reroofing old slate roof

Old 07-14-07, 04:25 AM
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reroofing old slate roof

I'm in Australia and have a one-hundred-year old house with a delaminated slate roof which needs replacing. I've been told various things about reroofing it.
1. Slate is very expensive to re-cover it with, so that's out.
2. Artificial slate is of very varied quality , i.e "Eternit" concrete slate.
3. Concrete tiles are much heavier than slate and so the roof trusses, et needs substantial reinforcing.
4. Terracotta tiles are also much heavier than slate.
5. Colorbond (i.e. corrugated iron) is lighter than slate, but the roof members have to be firmly strapped into the the house walls because the weight of the roof covering is so much lighter.( Theoretically in high wind things could move
6. A Colorbond roof, & sarking can be underlaid with plywood to add weight to it before it is bolted on to the battens and the rafters.
Has anyone had any experience of these problems? We live in a high-wind area,very hot in summer, but very exposed and fairly near the coast (though not on it). Can plywood make the roof more susceptible to termites or fire, etc?
Has anyone heard of this solution as a way of weighting up a colorbond roof
(which is lighter than slate) and so making gravity keep it in place on the roof trusses, etc,

We do not have shingles or shakes in Australia: the norm here is terracotta, concrete, colorbond or on very old houses, slate.

Has anyone any ideas?
Old 07-14-07, 06:18 AM
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I,ve never heard of any problems with a roof lifting in anything short of a tornadoe or hurricane. If the trusses or rafters are installed properly and the sheathing installed properly and everything is in good condition, it should never be a problem.

I am not familiar with colorbond but it looks to be a simply steel sheet roofing. If not attached properly, I can se it lifting independant of the roof structure but as ling as adequate attachment points are employed, I cannot see it as a problem.

Many industrial buildings here in the US are made entirely of sheet steel with no underlying sheething at all. It is simply placed on purlins and attached. The last one I saw have any problems was hit directly by a tornado, which as expected, did trash the building.

We have a product here for roofing that simulates slate but it is steel. I am having a difficult time finding a website to show you. Maybe one of the guys that doo roofing that frequent this site may be able to link a site for me.

It actually looks pretty good. The only question I have had about it is how durable it is so as to allow walking on the roof.

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