Securing floor boards with screws

[jwpzx9r]

Hi I am relaying a floor and want to use screws to hold the floor boards rather than nail them. The floor boards I am using are 20 mm white pine and tongued on two sides and grooved on the other two, The boards are being layed onto 100mm x 100mm Oak joists which are about 500mm centres and I want to know what size and length of screw to use I want to screw them through the tongue counter sunk at an angle is this ok or do I have to go through the top of the board. Also where a board joint is between joists do I need to put a noggin in or will it support OK . Any suggestions most welcome.

 

[big-all]

what length are the planks do the cover a minimum 3 joists
are you sure the centers arnt 400mm??

 

[jwpzx9r]

Hi big-all
Its an old French house so nothing is exact but the measurement is near as damn 500mm centres. The boards are 2.05M x 135mm x 20mm

 

[big-all]

ok fair enough lol
usually nails into tounges screws will not go flush and will probably split the tounge
more usual clamp and blind nail
or 2 screws in the top

you also need stainless or brass as oak eats steel

 

[jwpzx9r]

Hi big-all
I was going to use a drill and countersink combo to make the screw pilot holes would that be ok for securing through the tongue and the screw size and length ? Thanks for the advice!

 

[big-all]

screw length usually 2.5 times the thickness so 50mm
it may work through the tounge with a countersunk but never tried it
so will wait for others to comment

 

[Jackrae]

I suggest you use a slightly oversize drill for the pilot holes as oak, especially old oak, will be as hard as steel. I often enter a steel screw to "cut" the thread, then remove and fit a brass screw - but on a floorboard job this would be simply too tedious. May I suggest you do some trial drills and screw entry into the oak beam before you start fitting boards so's you establish the correct size of pilot hole - there's nothing worse than shearing off a brass screw due to too tight a hole !

Also be aware that stainless steel screws are generally as weak as brass ones and shear off just as easily (usually at the point where the thread changes to full shank) so don't expect them to take much abuse

 

[gregers]

also use something like tallow,so the screws go in smoothly.

 

[big-all]

i remembered seeing flooring screws some where not sure if they are meant for the tounge but the smaller head may help??
http://www.screwfix.com/p/tongue-ti...tracking url&gclid=CJOS_uSPwroCFSXItAodIFAA0g

ok the pictures to the l/h side shows the screws in the tounge