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Log cabin floor system question

Started by Mlanier, July 02, 2022, 08:27:38 PM

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Mlanier

I've noticed that most of the log cabins stack the logs on top of a floor system.
My question is for a smaller cabin why is this method better than having the floor joists butt into the first course and be supported by a ledger?

beenthere

Show us how you think that would work better. 
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

IndiLina

I'm building one with your proposed method. I'll let you know how it turns out if I ever finish it. 
Tracts in So. Indiana, Nor. NC, SW Virginia

kantuckid

My home is built mostly as a copy of a New England Log Homes pattern using local materials. They are engineered designs and my floor system uses their design of mostly standard joists system and support beams & support posts for inner log walls.
The log wall edges are much beefier design being the main exception to a stick building.
 The floor system sill sits on 12" blocks (not my 1st choice but...) then the rim joists are edge doubled plus a 12" wide box is built around the perimeter with spaced cross blocks between another inner joist. The subfloor sits on top of it, then the logs.
 
My current small cabin build I have 6 x 10 oak beams sitting on concrete piers, then the joists dropped within the oak beam frame.
 Just finished a diagonal pattern rough lumber subfloor on top for my "dance floor in the woods" affair :D 

Both log buildings I flashed the top edge of subfloor on the outside of the rim joists or oak beams to be later covered with peeled log slab trim boards. 
Kan=Kansas;tuck=Kentucky;kid=what I'm not

Don P

An inside, independent floor is typical in the old log cabins here. I removed and replaced with what I believe was the third floor system in one. It did allow independent levelling and repairs, foundations were junk. I put a stepped foundation in it, a 2' thick stone and concrete perimeter wall that had an interior dropped "shelf" extending inboard to support a modern treated sill and joists. I then tied the logs to the floor, get some diaphragm and connection outta that big flat plate.

Mlanier

I'm sure there are advantages to setting the first course, or round, of logs on the subfloor or most of the log builders wouldn't be doing it that way.
My thoughts are that wouldn't it be better to have the flashing right on top of a treated sill plate under the first course instead of having the flashing on top of a subfloor under the first course? 

Don P

Think about wiring... And I can't remember how we did the one I was describing. I'm doing a house now, stick frame with 8x8 sills, sort of the same challenge, drilling intersecting holes and fishing.

kantuckid

Quote from: Mlanier on July 03, 2022, 07:14:25 PM
I'm sure there are advantages to setting the first course, or round, of logs on the subfloor or most of the log builders wouldn't be doing it that way.
My thoughts are that wouldn't it be better to have the flashing right on top of a treated sill plate under the first course instead of having the flashing on top of a subfloor under the first course?
I have a bunch of new metal the mfg ran the wrong size for my homes gable rafters but will be used now on my subfloor with a 4" angle above and 7" hanging down onto my 10" oak. I'm placing a run of 5" alu flashing on the bottom edge of oak beams then the steel hangs and laps over that. The first log run will sit on the 4" angle sealed to the subfloor. 

What is your thinking towards the flashed sill vs. the subfloor? Not that mine will change since the subfloors down already :D. 
Kan=Kansas;tuck=Kentucky;kid=what I'm not

Mlanier

I was thinking the flashing on top of the pressure treated sill plate, which would be under the first course, then the flashing would bend down 90 degrees for 1/2", then bend out 90 degrees far enough to cover whatever stone veneer I choose to cover the foundation, then a slight bend to shed the water.

Don P

Deck/ porch attachment? Just hitting details as they come to mind.

Mlanier


Don P


kantuckid

Chiming in on Mlanier- I already did... ;D 
My front porch floor system perches a beam (also attached to the oak beams) across the long/front side upon an edge of a concrete pier then extends 8' across the front requiring three more piers in an area that places them in the way to construct my main log walls for now. 

"Some day", down the road, I have a nice, nearby collection of flat stones that showed up as I leveled the build site several years back, to be used as a means to make my end three concrete sonotube piers appear to be square rock support columns. I'll dig in a bit and lay them up surrounding those columns you see as you come upon my cabin. The oak frame gets slabs on it, no rock. My home I laid rock around the entire foundation up to a double row of slabs-after we moved our babies inside.  
Kan=Kansas;tuck=Kentucky;kid=what I'm not

Don P

That word picture would require a sketch. Mainly think through flashing and exposing hard to replace structural elements.

jake pogg

That's a tricky question. Both ways have their pluses and minuses,sometes significant ones.

Some things depend on what kind of log system is used.

If scribed round logs,try to picture the first half-course,and the three-quarter one going into concrete foundation,it could be tricky due to the taper especially.

I've done it both ways,and at times regretted not doing the Other way.


Once,when skirting the wall over the floor,I had significant trouble adjusting insulation to the logs on the inside(but that was a 5-sided cabin,a log builders nemesis and nightmare).
It's vastly simpler to put the logs onto the floor platform. Whatever aesthetic inconsistencies can be addressed later by using scrap remnants(log "siding" style).
That way all the flashing problems become much simpler,you're going from a dimensional rim joist to the foundation,and that joist can even be treated also.

I also hope that the flashing is pro forma,as in that your overhangs will be ample enough for it to almost never actually come into play...
"You can teach a pig anything,it just takes time;but what's time to a pig?"
Mark Twain

jake pogg

P.S.Skirting the logs over the wall will use up Considerably more logs,once it took me two and a half courses to clear the wall.

Make sure you take that into consideration.

"You can teach a pig anything,it just takes time;but what's time to a pig?"
Mark Twain

Joe Hillmann

My plan is to make my first course full length sill logs.

The second course will also be full length but notched out for the floor joists.  Then stack the wall on top of that.

I plan to do the same for the loft floor.
A full length log below the joists, a full length log at the joists that is notched out for the joists and continues stacking 4 rows on top of that.

Building this way I am using two extra courses of logs compared to starting on the floor.  If you are using sawn joists instead of log joists it would be more like 3 extra rows of logs.

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