DIY GUIDE · TRADES & CONSTRUCTION

How to sand and varnish a wooden floor yourself
A weekend. €295–€331 in machine hire, abrasives, varnish, filler and masks for a four-by-four-metre room.

Nails punched, drum moving whenever it touches the floor, every grit in order, dust contained, then thin coats.

DIFFICULTY
Moderate
no licence needed
TIME
A weekend
a morning to prepare, a long day of sanding through the grits
MATERIALS
€295–€331
a drum sander and edger for 24 hours with abrasives, two tins of floor varnish
A PRO CHARGES
€20–€45
typically €30
  • Every step, start to finish
  • Checked October 2026 — sources at the end
  • Honest about when to call a pro

FIRST, THE HONEST ANSWER

Do it yourself, or get a builder?

Do it yourself if…

  • The floor is solid timber boards or blocks, firmly fixed, with enough wood above the tongues to take a sanding
  • You can empty the room completely and close it off from the rest of the house
  • You can steer a heavy machine for several hours and carry it up the stairs in parts
  • The house was built after 2000, or you have checked there is no old black adhesive or old floor tile under what you are sanding
  • You can keep everyone out of the room while the varnish dries between coats

Get a pro if…

  • The floor is engineered board with a thin wear layer, or has been sanded several times before
  • There is old paint round the edges of the boards in a house old enough for it to contain lead, and it would have to be sanded off
  • There is parquet in black adhesive, or old vinyl tiles, in a house built or refurbished before 2000
  • Many boards are loose, split, rotten or badly cupped
  • You or someone in the house has asthma and the dust cannot be kept away from them

Safety first

  • Wear a well-fitted dust mask the whole time you sand, sweep or empty the bag. The safety regulator classes hardwood dust as a carcinogen, sets its exposure limit at 2mg/m3 against 5mg/m3 for softwood, says sanding machines make particularly high dust levels, and asks for at least a P2 filter.
  • Treat old paint on the boards as possibly containing lead. The safety regulator says most old houses contain some lead-based paint; do not dry-sand it, seal the room, and keep children and anyone pregnant away.
  • In a building built or refurbished before 2000, do not sand or grind old black adhesive, old floor tiles or anything you think might be asbestos. Stop and get advice, as the safety regulator's asbestos guidance says.
  • Wear ear defenders and safety glasses. A drum sander is loud for hours, and a nail it catches can throw fragments.
  • Keep the cable over your shoulder and behind you, never near the drum, and use the machine through a residual current device.
  • Fine wood dust can burn. Empty the bag outdoors into a metal bin, never onto a fire, and never leave a full bag on the machine.

MATERIALCOVERAGEFOR THIS JOB
Water-based floor varnishUp to 18m² per litre per coat, three coats16 m², three coats: about 2.7 litres, so two 2.5-litre tins
Wood fillerFor nail holes and small gapsOne tub
AbrasivesCoarse, medium and fine for each machineFrom the hire shop
Masking tape and polythene sheetTo seal doorways, vents and cupboardsOne roll and a few metres of sheet

How much varnish

36 m² of wall → 4 L for 2 coats. Buy about 4 L.

Litres = floor area × number of coats ÷ coverage per litre, rounded up to whole tins. A 4 × 4 m floor is 16 m²; three coats at 18 m² a litre is 48 ÷ 18 = 2.7 litres, so two 2.5-litre tins.

Freshly sanded bare wood soaks up the first coat, so real coverage is lower than the best figure on the tin. Buy the second tin before you start rather than running out between coats.

Drum sander and edger, together

The drum sander takes the open floor down evenly; the edging sander, a heavy disc machine, does the strip by the skirting and round doorways where the drum cannot reach. Hire both for the same 24 hours or a weekend. One Dublin hire shop prices a drum sander and edger together at €70 plus VAT for 24 hours, and the same for Saturday to Monday.

Abrasives in three grades

You need coarse, medium and fine abrasive for both machines. Hire shops sell them with the machines and some refund the sheets you do not use; the shop we read estimates €20 or €30 of sandpaper for a typical room. A floor in decent condition may start at medium; one with heavy varnish or cupped boards needs the coarse grade first.

