Just finished some dog jumps for a local training facility. There are also several more coming .
Right now they look great and i want them to retain some sort of beauty over the years. As with PT lumber, warping, twisting, cupping, crooking, bowing is unavoidable.
Can you experts suggest to me the best way to prevent or resist the natural tendancy to turn into pasta noodles.
Several sittes I have visited negated each other and differ in methods,
I need suggestions from people that have succesfully built out of PT wood and and retained their appearance (and reputation).
I have already advised my client that PT lumber is notorious for movement, but i still would like your advice.
thanks
Replies
I've built lots of stuff out of PT wood, not so much for clients but around our property. My considerations are:
- For any cuts made in the middle of a board, I always soak the end grain in wood preservative to allow the exposed untreated area to soak up preservative. Five minutes minimum.
- This may result in a somewhat blotchy look (as the soaking preservative always looks a little different from the factory preservative). In my experience the difference blurs after a few weeks in the weather, but if you're worried about the immediate acceptance of a client, take a minute and quickly brush a bit of the stuff all over the rest of the structure.
- I like PL Premium if I need glue.
- Of course always use fasteners rated for PT wood.
cuta
Screws b/4 nails.
Predrill slightly oversized for the shank-especially near ends.
When possible, keep open end grain away from direct ground contact.
Oh ya... Cal reminded me.
I don't know if this is being particularly "anal", but if I'm building a structure that requires boring largish holes for lag fasteners (maybe countersinks too), then I always dump a bit of preservative down the hole before driving in the fastener. The thought being that the hole is bored into completely untreated wood.
I have no idea if it makes a difference, but I figure it's a detail that a client might like.
Look for KDAT PT
Kiln Dried After Treatment
Lot less moisture in it to cause problems later...
Mostly you just want to seal the wood well, preferably before assembly. By sealing you slow the drying process and the wood dries more evenly. It's primarily uneven drying that makes wood warp.
There are some special wood coatings sold to folks who run their own sawmill operations, the coatings to be used to coat logs waiting for cutting and prevent splitting/warping. One of those coatings might be ideal.
This may not be practical for your situation, but
the two decks I've renovated both twisted, warped, bowed, cupped, etc. after a few years. I don't think this can be avoided with PT lumber. But what I've done is wait a few years for it to move all it's going to, then I'll replace all of the nails that pulled out with screws, and then belt sand everything flat. I did this about eight years ago on my current house, and it's still flatter than new, and the finish, an oil-based Cabot semi-transparent, lasts much longer..
end sealing
As others have said, sealing the end grain will help with the differential drying problems. Here is a link to an end sealer like Dan mentioned. It is available at a lot of places, but this is the most reasonably priced source that I've located.
http://www.woodworkingshop.com/cgi-bin/799DE316/mac/additmdtl.mac/showItemDetail?item=SK60000&qtyA=0&phsO=N&desc=SEALTITE%20WOOD%20SEALER%20%28G%29&drpshp=N&alOrd=Y&iQty=.000&oQty=.000&initQty=1&assortParent=N&itemForSale=Y&styleName=&fixD=&face=.00&gftc=&stck=Y&prefS=&calledFrom=DS&ordInfo1=&ordInfo2=&ordInfo3=&ordMan1=N&ordMan2=N&ordMan3=N&persCode=&persReqd=&persLink=%20&shipRemaining=0&daysBetween=0&daysBetweenFix=0&monthsBetween=0
However, that is really a temporary type product. People that do Adirondack chairs and other outdoor furniture use other methods. Some will soak the end grain in thinned epoxy or use something like the Minwax Wood Hardener to seal the end grain, but you probably need to let the wood dry out first. How those methods will work with very wet PT stuff, I don't know.