Here is how to do it properly.

Read the Boards Before You Touch Them

Before hiring any machinery, spend an hour inspecting. Walk the room and press down on each board — any springiness suggests the boards are loose or the joists beneath are failing. Lift a board or two in the corners, ideally where a radiator pipe rises, and look underneath with a torch. You are checking for damp, woodworm flight holes, and joists that have rotted where a pipe has been leaking quietly for years.

Deal with structural problems first. Rot and active woodworm need treating before you sand, not after. Then secure the floor:

• Punch every nail at least 3mm below the surface with a nail punch and a hammer, otherwise you will shred the sanding belt and scar the boards.
• Screw down squeaks using 50–60mm countersunk screws at a slight angle through the board edge into the joist, pilot-holing first to avoid splitting.
• Replace rotten sections with salvaged boards of similar age and width, cutting out the damaged run neatly at a joist and fixing with the tongue removed on the joint side.
• Check for hidden services — cables and pipes often run through notches just under the boards, and a long screw will find them.

Preparing the Room Properly

Dust is the enemy of a good finish, and sanding an entire floor generates a surprising amount of it. Clear the room completely, take up carpet and underlay, and remove every gripper rod, staple and tack you can find. Punch any remaining carpet tacks flush. Tape plastic sheeting across doorways and open a window where possible.

Hire a drum sander, an edging sander and a good dust extractor together if you can. The drum sander does the field of the floor, the edger gets within a few millimetres of the skirting, and corners and awkward spots are best dealt with by hand using a cabinet scraper and a shave hook. It is worth removing the skirting in a room you are redecorating anyway, because it gives you a clean edge and lets you hide the perimeter expansion gap properly when it goes back on.

Sanding in Stages

Work through the grits rather than trying to remove everything at once. On most old pine, start at 40 grit only if the surface is rough, cupped or coated in old varnish. Otherwise begin at 60. Severely cupped boards can be levelled by sanding diagonally at roughly 30 degrees to the board direction, but keep this brief — a pass in one diagonal direction, then another in the opposite, then straight along the boards to remove the scratch pattern.

Follow with 80 grit along the grain, then finish with 120. Take your time and keep the machine moving; pausing in one spot will gouge a hollow that no finish will hide. Empty the dust bag often, and vacuum the floor thoroughly between each grit so coarser particles are not dragged back across the surface. A final hand-sand along the edges, with the grain, makes the difference between a good job and a professional one.

Filling Gaps — Selectively

Gaps between boards are part of the character, but a 6mm gap with a howling draught beneath is not. Fill sensibly rather than comprehensively. Boards move with the seasons, expanding in humid summer air and shrinking when the heating is on, so a rigid filler in a wide gap will simply crack and fall through.

• Small gaps up to 3mm: mix fine sanding dust with a clear wood filler or PVA to a paste and press it in with a scraper, then sand flush once dry.
• Wider gaps: cut tapered slivers of matching pine, glue them in with wood glue and tap them home, then plane and sand flush.
• Draughty gaps you want to keep visible: push a foam backer rod or twisted rope into the gap from below, or lift the boards and insulate between the joists with mineral wool.
• Leave the perimeter gap alone — the 10mm or so beneath the skirting is what allows the floor to move without buckling.

Choosing a Finish

The finish decides how the floor looks and how much work it will be in five years. A hardwax oil soaks into the timber, leaves a soft matt sheen and can be spot-repaired without sanding the whole room — ideal for a busy family home. A water-based lacquer builds a tougher surface film, dries quickly and suits hallways and kitchens, though repairs are more visible. Traditional varnish is durable but can yellow and is awkward to patch. Wax looks wonderful on old oak but needs rewaxing twice a year and marks badly if anyone leaves a wet glass on it.

Whatever you choose, apply two or three coats with a brush or applicator pad, working with the grain and keeping a wet edge. Denib lightly between coats with a fine abrasive pad. Ventilate the room, keep people and pets off the floor for the full curing time, and resist the temptation to move furniture back early — oil finishes in particular take days, not hours, to harden properly.

Living With a Restored Floor

Once it is down, treat it kindly. Fit felt pads to every leg of every chair and table, and lift rather than drag. Sweep regularly, because grit acts like sandpaper underfoot, and clean with a pH-neutral wood cleaner rather than a wet mop. Re-oil high-traffic areas such as doorways every year or so, and keep the room at a reasonably stable humidity through the winter, since central heating is the main cause of new gaps appearing in a floor you have just finished. Get those habits right, and the boards you have just brought back to life will comfortably outlast the next round of decorating. If the joists are suspect, the room is very large, or the boards are badly cupped across the whole floor, a specialist will save you both time and timber — but on a straightforward Victorian terrace, this is a job a careful amateur can do well.