On Sat, 12 Jan 2008 12:42:53 -0000, "Andrew Mawson"
wrote:

I need to insulate a building (roof & walls) that will
be my workshop. Roof is brand new fibre reinforced corrugated cement,
walls are cement block to waist height then timber studding above. I
had planned a suspended ceiling with rockwool on top, but I have
headroom constraints that make the sprayed polyurathane look more
promising. Walls could still be rockwool as it will be faced with 18mm
boarding.

Wouldn't you be better lining it all (Walls and roof) with
Polyisocyanurate foam sheets (Kingspan/Celotex)?
http://www.secondsandco.co.uk/

The only workshop I've seen with a sprayed roof had wriggly asbestos
cement sheet roofing panels and while the sprayed finish underneath
worked as insulation after a year or so it was very dirty and
impossible to clean because of its rough surface.