Flat Concrete Roof

Claw Hammer

I have been looking at a property which has a flat concrete roof over a portion of it. It does not seem to be feasible to build a conventional roof on top. Can the existing roof be sprayed on the outside for insulation?

listermint

Any pictures ?

What do the neighbouring properties look like generally you can pick up what can be done by viewing the similar neighborhood properties

Claw Hammer

It is a one off. There are no similar neighboring properties. The neighbours all have conventional roofs. I don't have a picture as it can't be seen from the road.

bemak

You would need to assess whether the existing roof is damp first but in theory you could potentially put rigid insulation down (to falls) on top of the existing roof and then apply a new membrane to that. You'd probably need new upstands on all sides and allow for the roof to drain to one or both sides where it would be picked up by a hopper and downpipe.

Claw Hammer

There is no dampness internally. I can't see if there is ponding on the concrete or not. My concern is with heat loss. I dot think I can afford to lose ceiling heignt by insulating internally.

bemak

Claw Hammer wrote: »

There is no dampness internally. I can't see if there is ponding on the concrete or not. My concern is with heat loss. I dot think I can afford to lose ceiling heignt by insulating internally.

I meant insulate it externally

Claw Hammer

bemak wrote: »

I meant insulate it externally

I was wondering if I could just spray it externally.

BryanF

Listen to bemak please. If the concrete is sound.. then mechanically fix PIR insulation above the concrete and install a roof finish above that.

Forget spraying anything anywhere.

Best of luck.