PT stair stringer ?? – allow for shrink?
McDesign
| Posted in Construction Techniques on
Okay – always when making exterior porch stair stringers from SYP PT 2x12s, they’re soaking wet from the treaters. Lay ’em out really nice, make the stairs. As the 2x12s dry over a few months, the “points” of the stringer shrink towards the back – slightly tipping the stair tread down, and the riser back.
It’s not a lot, but it does happen. Has anyone ever “pre-compensated” for the shrinkage by initially angling the tread up at the front, and the riser forward at the top? Say each about a degree? This would make the initial included angle of the tread to riser about 88º rather than 90º.
Might try this on these stairs tomorrow – found some sweet Ipe for the treads and risers.
Forrest – not a Stan
Replies
I try to think far enough ahead and select good PT stock for those, then get it drying someplace.
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Over here all the wood we use is PT and soaking wet from the sea voyage and sitting out in the rain every day. The wood is so wet that the water and PT run out in front of your saw blade and there is no sawdust if you try to use the wood straight from the LY. So, I always try to sticker a pile of wood at the jobsite about 3 weeks ahead in a dry and possibly sunny location. That takes care of the shrinkage, extra weight, and moisture. Oh, what was it like to be able to lift six studs at once, on two or sometimes three over here, until you get 'em dry. What to do about your current problem, I don't know?Never fear the want of business. A man who qualifies himself well for his calling, never fails of employment.
Thomas Jefferson
3rd president of US (1743 - 1826)
Sorry Piffen, I meant that for the OP, just another one of those return button things. Too quick on the button.Never fear the want of business. A man who qualifies himself well for his calling, never fails of employment.
Thomas Jefferson
3rd president of US (1743 - 1826)
No sweat.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Morning bump.Yeah, I know I could have gotten the wood in the summer and let it dry. Unfortunately, she just decided she wanted new steps a couple weeks ago.Sheesh.Forrest
Well, how about trying your scenario, but without the fancy ipe treads/risers. If you have some sacrificial types available you won't risk anything if the shrinkage doesn't play out to your preconceived notions. And you can swap them out for the real thing on your next trip up.Steve -- An Azektec - a central American tribe favoring sacrificial rites for wood and non-wood products.
'Man who say it cannot be done should not interrupt man doing it' ~ Chinese proverb
I try to pick out qtr.sawn PT for strings- I look thru the lumber piles for it. But my lumber yard will allow this- some won't.
Qtr.sawn minimizes the shrinkage across the board.
Well, I didn't pre-slope them, but I did try to pick out "sorta-quarter" sawn PT 2x12s. See what happens.
Forrest
It's worked pretty well for me. It does shrink, but ( I think) not as much as flat sawn.
Is that the stairs where you're looking for the CMUs?
Yes - not only were they wet, I sawed and put them in in the rain.
Forrest
Have you check with your suppliers to see if anyone has KDAT (kiln dried after treatment) lumber..
.
A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
You gotta wait until the first rain you guys have had in months to to this outside work?
Work was in VA - we did get lots of rain here, it turns out.
Forrest
Can you rough cut them and fit them in your kiln shed and fire something?