Water-based varnish

A water-based floor varnish dries fast, has little smell and does not yellow. The one we priced is touch dry in 30 minutes, can be recoated after two hours and needs three coats, covering up to 18m² per litre. It forms a hard film on top of the wood.

Oil instead of varnish

A hardwax oil soaks into the wood rather than sitting on it, gives a softer, more natural look and can be patched in one spot later. It needs longer between coats and more upkeep. Whichever you choose, use one product for every coat.

Gaps between boards

Small gaps and nail holes can be filled with a wood filler, or with filler mixed with the fine dust from the final sanding for a matched colour. Wide gaps take thin timber slivers glued on one side. Many people leave gaps open; the boards move with the seasons and rigid filler often cracks out.

When not to sand

If you cannot see how thick the wood is above the tongue or the wear layer, lift a threshold strip or a heating vent cover and look. Engineered boards can have a top layer a drum sander removes in minutes.

Buy all the varnish at once from the same batch, with enough for three coats.
Try the finish on a sanded offcut or a board inside a cupboard to see the colour first.

THE PART THAT DECIDES THE FINISH

Preparing the floor — by what you start with

Most of a good sanding job is done before the machines arrive. One proud nail head rips an abrasive sheet and scars the boards, and a loose board chatters under the drum. Find your floor below and do its list first.

Pine boards that were under carpet

The most common starting point.

  1. Lift the carpet, underlay and every gripper strip, and pull every staple and tack with pliers
  2. Punch every nail head well below the surface; screws must be countersunk
  3. Screw down boards that move or creak
  4. Scrape off lumps of old glue, paint drips and underlay foam
A varnished or waxed floor

A hardwood or pine floor that has gone dull or grey.

  1. Test a hidden spot with a little white spirit on a cloth; wax softens and smears
  2. Scrape heavy wax off by hand first; it clogs abrasive within seconds
  3. Expect to start with the coarse grade to cut through old varnish
  4. Plan on changing abrasive sheets often
Boards with painted edges

A painted border round where a rug once lay, common in older Irish houses.

  1. If the paint is old, treat it as possibly containing lead; the safety regulator says most old houses contain some lead-based paint
  2. Do not dry-sand it; strip it with a chemical stripper and scrape it off wet
  3. Seal the room off, wear a P3 mask, and keep children and anyone pregnant away
  4. Clean up with a damp cloth and a fine-filter vacuum and bag the waste
Parquet or wood blocks

Sandable, but slower and more demanding.

  1. Check every block is firm; reglue loose ones before sanding
  2. In a house built or refurbished before 2000, do not sand down into any black adhesive; it could contain asbestos
  3. Sand at an angle to the blocks on the first pass, then along the main direction
  4. Take care with the fine grade; parquet shows cross-grain scratches
Cupped or uneven boards

Edges higher than the middle, or boards at different heights.

  1. Let the floor dry out first if the cupping comes from damp; sanding a wet floor flat leaves it crowned when it dries
  2. Plan the first coarse pass diagonally, as the sander's instructions describe for uneven floors
  3. Fill or sliver wide gaps after the coarse pass
  4. Replace split or rotten boards with reclaimed boards of the same thickness first

THE JOB

How to sand and varnish a wooden floor

  1. Empty and seal the room

    1 hour

    Take everything out, curtains included. Tape polythene over the doorway and over air vents and cupboard doors, and put a damp towel along the bottom of doors to the rest of the house. Open a window. Then go to the section above and work through the list for your floor.

    • Cover or take down smoke alarms in the room while sanding, and refit them when you finish
    • Plan a way out that does not carry dust through the house
    • Keep the machines' cables in mind; plug in behind or beside where you will work

    Mistake to avoid: Sanding with the door open. Fine dust settles on every surface in the house.

  2. Punch, fix and check the floor

    2 hours

    Work across the room board by board. Punch every nail below the surface, countersink every screw, pull staples and tacks, and screw down loose boards. Run a gloved hand over each board to feel what you cannot see. Do the lead and asbestos checks for your floor before any machine is switched on.

