Low clearance deck solutions

Greetings all,

I've been trying to wrap my head around a design solution for a deck outside some sliding doors. There is a slight downward slope from the house, but a shallow space (perhaps 9") in which to build the substructure (where it abuts the house). The deck surface of choice is 1 3/8" x 6" cedar, and with plenty of hemlock on the lot my original thoughts were to use 6-7" round logs spaced 3-4' OC. (Planing the top of the logs where needed. The 12' length would be supported midway by a concrete pad. Am I asking for trouble (in the form of decay) by using hemlock where it will be so close to the ground? I could find a supply of 2"x8" cedar, but wish to avoid the expense, and would enjoy the experience of taking my own trees and notching the substructure. Naturally, I'd need a barrier between the concrete and the wood too.

There are many questions attached to this all, but I'll start with the issue of ground clearance in an exposed application.

Cheers,

Craig
Maine (Penobscot County)

Hi Craig,

Full disclosure: I am a decking contractor. I also have zero experiance with hemlock as it is not a species available where I live.

That said, hemlock is rated low for durability and susceptible to insect attack http://www.wood-database.com/lumber-identification/softwoods/eastern-hemlock/

Consider the difficulty in replacing one of these members if it were to fail. Low level decks are already high risk as far as decay and insect damage goes and In those situations I always specify the best quality product available. Reason being, if one of the decking boards fails it is an easy repair to remove the offending board and replace it. But if any part of the sub floor frame fails it means demolishing the deck to get to it. Especially if there is zero crawl space.

I'd suggest that the wisest place to spend your money is in the framing.

With regard to low decks in general.... Drainage, drainage, drainage. Consider areas where water will pool and allow for drainage to reduce the likely hood of your foundations sitting in permanent puddles.

Hope this is of some help to you

Check out member Jay C. White Cloud's(Master natural builder)Stone plinth techniques and I think you will find the solution that you are after.

Thanks Steven and Bill,

You've all confirmed my fears that hemlock as a species, whether because of moisture or infestation (carpenter ants, in my case), is probably not a good idea. I caught onto Jay's contributions regarding stone plinths earlier on, and think very positively of them. (And aren't they elegant?) I think that the minimal ground clearance here, coupled with the species itself, should push me to pursue other design ideas, though. I'll check that resource for information on cedar. The stock answer around these parts is, of course, "pressure treated!", but... (well, I'm preaching to the choir here...) I'll pave with flat stones or slate before I do that.

Craig

Craig Butler wrote:Thanks Steven and Bill,

You've all confirmed my fears that hemlock as a species, whether because of moisture or infestation (carpenter ants, in my case), is probably not a good idea.
Craig

Personally, I love hemlock and all other firs. These are my primary building materials. It all depends on the treatment; finish, drainage and drying.

Here is one way. The photos here of mine are Douglas Fir, not much different than hemlockYakisugi

Wow, Bill, you really have my attention now. If I mill hemlock (or spruce) green (to say, 2"x8"), and attempt this sort of scorching, obviously I'm not really drying the whole piece. Is that not a concern?

Thanks,

Craig

Working green wood has it's own skill set, but is actually more traditional than all this drying and aging. For some things dry wood is necessary, but not here, just keep in mind that wood shrinks much more across the grain than with. Study old school green woodwork and you will find joints that tighten with drying.
Charring the outer surface of a board digests the sugars that could possibly be food for mold, so you can use pithy wood without worry. The only problem I have with greenish firs is resin appears on the surface of the wood as it dries. This dries to a powder and can just be wiped off.
I think the reason for kiln drying is actually the predominance of film forming finishes that would delaminate if resins from inside the wood migrated outward. I never use these!

Thank you, Bill, for explaining why the scorching renders [green] wood less susceptible to rot and insects and thus more suited to close to ground applications. Now to the design itself, and the selection of an environmentally appropriate sealant.

Craig