i'm planning to install UFH in a ground floor on a timber floor. the floor is not exactly suspended, more the joists are laid resting on bricks and stones at intervals over a solum which has had tar (mastic asphalt i think the BC guy said) poured as a DPC. the joist are in good nick so the DPC seems to have been doing its job.
i've been googling for dead load tables and they all seem to work the opposite way from which i need ie they quote permissable span for for a range of dead load. i need to know will my floor (approx 450mm centres 7"x3" joists) take a dead load of 30kg / m2 (which is the weight of a 25mm screed required for the UFH).
the joists run parallel with the longest wall and the area is about 70 m2 (which will require about 2 tonnes of screed)
could the spot loading ie where a stone/brick supports the joist cause any problems?
i'll ask an architect friend ... but i thought i'd try here too... advice is usually excellent