Woodworking Talk banner

1 - 8 of 8 Posts

·
Registered
Joined
·
3 Posts
Discussion Starter #1
I have a pressure-treated 6x6 post pergola on my back deck. I have added a little design element and made some post bases that I've just lightly nailed on. I wasn't sure if I was going to like it when I installed it last fall, so I had only put in two or three nails in to temporarily hold it on. The bases are mitered pieces of pressure treated 1 by lumber. Now I've been dealing with some water causing warpage. I believe the 1by lumber is just too thin to hold its shape.
So I'm looking for advice on how to make this fit better and deal with [less] warping. I'm not sure if doing miters was a good thing. Perhaps I need a different fastener, glue, or a different kind of joint.
I attached a couple pictures, you can see the gap on a dry day, and then you can see it on a wet day.
 

Attachments

·
Registered
Joined
·
26,202 Posts
It looks more like a problem with the trim shrinking than warpage. In any case treated wood comes from the factory dripping wet so it should be dried before using it. It would also help if you would run grain perpendicular in direction than the post. The wood won't shrink very much lengthwise.
 

·
Registered
Joined
·
3 Posts
Discussion Starter #3
ok good to know about the grain direction. You're right, it is shrinking rather than warping (to an extent). It goes back and forth though, pretty quickly too. You can almost see it before your eyes...like an alien breathing, lol.
 

·
Registered
Joined
·
4,232 Posts
Steve has already addressed the shrinkage we expect from TL. When wrapping a post, you need dry lumber that is sized. For deck boards, railing and trim we also know screws offer more holding power than nails. For trim boards, finish screws (small headed) are preferred. All screws should be galvanized. Also caulking the seams of the trim can help keep moisture from getting between the post and the trim. If the deck will be stained or left natural you can use a clear silicon caulk.
 

·
Registered
Joined
·
646 Posts
Here’s how my cedar pergola kit was wrapped. The 2x pieces were butt jointed. Instructions were to fasten together, allowing enough slack so that they could slide up & down. Works well. It’s easy to check the fasteners to make sure everything is secure. Water also drains well (on the rare occasions that we actually get some rain).

Photos:



Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
3 Posts
Discussion Starter #6
Thanks for the pictures. That's a good idea. I think that simple screw joint you did is probably the strongest....way better than my mitered corners.
 

·
Registered
Joined
·
12,538 Posts
Here’s how my cedar pergola kit was wrapped. The 2x pieces were butt jointed. Instructions were to fasten together, allowing enough slack so that they could slide up & down. Works well. It’s easy to check the fasteners to make sure everything is secure. Water also drains well (on the rare occasions that we actually get some rain).

Photos:



Sent from my iPhone using Tapatalk

Hello. You in the dry land or irrigated cotton country?


George
 

·
Registered
Joined
·
646 Posts
When I got here some 40-odd years ago it was all dryland. Now pivot systems have increased so much that I believe 1/2 or maybe more is irrigated.

Here is how my homeplace looked this morning after last night’s storms:



Sent from my iPhone using Tapatalk
 
1 - 8 of 8 Posts
Top