Don’t Choose the Wrong Dimensions For Your Oak Flooring


This post will describe how the length, wide and thickness of your oak flooring will change the overall appearance of your room.


Author: Richard Penny

engineered oak flooring brushed and fumed


Many mistakes are the result of incorrectly choosing the wrong dimensions for your oak flooring.

The individual floorboard consists of 3 main dimensions; its length, width and thickness.

Together, these can proportionally create a stunning room layout but also, if not carefully selected, it can result in a visually odd appearance.


The length of the floorboard is important, as it is responsible for achieving a calming or busy effect.  Be careful to ensure that the floorboards are of sufficient length to create the effect you want.

Some suppliers selling more high-end boards often point out their boards do not contain short (normally less than 1000mm) boards.  Ideally, if you are covering a large area (25 sqM+), you would look to have all boards over 1800mm and preferably 2400mm in length.

A shorter board means more boards to cover the same area; this can also result in more installation time.

Engineered Oak Flooring
engineered oak flooring


As a rule, floorboards are normally laid down the length of a room if the room is not square.  This gives a more natural appearance, otherwise, the result would be more ladder-like if laid across a narrower room.

The width of a floorboard is therefore calculated by the width (not length) of the room.  Although not a strict formula, for all rooms under 4000mm in width, regardless of its length, use 5% to 6% as a guide.

For example, a room has a width of 3400mm – use a board between 170mm and 200mm

For rooms greater than 4000mm, any width board over 200mm will be ok.

The only exception to this may be a long corridor, hallway or landing area.  There is no set guide for this but sometimes a narrower board is more in keeping.  Without complicating matters, the exception to this is where you have an adjoining room where you wish to keep the continuity of the width of the board in both areas.


Solid oak floorboards tend to be available in 15mm, 18mm and 20mm.  As underfloor heating is becoming the norm, solid oak flooring is not recommended and therefore we recommend you choose an engineered board.

Solid oak flooring can still be laid (glued, nailed or screwed) over existing boards, but only 20mm should be used if fixing directly to wooden joists at 400mm centres.

An engineered board is described as having two layers; a base layer and a top layer.  With a range of different boards on the market, the overall thickness tends to be 15mm or 20mm.  When laying over underfloor heating, it would make sense to fit a thinner board to allow any heating to travel through the board.

The one point to bear in mind it the thickness of the top layer.  This can range from 2mm to 6mm of oak depending on the quality of the board.  This difference can become apparent depending on its use and wear resulting in its longevity.


In general, the larger the room, the longer and wider your oak floorboards need to be.

The thickness is only important if you are laying directly on to joists, considering underfloor heating and/or the type of room and therefore daily use, the flooring will undergo.

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