Drawboring treated lumber

[Charles Wiggins]

I need to build a stand to elevate a water tank we're going to use to collect rainwater for watering the lawn & garden during dry weather. I'm planning to set 4x4 posts on Handi-Blocks and build a platform atop that, kind like a mini deck. I thought I would mortise stretchers between the 4 bys to give it some stability, kinda like a Roubo workbench. I figure it would save on the hardware expenses and give me some experience doing M&T joints and drawboring.

Never done anything quite like this, so I have questions:

1. Anyone ever done a drawbore in treated lumber? I have a feeling it will be problematic.
   
2. Should I just peg it instead of doing a drawbore?
   
3. I have white oak logs on hand, but should I use something else for the pegs?
   
4. Will it be more problematic, being out in the weather?
   
5. Is this just a bad idea?

Thanks,
Charles

[Jim McGee]

If it was me I would probably skip the treated wood, heavy wet stuff. the treated wood will probably warp or twist as it dries. I would try to buy air dried rot resistent wood like cypress.

Look for wood with straigh grain, no grain runout .

[greg Forster]

If I understand correctly, you will be building a stand to place a rain barrel on. Pressure treated 4x4s with cross bracing- thru bolted with galv. carriage bolts; since you are setting on blocks vs posts in post-holes, you will need
the braces and platform to provide the rigid structure. I would not to build a stand more than a couple of feet in height.

Save the draw-boring/pegging/etc for another project- maybe a garden gate?

[Andrae Covington]

I've never tried it, but my guess is that the pressure-treated wood won't play nice. I agree with Jim that it tends to be sopping wet when you buy it and then likes to warp as it dries. In 2x# boards, you could dig through the pile for ones that are more quartersawn, but with 4x4's, about the best you can hope for is riftsawn, and it's still going to twist. Beyond that, I think the wet wood will have a tendency to close up on your bit as you drill. If you can get it all together though, ironically the pegs might last longer than carriage bolts or screws, since the pressure treating chemicals corrode metal fasteners after a while. White oak is a good choice for the pegs, it is a reasonably durable outdoor wood due to tyloses in the pores; red oak by comparison would rot in no time. As an alternative, Greg's crossbracing idea sounds good to me.

[Russ Webb]

I've done it and it seemed to work fine. There are considerations with wet wood of course but it's worked fine for me so far. However, if the wood won't be in ground contact I'd probably use cedar or doug fir posts to avoid the chemicals. All the construction lumber I buy is wet but I've been able to pick through and find some very nice straight grained cedar from time to time. Good luck.

[Mark Kornell]

I've also done it. PT 6x6 posts, and untreated dimensional lumber for the rest. All drawbored with white oak pegs - the only metal is the fasteners holding the posts in the saddles at the ground. Very sturdy when locked together.

Garden Arbor - Unfinished - Iso Low View - Web.jpg

The wet wood made some of the joinery tiresome, but otherwise was fine to work with. Just keep your chisels and saws sharp. And knocking the pegs through 5 1/2" of wet wood worked best with a sledgehammer.

The wet posts shrunk slightly when drying, and completely locked in the oak pegs. If I wanted to remove them, they'd have to be drilled out.

The lumber does look better painted:
Garden Arbor - Finished - Iso High with Trellises.jpg

[Russ Webb]

Very nice! I'd say your project is proof of concept. And you are absolutely right about the tiresomeness of working with wet wood.

[Jessica Pierce-LaRose]

After building a couple of things with construction lumber that's quite wet by cabinet making standards, I'd prefer drawbores to through-bolting; Drawbores seem to tighten as the wood shrinks it (as Mark says) where-as with through bolted things, I've actually had to go back and retighten bolts as things have shrunk. I imagine that was because of the length the bolt was passing through (a 2x6 if I remember correctly), a narrower member would shrink less in width, I would assume.

That said, I have much less experience in this front than others, so my thoughts aren't worth much here.

[Charles Wiggins]

There have been a number of comments about wet wood. Most of what I'd be working with are leftovers from other projects that have been sitting around in the garage anywhere from a couple of months to several years.

It would probably take me longer to do a SketchUp model than it would to build the thing, but essentially I am building a stand to elevate an IBC tote. The cage seems to be designed to transfer all of the weight to the outer rim of the base, thus they are stackable.

So I am working up designs in my head. I have a number of pieces of treated two-by, four-by, and six-by - most of them around 4' or less. I was thinking of doing a rectangular six-by frame on four-by stilts with two-by stretchers to stabilize the stilts.

Any better ideas?

[Mark Kornell]

Just do it. With lumber that size, it will be plenty strong, and drawboring will lock in rigidity.

At the very worst, you'll practise large-scale M/T joinery on some wood you don't seem to have another use for...

[Mike Holbrook]

I have been doing construction projects at my home and business for 17 years now. I am making a natural transition to cabinet and furniture construction now. I am also very interested in drawboring, but I don't think I would start with a project like yours. Lag screws and bolts are faster, stronger and much easier to remove/adjust...Any home project store will have: joist hangers, corner braces...at very reasonable prices that will make your corners and joists very strong. Many of the screws sold at home stores are used in treated wood so in my experience they are made with those requirements in mind. If you want better screws & coatings try McFeely's or GK Fasteners. Some of these screws are designed to live under salt water in lumber designed for the same purpose. Why not use the fasteners & weight supporting connectors the construction industry has designed to handle this kind of job? A woodworking friend of mine has been known to tell me not to try to make a silk purse out of a sow's ear, which may apply here.

Why not start a project to make a saw bench, workbench, tool cabinet... and practice this technique on a piece that you will have hands and eyes on for years to come.

[Dan Hulbert]

As a long time hobby woodworker, I'll offer my view: Similar to "Every project needs a new tool"I've adopted a second rule of projects "Every project needs a new skill or technique." I say, go for the draw bore.

[Harlan Barnhart]

Go for it. Drawboring works for joining green wood. Let the treated wood sit around for awhile and dry out first.