The new deck is fabulous. We can sit under the large roof with the propane fire pit burning, and stay dry up here in Rainland. The cats like it too.
The cats like to scratch on one of the 4x4 roof supports. It’s on the weather side. The roof extends about a foot past the support, but it does get wet – which is why it’s pressure-treated. It would be nice if the cats had something other to scratch than the wood, so I was thinking about wrapping the bottom couple of feet in rope. Of course that would retain water around the post. Is that a Bad Thing™? ISTM that pressure-treated wood isn’t bothered much by the wet. The previous deck lasted decades. But I thought I’d ask before I did anything.
My gut says it’s okay, look to see if the wood you used can withstand direct burial in dirt or be encased in concrete (ie be used for fence posts without being up off the ground). If it can be, my guess is that it would be okay to have water being held against it, especially if it’s in a place where it’ll dry out soon after the sun comes back out.
However, you might just want to think of a way to not have moisture in direct contact with structural support if you can avoid it. Even something as simple as nailing some 1 or 2 by 4’s around the post and wrapping that in rope. That way they can rot and are easily replaceable every few years.
Also, check to see what your pressure treated wood is made from. Some of them have some nasty chemicals in them like arsenic, some have less nasty chemicals like copper. You might not want your cat scratching at that.
Where is the moisture arriving from? If it’s running down the post, you could affix pieces of chamfered timber immediately above the coil of rope - mitred so they enclose the post perfectly and smeared with silicone before you nail them on, so they seal against the post surface - these would drip any running water over the outside of the rope rather than allowing it to run down behind the rope.
if it’s splashing directly on, or soaking up from the ground, that’s a different matter and probably harder to control, but you could construct a ply box around the bottom of the post, stood off from the surface of the wood, with an air gap for ventilation, then wrap the box in rope.
If it has stiping on it it should be PWF which is rated for ground contact. It can take some moisture. Most 4x4, 4x6 and 6x6 timbers are PWF anyway. The treatment is likely ACQ but no wood treatment is meant to be ingested. Wrap it with sisal rope and your cats will love it. Post might only last 25 years instead of 30.
PT doesn’t last forever. More moisture will shorten it’s life. How much shorter a life be wrapping it with rope isn’t clear, but it will be there for years. You can minimize the problem by coating the wood with a sealant before wrapping it. Try some spray on undercoating for cars. Or do nothing, it’s not that big of a problem.
You need proper drainage. It seems to me the obvious solution is to wrap the rope around some spacers to allow an air gap. I would go to a hardware store and get some galvanized wire mesh, staple a layer or two of that around the post and then wrap the rope around the mesh. That should provide a decent air gap and the mesh wouldn’t be visible if you’re careful with the rope.
How about a box with stand-off connections to post?
Imagine a nail going through a 1x4, a stack of fender (or, better, AN370) washers, then into the post. Wrap the 1x4’s
Or get a commercial scratch pad (or 4 of them) and tack onto post.
I do hope the wood came from a real lumber yard - and that it is green in color, not brown.
The big boxes sold green lumber for years - the P-T was the only thing larger than 2x4 which was worth even thinking of buying there.
Now they’ve even got P-T unfit for any use lasting more than 3 years.
Non-Pressure Treated:
KD - kiln dried. Should be dimensionally stable.
Green - as harvested. Still full of sap, etc. Will twist, warp and split with age.
When they put “Green” on the bin, you can’t claim concealed defect.
This is one time when “Green” is NOT desirable. Green wood is not even good for firewood - it burns hot and fast and the sap explodes.
I decided not to wrap the post in mesh. The wood is rated for direct contact with the ground, and there is an air gap around the sides, which is naturally formed by the rope when it’s wrapped. I used ⅝" manila rope, since that was the closest thing the hardware store had to what’s on the indoor cat tree. They had a spool for 49¢ per foot, so I bought two 50-foot rolls for $15 each and tied the ends together with a square knot. I’d rather have wrapped the post with a single length of rope, but not if it’s going to cost an extra double-sawbuck.
Creamsicle showed up soon after I finished, sniffed around it, and started sharpening her claws. Tonka was in a chair, and I have not seen him use it yet.