Stainless deck screws

[SBartleet]

Hi,
I elected to screw my deck boards onto my hardwood joist. I have been lead to believe that screwing the deck is better than nailing (lasts longer). I bought 1500 stainless steel deck screws (Wilbert? Stainless steel Type 17) 50mm long. I believe that they are grade 304 Stainless and gauge 10.

I am having a huge problem with the screws shearing off when I try and screw then in. I experimented on an of cut and found that I could screw them in without pre-drilling but if I stopped before they were flush the screws would shear off if I tried to drive them in further or remove them. Then I experimented with pre-drilling with a compound drill bit (small hole at bottom, larger hole at top and countersink all in one. That seemed to work fine on my test pieces. I could screw in and out.

So on to the real thing and the first screws I put in sheared before it was home. So I tried pre-drilling with a 2.5mm bit and the next screw sheared. On the third on I tried with a 3mm bit ad it still sheared. So on to a 3.5mm bit and I got two screws in before shearing the next two.

Sheared screws become a major problem as I can't get the broke off bit out without destroying my joists and I can't get another screw in without leaving holes all over the deck boards.

The screws have a 3.5mm shaft at the top, a 3.2mm shaft in the threaded portion and the threads have an outside diameter of 4.6mm.
I am concerned that if I drill a bigger hole the screws will not hold.
I am wondering if I have got poor quality screws. Are stainless screws inherently weak?

Should I be looking at stainless steel twisted nails? I am concerned with nails as if I hammer one in screw I will have to ruin the deck board to get it out. I though that screws would be more forgiving.

Any comments will be appreciated as I am becoming really frustrated.

Thanks.

Sean

[zenwood]

4.5 mm holes?

[Dr Dee]

Sean,
I used stainless twist NAILS for a small deck I built a while ago. Worked fine and none have popped even though the deck has been through a few wet/dry cycles.

If you can't return the nails, then as zenwood suggests make the hole bigger since the fact that they are shearing means you still have a problem. What are you using to screw them in? If you are shearing them off then it sounds like you are using a drill not a driver with a clutch. Better to get one.

You say the joists are hardwood so if it is really hard and dry, probably you will need predrill. I normally drill a hole which is the same diameter as the base of the thread at it's thickest point. Otherwise just keep making the hole bigger until all goes well. Make it too big and you lose the benefit of screws.

cheers

[rod1949]

You must have or should I say had lots of dollars for SS screws.

Being in hardwood, you will need to drill pilot holes (should do this for any wood actually) for nearly the full length/depth of the screw.

A bit of lubricant like scraping the tips of the screws into moist soap will work a treat, or bees wax or grease. But with grease the bit that oozes back up to the surface could affect you finish if not cleaned off properly.

[Trav]

Sean

I used some SS screws for a garden screen I made (see http://www.woodworkforums.ubeaut.com.au/showthread.php?t=20204) and I had the exact same problem. The damn screws kept shearing off and you couldn't do squat to get them out. I actually glued a few heads back on to keep the uniform look. Don't tell anyone. :eek:

My solution was to keep increasing the pilot hole until they were easier to drive. I can't recall what size bit I ended up with.

I built the deck using hot dipped gal twist nails and that worked a treat. I still needed to pre-drill, but they were pretty easy to drive home. The screen was built in-situ so I couldn't hammer the nails in easily, hence the screws.

My advice is to increase your bit size and countersink the heads (although I don't think countersinking will help stop shearing). If that doesn't work, switch to nails. :)

1500 screws - I hope you have a good drill and driver. :D

Trav

[gatiep]

Predrill to beyond the full depth of the screw, use lubricant and a driver with a clutch. If they still break, perhaps exchange the few you havn't broken for some brass screws.

[Ashore]

Can think of a couple of things

for ten gauge screws the drill size is 1/8" or 3.2 mm
if they are full thread screws and the stainless ones usually are then this is ample
If they are not full thread then you will have to drill clearence hole for the shank
A common reason for breaking is that the boards are not down hard on the bearers , the thread in the bearer is still trying to pull the board down , but the thread in the board is down hard against the counter sunk head
Drill a clearence hole through the board and only drill a 3.2 or 3.5 hole in the bearer to pull the board down
Or clamp each board at each bearer before drilling and screwing , though I think a clearence hole , bigger than the outside size of the thread through the top board will solve your probilms.

Also go with the lubricant , even oil helps
Make sure your drill is on clutch and not direct drive, though this shouldn't be your problim on this job
Russell



Useless infomation for the day

If you drive like hell, Your bound to get there.

[BrisBen]

Impact driver

They work quite well although they can be expensive

Also see if you can find a contact number for the screw manufacturer and enquire about the optimum RPM and torque for driving the screw - they should have this data.

Then you can work out if you are driving them to fast, to slow, with too much torque or not enough

or you just have the wrong screw gun...

