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Can anybody tell us why we use rot resistant species for decks and exposed wood? PT, cedar, redwood, cypress, all are a good idea in contact with the ground, but up on the deck what’s the point?
We’ve got to do something to seal the deck to protect it anyway, why not just use regular lumber and seal it against the weather. Rot really isn’t an issue above grade, not nearly as big a deal as cracking, splitting, cupping, etc.
We’ve all seen 100 year old window sills that were kept protected and are in great shape after a century of weather exposure.
So why do we do this?
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Ryan,
It's because it's easier. Deck boards are made out of this stuff. Otherwise, you'd be using dimensional spf, and have to rout the edges and treat each cut, prime like a fool. Think about the quality of the boards too-these days pt deck boards are much better quality than most dimensional construction lumber.
And, it would still not last as long. Don't forget that your work would be subject to the homeowner's maintainence schedule-do you want that?
MD
*ryan .. i've been building since before there was pressure treated available anywhere except marine construction....there was plenty of rot in deck boards.. no matter how careful.. no matter how they were sealed... do you remember cuprinol green..or creosote ?any how.. the PT has changed the way things are done.... for the better..i've had excellent luck with luan decking. with no sealer... but PT is the average man's answer to a along lasting deck.... my own favorite is trex..the PT lasts but the splinters and splits and checks are just too much...
*Mike:Wasn't it "fun" getting all the creosote off everything? Or, spilling some where the owner didn't want it?No, I agree you can build without pressure treated, and it will do just fine if the situation is right. But, PT makes things so much easier and better.
*Ryan - how you gonna recoat the tops of deck joists? Or the joists of a low deck? I really like the rot and bug resistance of PT structural members for decks, but still prefer Western Red Cedar for the deck boards themselves.
*just to add my two bits, I just demo'd a small deck that bore pt joist on a pt 4x4 grade beam over pier pads. Now this 4x4 was just high enough to keep the bottom of the joist off the dirt. The joist had much problems, getting eaten by ants, and showed signs of failure, especially at the cut ends into the ledger, and at the cuts for the step. We were sort of marvelling at how poorly the pt joist had held up to only 14 years of weather. Then we got to the 4x4 that had spent the years half- buried in the dirt. No rot, no carpenter ants, very solid. Whats up? Doug fir 4x4 and hem fir joist? Do you guys know of any product that will add extra protection from carpenter ants and rot, over and above CCA? Using ground-contact on the new structural members, over a concrete grade beam with pt mudsills. Anyone ever joist an exterior deck with steel? Mad Dog, the esteemed and highly respected architect has erased the porch on the sides of the house, so I'll post a drawing of my idea for the radius corner sometime for your perusal.
*Ryan I wish I new why we have to pack these fresh out of the pond, incised pressure treated hem fir joists that weigh a ton, from the front of the house to the back , probably cause there are no alley's in the burb's of Seattle. I do know that you can't save the extras for the next job, cause they shrink a full 1/2" when they dry out. Athough they are guaranteed against bugs and rot for fifty years I'm not going to be around to validate that. I do know that I replace alot of decks that are not treated due to rot, but then again it is known to rain a little here in WA.
*Nathan:The 4x4s were .40 treated heartwood from a lumber yard. The joists were .20 treated from Lowes! It used to be that you didn't see too much .40 dimentional lumber. We are seeing it more and more these days.
*I think Matt has the answer. Although around here all of our PT 4X4 posts are .60 and the joists are .40 with .60 being available on special order. .60 is specified for PTW foundations or "foundation grade". I never was sure whether the PT was heavy because it was fresh from treatment or because the lumber yard never kept it out of the rain. Now that we had such a hot dry summer and the PT is STILL weighing in like solid steel it MUST be chemicals...gloves anyone??? Now if I could just find some of that phantom KDAT (Kiln Dried After Treatment) Wonder what IT costs.
*Fred, Mike,Your comments on creosote reminded me of a funny (in hindsight) experiance I had. It was summer between my junior and senior year of high school(1970). It was also my first summer working for my mentor, a local contractor who did just about everything "pertainin' to a house or building".He left me and another guy on a small job while he ran a "quick" errand. We finished the work, and being such a hot day, went out to the devilstrip to wait for him in the shade of a big maple tree. The electric company had a brand new utility pole laying there that was just the right size for me to sit on. It was brand new and practically dripping with creosote.You can probably guess what happened.I didn't notice a thing until after about thirty minutes or so. I began to feel a strange itching sensation on my rear end. By the time the boss showed up that itching turned into a full blown burning sensation. I hopped in the truck, and couldn't sit down, it burned so bad. He had to explain to me, through the laughter, why I was in such pain. He was laughing because it apparently was quite a sight to see me wedging myself up with my elbows, hands, and feet, so that my ass wouldn't touch the seat. I failed to see the humor.He took me home, and I spent the next two hours sitting in a tub of cold water. That creosote burned my rear as bad as any sunburn I ever had. It even blistered and peeled like a sunburn. That was a lesson I'll never forget. If only I had known the following summer, while painting a house(we used oil based paint exclusivly back then) that a terpentine soaked rag stuffed in my back pocket would have the exact same effect.........John
*JOHN.. yep , i've had the creosote burn.... 'n the turrpentine rag in the back pocket... and pumpin gas in sneakers with a gasoline burn..and the alltime one that still gets me is the carrying rolls of 15 lb. felt on your shoulder so you get the burned neck... some of us just never learn......
*Oh that does bring back the memories! Remember cleaning stuff in leaded gas, or carbon tet? Maybe that is why we are the way we are now, eh?