hemlock sill beams vs PT

[Spruce_Goose]

Hi all.

I'm planning a 'garden tool shed' build a la Jack Sobon and Roger Schroeder. Plan calls for 12' by 16'. 3 bents. 12/12 roof pitch yielding a 16' tall structure. Will be a storage shed. Doing it mostly for the experience (and need for shed).

I am debating a handful of things right now. There are a couple canoes I would like to store in the loft that happen to be between 16' and 17'. So I was thinking of bumping the shed to 18' long. Aesthetically, does anyone have an opinion on whether to bump the width to 14' or so? I checked just for fun, and 12' by 18' is actually pretty close to the 'golden ratio' so perhaps that would look fine/good ? Going with vertical siding fwiw.

I am milling the timber from hemlock on site (chainsaw mill). Likely will mill this winter, stack it, then build next summer. I will try to box heart at least all the major timbers (8x8) but will end up with other members cut otherwise. I may be a little short on timber and may have to buy some. I am considering a conventional (or at least somewhat conventional) deck of PT then doing the timber frame atop that. Does anyone have recommendations as to how to set the posts on a conventional frame, or recommendations to not attempt it at all perhaps? Otherwise would 8x8 pt for sills be worth it or if I have it, should hemlock fair ok? Foundation isn't decided for sure but probably either stone or cinder blocks. Ground is a tad mossy but not a low spot and is basically lawn.

Thanks for any guidance,
Spruce_Goose

[logman]

I built my 12x16 shed on a PT foundation sitting on concrete blocks.  It's been up for around 5 years now with no signs of settling or shifting. 

[Brian_Weekley]

I am debating a handful of things right now. There are a couple canoes I would like to store in the loft that happen to be between 16' and 17'. So I was thinking of bumping the shed to 18' long.

Increasing the bent widths from 8 to 9 feet would be fine (I increased mine to 10 feet).

Aesthetically, does anyone have an opinion on whether to bump the width to 14' or so?

Increasing the width from 12 to 14 feet is fine too.  However, I did upgrade my tie beam size from 8x8 to 8x10.  You might want to consider increasing the post heights from 10 feet to 12 feet to give you a little more headroom on both the lower and upper levels.

Otherwise would 8x8 pt for sills be worth it or if I have it, should hemlock fair ok?

Hemlock would be great for sills.

[Jim_Rogers]

If you build a 2by deck, just create a pocket for a tenon to hang down below the deck and peg it off:



  



 

Jim Rogers

[Spruce_Goose]

Increasing the width from 12 to 14 feet is fine too.  However, I did upgrade my tie beam size from 8x8 to 8x10.

I could certainly do that given the trees no problem. This would only be to increase the strength of the loft floor, no? The roof loading is unaffected I would think. In other words if the loft is intended to see little to no load, would an 8x10 offer anything over an 8x8 (larger tenon, but I assume given the tensile strength of wood, that a proper tension joint there would be fine in an 8x8 as much as an 8x10).

Hemlock would be great for sills.

That's what I am leaning towards. Information on Hemlock is confusing to say the least. I build trail bridges with Hemlock based on word of mouth info that it is relatively strong and relatively rot resistant. Steve Chapell in his book "A Timber Framer's Workshop" however claims that hemlock is NOT rot resistant despite some people thinking it is. A world of confusion. I may have to run some of my own scientific tests.

If you build a 2by deck, just create a pocket for a tenon to hang down below the deck and peg it off:

Thanks Jim. That seems like a good idea. Do those doubled up 2by's you see in that pocket where the post rests run the entire length of the frame, or are they essentially just short segments of blocking?

[Brian_Weekley]

Increasing the width from 12 to 14 feet is fine too.  However, I did upgrade my tie beam size from 8x8 to 8x10.

I could certainly do that given the trees no problem. This would only be to increase the strength of the loft floor, no? The roof loading is unaffected I would think. In other words if the loft is intended to see little to no load, would an 8x10 offer anything over an 8x8 (larger tenon, but I assume given the tensile strength of wood, that a proper tension joint there would be fine in an 8x8 as much as an 8x10).

The wider the building, the greater the outward stress exerted by the rafters.  The author told me the tie beam-post connection is the weakest point of the building and suggested using 8x10s for both the posts and tie beams.  I don't know if that's overkill, but it sure is sturdy!



Where 'bouts in Maine are you?  I built mine in Montville, ME.

[thecfarm]

Hemlock is more rot resistant than white pine. But less than cedar. 
I have used hemlock on my out buildings and will use it on a couple more I have planed out. If it's going to have a roof over it,anything will last as long as the roof is there.
Hemlock is a good strong wood,but can be hard to work with when dry,due to it wanting to split when nails are used. I just about go from stump to building in one day,so the dryness is not a bother.

[petefrom bearswamp]

I remember my dads old trick to lessen the splitting in Hemlock
He turned the nail point up and flattened the point with a hammer.
Seemed to help a lot.
My builder friend says that the new formula treated lumber isnt worth spit.

[Spruce_Goose]

Where 'bouts in Maine are you?  I built mine in Montville, ME.

Central Maine: Readfield. I am also planning on doing the wedged dovetail, which should be stronger than the pegged tenon in the plans, so I would reason that 8x8 would still be fine at 14' if loft loads are discounted.

Hemlock is more rot resistant than white pine. But less than cedar.

I always knew cedar, tamarack(eastern larch), and white oak topped out the list above hemlock, but I did start questioning if hemlock had anything over species like pine, spruce, fir, and red oak after reading a few statements about its lack of rot resistance.

[Spruce_Goose]

So perusing Steve Chappell's book I came across this little bit on stacking hemlock:

"Hemlock and oaks, on the other hand [vs. pine], should be stacked tight to prevent sweeps and crowning. ... Packing tight, under weight or with straps will help with their long term stability. You want to keep hemlock wet until the day you start cutting it, or it will just fall apart due to its brittleness." - A Timber Framers Workshop

Would anyone recommend stacking hemlock this way? Has me a little worried about it rotting, at least if I don't get to the build until mid to later summer. Not too worried about it over the winter, outdoors under loose tarp. Less confident about spring and summer with heat, humidity, and insects.

Comment about it falling apart seems weird. If it falls apart once dry, how is it supposed to stay together as a timber once dried in the frame? A bit dramatic perhaps.

[petefrom bearswamp]

I have dead stacked Hemlock boards tight in the summer and they practically  grew back together from some white type of mold between the boards.
I have left Hemlock logs over the winter with no adverse effect.
The bark fell off nicely when handled in the spring.
It does nail nicely (boards) when green but does shrink and will split near the edge when this method is used if too closely nailed.