Ask a Tradesman
Is it ok to leave an asbestos roof on an extension. Can it be insulated from underneath./ How long do they last. My one is covered with moss should we leave this alone.
Generally if it is not leaking then leave alone. If you insulate a roof from the underside then it is still a cold roof and requires ventilation. If you place internally then you may get condensation occurring in the cold weather and the formation of drips throughout the undercarriage.
Generally old cement sheets will only contain white asbestos and can be removed and disposed of at a reasonable cost.
Leave all moss alone since if the roof does contain asbestos (ACM) then you would be disturbing fibres which can then be inhaled and pose a risk albeit minor. Ideally get the roof tested prior to any works for your own piece of mind and for the safety of the contractor.
Answered 30th Jul 2012
agree with all fibretech says
if you really want to insulate it would be best to fix a 50mm batten to the top side of the timber supporting the sheets and then use rigid celotex type insulation .the batten will stop you pushing the celotex up too far and help maintain an air gap between insulation and sheets and stop condensation. a vapour check with also be needed if you intend to board over/ plaster. 150mm of celotex would be best.
Answered 12th Aug 2012