Home>Discussions>EXTERIORS>Basic Carpentry Project - Screw Questions
13 posts / 0 new
Last post
jmcgowan
Basic Carpentry Project - Screw Questions
jmcgowan

Hi - I am new to this forum, and also new to building things. My first project is a raised garden bed, which will be of 2-by-12s of cedar. The dimensions will be 30" W x 12' L. Four 4-by-4 posts, 18" L, will hold the four boards together.

1) The directions call for "3-1/2 inch #14 wood screws". I cannot find these at my local hardware store (or HD) in stainless steel. (I want stainless steel since the bed is outside and I don't want the screws to rust.)

Can I use a 3-1/2" stainless steel "deck" screw instead? Or another type of screw? Other than stainless steel, I'd like the screw to be flush with the wood.

2) I am attaching via clamps eight 12" long, 1" diameter PVC pipes to the inside of the bed so I can bend pipes and connect them between the two 12' sides, so "half hoops" are formed. This will allow me to place a cover over the hoops to keep the garden bed warmer during the cold growing months.

The directions call for 1/2 inch #8 wood screws. If I cannot find these in stainless, either, can I use a 1/2" to 3/4" stainless screw as long as it fits in the clamps' holes?

Sorry, I know this is basic but I'm getting different answers and thought someone knowledgeable here could help me.

Thanks! Jody

A. Spruce
Re: Basic Carpentry Project - Screw Questions
A. Spruce

Screw technology, or rather, coating technology has progressed over the past decade or so. I'd be willing to bet that you could use a coated "deck" screw without fear of it rusting or staining the materials. Keep in mind, that as the material ages, it is going to weather, a little fastener discoloration or rusting is merely going to add to the natural patina of the wood.

I just built several raised beds myself, and I used a #10 coated deck screw. I can tell you that the beds that these replace lasted about 10 years, and it was the lumber that rotted away, not the screws.

As for what to use on the pvc tube clamps, I'd stick with a shorter version of the coated deck screw, which can be had to as short as 1-1/4". Assuming the tubes are attached to the inside of the bed, there is no real tension on these screws, the nature of their environment is going to promote corrosion/wood decay along the threads of the screw, a screw longer than 1/2" will survive over time, where the shorty will simply "rot" and fall out after a few years. If you are attaching the clamps to the outside of the bed, then you're definitely going to want longer screws to withstand the tension of the canopy rods.

ed21
Re: Basic Carpentry Project - Screw Questions
ed21

Pretty much agree with what's said. Drill proper sized pilot holes. Countersinking for flush fit may not be required since cedar is fairly soft, but a slight countersink may help get it started. It is a garden bed, not a piece of furniture though. :)

dj1
Re: Basic Carpentry Project - Screw Questions
dj1

"1) The directions call for "3-1/2 inch #14 wood screws". I cannot find these at my local hardware store (or HD) in stainless steel. (I want stainless steel since the bed is outside and I don't want the screws to rust.)"

You can use galvanized outdoor screws or nails, if you can't find deck screws in the size you need. Keep in mind, there are no 100% rust free fasteners.

keith3267
Re: Basic Carpentry Project - Screw Questions
keith3267

You don't have to use the exact size of everything specified. A 3.5" #9 or #10 deck screw will work just as good. You can get them in ceramic coated steel or stainless steel, both are very corrosion resistant. You will find it a lot easier if you get torx head screws with the self drilling and tapping tips.

If you haven't bought the PVC tubing yet, let me suggest an easier alternative, concrete reinforcing mesh. Its a 6x6" mesh of soft steel wire. You can get it 6' wide in 20 or 50' lengths. Its easy to shape and you can attach it to the wood with crown staples or nails. You can use it to make tomato cages as well.

Another alternative for the screws would be headlock screws. They grip much better than deck screws, but they cost quite a bit more.

Re: Basic Carpentry Project - Screw Questions

Thank you for your responses! I really appreciate it, very helpful information. Cedar is being delivered today, so I'm out to buy the screws based on your advice :)

Sombreuil_mongrel
Re: Basic Carpentry Project - Screw Questions
Sombreuil_mongrel

I second the Headlok screws, use the 4 1/2" length. pre-drill with a long 3/16" bit

Casey

keith3267
Re: Basic Carpentry Project - Screw Questions
keith3267

Pre-drilling is optional with headloc screws, they have a chisel point that drills and taps as they go, and cedar is a soft wood so it is less prone to splitting. Pre-drilling the first inch does make them easier to screw in though.

A. Spruce
Re: Basic Carpentry Project - Screw Questions
A. Spruce
keith3267 wrote:

Pre-drilling is optional with headloc screws, they have a chisel point that drills and taps as they go, and cedar is a soft wood so it is less prone to splitting. Pre-drilling the first inch does make them easier to screw in though.

The thing about pre-drilling, even with a headloc screw, is that it allows the shank of the screw to slip in the first piece so that it draws it down tightly to the second piece. While not a necessity with a soft wood, definitely a benefit.

To Jody, if you decide to pre-drill, choose a drill bit that is the same diameter or slightly smaller than the shank (no threads ) portion of the screw. When drilling you want to penetrate all the way through the first board and slightly into the second, which will align the pieces and start the screw in the right direction to pull the pieces tightly together in alignment.

Good luck, take pics, and report back on your progress.:cool:

Sombreuil_mongrel
Re: Basic Carpentry Project - Screw Questions
Sombreuil_mongrel
A. Spruce wrote:

The thing about pre-drilling, even with a headloc screw, is that it allows the shank of the screw to slip in the first piece so that it draws it down tightly to the second piece. While not a necessity with a soft wood, definitely a benefit.

To Jody, if you decide to pre-drill, choose a drill bit that is the same diameter or slightly smaller than the shank (no threads ) portion of the screw. When drilling you want to penetrate all the way through the first board and slightly into the second, which will align the pieces and start the screw in the right direction to pull the pieces tightly together in alignment.

Good luck, take pics, and report back on your progress.:cool:

We were on one job where we were buying those screws in 250-piece buckets, so while drilling is officially optional, I would still recommend it.
The drawing-together part is not an issue, because only the last 1 1/2" of the end is threaded. I would drill so there is no thought of splitting, and so the screw drives in the exact direction you want. They can follow the grain.
If this is nice clear dry cedar, take the extra step and seal the end grain of the corner joints with some Titebond III glue, it will prevent water damage; the end grain is like a sponge.
Casey

keith3267
Re: Basic Carpentry Project - Screw Questions
keith3267

Unlike most screws, the threads on the headloc screws stand proud of the shank. This means the shank now slips easily in the hole after the threads have passed through and allows them to draw up easily even when the wood is not predrilled. This also makes them grip better.

Pages

Sponsored Stories

TV Listings

Find TV listings for This Old House and Ask This Old House in your area.