I currently have a detached shop building that is 36' x 28' with 13'
eaves. This is a "pole" building that is wired, insulated, and finished
on the inside.
I want to put an extension on the back of the shop. The extension will
start out as a wood shed/lean-to and morph into an actual
walled/finished extension of the building. As such I'd like to design
the wood shed/lean-to with that in mind. Basically I would make or buy
some sort of trusses that would be attached to the side of the shop and
then be supported by 4x4 posts around the perimeter. The roof of the
lean-to (and eventually the walls) will be finished in the same
corrugated metal siding/roofing that is currently on the shop.
This is the back of the shop where the lean-to will be. You can see part
of the white mandoor in the lower right of the picture. The lean-to will
start to the left of the door and extend to the left down to the end of
the building - this distance is 22'. The lean-to will be 16' deep
extending out from the building.
Size and truss framing details:
I would like the height (eave) of the end or perimeter of the lean-to to
be at least 7'. I want to be able to walk in and out of this shelter
without having to duck down. I'm thinking about starting it at the
second from the top perlin as you can see in this interior pic that was
taken before the walls were finished. That perlin gives a good anchoring
point for the trusses and provides a place to anchor the flashing up
under the existing siding. That perlin is at roughly 11.5' or so. I can
go smaller than 22x16 and possibly a little bigger on the 16' dimension
if that makes more sense from a design/material use standpoint ( I don't
recall how long the metal siding/roofing panels come in?)
finished walls - current pic:
1. Is there a better size from a material use standpoint than 16x22??
2. Is it possible to design and build trusses that would extend out 16
feet from the side of the building to a header supported by 4x4 posts on
the perimeter of the concrete pad? Without having to put any posts in
the center of the pad/structure???
Thus, I would envision pouring a 22' x 16' concrete pad and have a
couple of questions relative to this part of the project.
1. What is the best way to butt the new pad up against the existing
building? As you can see in this picture the siding extends down over
the 2x4 perimeter boards on the existing concrete shop floor. I
recognize there will be some gaps between the two concrete pads once
everything gets walled in and can live with that, but was wondering if
there are any special considerations? Do I just frame up the new pad
right next to the existing floor?
2. The back of the building is inaccessible from a vehicle so I'm
assuming a pumper truck would be needed to pump over the top of the
building from the front. The front of the building is on a narrow single
lane deadened road, and getting both a pumper truck and a concrete truck
on this road may be problematic. Are there other options besides a
pumper truck for a 16x22, 5" thick pad? Can I pour something like this
myself with a concrete mixer??? Do they make any sort of chute
extensions for a concrete truck whereby the truck could dump "around"
the end (28') of the building???
1. How should the 4x4 posts be anchored to the pad, remembering that it
will be walled in later? Should I just put some post anchors in the
concrete for now then frame around the 4x4's later??
Note: I recognize it would probably be preferable to put the walls up
and finish the extension rather than trying to convert from the lean-to,
but I won't be able to swing that.