Wood flooring, Doubt on expansion gap

[vineeth]

Hi,

Planning to lay engineered wood on living, dining and kitchen floor (Cambridge, UK). Most videos that I watched starts off with nailing the first and last planks or glue the entire floor to sub-floor leaving an expansion gap of ~15 mm. My doubt is if the fist and last planks are nailed or glued, how would the floor ever move to occupy the space left by expansion gap?

Thanks

 

[vinn]

You have things wrong.
There are various types of engineering flooring so take your Brand Mfr's tech advice for how to lay their flooring.

 

[Doggit]

You haven't mentioned which type of engineered floor you're using, nor onto what it's going. By virtue that you're considering nailing it, that implies it's going onto a wooden floor.

 

[vineeth]

Planning to use the following engineered wood over thermal overlay over ply. As per instructions, I should be nailing the first plank to the ply and then use tongue and groove till the last plank and nail that to ply.

Also what difference does it make it I am laying engineered wood over wooden floor vs ply?

https://www.discountflooringdepot.co.uk/installing-solid-and-engineered-wood-flooring-i69

Thanks

 

[vinn]

OP,
You are still wrong - read the instructions you've posted.

 

[Doggit]

If you're going to lay the woof over thermal underlay, which is on top of ply, then you'd treat it as a floating floor, and you'd glue the tounge and groove joints instead. It's normally a 12mm expansion gap that you leave around the edge, and I fit cork strips in the expansion gap, but a lot of people disagree with me.

If you were to nail the first and last planks, then as it expands, it'd rise and buckle in the centre of the floor. If you're nailing the floor, then you'd nail or staple every board as you go, through the T&G at an angle. How thick is the ply, and what's underneath that.

 

[vineeth]

As per instructions from the site https://www.discountflooringdepot.co.uk/installing-solid-and-engineered-wood-flooring-i69:

"
NAIL/STAPLE INSTALLATION
Use this method for engineered or solid tongue and groove flooring fitted over plywood. Nails and staples should be chosen in accordance to manufacturers recommendations.

INSTALL THE FIRST ROW
When happy with the fit, nail/staple the first row to the plywood at proper intervals.

INSTALL THE MAIN PART OF THE FLOOR

INSTALL THE LAST ROW

• Top nail / staple the last row in place. Nail in more frequent intervals as this row is holding several in place.

"

If I were to use engineered over ply (Say no thermal insulation), the instruction says clearly to nail the first, lay the rest, and nail the last, leaving expansion gap around the floor. That's why I just cannot understand, if the wood starts to expand, the nailed planks would stop the wood from expanding and hence buckling?

Thanks

 

[Doggit]

The instructions are a bit economical for a beginner. The first row need careful setting up, so that the other rows follow neatly, and without gaps appearing; and the last row needs nailing straight downwards at a position that will be covered by the skirting board, because you can't angle the nails close to the wall, or possibly the previous row or two.

But the instructions assume that you know the rows need nailing as you go.

The expansion gap is there to allow the wood to expand and contract (that's why 15mm is too much, as it might shrink out from under the skirting boards) but it'll only move by millimetres at the most.