Decking screws - recommendations

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mdf

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#166331 9-Mar-2015 20:26

I'm building a deck for my mum. I seem to spend a lot of time on here recently looking for help with her problems.

Decking is 140x19mm smooth faced kwila (I'd have preferred not to use kwila, but that's what she wanted).

I'm looking for recommendations for screws (or other fasteners) to attach the decking to the joists.

I was planning on using pan/rose headed stainless steel screws, but (a) mum isn't that much of a fan of the look of them and (b) they can get really pricey, particularly for the better quality ones. I've also had my share of issues popping the heads off stainless steel screws, particularly the cheaper ones.

I've looked into a couple of options, but just wanted to know whether anyone had first hand experience of any of these:

Spax (the site seems incredibly slow to load) - these screws have a double thread and a really small head that goes into the board flush. The demo however shows the screw going into ridges, whereas I have smooth boards. I'm also having trouble finding anywhere to source this online, but I haven't tried the suggested suppliers (ITM) yet.

Kreg - this is a hidden screw system where the screw goes in the size on an angle via a jig. I wasn't sure how well this would hold compared to a traditional screw though. The amount of wood "under" the screw (the corner of the decking board) seems pretty small. Amazon will ship to NZ at a pretty reasonable cost.

My old school builder mate is adamant that I should just nail it, but it seems a crime to use jolt headed nails on kwila, and I'm not sure how well they will hold.

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#1254342 9-Mar-2015 20:37

Try this link to Spax.

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mattwnz

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#1254343 9-Mar-2015 20:41

Nails should be fine, but I would have though galvanized jolt head ones (which are similar to finishing nail heads) which aren't as visible due to having smaller heads would be ok. You don't want flat heads which have a big head on them. Screws are VERY expensive compared to nailing. There was a similar thread to this a month or so ago about deck screws, so you may want to check the archives.

ubergeeknz

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#1254354 9-Mar-2015 21:00

That Kreg system looks to me as if it would be very strong b/c the screws are on opposing angles. Neat idea.

Fred99

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#1254357 9-Mar-2015 21:05

The hidden screw systems have a potential problem - hardwood decking boards come in a pack of assorted lengths, and assorted quality, unless you could hand-pick every board (and then you'd be lucky) then replacing the odd board which splits/warps after fitting just got a whole lot harder.
I couldn't get the spax site to load, but if they're what I think they are - with a double thread and little "wings" in between to cut through the hardwood decking, then they didn't work for me (purple heart - which is a bit harder than Kwila, but similar). First problem was that they were supposed to be self-drilling, but all I got was a lot of smoke and grief. Next was that as the little wings were supposed to be cutting through the hardwood, there was no "feedback" as to what you were doing, and instead of pulling down, the screw would rotate and strip out the hole in the joist unless you put your whole body weight on the driver. So you'd need to pre-drill anyway - which makes them pointless. (good for pine decking - perhaps).

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#1254358 9-Mar-2015 21:13

Fred99: ... Next was that as the little wings were supposed to be cutting through the hardwood, there was no "feedback" as to what you were doing, and instead of pulling down, the screw would rotate and strip out the hole in the joist unless you put your whole body weight on the driver. So you'd need to pre-drill anyway - which makes them pointless. (good for pine decking - perhaps).

North American "hardwood" is a lot softer that Australasian hardwood. The extreme example is Australian ironbark.

[Extremely off-topic trivia: Balsa wood is classified as a hardwood despite the wood itself being very soft. It is the softest commercial hardwood.]

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DarthKermit

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#1254362 9-Mar-2015 21:28

Stainless steel screws are a softer alloy than steel screws. Our house is all old rimu, 60+ years old and as hard as hell.

If I'm installing anything with stainless steel screws into the native timber, I prefer to:

Drill a pilot hole (and a counter sunk hole if needed)
Use my cordless drill to install a steel screw of the same size as the stainless steel one that I want to install.
Remove the steel screw
(Spray the hole and stainless steel screw with silicone spray if needed)
Insert the stainless steel screw

This has saved me many a time from stripping the heads of more expensive stainless steel screws.

Whatifthespacekeyhadneverbeeninvented?

mdf

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#1254364 9-Mar-2015 21:32

Fred99: The hidden screw systems have a potential problem - hardwood decking boards come in a pack of assorted lengths, and assorted quality, unless you could hand-pick every board (and then you'd be lucky) then replacing the odd board which splits/warps after fitting just got a whole lot harder.
I couldn't get the spax site to load, but if they're what I think they are - with a double thread and little "wings" in between to cut through the hardwood decking, then they didn't work for me (purple heart - which is a bit harder than Kwila, but similar). First problem was that they were supposed to be self-drilling, but all I got was a lot of smoke and grief. Next was that as the little wings were supposed to be cutting through the hardwood, there was no "feedback" as to what you were doing, and instead of pulling down, the screw would rotate and strip out the hole in the joist unless you put your whole body weight on the driver. So you'd need to pre-drill anyway - which makes them pointless. (good for pine decking - perhaps).

You can still replace a board without pulling everything up. The angle is such that you can still get into it if you have to - this is how you do the side of the board facing the existing boards (rather than the open side).

I was planning on pre drilling regardless, it was more how the little heads hold?

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mdf

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#1254373 9-Mar-2015 21:44

mattwnz: There was a similar thread to this a month or so ago about deck screws, so you may want to check the archives.

This one?

Its got some good info for sourcing "regular" screws, but it would be good to get any feedback on the non-standard alternatives.

Handle9

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#1254374 9-Mar-2015 21:52

mattwnz: Nails should be fine, but I would have though galvanized jolt head ones (which are similar to finishing nail heads) which aren't as visible due to having smaller heads would be ok. You don't want flat heads which have a big head on them. Screws are VERY expensive compared to nailing. There was a similar thread to this a month or so ago about deck screws, so you may want to check the archives.

