In message , Maurice Gavin
writes
We need some practical advise re mounting telescopes on a large flat
roof [immediately overlooking fields to the E/S/W] to minimises
potential vibration mainly from dozens of observers walking about.

You could try nailing the observers down. Or at least discourage them
from walking around too much. Cork isn't too bad at absorbing vibration.

We are aware of the potential thermal problems from the building
- a substantial 1930s three storey brick structure with protective
parapet and rc asphalted roof. There are no pumps/ machinery/ people
within the building and no option for independent piers down to ground
level. The asphalte membrane cannot be disturbed to mount the
telescopes direct onto the concrete structure below.

Pity. The easiest way to do it is with isolated piers for the scopes.

You might get away with it though if the structure is heavy and rigid
enough. Try a site survey with an 8" SCT to see how bad the problem is
with a couple of guys jumping up and down on the roof.

You might get enough mileage by putting the scopes on a couple of sacks
of damp sand for isolation. (Or the bits sold for record turntables).
Put the scopes immediately above load bearing walls and they may be OK.

The scopes range from 10cm - 40cm aperture and weight is not a problem
for roof loading. Non-portable telescopes will be protected with
run-off sheds/ grp domes.

Any thoughts? Should the walk-about area be padded and with what?
Such mats must remain in place and be safe, self-draining and
rotproof. TIA.

Cork mats probably meet your requirements, but if the structure is big
and heavy enough the effects of a few people wandering around may not be
all that bad (unless they all decide to march in step - a la blade of
light).

--
Martin Brown