Best screws for loose floorboard?

Marvqn1

Bendy_House said:

I recall that a screwdriver bit came with SF's plasterboard screws, so you never know - their reviews would mention this, I think.
If not, a standard PZ2 will likely fit, and every kit should have one....
Anyhoo, the idea is to tightly pull the floorboard down on to the joist, so that means either drilling a virtual 'clearance' hole in the 'board (say, ~3mm), or else using a special screw which has 2 different thread pitches, a coarser one first. 
With the near-clearance hole, the screw will go through the board with only lightly biting in to it, but will then screw properly into the joist below. This means the screw will pull the 'board down tightly on to the joist, which is what you want.
With the special screw (is that what the Floor Titles are?), The coarser main part of the screw thread goes through the 'board more quickly, and then in to the joist. The finer-pitched last part will bite into the boards, but at a slower rate. Therefore the faster, coarser part going through the joist will pull the slower board down tight to it.

When drilling the pilot hole into the floorboard, what thickness of drill piece should be used compared to the thickness of the screw to ensure that the screw will only lightly bite into the board when it goes through?

For example, if the screw is 4.2 x 55mm. I guess the 4.2 refers to the screw thickness?

bpj

I like the spax flooring screws, e.g.:

https://www.screwfix.com/p/spax-wirox-tx-countersunk-wirox-flooring-screw-4-5-x-60mm-300-pack/88716

They come with a TX20 bit, you would want to use with a bit holder (same goes for any bit).

Probably overkill to buy specific screws if it's only one board though.

Bendy_House

Marvqn1 said:

When drilling the pilot hole into the floorboard, what thickness of drill piece should be used compared to the thickness of the screw to ensure that the screw will only lightly bite into the board when it goes through?

For example, if the screw is 4.2 x 55mm. I guess the 4.2 refers to the screw thickness?

Probably best to use screws designed for this job, such as the ones linked to by bpj.

But, to try and answer your Q, a 'pilot' hole is usually drilled for a number of reasons. One is to prevent splitting of the wood, so you'd drill them if you were screwing close to the edge (matron!), or through a narrow batten which could be split by the wedging action of the screw going through. A 'safe' pilot hole size would be to roughly match the 'shank' of the screw, ie the solid tapering part that the thread spirals around. I'll often hold the screw up to the light, and place a drill bit in front of it - if the drill is pretty much the thickness of the solid shank, that's a safe 'pilot'. Only the actual thread would then bite into the surrounding timber, which should still give it good purchase, whilst lessening the risk of splitting the wood.

You might also use a pilot hole if drilling into a hard hardwood - some will be really tough to screw through without a pilot hole first.

And another reason - the one for this post - is so that the screw doesn't secure itself quite as solidly in the 'board as it does the joist (and the joist ain't going to split in any case as it's so chunky).

Imagine placing a 'board over a joist. You start to drive a screw through both - no pilot hole - and all is well. The screw tip bursts through the bottom of the board, breaking out bits of timber, and then starts to screw into the joist. If you aren't pressing the 'board down hard on to the joist as you do this, then the burst fibres will slightly lift the 'board away from the joist, leaving a wee gap. Another thing you'll likely notice when you start to drive a screw into wood is that it lifts the timber surface like a wee volcano - a tiny pyramid. Yes? So, you have the 'burst out of the bottom of the 'board (missus!) coupled with a wee pyramid forming on the surface of the joist. These two could easily amount to - ooh - a 3-odd mm of debris causing a gap between the two timbers - yes? So now the 'board could be sitting 3mm above the joist as the screw continues on its journey into the joist.

You drive the screw 'home', until the head is flush or slightly countersunk in the 'board. Looks good, except there's still a 3mm gap between the two timbers, and no amount of screwing (m...!, damn, I can't think of anything else) will pull that gap closed as the thread going through both are the same. Gap = recipe for future creaks.

Hence either using a special screw like the one linked to before, or else drilling a pilot hole - not so much to prevent splitting (tho' it will), but to allow the screw to slightly 'slip' through the board's grip, and for the joist to pull it down tightly.

For the purpose of allowing the 'board to be pulled down tightly, the 'pilot' hole would actually be closer to being a 'clearance' type - ie almost large enough to allow the thread, too, to pass through unhindered. 

I'm repairing a shed-load of fence panels at the mo' (thank you, storms x 3), and these have ~1"-wide battens running down both sides opposite each other, secured with serrated nails passing through. I'm reinforcing these with screws - far stronger. However, I NEED to drill clearance holes on the leading battens for the above two reasons - one is to prevent the narrow 1" batten from splitting, but mainly it's so that the rear batten continues to be pulled up tightly towards the front one even after the screw head has gone home, squishing the lap panels nicely in between. Without the pilot/clearance hole, once the screw starts to go through the rear batten, the gap between the two battens has been fixed, and they won't be pulled any closer together, which would be pants.

SueHender

It's like an annoying squeaky wheel but on your floor! Nobody wants to deal with damaged screw heads.