Screw Spacing questions

[Mercer77]

Hi all,

I am about to start to lay the decking boards but I have few questions.

Specifications: 90x19 Merbau decking boards, 90x45 TP joists.

Normal 90x19 over the 90x45 joist
1. How far in, the screws will need to be positioned from the side of the decking board? Or what is an acceptable distance between the screws?
2. How far from the end of decking I need to screw the screws in to avoid splitting (when I do the ends)
3. Would the screws need to be staggered or in line should be just fine. (Given that I will predrill the holes in a slight angle - left/right). I am a bit concerned that if I have them staggered then the screws would be too close to the edge and it will split.

Joining two decking boards (with the above specifications)
4. When joining two decking boards on a 90x45 tp joist, do I need to cut the decking boards in a slight angle, and if yes 1 or 2 degrees would do?
5. Do I need to leave a space between the ends of the decking board when joining (for movement and such) ?
6. How far in are screws to be from end of decking (when butting decking boards against each other)?

[r3nov8or]

Others may have differing views -


Hi all,

I am about to start to lay the decking boards but I have few questions.

Specifications: 90x19 Merbau decking boards, 90x45 TP joists.

Normal 90x19 over the 90x45 joist
1. How far in, the screws will need to be positioned from the side of the decking board? Or what is an acceptable distance between the screws? about 15mm
2. How far from the end of decking I need to screw the screws in to avoid splitting (when I do the ends) as much as possible. Can depend on how your joists are placed. At least half the joist. Also depends on the screwing pressure you allow onto the board - "just enough" is plenty.
3. Would the screws need to be staggered or in line should be just fine. (Given that I will predrill the holes in a slight angle - left/right). with TP in line should be ok. The decks I've done on TP are all in line have had no joist splitting. This is more of a problem with hardwood joists. The slight angle will help, but not too much as you will notice the heads are not flat to the surface. Some may even say don't angle at all. I am a bit concerned that if I have them staggered then the screws would be too close to the edge and it will split.

Joining two decking boards (with the above specifications)
4. When joining two decking boards on a 90x45 tp joist, do I need to cut the decking boards in a slight angle, and if yes 1 or 2 degrees would do? Yeah, a slight undercut can help achieve a good tight butt join and help the end grain breath a little. Everyone likes a tight butt
5. Do I need to leave a space between the ends of the decking board when joining (for movement and such) ? No space. The boards won't get longer or shorter, just wider and narrower.
6. How far in are screws to be from end of decking (when butting decking boards against each other)? Again, as much as possible. 22.5mm is half the joist and with a slight angle inwards you'll hit the joist ok.

[Mercer77]

Others may have differing views -

Thanks mate! Much appreciated.

Joining on joist
90x45 - Say the decking board meet right in the middle at 22.5mm, right? If I go 15mm in from the end of the decking board I will have about 7.5mm from the screw to the end of the joist. Would that be enough for the decking board and the joist? I am afraid that if I go 20mm then I have only 2.5mm to play with and i might split the joist.

Also, I want to have a board perpendicular with the running lenght (along the house at both ends) that will give the deck a realy neat look. (with the ends joining in 90 degree with a 45 cut). When I do this, I assume I will need to screw the all 4 ends and then do the middle decking boards, right? A bit more work but it will be all worth it.

ps. As for the tight butt...mmmm...well i know I do! :D I tend to believe that the terms used in deck building are somehow se* related: deck, butt, screwing, nailing...nuff said!

[r3nov8or]

.
Thanks mate! Much appreciated.

Joining on joist
90x45 - Say the decking board meet right in the middle at 22.5mm, right? If I go 15mm in from the end of the decking board I will have about 7.5mm from the screw to the end of the joist. Would that be enough for the decking board and the joist? I am afraid that if I go 20mm then I have only 2.5mm to play with and i might split the joist. A small angle on the screw buys you a couple of mm when exiting the bottom board and several mm into the joist at full screw depth. If uncertain do a few tests on joist and decking offcuts. I think 15mm is too close to the end.

Also, I want to have a board perpendicular with the running lenght (along the house at both ends) that will give the deck a realy neat look. (with the ends joining in 90 degree with a 45 cut). When I do this, I assume I will need to screw the all 4 ends and then do the middle decking boards, right? A bit more work but it will be all worth it. This is called 'framing' the deck. Yes, that method would allow you to inlay the decking boards and leave the correct spacing on the ends. Alternately if you leave the correct gaps around the entire edge you could frame it at the end after trimming your ends with a straight edge. Depends what you are most comfortable with. Framing means you will need to arrange double joists at the ends, one to take the framing board and then one for the inner board ends.

ps. As for the tight butt...mmmm...well i know I do! :D I tend to believe that the terms used in deck building are somehow se* related: deck, butt, screwing, nailing...nuff said! recommeded preparation - penetrating oil :B

[Mercer77]

" small angle on the screw buys you a couple of mm when exiting the bottom board and several mm into the joist at full screw depth. If uncertain do a few tests on joist and decking offcuts. I think 15mm is too close to the end. " - So you reckon I should go 20mm in from the end of the decking board.
In

In regards to fremming the deck (I wasn't sure how it's called) you are saying that I could lay the framing boards first and then work on the middle bit, or lay the decking boards and then cut or trimm the ends so I can frame it afterwards?

I forgot to ask: What should I use to close the deck on the sides? I mean I could use the decking boards I guess or use another wide piece of timber attached to the sides?


"recommeded preparation - penetrating oil :B" I almost forgot about the oil...let's not forget the drills and drill bit(s). :D

[ringtail]

You can use whatever you like really. Pine fascia works ok, 6 mm hardiflex is good and super durable, or just more decking ( expensive though). Be careful "framing" the deck. Get it right and it looks good, get it wrong and looks bloody awful. The decking must be laid absolutely spot on with no real margin for error. The mitres on the "framing" must be perfect and must be glued as well as screwed or they will open up and look very ordinary. Even with glue and screws perfection is hard to keep over time with things moving a bit here and there.

[Mercer77]

You can use whatever you like really. Pine fascia works ok, 6 mm hardiflex is good and super durable, or just more decking ( expensive though). Be careful "framing" the deck. Get it right and it looks good, get it wrong and looks bloody awful. The decking must be laid absolutely spot on with no real margin for error. The mitres on the "framing" must be perfect and must be glued as well as screwed or they will open up and look very ordinary. Even with glue and screws perfection is hard to keep over time with things moving a bit here and there.

Well, more and more people I see putting a frame around it and I reckon it looks ok, but you're right things will move here and there but then again, if that is the case i could frame it afterwards, as i wont be doing any drilling or pulling. Also, what kind of glue should I use?
Do I have any other option other than the usual deck (no framing)? I mean I could bring the sides up to be level with the decking boards. That would probably look ok too.