Plywood Overlay Before Vinyl or LVT Flooring
Why plywood overlay boarding is used over timber subfloors before fitting vinyl or LVT, and how it differs from screeding.
Timber floorboards move, flex and often have small gaps between them — none of which LVT or sheet vinyl tolerates well. Plywood overlay boarding is fixed across the existing timber to create a rigid, flat, continuous surface that hides board joints and stops movement transferring up into the new floor.
It's a different approach to levelling compound, which is used on concrete and hard screed. On timber subfloors, screed generally isn't suitable, so plywood is the standard solution used across the trade.
Older Victorian and Edwardian properties in particular often have boards that were never intended to be seen or walked on directly with a hard floorcovering — some have been lifted and relaid multiple times over the decades for pipework or cabling, leaving them slightly uneven and inconsistently fixed even where they look sound to the eye.
Why timber floorboards can't take LVT or vinyl directly
- Gaps between boards can telegraph through thin flooring as ridging
- Boards flex slightly underfoot, which can stress LVT joints over time
- Uneven or cupped boards create visible undulation in a smooth-finish floor
- Loose boards can squeak once new flooring is bonded or clicked over them
Plywood grade and thickness
Flooring-grade plywood is used rather than construction ply, as it's manufactured with a smoother face suitable for direct floorcovering. Thickness is typically 6mm to 12mm depending on how much the existing boards need bridging and stiffening, and it's screwed down at close centres to avoid movement.
Cheaper shuttering-grade ply can have voids in the inner layers and a rougher, splintery face, which can telegraph through thin LVT and is more prone to swelling if it ever gets damp during the job — using it as a substitute for flooring-grade ply is a false economy that occasionally causes callbacks months later.
Checking the joists before boarding over
Before any plywood goes down, a fitter should check for soft or springy sections that point to joist problems rather than just board problems — bouncy floors are sometimes a symptom of undersized or damaged joists, which boarding over will hide rather than fix. Where this is suspected, it's flagged rather than simply covered.
Overlay boarding versus full re-screed
On a timber suspended floor, replacing boards with screed isn't generally practical without significant structural work, so plywood overlay is the standard route. On a solid concrete floor, by contrast, levelling compound is usually the better and less costly option — the two aren't interchangeable, they suit different subfloor types.
Fixing method and finished floor height
Plywood sheets are laid in a staggered pattern, screwed rather than nailed so they don't work loose, with joints filled or taped where needed. Adding a plywood layer does raise the finished floor height by the thickness of the board, which occasionally needs allowing for at doors and thresholds.
Guide cost for plywood overlay
As a guide only, plywood overlay is typically priced per square metre including materials and fixing, and forms a distinct line on your quote rather than being bundled invisibly into the flooring price.
Working around skirting, doors and pipework
Sheets are scribed around radiator pipes, door architraves and any awkward corners rather than simply cut square and gapped, since gaps at these points can telegraph as shadow lines once the new flooring goes over the top. Doors often need trimming afterwards to clear the new, slightly higher floor level, which is worth mentioning to your fitter in advance if you have a particularly tight-fitting door.
Frequently asked questions
- Is plywood overlay always needed over floorboards?
- Not always — if boards are flat, well-fixed and free of significant gaps, it may not be necessary for some products. Our survey checks the condition of the boards to confirm whether overlay is genuinely needed.
- Does plywood overlay work under carpet too?
- Carpet and underlay are more forgiving of minor board movement, so overlay boarding is far less commonly required there. It's mainly specified ahead of LVT, sheet vinyl or similar rigid or semi-rigid floorcoverings.
- Will adding plywood raise my floor level noticeably?
- It adds roughly the thickness of the board, commonly 6–12mm. This is usually manageable at doorways but worth checking during survey, especially where floor levels meet other rooms.
- Can plywood overlay be fitted in a day?
- For an average room, yes — but timing depends on room size and how much preparation the boards need first. Your fitter will confirm timescales as part of the quote.
Keep reading
What proper subfloor preparation involves before new flooring goes down, why it matters, and what our fitters check on survey day.
How latex self-levelling compound works, when it's needed, and how it differs from full sand-cement screed before new flooring.
How LVT wear layer thickness and AC/commercial use class ratings relate to durability, and which specification suits which room.
See how we survey, prepare and fit LVT across Kent.
See how we survey, prepare and fit vinyl across Kent.
Talk it through with a fitter, not a call centre
Book a free, no-obligation survey with Kent Flooring Warehouse and our in-house fitting team will check your subfloor and confirm the right subfloor overlay method before you commit to anything — call 07702 737267.