    • A magnet swept over the boards finds hidden nail heads
    • Mark anything doubtful with chalk
    • Vacuum the floor to remove the grit you have loosened

    Mistake to avoid: Missing a nail head. It tears the abrasive and makes the drum jump, leaving a scar across the boards.

  3. Load the drum and practise

    20 minutes

    Unplug the sander. Tip it back onto its handle, open the drum guard and fit a coarse sheet under the clamp bar, wrapping it round once and tucking the other end under the same bar. Pull it tight, square to the drum, and tighten the screws so it is skin-tight. Adjust the handle so your arms are slightly bent. Practise raising and lowering the drum with the motor off.

    • Curl a coarse sheet over a bench edge first so it wraps easily
    • A loose sheet tears and can damage the floor
    • Hold the cable in a loop over your shoulder, as the instructions show

    Mistake to avoid: Fitting the sheet loosely. It slaps, tears and gouges the floor where it lets go.

  4. First pass with the coarse abrasive

    3 hours

    Start against the right-hand wall with about two-thirds of the room ahead of you. With the drum raised, switch on, walk forward at a slow, steady pace and ease the drum down as you move. Raise it before the end of each run while still walking. Pull back over the same path, then move across by about 75mm for the next run. When two-thirds is done, turn round and do the rest, overlapping the first area by 0.6 to 0.9 metres to blend.

    • Let the machine set its own pace; do not push it or hold it back
    • On uneven boards, go diagonally first, then along the boards
    • Change the sheet as soon as it stops cutting

    Mistake to avoid: Letting the drum stop while it is down. It digs a hollow across the boards in seconds, and the only cure is sanding the whole floor down to it.

  5. Edges with the coarse disc

    1 hour

    Fit a coarse disc to the edger. Work along the skirting and round the doorways in smooth arcs, blending into the strip the drum left. Keep the edger flat and moving; it digs in wherever it pauses.

    • Keep a hand on the machine's top handle so it does not tip
    • Watch the skirting and radiator pipes; the edger marks them fast
    • Do the edges after each drum pass, with the same grade

    Mistake to avoid: Tipping the edger onto its rim. It cuts curved gouges that show through every coat of varnish.

  6. Fill, then sand with medium

    2 hours

    Vacuum thoroughly. Fill nail holes and small gaps with wood filler, or filler mixed with fine dust, pressing it in slightly proud; glue slivers into wide gaps on one side only. When it is dry, fit medium abrasive and sand along the boards with the same raise-and-lower technique, then do the edges with the medium disc.

    • Always go along the boards on this pass, never across
    • Vacuum between grits so coarse grit cannot scratch the finer pass
    • Look across the floor towards a window to see scratches

    Mistake to avoid: Skipping a grade to save time. Each grade only removes the scratches of the one before it; skip one and swirls show through the varnish.

  7. Fine pass and hand finishing

    2 hours

    Fit the fine abrasive and sand along the boards, then the edges with a fine disc. Scrape the corners and under radiators by hand with a sharp scraper along the grain, then a sanding block. Empty the dust bag outdoors into a metal bin whenever it reaches its line and before every break; the sander's instructions say never to leave the machine with dust in the bag.

    • Never empty the bag onto a fire or into a stove
    • Scrape with the grain, never across it
    • Vacuum the skirting tops and window sills too

    Mistake to avoid: Leaving a full dust bag on the machine overnight. Fine wood dust can heat and smoulder.

  8. Clean for finishing

    45 minutes

    Vacuum the whole room twice, including skirting tops, sills and the edges of the doorway. Wipe the floor with a barely damp, lint-free cloth to lift the last of the dust and let it dry. Check the room is warmer than 10 degrees, as the varnish maker we read asks, and that it will stay so overnight.

    • Wear clean socks, not outdoor shoes, from now on
    • Close the window if it is dusty or windy outside
    • Keep pets out of the room

    Mistake to avoid: Varnishing over dust. Every speck is sealed into the finish and feels like sand under your feet.

