Rooftop pool
We’re working on a hotel with a rooftop pool that sits over conditioned space. The depression of the pool (concrete) is formed with 9″ thick gunite and fnished out with tile. The current drawings call for 4″-6″ of rigid insulation to be run into the pool sitting on top of the concrete. We have a pool consultant on the team who says he has never installed rigid between the concrete and gunite. Thoughts?
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Replies
Heather,
The terms gunite, shotcrete, and "low-velocity sprayed concrete" are used interchangeably by some writers, although other writers make distinctions between these terms.
To answer your question, sprayed concrete (or shotcrete) can be applied to rebar and wire mesh adjacent to rigid foam. This technique has many applications, and the resulting concrete assembly can be quite strong, as long as an engineer is involved to determine the necessary steel reinforcement and the concrete thickness, and as long as the installers are experienced and skilled. For an overview of the technique, see "Building Walls with Low Velocity Sprayed Concrete."
In the case of a rooftop swimming pool, the engineer has to consider both structural issues (involving the weight of the water in the pool as well as the weight of the concrete, of course) and water-entry issues (which require assurances that the pool itself is waterproof, and that the rigid foam insulation stays dry).
Heather,
is between the Gunite and the concrete the best place for the insulation? would it perhaps be better on the inside and underside of the concrete slabs?
Seeing now common roof top pools now are, what is the standard detail other architects are using?