First, Work Out What You've Got

Most original boards in a period cottage or townhouse are pine — often slow-grown Baltic pine with tight grain and a warm honeyed colour once sanded. Georgian and Victorian boards tend to be 18–22mm thick and run from 100mm to 250mm wide, either butted and simply nailed or tongue-and-grooved. Oak, elm and ash turn up too, usually in older properties or in the "best" rooms.

Before lifting anything, lift a corner of carpet or a section of old hardboard and have a proper look. Shine a torch between the boards and check for damp patches, dark stains around joist ends, and the state of the airbricks in the outside wall. If the timbers are wet, fix the cause first — a blocked gully, a leaking downpipe, earth piled above the damp course — because no finish will survive on damp wood.

It is worth saving boards when they are thick, sound, and reasonably level. It is usually not worth it when they are thin, riddled with rot, or so cupped and twisted that you would lose most of the thickness flattening them.

Lifting Boards Without Wrecking Them

Work out which board you want first, then cut carefully rather than prising blindly. On tongue-and-grooved floors, set a circular saw to the board thickness and run it down the tongue line, or use a floorboard saw by hand. That releases the board so it lifts cleanly instead of splintering its neighbour.

• Mark the board number and orientation on the underside with a pencil — you will thank yourself later.
• Slide a wide scraper or a thin batten under your crowbar to spread the load and protect the joist edge.
• Lift the board nearest a joist first, then work along the run, easing as you go.
• Watch for cables, pipework and old gas runs. Assume they are there, even if they shouldn't be.
• Punch old nails through from the underside rather than hammering them back, which mushrooms the board face.

Store lifted boards flat and off a damp floor, ideally in the room they came from so they acclimatise.

Woodworm, Rot and Spliced-In Repairs

Common furniture beetle leaves 1–2mm flight holes and a fine, sandy frass. If the frass brushes away and holes look bright, it may still be active; if it is packed and dull, it is historic. Activity needs damp timber, so drying the space out and improving ventilation is half the cure. Treat bare timber with a boron-based preservative, working it well into the holes and end grain. Wear a suitable mask, gloves and eye protection, and ventilate the room thoroughly.

For damaged sections, cut back to sound timber between two joists and splice in a piece of reclaimed board of matching species, width and thickness. Avoid tiny patches under about 150mm — they work loose. Fix with cut floor brads or annular ring-shank nails, punch them below the surface, and leave a 1–2mm gap at the joint so the boards can move with the seasons.

Gaps, Draughts and Uneven Joists

Gaps of 5–10mm are normal in old floors and are part of their character, but they whistle in winter. Twisted jute or hemp rope pushed into the gap, or foam backer rod, cuts draughts while letting boards move. For a more permanent job, glue slim slivers of pine to one side of each gap with PVA — never fill with filler or grout, which will crack and crumble.

Unevenness usually comes from sagging joists rather than the boards. Pack low joists with slate slips, galvanised washers or hardwood wedges fixed with screws — never just sand the high spots flat, as you will thin the boards badly. Check that joist ends built into the wall are sound; if they are crumbling, sister a new timber alongside. If you are lucky enough to find a painted border around the room's edge, leave it alone and keep the rug in the middle.

Sanding Back Without Losing the Patina

Preparation is everything. Punch every nail at least 3mm below the surface, remove staples and old carpet tacks, and scrape off adhesive or bitumen with a scraper rather than solvent. Seal doorways with plastic sheeting and open windows — the dust gets everywhere.

Use a drum sander with a light cut along the grain, starting at 40 grit only if the surface is rough, then moving to 60, 80 and finishing at 120. Follow with an edge sander for the perimeter. Old pine is soft, so keep the machine moving and do not linger. Stop when the wood is clean and even, not when it is pale and flat — you want to keep the colour and the odd mark that shows its age.

Finishing and Living With Them

Avoid thick polyurethane films, which trap moisture, scratch visibly and are miserable to patch. Breathable finishes suit old timber far better: hardwax oil, traditional boiled linseed oil built up in thin coats, or beeswax over a sealed base. Floor paint in a soft grey-green or off-white is wonderfully cottage-appropriate for plainer rooms. Whatever you choose, test on an offcut first.

Afterwards, sweep or vacuum rather than wet-mopping, use felt pads under furniture, and keep the room's humidity reasonably steady. Patch repairs with matching oil or wax as they happen, and the floor will comfortably see out another century.