re: concrete domes and stuff
13 jun 2000
>foam on the outside means birds peck holes in it to build nests.
apparently not, with monolithic domes. they have been building these
all over the world for about 25 years now. the largest are about 400'
in diameter. they have indeed survived caribbean hurricanes and alaskan
earthquakes. (one "survivor" at a monolithic convention described a
church service inside an alaskan dome during a 6.5 scale earthquake:
"everyone fell down, the floor began to heave up and down, and when
it was over, we noticed a few surface cracks in the concrete.")
i have heard of woodpeckers attacking dri-vit walls...
>foam is not a weatherproof material.
it needs some protection. mastic paint, some sort of roofing material,
or leaving the cloth airform in place (which also weathers, but more
>so your plan is: a conctrete dome, then foam on the outside, them
>a rubberized membrane over the foam to waterproof it?
no. first inflate the membrane, then spray urethane inside, then wire
up reinforcing rods inside while the foam is still sticky, then spray
shotcrete, wait a couple of days, take a deep breath, and turn off the
>weren't we building a dome because we wanted to save money???
sounds good to me. about 10 cents per board foot for 2" of concrete,
20 cents per linear foot for rebar every 4" or so, 25 cents per board
foot(?) for 3" of foam, and $2/ft^2 for the airform, without much labor,
a total of $25 per square foot of floorspace for a turnkey shell from
a number of monolithic contractors. one might add a lifetime layer of
epdm rubber over it all when it's done, for another 30 cents/ft^2.