[Chris Parks]

I suppose I have put in about 5,000 SS screws in decks and fences. I used 8 guage 40mm, some into hardwood and some into pine. I used a 9/64 drill/countersink for all of this and the only problem I had was making sure the drivers were in good condition, as worn ones rip out the tops of the screws. If you are seating the screws and they are snapping off at that point use a softer clutch setting on the driver. I used screws with the view to having to replace boards and I have found this necessary and easy over the years. SS screws bought in big quantities are not hugely expensive and always look good, they can be re-used and removed with no problems at all. Definitly use as big a drill as necessary in hardwood. They won't come loose.

[kiwi_alien]

Where does one find decent SS screws...

When you're needing a thousand or so it'll be nice to find a good supplier.

Austin

[manoftalent]

Can think of a couple of things

for ten gauge screws the drill size is 1/8" or 3.2 mm
if they are full thread screws and the stainless ones usually are then this is ample
If they are not full thread then you will have to drill clearence hole for the shank
A common reason for breaking is that the boards are not down hard on the bearers , the thread in the bearer is still trying to pull the board down , but the thread in the board is down hard against the counter sunk head
Drill a clearence hole through the board and only drill a 3.2 or 3.5 hole in the bearer to pull the board down
Or clamp each board at each bearer before drilling and screwing , though I think a clearence hole , bigger than the outside size of the thread through the top board will solve your probilms.

Also go with the lubricant , even oil helps
Make sure your drill is on clutch and not direct drive, though this shouldn't be your problim on this job
Russell



Useless infomation for the day

If you drive like hell, Your bound to get there.

yep in agreeance there .....make sure you drill through the hardwood barers too...now to set up your drilling .....drill a pilot hole with what you think should work ..I never use any drill bit more than half the thickness of the screw used ....as a guide ...now drive it in by hand using a screwdriver ......( its that long thingy with a handle on it :U )...now did it get really tight before it hit home? did you almost rip the head ?.....try countersinking just a tad deeper ......and redrill a bit deeper (put the whole bit in it wont hurt).....then try another by hand ...if this feels easier , then it stands to reason it should work ok with a handdrill....

sometimes these all in one drill/countersink bits are not exactly right for the particular job ....(timber may be too dry, hard,etc)....you may be better off using a seperate drill bit , and then countersink ....

[UteMad]

Hi,
I elected to screw my deck boards onto my hardwood joist. I have been lead to believe that screwing the deck is better than nailing (lasts longer). I bought 1500 stainless steel deck screws (Wilbert? Stainless steel Type 17) 50mm long. I believe that they are grade 304 Stainless and gauge 10.

I am having a huge problem with the screws shearing off when I try and screw then in. I experimented on an of cut and found that I could screw them in without pre-drilling but if I stopped before they were flush the screws would shear off if I tried to drive them in further or remove them. Then I experimented with pre-drilling with a compound drill bit (small hole at bottom, larger hole at top and countersink all in one. That seemed to work fine on my test pieces. I could screw in and out.

So on to the real thing and the first screws I put in sheared before it was home. So I tried pre-drilling with a 2.5mm bit and the next screw sheared. On the third on I tried with a 3mm bit ad it still sheared. So on to a 3.5mm bit and I got two screws in before shearing the next two.

Sheared screws become a major problem as I can't get the broke off bit out without destroying my joists and I can't get another screw in without leaving holes all over the deck boards.

The screws have a 3.5mm shaft at the top, a 3.2mm shaft in the threaded portion and the threads have an outside diameter of 4.6mm.
I am concerned that if I drill a bigger hole the screws will not hold.
I am wondering if I have got poor quality screws. Are stainless screws inherently weak?

Should I be looking at stainless steel twisted nails? I am concerned with nails as if I hammer one in screw I will have to ruin the deck board to get it out. I though that screws would be more forgiving.

Any comments will be appreciated as I am becoming really frustrated.

Thanks.

Sean

Hi Mate...

You will definately need to pilot and countersink the board regardless of the joist material for a quality job.... My guess is you have been sold the chipboard version of the screw as they are cheaper for the merchants to buy.......


The proper 10Gauge screw will need a 1/8 pilot and 10g countersink
If you compare your screw to a chipboard screw of the same size you should notice the following


The thread on the chipboard should not match your stainless screw ... your staainless screw should have a flatter less aggressinv thread ( more turns for the same length)
Your screw should have a deeper coutersink (Marginally)
The shank where the thread stops should be a lot thicker than the chipboard screw......
Yours should look like an old 10 gauge wood screw of the flat head era

The hardwood batterns aren't kiln dried are they???

My guess is you have worked out that your screws are stainless chipboards which are classified as 8 - 10G which is a massive over statement..... Did you pay around 150 bucks per thousand??

cheers utemad

www.dialadeck.com.au (http://www.dialadeck.com.au)