Wood Flooring
for Extensions.

Extensions and rear additions present a specific flooring challenge — matching what is already there, or starting fresh in a way that creates unity across the whole ground floor. Get it right and the extension disappears into the house. Get it wrong and the join is visible forever. LIGNORA installs wood flooring in extensions across London and the South East.

HerringboneWide PlankChevronUFH CompatibleBifold Extensions

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Pattern & Format

Choosing the Right
Extension Floor Approach

Herringbone

If the existing house has herringbone — or you want the extension to be a statement — herringbone throughout the ground floor creates a unified, considered feel. The key decision is whether the pattern runs continuously through the extension join or changes direction at the junction. We advise on this at survey stage based on the room geometry.

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Wide Plank

For extensions designed to feel open, calm, and contemporary — particularly those with bifold or sliding doors to the garden — wide plank at 190mm or 220mm running the length of the space and continuing into the house creates a sense of continuity and scale. The boards draw the eye toward the garden and make the internal space feel larger.

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Matching an existing floor

If the extension connects to an existing floor that must be matched — whether engineered oak, solid oak, or parquet — we assess the existing product specification and source the closest available match. Where an exact match is not possible, we advise on how to handle the junction cleanly, whether through a threshold detail, a change of pattern, or a colour-matched transition strip.

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The Extension Floor Challenge

The Case for Getting the Junction Right

The junction between an existing floor and an extension addition is where most extension flooring projects fail. The subfloor heights rarely match exactly. The existing floor has settled. The new screed or concrete slab has different moisture characteristics. All of this must be resolved before a board is laid.

Subfloor height matching. The extension subfloor is almost always at a different height to the existing floor. We assess the differential at survey, specify the correct build-up — whether self-levelling compound, isolation board, or a combination — and confirm that the finished floor height matches at the junction without a step or a visible transition bar.

Underfloor heating compatibility. Most extensions are designed with wet UFH in the screed — it is the most efficient heating method for a ground-floor extension. All engineered oak in our collection is UFH compatible. We confirm the adhesive specification is rated for the system temperature range at survey stage.

Bifold door thresholds. Where bifold or sliding doors open onto the garden, the external threshold detail requires specific attention — the floor must terminate cleanly at the door sill, be protected against weather ingress, and handle the slight moisture variation at the external opening. We detail this junction correctly as a standard part of every extension installation.

What to consider
in an extension specification

Build programme timing. Wood flooring should be the last trade in an extension — after plastering, decorating, kitchen installation, and UFH commissioning. We work with your project manager or architect to confirm the correct installation window and ensure the extension environment is ready before we begin.

Moisture testing. New concrete slabs and screeds require a minimum drying period before wood flooring can be installed — typically 6–8 weeks per 25mm depth. We test relative humidity and moisture content before installation begins. Installing over a slab that has not dried is the single most common cause of extension floor failure.

Matching the existing floor. If the extension connects to an existing oak floor, we assess the existing product at survey stage and advise on matching options. An exact match is not always possible — particularly with older or discontinued products — but a well-chosen complement is often a better result than a poor match.

Samples brought to every survey

Survey to Installation

What Happens at
an Extension Survey

Samples in Your Light

We assess the extension subfloor — type, height relative to the existing floor, moisture content, and UFH system present. We then assess the existing floor and advise on matching, complementing, or separating the two areas with a defined junction detail.

Subfloor Assessment

Extension subfloors are typically new concrete or screed — and require specific preparation before wood flooring can be installed. We check moisture content, assess the need for priming or levelling compound, and confirm the build-up specification before quoting.

Junction Planning

The junction between the extension and the main house is planned at survey stage — not decided on installation day. We specify whether it will be a continuous run, a threshold bar, a change of pattern, or a level change detail, and price this as part of the original quote.

Fixed Price Quote

Following the visit, we send a written quote that breaks down product, underlay, adhesive, fitting and any trimming needed.

Extension Floors,
Answered

The questions we are asked most often.

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Can the same wood floor run from the house into an extension?

Usually, yes. Engineered oak can run across both the old floor structure and the new screed, so the ground floor reads as one room. We check the heights and subfloors first, and match or replace the existing floor where it meets the new one.

Can wood flooring go over underfloor heating in an extension?

Yes. Every engineered oak floor we supply is suitable for underfloor heating. In an extension it is glued to the screed once the screed is dry and the heating has been commissioned.

How long should a new extension screed dry before the floor goes down?

Until a moisture test shows it is dry enough for the adhesive and the floor being used. A traditional sand and cement screed is often quoted at around a day per millimetre for the first 40mm, and longer beyond that, but we test rather than guess.

What if the extension floor is higher or lower than the house?

We level the difference before fitting, with self-levelling compound or a built-up subfloor, so the finished floors meet without a step. Where a level join is not possible, a matched threshold covers it neatly.