The decking saga continues

I’m about to fit my noggins and have been advised to pre drill the joists but not the noggins.

What size hole in the joists for 5mm screws do I need?

Ta

Anything that’s just a bit smaller than the screw. Hold up your drill bit alongside the screw. You just need the screw threads to bite into the wood

In your case a 4mm wood drill bit? I sometimes use metal drill bits for pilot holes as they tend to be smaller sizes than wood ones.

I hope that helps

Wot he sed

Brilliant , thanks

Actually won’t matter too much, the thread of the screw will bite into the end grain of the noggin.

What jon says, you don’t need the screw to bite into the joist, only the noggin.

As the previous two posts, I’d say 5mm, if I’ve understood the configuration. You want the screw to rotate freely in the joist, and engage in the noggin. If the threads bite in the joist, the screwhead will lock up and you won’t be able to draw the noggin against the joist.

All the above is technically correct. Personally I never pre drill soft wood, including decking. Screws can be driven in directly with a reasonable cordless drill.
I’m on my second bucket of 5×70 screws for stud walling and not pre drilled one hole. It’s rock solid.
Enjoy the project, decking construction is quite therapeutic.

Any pics? This is on my radar for “this summer” but typically for me I may run out of time….

As bikebob says, I never predrill either, use Spax screws form Screwfix, they’re superb.

https://www.screwfix.com/p/spax-wirox-cylindrical-head-decking-screws-silver-4-5-x-60mm-250-pack/8667t

If you use screws that have a cutting piece on the tip (Reisser, Spax, and I think now Goldscrew) they will fly through softwood. But get ones which don’t have the thread all the way up the shank because as they hit the noggin, they push it away a bit and the naked shank allows the noggin to be pulled tight, whereas the threaded ones don’t, unless you back off and go in again.

Use an impact driver! Don’t think the goldscrews do have the cutting tip, you need goldscrew plus.

I agree with you on both points Stumpyjon!

“So I asked him if he wanted decking and then I don’t remember anything until I woke up here…”

Sorry, just realised there were replies..

so I did end up pre-drilling for my noggins.

I have however, another question 🙂

So, the decking saga continues and a combination of uni exams and constant rain mean I have a frame that’s not level and no deck boards down.

For some unknown reason, where I built up brick and mortar supports on paving slabs some (maybe a third) of the supports are up to 3/4 inch too short and off level.
I was planning to use slate to level small differences but for the big ones was going to stick some 3*3 post next to the brick and mortar upright and screw into the joists.

Question is…. should i pre-drill to attach a 3*3 post to a 2″ wide joist? I appreciate that this isn’t an ideal solution but i’m trying to make the best of my very bad DIY job!

Any other ideas as to what i can fill a 2/3″ gap with between support and joists would be very welcome! I thought about filling in with more ready mixed cement but then thought the rain might sit in the channel made of joists sat in cement?

thanks again

I’d just be ripping up the slab, throwing a load more muck in there and putting them back in again.

are you sure its that the footings aren’t level, not that the decking frame has warped upwards?

Aye, what 5lab said, packing it with stuff is a bodge.

One of my pet hates is folk not through drilling (a 5mm drill is right for 5.0 gauge screws). By not through drilling you are in effect just putting a screw into two pieces of wood not fixing them together. Often it doesn’t matter too much but with floor boards it really does as the boards don’t pull tight and the screw head buries deep into the board (plumbers floorboard syndrome). I do through drill with framework but I think most chippies don’t.

Predrilling for old fashioned lags and rolled construction screws I can understand but modern designed fasteners don’t need this. GRK for example self cut, self bore and self lock and you don’t have to use 2 tools for each hole. I pay the premium almost every time.