A guide to patching hardwood floors.

Patching is a fiddly job, but not difficult.

Hardwood Floors need patching when

• Pet stains are just too deep (sanding can only fix so much)
• Walls or cabinets are moved
• Old vent or duct openings become obsolete

While tongue and groove flooring is modular and designed to allow for replacement, patching can be a fussy and tool-intensive process. Sometimes even small, seemingly innocuous patches require the use of a up to three types of saw (circular, chop and table), a router, a nailer AND a drill.

In general, the older the house, the older the wood; the older the wood, the less likely it is to a standard shape and size and the more you will work to get replacement boards to fit.

For non-carpenters, allow at least half a day to complete even the smallest patch. And don’t go rent your sanders until all your patching is done! Watch Bob do a pretty, laced-in patch on our YouTube channel!

First, replace any missing subfloor.

Cold-air return patches like these are a pain because the hole you’re fixing goes right through to the level below! All hardwood flooring – even small patched areas – needs to have subfloor underneath; hardwood floor alone isn’t strong enough to hold you and all your crazy stomping. And you won’t have anything to fasten the hardwood floor to without a subfloor.

But fixing a subfloor that is already largely covered with hardwood is like trying to change your underwear while you still have pants on: you’ll need to remove more than you want.

In other words, you’ll have to remove hardwood beyond the area you’re patching so you can get to the floor joists (which are usually 16″ on center) and then make sure that you screw the new subfloor to those floor joists. Then you can replace the hardwood floor itself.

There is a right way—and a wrong way—to design your patch.

If you’re not going to use a framed patch, make sure you stagger your board ends.

And we mean really stagger them; never have two adjoining boards end within 4″ of each other (this may mean that you remove portions of boards that are not damaged – but the sacrifice is worth it!)

Remove the unwanted wood.

If you’re replacing an area where the tongue and groove are still intact, you’ll need to destroy at least one board; this will create enough space for you to get a pry bay under the adjacent boards.

The best way to remove that starter board is to use a spade bit to drill a large hole at each end and then use a circular saw (set the saw cut depth to exactly the thickness of wood to be removed) to cut two lines, connecting the holes.

You’ll take out the loose center piece with a hammer and a chisel, then carefully ease out the remaining two edge sections.

Now your pry bar will have a space to get under the other adjacent boards that need to be removed.

Fill the empty space with hardwood!

This is a good point to double check that you are using the right wood in your patch.

At the bare minimum, make sure you are using the same widths and species of wood. And, if you can, use wood of the same age, particularly if you are patching maple.

Use a chop saw to cut the boards to fit each row of your opening. For the laced-in patches, you’ll need a hammer or mallet to persuade the new boards to thread back into your staggered openings. If they can’t be persuaded with a mallet, you may have to open up your grooves or thin down your tongues using either a router or a table saw.

Blind nail the boards as you go using a flooring nailer or even just a pneumatic trim nailer held at a 45° angle.

Just be sure you’re using at least a 16gauge 2″ nail or staple – 18gauge trim nails aren’t robust enough to hold flooring. And any fastener labeled as a brad is definitely too delicate for this job.

Make sure you’re using a fastener about every 8 inches, with at least two fasteners per board (even if the boards you took out were nailed every 16″). If your patch finishes against a wall, you may to rip down the width of the final board to get it to fit, which is when a table saw becomes useful.

Can I just replace one single board?

Absolutely – just be extra careful not to damage the surrounding floor as you remove the sacrificial board. Cut a new board exactly to length to fit into the opening, but you’ll have to remove the bottom of the groove to get it to drop in.

Dry fit it first – if it’s too low, you’ll want to build up underneath with cardboard or rosin paper. Pre-drill and face-nail the board in place with 2″ trim nails or screws, preferably at an angle to improve holding power. If you haven’t had to shim under the board, you can use a squirt of construction adhesive instead of fasteners.

Don’t try to use filler to avoid a patch!

This is just shameful; don’t do it.

Filler is never meant to be used like spackle. This might be fine if you plan to paint or carpet over this floor, but if the wood is going to show, replace the damaged sections.