  9. First coat of varnish

    1 hour

    Stir the varnish well. Begin at the far side of the room from the door and work along the boards a few at a time, laying thin, even coats and brushing out along the grain. Keep a wet edge so each stroke runs into varnish that is still wet. Work your way back towards the door.

    • Thin coats dry harder and clearer than thick ones
    • Work in good light so you see missed areas
    • Plan your route so you finish at the door

    Mistake to avoid: Flooding the floor. Thick varnish dries slowly, stays soft and can wrinkle or show runs.

  10. Denib and apply the next two coats

    1 hour

    Wait at least the recoat time on the tin; the varnish we read can be recoated after two hours. The first water-based coat usually raises the grain slightly. Rub the floor down lightly with a very fine abrasive pad along the grain, vacuum, wipe, and apply the second coat. Repeat for the third coat, which is the number the maker asks for.

    • Rub down lightly; you are smoothing, not removing varnish
    • Vacuum and wipe before every coat
    • Use the same product and batch throughout

    Mistake to avoid: Recoating before the previous coat is dry. The coats do not bond and the finish stays tacky or peels.

  11. Let it cure before using the room

    2 days

    Keep everyone off until the last coat is dry enough to walk on in socks. Wait longer before lifting furniture back in, and longer again before laying rugs, following the times on your tin. Return the machines cleaned and with their dust bags emptied.

    • Put felt pads on every furniture leg
    • Lift furniture in; never drag it
    • Leave rugs off until the finish has fully hardened

    Mistake to avoid: Laying a rug too soon. It traps the curing finish and leaves a mark the shape of the rug.

The mistakes that show

  • Letting the drum stand still on the floor while it is running
  • Leaving a nail head proud, which tears abrasive and scars the boards
  • Skipping a grade, so swirls show under the varnish
  • Dry-sanding old paint that could contain lead
  • Flooding the varnish on in thick coats
  • Recoating before the previous coat has dried

Stop here and get a floor sander

  • The floor is engineered board and you cannot confirm the wear layer is thick enough
  • Old painted borders may contain lead and would have to be sanded off rather than stripped
  • Parquet sits in black adhesive, or there are old tiles, in a building from before 2000
  • Many boards are split, rotten or loose and need replacing first
How to hire a floor sander →

Dips or wavy chatter marks across the boardsThe drum stopped while lowered, bounced over a loose board, or was lowered too fast. Fix the board and sand the area again with medium abrasive, feathering well beyond the mark.
Swirls near the skirtingThe edger was tipped or left in one place. Sand again with a finer disc kept flat and moving, then scrape and hand-sand along the grain.
Scratches showing through the varnishA grade was skipped or grit was left between passes. Sand that area back to bare wood with the missed grade, work up through the grades, and recoat.
The varnish feels roughDust in the wet varnish, or raised grain after the first coat. Rub down with a fine abrasive pad, vacuum and apply another thin coat.
Patches look darker or blotchyUneven sanding, or filler taking the varnish differently. Sand the patch evenly back to bare wood and refinish; filler mixed with the floor's own dust matches better.
The varnish is still tacky the next dayToo thick, too cold or poorly ventilated. Warm and ventilate the room and wait; if it does not harden, it has to be sanded off and redone.
Gaps reopened after the winterThe boards shrank as the heating dried them, which is normal in timber. Flexible filler or slivers glued on one side cope with it better than rigid filler.
The varnish is peelingIt went over wax, dust or old finish not fully removed, or was recoated too soon. Sand back to bare wood in that area and refinish.

WHAT YOU SAVE

What it costs to do it yourself

Drum sander and edger for 24 hours, with abrasives, including VAT€100–€120
Water-based floor varnish, two 2.5-litre tins€179.98–€181.98
Wood filler€10.49–€24.49
Disposable respirators€4.99
Total€295–€331
DIY total€295–€331
A floor sander charges per m²
LOW
€20
TYPICAL
€30
HIGH
€45
Floor Sanding price guide →

Guide prices compiled by the Locufy team from published Irish and UK provider price lists and 2026/27 cost guides. Updated 2026.

