Can You Install Timber Flooring Over Concrete? Here's How It Works

Quick answer: Yes. Timber flooring can be installed over a concrete slab by gluing it directly to the slab, floating it over a moisture barrier and underlay, or fixing it to plywood or battens laid over the concrete. What decides success is the prep: the slab must be dry, flat and clean before the first board goes down.

Almost every home we work in across Perth sits on a concrete slab. Double brick on a slab has been the standard WA build for decades, so "can you install timber flooring over concrete?" isn't a niche question here. It's the question.

And the answer is yes. Engineered, solid and hybrid floors can all go on a slab. Where things go wrong (hollow spots, lifting boards, gaps, cupping) it's rarely the timber. It's almost always the slab underneath, or the step that got skipped to save half a day.

This is how the job works, from bare concrete to finished floor.

The Three Ways to Lay Timber on Concrete

1. Direct stick (glue-down)

The boards are glued straight to the prepared slab with a flexible flooring adhesive, usually a polyurethane or MS polymer type. Many of these adhesives also work as a moisture barrier.

This is our preferred method for engineered timber flooring in most Perth homes. The floor feels solid, sounds quiet, and adds very little height, which matters where timber meets tiled bathrooms or sliding door tracks.

Best for: engineered timber and many solid pre-finished boards. Watch out for: a slab that isn't flat, or one with too much moisture. Both cause failures.

2. Floating floor

The boards lock together (click or glued tongue-and-groove) and sit on an underlay, without being fixed to the slab. A moisture barrier goes under the underlay: usually 200 µm polyethylene film, overlapped and taped at the joins.

Hybrid flooring is always floated, and some engineered products are too. It's quick and it handles a bit of slab moisture better, because the barrier and underlay separate the floor from the concrete.

Best for: hybrid and some engineered boards, apartments with acoustic rules. Watch out for: a slightly hollow sound if the slab isn't flat, and perimeter expansion gaps that must be left clear.

3. Plywood or battens over the slab

A layer of structural plywood is glued and fixed to the concrete (or timber battens are fixed to it), and the timber floor is then nailed or glued to that. It's the traditional way to lay solid tongue-and-groove boards on a slab.

Best for: solid timber flooring, matching an existing raised timber floor, or where you want a softer feel underfoot. Watch out for: extra height (often 15–25 mm more) and extra cost.

The WoodSolutions Timber Flooring Technical Design Guide covers all three methods in detail if you want the technical version.

Step 1: Moisture Testing the Slab

This is the step that decides whether your floor lasts.

Concrete holds a lot of water. A new slab keeps drying for months, and even an old slab can pull moisture up from the ground if there's no membrane underneath or if the membrane is damaged. Timber sitting on damp concrete absorbs that moisture from below. The boards swell, the edges curl up (called cupping), and in bad cases the floor lifts off the adhesive.

So before anything else, the slab gets tested. Surface meters give a quick read across the room and show wetter patches. For accurate numbers, in-situ relative humidity probes are drilled into the slab and left to settle. Each adhesive and flooring manufacturer sets its own maximum moisture level, and the result has to be within that limit before the warranty applies.

If the readings are high, there are options: a moisture-barrier primer or epoxy under glue-down floors, a heavier barrier under a floating floor, or more drying time. What's not an option is laying the floor anyway and hoping.

The ATFA offers independent concrete and timber moisture testing if you ever need a third-party report. On our jobs, a moisture check is part of the free on-site measure, before we quote.

Signs a slab may have a moisture problem

You don't always need a meter to get suspicious. Before you pull up old flooring, look for:

• White, powdery salt deposits (efflorescence) on bare concrete or in tile grout
• Old vinyl or carpet underlay that smells musty or feels damp underneath
• Dark patches that don't dry out, often near external walls or wet areas
• Skirting boards that are swollen or stained at the bottom
• Tiles that have lifted or sound drummy for no obvious reason

Any of those means a proper moisture test before timber goes down, and probably a moisture barrier. It doesn't rule out timber flooring. It just changes how it's laid.

How Long Should a New Slab Dry Before Timber Flooring?

A common rule of thumb is about one month of drying per 25 mm of slab thickness in good conditions. A typical 100 mm residential slab can take around four months, sometimes longer in a cool, damp Perth winter or when the house is closed up.

Treat that as a guide only. On new builds, we test rather than go by the calendar. Builders are often keen to get floors down early, and a slab that looks dry on top can still be wet underneath.

Step 2: Grinding and Levelling

Timber floors need a flat base. Most manufacturers want no more than about 3 mm of variation under a 3 m straight edge. Plenty of Perth slabs don't meet that, especially older ones or those that had tiles glued down.

Here's what the prep usually involves:

• Strip-out. Old tiles, carpet, glue and staples are lifted and carted away. Our floor strip-out service handles this with dust extraction.
• Grinding. A diamond grinder takes off high spots, old adhesive, paint and the weak top layer of the concrete so the new adhesive has something clean to grip.
• Crack and joint repair. Cracks are checked and filled where needed.
• Self-levelling. A cement-based compound is poured into low areas to bring the floor flat.

It's the least exciting part of the job. Nobody posts photos of a ground slab on Instagram. But it's what decides whether your floor sounds solid and stays flat for 20 years. It's why "bare concrete to finished floor" is how we describe our process.

Step 3: Acclimatisation and Laying

Modern Australian hardwood flooring is made to a moisture content of about 10–11%, and the ATFA's acclimatisation guidance notes that long acclimatisation usually isn't needed in typical homes. We still check the boards' moisture content against the slab and the room conditions before laying.

Expansion gaps are left around the edges of the room, usually hidden under the skirting. Timber moves with humidity (about 0.25 mm for every 1% change in moisture content on an 80 mm board, according to WoodSolutions), and a floor pinned tight against the walls has nowhere to go but up.

