As emphasised many times before within this blog and on our
website, oak flooring will expand and contract as its moisture content changes,
so an allowance for this must be considered before installation begins.
Firstly solid oak will move dimensionally more than
engineered because of the difference in construction; as explained previously,
more info here; Solid v Engineered
This means that the allowance for expansion for engineered
oak doesn’t need to be as much as for solid; 1mm per linear metre for
engineered and 2mm for solid should be enough).
But let’s be really clear about expansion gaps, what they’re
intended for and what can happen…
The main challenge when a floor expands isn’t the flooring
buckling up at the centre of the room because although this may seem terrible
at first, this is simply a ‘relief’ mechanism for the finished floor that
actually prevents more damage being caused.
The very worst thing that can happen when a floor expands is
that it increases in size so much that it actually pushes walls outwards and
causes a structural problem but this is very rare if sufficient expansion
allowance is left around the floor.
Leaving sufficient expansion gap around the perimeter of the
room and around any vertical obstructions actually prevents this horrible and
costly situation from happening because when the outside planks of the floor
move too much they actually become loose and pull away, so being allowed to
buckle upwards.
The clearance around the perimeter of the room actually has
no effect on the planks at the centre of the floor and if the centre of the
room becomes too ‘wet’ it will expand and buckle there.
The expansion gap around the perimeter is there to allow the
last few rows of flooring to become loose and pull away from their fixing, so
allowing the boards to buckle upwards rather than stay in place and exert
pressure against the walls.
If an oak floor is nailed down by secret nail method, because
each nail is at a 45 degree angle through the tongue of each board, the greatest
movement will be towards the tongue because each plank will find it easier to
pull the nail outwards in that direction. See the image under ‘Secret Nailing
Method Explained’ in our Free Info Pack
In large room areas of flooring, starting the installation
at the centre of the room and installing the two halves of the room’s flooring ‘opposite’
to each other can reduce such problems from occurring.
When an oak floor is installed using the floating method, even
though we recommend only using engineered flooring, this means that the
finished floor behaves like one huge board, so expansion gaps surrounding the
floor are vital and should be carefully calculated.