Hire from a Dublin hire shop's published rates and materials from an Irish DIY retailer, October 2026. Hire shops elsewhere charge differently and some charge for abrasives as used. The professional price per square metre, from the price guide, is shown alongside.

RATHER NOT?

Floor sanders near you, with prices shown

The ones who cover your area, nearest first, with one score from every review. No account needed to look.

Or post the job free and let them come to you.

Let the varnish cure

Walk on it in socks once it is dry, but keep heavy furniture, dragging and rugs off until it has hardened fully, and mop only with a barely damp mop.

Dispose of the dust, offcuts and tins

Bag cold sanding dust tightly for the general waste. Old boards and offcuts are building material for the civic amenity site, as mywaste.ie lists them. Leftover water-based varnish can go to a civic amenity site that accepts paint, and a nearly empty tin can be left open to harden before going in the general waste; solvent-based products and white spirit go to the civic amenity site as hazardous waste.

Return the machines clean

Empty the dust bags outdoors, wipe the machines down and return unused abrasives if the shop refunds them.

Look after the floor

Felt pads under furniture, a mat at each outside door, a dry vacuum most of the time and a barely damp mop when it needs more.

Sanding and varnishing a wooden floor: questions people ask

Yes, with a hired drum sander and edger, if the boards are solid, fixed down and thick enough. Punch every nail, keep the drum moving whenever it is down, work through every grade, and contain the dust.

The coarsest the floor needs, then medium, then fine, without skipping a grade. A floor in good condition may start at medium; old varnish or cupped boards need coarse first.

Usually three. The water-based varnish we read asks for three coats, with two hours before each recoat.

Not by dry sanding. Old paint may contain lead; the safety regulator says most old houses contain some lead-based paint. Strip it chemically and scrape it off wet, with the room sealed.

One Dublin hire shop charges €70 plus VAT for a drum sander and edger for 24 hours, and estimates €100–€120 all in with VAT and sandpaper.

The Locufy price guide for Ireland puts professional floor sanding at €20–€45 per m², with €30 typical, usually including the varnish.

MORE GUIDES

More DIY guides

Fitting a carpetLaying click laminateTiling a wall or a small floorPainting a roomInsulating an attic between and over the joistsTesting your home for radon
All 90 DIY guides →How to hire a floor sander →Floor Sanding price guide →Floor sanders on Locufy →

Sources — checked October 2026

  1. Hiretech floor sander operating instructions, from a Dublin hire shop: punch nails, skin-tight abrasive, overlap runs by 75mm, two-thirds then one-third with a 0.6–0.9 m overlap, diagonal first on uneven floors, never dwell, empty the bag at the line and never into a fire, residual current device recommended
  2. Ronseal — Diamond Hard Floor Varnish: up to 18m² per litre; touch dry in 30 minutes; recoat after two hours; three coats; room warmer than 10 degrees; mask when sanding
  3. HSA — Wood Working information sheet: hardwood dust a carcinogen with an OELV of 2mg/m3, softwood 5mg/m3; sanding machines generate particularly high dust; at least a P2 filter
  4. HSA — Safety with Lead at Work: most old houses or buildings will contain some lead-based paint; seal off work areas
  5. HSA — asbestos information sheet: asbestos can be hidden in any building built or refurbished before 2000; stop work and get competent advice
  6. MyWaste — wood and timber: building material to a civic amenity site
  7. MyWaste — paint: civic amenity sites that accept paint; harden small amounts; solvent products as hazardous waste
  8. Hire Here, Dublin — floor sander hire: €40 a day plus VAT; drum sander and edger for 24 hours €70 plus VAT; €20 or €30 of sandpaper; €100–€120 all in with VAT
  9. Woodie's — floor varnish price check, October 2026: 2.5-litre tins €89.99–€90.99
  10. Woodie's — wood fillers price check, October 2026: €10.49–€24.49
  11. Woodie's — tiling tools and accessories price check, October 2026: cup respirators, pack of three, €4.99