We had a pine deck with jolt heads. Never again. When they pop - all decking nails pop - they are horrid on bare feet.

When we redid the deck with 140 x 9 Vitex, which is a similar hardness to kwila, our builder used flat head nails. They are much kinder, but you do need to spend 20 minutes every year knocking them back in. Our builder predrilled for the nails, and compared to a mates deck with counter sunk screws our deck is nicer visually, and to walk on. I would use Vitex again, it's a neat product.

Edit: Typo

mdf

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#1254384 9-Mar-2015 22:08

Handle9: When we redid the deck with 140 x 9 Vitex, which is a similar hardness to kwila, our builder used flat head nails. They are much kinder, but you do need to spend 20 minutes every year knocking them back in. Our builder predrilled for the nails, and compared to a mates deck with counter sunk screws our deck is nicer visually, and to walk on. I would use Vitex again, it's a neat product.

I like vitex too. I used it at home, and it's really warm to look at, especially after a couple of coats of oil. It's also pretty sustainable and you're supporting native Solomon Island loggers. Notionally the kwila we get here is from sustainable (ish) sources, but I worry about how much orangutan blood it's been soaked in on the way here.

Fred99

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#1254385 9-Mar-2015 22:09

Vitex doesn't bleed like kwila - which can be a big advantage.
For 140 x 19 purple heart, I used 12 gauge x 65mm bugle head SS 316 screws. The countersinking tool was expensive. The screws had 4mm hex (most bugle head are 5mm). 4mm looks better - as the holes are smaller - and look round from normal viewing distance. Problem is that impact rated 4mm hex driver bits aren't commonly available.
Whatever you choose - test it thoroughly first. Start breaking screw heads off, and you'll have a problem. That other thread on screws, the poster bought 8 gauge screws. Very small IMO - about what I'd use to fix 10mm plywood - not 20mm hardwood.

mdf

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#1254386 9-Mar-2015 22:14

Vitex does have this sappy stuff in it when you first lay it. Every time it gets wet you get this sort of sticky foam. Wears off after a little while though. It's also very random lengths, and because its usually felled by locals using small portable mills, you tend it get it in smaller lengths. It can also crack slightly on the surface (doesn't affect the structural integrity).

According to the man at Dulux, some people also have trouble getting stain to stick to it. You need to let it weather in first.

But it looks great and its nice to work with.

mattwnz

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#1254394 9-Mar-2015 22:45

Handle9:
mattwnz: Nails should be fine, but I would have though galvanized jolt head ones (which are similar to finishing nail heads) which aren't as visible due to having smaller heads would be ok. You don't want flat heads which have a big head on them. Screws are VERY expensive compared to nailing. There was a similar thread to this a month or so ago about deck screws, so you may want to check the archives.

We had a pine deck with jolt heads. Never again. When they pop - all decking nails pop - they are horrid on bare feet.

When we redid the deck with 140 x 9 Vitex, which is a similar hardness to kwila, our builder used flat head nails. They are much kinder, but you do need to spend 20 minutes every year knocking them back in. Our builder predrilled for the nails, and compared to a mates deck with counter sunk screws our deck is nicer visually, and to walk on. I would use Vitex again, it's a neat product.

Edit: Typo

I have never had that problem, but I am using the thicker decking timber, 100x40, and the joists are quite close together, probably about 400. The deck was down for 25 years previosuly, and it has just been replaced again, and never any problem with the nails or boards popping up. So it would depend on a range of factors. Screws are probably better if you require less fixings, as they can probably hold down more load than a nail, which is essentially a friction connection. Predrilling boards for nails probably makes them less effective too, as you are reducing the friction on them. The nails also have to be skew nailed, otherwise you can potentially have the problem of the boards warping and pulling the nails up, so you pine deck may not have been built right for that to happen.
Pine decking and nailing though is substantially cheaper than kwila and screwing. You can pickup pine decking for a little over $2 per m merchant grade, at trade price. But kwila ranges from 2.5-4 times that price.

KennyM

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#1254851 10-Mar-2015 18:23

I would never nail a deck down, ive seen far to many that have pulled up.
However i think there is some proper decking nails that have barbs that are supposed to stop them pulling out once installed. (think fish hook)

I used 10 x 65 Stainless screw when I did our deck last year, I predrilled but didnt countersink, we only have pine and just drove the screw in until they were in far enough.
I could do that, but my partner couldnt push hard enough to do it (would strip head)

I would recommend a drill bit with the countersunk bit on it already, do it in 1 motion.

That kreg hidden fixing looks good, I would check tho that 140mm isnt too wide to only have a screws right on the edges.

mattwnz

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#1254853 10-Mar-2015 18:26

KennyM: I would never nail a deck down, ive seen far to many that have pulled up.
However i think there is some proper decking nails that have barbs that are supposed to stop them pulling out once installed. (think fish hook)

I used 10 x 65 Stainless screw when I did our deck last year, I predrilled but didnt countersink, we only have pine and just drove the screw in until they were in far enough.
I could do that, but my partner couldnt push hard enough to do it (would strip head)

I would recommend a drill bit with the countersunk bit on it already, do it in 1 motion.

That kreg hidden fixing looks good, I would check tho that 140mm isnt too wide to only have a screws right on the edges.

The length of the nails do make a big diffference, as does skew nailing. Galvanising does create a lot of friction, but you can also get grooved ones with larger heads. My main reason for not using screws is cost, as if you have got a large deck like I have, it would cost a substantial amount compared to nails. The bigger problem with decks is deterioration and them getting slippery. Don't ever put pots on decks, as they cause big problems.

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