we are building new home with colorbond roofing, we have been recommended to add sarking for the roof, is it something we should have or can ditch that?
What's your location/climate and what insulation will you have between the living space and ceiling space, or is it a flat roof? Every colorbond roof under construction I've seen here has a layer of insulation go down first, it looks like combined sarking with batts. It could be different now or different in other climates though. So the context of your question is helpful. A long time ago I stayed in an old tin roof house and at night the ceiling had condensation so that's something else I'd wonder about.
check yourhome.gov for advice about insulation for your area but insulation and waterproofing is the cheapest form of temperature control but check your BASIX certificate and you will probably discover it's a legal requirement with a specific rating needed for your house and not an optional extra
The Sarking under a steel roof is there not just as insulation or a Fire spark barrier but it is mainly there under steel rooves as a vapor barrier. In our cooler months, water condensation forms on the underside of the steel and will then drip onto the ceiling materials. The Sarking first reduces the amount of condensation that forms on the steel and also catches any drips; then allowing the water to disburse without causing damage to roof timbers or ceiling linings like ceiling Plasterboard which are not water proof.
So in short, yes Sarking really is quite important over the long term.
macyjean
oklouise
Compass Kitchens
Smita Sinha