Floor removal and subfloor preparation

Removing the old floor

Carpet

Carpet is the most common thing we take up. It comes out with the underlay, the gripper strips around the walls and the staples holding the underlay down. Every staple and tack has to come out, because anything left behind will show through or push up a floating floor. We have done this in houses and apartments. One customer had the carpet upstairs replaced with timber in three days. Another had old carpet removed from their apartment and new boards laid, and mentioned everything was left clean and tidy at the end.

Tiles, vinyl and old timber

Hard floors take more work. Tiles are broken up and the adhesive bed ground back, which is noisy and dusty. Vinyl and old floating floors are simpler to lift, though glue left on the slab often needs grinding. Old timber can sometimes stay as the base for the new floor if it is flat and firmly fixed, and sometimes it has to come out. We assess this at the measure, and the outcome is shown on the quote.

Rubbish

Old flooring is bulky. We take it away as part of the job, along with offcuts and packaging from the new floor.

Checking the subfloor

Once the old floor is up, the subfloor is checked for three things.

Flatness. Floors are rarely perfectly flat. Manufacturers set a limit on how much a subfloor can dip or rise over a given distance, and the installers check against it with a long straight edge. A floor outside that limit will feel springy, joints can open or peak, and click joints on floating boards can break.

Soundness. On timber subfloors we look for loose or squeaky sheets, soft patches and signs of old water damage. Loose sheets are screwed down and damaged sections are replaced. Many older houses around the eastern suburbs have timber floors on joists instead of a slab, where the usual issue is movement: squeaks, springy spots and old boards that have cupped. Those are fixed down or packed flat before the new floor goes on.

Moisture. This mainly matters on concrete, and it is covered in its own section below.

Grinding and levelling

High spots on a slab are ground down. Low spots and dips are filled with a levelling compound, a cement-based product that is poured or trowelled on and sets hard. A small dip might only need a patch, while an old slab with a lot of movement might need a whole room levelled. Levelling compound needs time to cure before boards go down, and that can add a day or more to the job.

How much levelling a floor needs is hard to know until the old covering is up. We give our best estimate at the measure. If anything unexpected appears once the carpet is off, we will discuss it with you before doing any extra work.

Moisture in concrete slabs

Concrete holds water for a long time after it is poured, and ground-floor slabs can draw moisture up from the ground. A slab can feel dry on the surface and still carry enough moisture to make timber cup, swell or let go of the adhesive.

That is why flooring manufacturers generally require slabs to be moisture tested before timber is installed, and many require a moisture barrier on ground-floor slabs whatever the reading. New builds, recent extensions and houses with a history of leaks need the most care. If a reading is too high, the choices are usually a barrier system or more drying time. Laying over a wet slab is not an option.

How slab moisture testing works

There are two broad kinds of test. A handheld meter used on the surface gives a quick reading and is good for finding damp patches, such as along an outside wall or where an old leak was. It only tells you about the top of the slab, though. A more thorough method measures relative humidity inside the concrete, using probes set into small drilled holes and left for a period before they are read. Which test is needed, where to test and what reading is acceptable all come from the board and adhesive manufacturers’ instructions.

If a slab is too damp, the usual options are a moisture barrier system applied before the boards go down, or more time for the slab to dry. On a new build, that can mean waiting.

Why it matters for your warranty

Board warranties come from the manufacturer, and they almost always depend on the floor being installed to the manufacturer’s instructions. Those instructions cover subfloor flatness, moisture limits, barriers, acclimatisation and expansion gaps. If a floor fails and the subfloor wasn’t prepared to that standard, the claim can be refused, even if the boards themselves were fine.

We have seen what happens when preparation goes wrong. One customer came to us after their engineered boards were damaged by another contractor, and we helped them work through the repair. Doing it correctly the first time costs less. The care and warranty page has more on how warranties work.

Skirting boards: leave them on or take them off?

Every timber floor needs an expansion gap around the edges, and something has to cover it. There are two usual ways.

Leave the skirting and add scotia or beading. The skirting stays put, the boards stop just short of it, and a small moulding is fixed along the bottom to hide the gap. It is quicker, costs less and avoids any risk to the plaster. The line at the base of the wall is a little busier, and the scotia needs painting or finishing to suit.

Take the skirting off and refit or replace it. The boards run close to the wall and the skirting goes back on top, which gives a cleaner line. Old skirting doesn’t always come off in one piece, and the plaster behind it can get marked, so this often ends up as new skirting plus painting. It makes most sense when you are replacing or repainting the skirting anyway.

Floor heights and doorways

Removal and preparation both change the floor height, and that shows up at every doorway. Taking up tiles and their bed can drop the floor. Levelling compound, underlay and a moisture barrier add height back. The new floor then has to meet tiled bathrooms and laundries, the front door, sliding doors and any carpet that is staying. A small step is covered with a transition trim or a reducer. A bigger one may need the subfloor built up, or a different finish at that doorway. We look at each threshold at the measure so the heights are worked out before the old floor comes up.

Apartments

Apartment jobs have a few extra steps. Most owners corporations have rules on hard flooring, often including an acoustic rating for the underlay, and some need you to apply for approval before work starts. Removal also means getting old carpet down in the lift, so the lift needs to be booked and building management told about work hours. We recommend checking the rules before you choose a board. For apartments we can supply acoustic underlays including Peaceful Warrior and Quiet Achiever. In an independent field test (14 mm floating engineered timber over a 257 mm concrete slab) both rated L’nT,w 49 dB, measured in a large room below. For a bedroom-sized room underneath, the report points to the L’n,w figure instead: 56 dB for Peaceful Warrior and 55 dB for Quiet Achiever. All of these are under the 62 dB limit in the National Construction Code, and we can give you a copy of the test report for your building manager. The final acoustic result, and whether your building approves it, depends on the apartment’s floor construction and the building management’s requirements, so we check those with you before you order.

Next steps

You are welcome to send us photos of the existing floor with your enquiry, or book a free measure & quote. For the rest of the install, see supply and installation.

Related guides: Laying a Timber Floor on a Concrete Slab: What Happens First · How to Replace Carpet with Timber in a Doncaster Home