Hello all!

I am about to raise a little timber framed porch for my cabin and have a question regarding water proofing the butt-ends of my posts.

The porch will be roofed, but won't have walls. I am not using water-resistant species for the frame (am using pine hemlock and oak for the posts). The posts just have butt-cuts and will sit directly on the porch decking (with proper blocking and supports beneath). I am worried that during heavy rain and snow storms, water will get on the deck, and could pool around and possibly under the post bottoms.

What can I use/do to separate the post bottoms from this water? I do not want to put a block of PT or water resistant wood under them, as that won't work aesthetically. I was thinking of stapling 2 or 3 layers of 30# tar paper to the bottoms and using them as a mini-gasket.

Any better ideas? I want to do something that is, ideally, hidden from sight.

Thanks!
Dan

Hello,

What is directly below the decking? Maybe make some sufficient drainage/circulation holes there under each posts. If that's not feasible I have cut channels in the post ends for air to move through, (in theory that is, does wonders for your peace of mind anyway).
I would be wary of any gasket idea that could hinder circulation and trap moisture at such a vulnerable place.

Greetings,

Don Wagstaff

use some abs or similar plastic, 1/4" (ideally 1/2"-3/4" or more, for better protection), you can get it in black.
cut it so you have 1/2" reveal all the way around, when centered under the post.
it will create a simple shadow line, and help prevent water from being drawn up into the post.

and you can add some ice and water shield to the post bottoms, or heavily coat them in anchor seal.

you do need to get them up off the deck.

One idea that I have had for this is to relieve the bottom of the post 1 1/2", 45 degrees on the perimeter. You can then inset a 2x treated piece on to the bottom of the post and never see it.

Hello,

But keep in mind the root cause of the problem at hand which is, unavoidably, the posts being supported at the deck. From this beginning point all remedies will be band-aids and if not broadly considered will simply displace the potential for real problems and, worse yet, create new headaches. With the suggestion of a gasket or elevating the posts, the problem there at the posts may well be addressed but what about the decking material where there is now a place cut off from proper air circulation and an interface of two dissimilar materials where condensation will build up and be retained, microbes will become active, wood rot will set in.

Short of a structural solution, I would go even further than I suggested to begin with, outlining the place of the posts on the deck, hollowing the material out there by 3 to 5 mm, leaving a ledge of a centimeter or so supporting the perimeter of the posts, sloping to a drainage hole centered directly under the posts, plus cutting two channels through the bottoms of the posts, 25 mm deep by 10 mm wide, perpendicular to each other, crossing at the center point of the post, or another configuration of your choosing. It's a matter of creating the maximal potential for circulation within the parameters Dan has given.

Greetings,

Don Wagstaff