Which Timber Floor Works Best Over Concrete?

Floor type	Method on slab	Height added	Feel	Our take
Engineered timber	Glue-down (or floating)	14–21 mm	Solid, quiet	Best all-round choice for most Perth slab homes
Solid timber	Glue-down or over plywood	19–40 mm	Very solid	Premium, but plan for height and cost
Hybrid	Floating over barrier	6.5–9 mm	Firm, slightly hollow if slab is uneven	Budget-friendly and waterproof

Engineered timber suits Perth slabs particularly well. The cross-laid core is stable through our dry summers, it glues straight down, and it gives you real timber on top. For a full side-by-side, read our engineered vs hybrid flooring guide.

Will Timber on Concrete Sound Hollow?

It shouldn't. A hollow or "drummy" sound almost always means one of two things. Either a floating floor is sitting on an uneven slab, so there are small air gaps under the boards, or a glue-down floor didn't get full adhesive contact.

Proper levelling fixes the first. Using the right trowel and checking contact fixes the second. Glued engineered timber on a well-prepared slab sounds almost exactly like solid timber.

What About Underfloor Heating?

Engineered timber usually works well over hydronic or electric underfloor heating in a slab, because it's stable and thin. Manufacturers typically set a maximum floor surface temperature (often around 27°C), and the heating needs to be run up and down gradually at the start of the season. Solid timber is less suitable because it moves more. Always check the specific product's warranty.

Underfloor heating isn't common in Perth homes, but we see it more often in new builds and renovations in the Hills. If you're planning it, tell your builder and your flooring installer early. The heating, the screed over it and the floor all need to be chosen to work together, and the slab needs extra drying time before the timber goes down.

Common Mistakes on Concrete (And How to Avoid Them)

A lot of the floors we're called out to fix failed for the same few reasons.

Laying over leftover tile adhesive. Old adhesive ridges stop new glue from bonding properly and create high spots. The slab needs to be ground back to clean concrete.

No moisture test. A floor looks fine for three months, then the boards start cupping in winter. By then the only fix is lifting it.

Skipping the levelling. Especially with floating floors. Every dip becomes a soft, clicking spot, and click joints can break over time.

No expansion gap. Boards laid hard against walls and kitchen cabinets. When the timber takes up moisture in winter, it has nowhere to go and the floor peaks up in the middle of the room.

Wrong adhesive. Cheap or rigid adhesives can't handle timber's natural movement. Flexible flooring adhesives from established systems are made for exactly this.

None of these are hard to avoid. They just take time, and time is the first thing cut from a cheap quote.

Converting Tiles or Carpet to Timber on a Slab

This is the most common job we do: a Perth home with 1990s tiles or tired carpet, converted to timber. The steps are the same as above. Lift, grind, test, level, lay. Removing glued tiles is the slowest and most expensive part, usually $35–$75 per m² in Perth.

Our Perth timber flooring cost guide includes a worked example of exactly this job. And if you're still deciding whether to keep some tiles, our timber flooring vs tiles comparison is worth a read.

From Bare Concrete to Finished Floor

Nulook Timber Flooring handles the whole job with one in-house team, so there are no hand-offs between trades: strip-out, grinding, moisture testing, self-levelling, then laying and finishing the floor, skirting and stairs. We use professional adhesive and preparation systems from Sika, Uzin, Wakol and Wolff, and we start every job with a free on-site measure and moisture check. Book your free measure and quote or call 0405 821 884.

Frequently Asked Questions

Can you install timber flooring over a concrete slab?

Yes. Timber flooring can be glued directly to a concrete slab, floated over a moisture barrier and underlay, or fixed to plywood laid over the slab. The slab must be dry, flat and clean first.

Do you need a moisture barrier for timber floors on concrete?

Usually, yes. Floating floors need a polyethylene moisture barrier, typically 200 µm, under the underlay. Glue-down floors use a moisture-barrier adhesive or primer. The slab should also be moisture tested before installation.

How long should a new concrete slab dry before laying timber?

A common rule of thumb is about one month per 25 mm of slab thickness in good drying conditions, so around four months for a 100 mm slab. Moisture testing, not the calendar, should decide when it's ready.

Is glue-down or floating better on concrete?

Glue-down usually feels more solid and sounds quieter, which is why it's preferred for engineered timber. Floating is faster, suits hybrid flooring and copes better with minor slab moisture when a proper barrier is used.

How flat does a concrete slab need to be for timber flooring?

Most manufacturers require no more than about 3 mm of variation under a 3 m straight edge. High spots are ground down and low spots filled with self-levelling compound.

Can solid timber be laid directly on concrete?

Yes. Solid timber can be glued directly to a well-prepared slab or fixed to a plywood layer that's been glued and fixed to the concrete. The plywood method adds height but suits traditional tongue-and-groove boards.

Why does my timber floor on concrete sound hollow?

A hollow sound usually means the slab wasn't levelled properly under a floating floor, or a glue-down floor didn't get full adhesive contact. Correct slab preparation prevents it.

Can you put timber flooring on concrete with underfloor heating?

Engineered timber usually works with underfloor heating, provided the floor surface temperature stays within the manufacturer's limit, often around 27°C. Solid timber is less suitable because it moves more.

How much does it cost to prepare a concrete slab for timber flooring?

In Perth, subfloor levelling typically costs $32 to $94 per square metre where needed, and concrete grinding around $150 per hour. Removing old glued tiles adds about $35 to $75 per square metre.

Which timber flooring is best over concrete?

Engineered timber is the best all-round choice for most concrete slabs. It's stable, glues directly to the slab, adds little height and gives a real timber surface. Hybrid is a cheaper, waterproof alternative.