# New wooden floor on battens on concrete. Leave a gap ?

#### wertert

Hi All

I am about to start on the last phase of laying my wooden floor. I have battens at 40cm centers on a flat concrete base. I have fitted insulation and UFH in the void between the battens. The last step is to fit the boards on top.

The boards are old pitch pine and are 18cm wide and about 2cm thick. They are old roofing boards. Lots of various lengths. Wood has been stored in centrally heated house for 6 months. Seem bone-dry.

I've spoken to a friend of mine who's done this before and he says to butt the floorboards up against each other ( both on width and length ). Basically lay 3 rows of floorboards down the length of the room. Tighten them up with wedges and fix through. Leave a 10mm gap around the edge of the room which will be covered with the skirting. I was planning to use screws because of the number of pipes under the floor.

I'm slightly worried about this as I was planning to leave 1mm gaps between boards for expansion. Wood moves. I'm concerned that if I have everything butted up I could get boards 'banana-ing' up.

Any advice you really help as I was going to start this weekend. Just ordered my chop saw

Thanks

jeff

How wide is the room (or in other words, how wide will the floor be?)
Rule of thumb with Oak = 3.5mm gap per meter width with a minimum of 10mm; for Pine I would calculate 4 - 4.5mm per meter width with a minimum of 15mm gap all around the perimeter of the floor.

How wide is the room (or in other words, how wide will the floor be?)
Rule of thumb with Oak = 3.5mm gap per meter width with a minimum of 10mm; for Pine I would calculate 4 - 4.5mm per meter width with a minimum of 15mm gap all around the perimeter of the floor.

Hi - room is 4m wide and 8m long. Boards are running down the length of the room.

Are the gaps you've given for width only ie not along the length of the boards ?

You calculate the width of the gap you keep everywhere based on the width of the room. In your case: 4 x 4.5 = 18mm.
18mm gaps along every wall, door post, fireplace, patio doors etc etc

You calculate the width of the gap you keep everywhere based on the width of the room. In your case: 4 x 4.5 = 18mm.
18mm gaps along every wall, door post, fireplace, patio doors etc etc

Oh right I get it now. This is the calculation for the gap round the edge.

I thought you were meaning 4.5mm of gap per m of boards laid i.e boards are 18cm so approx 5 per m. 4.5/5 = 0.9mm gap between boards. How wrong did I get that......

So I'll leave 18mm round the edge with no gaps between the boards ?

That's down to you, we normally wouldn't but some do (credit card "thickness")

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