Key Design Decisions
There are a few key decisions that we made to suit the building to
its site and purpose. They won’t work for everyone, and some
of them made the building either harder to build or more expensive.
So far I don’t regret any of them. Follow the links in the
nested menus to the left for detailed construction
photos.
Sonotube
footings set into ledge: Bedrock is one thing I’ve got
plenty of, and the site is very uneven with more than four feet of
elevation change across the footprint of the building. The footings
were easy to place, solid, and I wanted to avoid the thermal mass
of a concrete slab.
Main
beams and cantilevered joists: By carrying the entire building on a
couple of main beams I avoided worrying about accurate placement of
the footings: it doesn’t make any difference. The joists are
cantilevered and span distances are reduced.
Observing
Room / Warm Room: One of the fundamental goals was to
create a structure that would eventually support remote operations,
along with comfortable visual use under year-round northeast
conditions in the meanwhile. To me, that meant a separate warm room
/ office integrated into the building.
Split-Level:
Having a warm room you can
stand up in - and walls your scope can look over - is a
contradiction. The solution is a split-level building. I placed the
warm room directly over the main beams, and elevated the observing
room on a couple of box girders fabricated from 2x4’s and
plywood
Steel
track and caster system: I wanted to concentrate weight in the
rolling roof where it would contribute to strength and rigidity,
and avoid it where it wouldn’t. I thought that New England
moisture and humidity would eventually cause a wooden roller system
to deform and cause problems. Bob Luffel’s structural tube system
seemed like the
solution.
Metal
Roof: Ribbed
Galvalume was selected for light weight, durability and ease of
installation. It installs on purlins, so no plywood sheathing and
no heavy asphalt shingles = a much lighter structure. I chose a
white roof to reject solar energy and installed a full-length ridge
vent.