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Asbestos roofing...or not?


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I am thinking about the best way to replace an unsightly roof of an old cognac distillery which will later be converted into rentable dwellings.

It's a large roof, about 275m2, perhaps 15-20 years old, which is covered with corrugated grey sheets (which I believe are asbestos) which undulate at approx. 15 cm centres.  The sheets look like the same stuff found on garage roofs etc in the UK.  Their surface is slightly dimpled in texture and (when dismantled and on the ground) it breaks with some force if you stand on it. 

Hundreds of sheets are fixed directly to the rafters below with long bolts, many of which have rusted over time and would probably need cutting rather than unbolting if removed.  The rafters sit on purlins and these sit on a series of 7 kings beams set at 6 mtr centres along the length of the building.

Some questions are running through my mind which I'd appreciate any views on:

  1. If these are asbestos sheets, do their properties pose a health risk akin to the same asbestos products that were used for roofing in the UK, and if so, like the UK legislation, must these be disposed of in a special way?

  2. I was told by a local Francais that there is a good second hand market for this kind of roofing, especially agricultures seeking to renovate a barn roof, so much so that the buyer will dismantle the sheeting themselves?!?.  Anyone come across this?

  3. If the sheets were left in place because they pose no health risk at all, could canal tiles be put on top of the sheets over the whole roof and offer an effective roofing solution?

Any thoughts would be appreciated.  Regards,

Ali

 

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Q1   If these are asbestos sheets, do their properties pose a health risk akin to the same asbestos products that were used for roofing in the UK, and if so, like the UK legislation, must these be disposed of in a special way?

 Firstly, they are not asbestos sheets, they are a compound possibly containing asbestos, if they are no older than 20 years they will not contain asbestos. If they do have an asbestos content, they are best left alone but if you want to take them off, the disposal varies from department to department.  In some the Decheteries take them without a problem, in others you have to dispose of them as special waste and that is expensive.  Do a search on here on asbestos, where it is a problem was highlighted some months back.

Q2 I was told by a local Francais that there is a good second hand market for this kind of roofing, especially agricultures seeking to renovate a barn roof, so much so that the buyer will dismantle the sheeting themselves?!?.  Anyone come across this?

No,  but if he told you that ask him if he knows anyone who wants it, it may be snapped up  if you are giving it away!![:D]

Q3 If the sheets were left in place because they pose no health risk at all, could canal tiles be put on top of the sheets over the whole roof and offer an effective roofing solution?

There is no health risk in leaving them alone even if they do contain asbestos, the risk comes when you drill, sand or break them.  You could put canal tiles on top but what would you secure then to?  And that is always assuming the pitch of the tles is the same as the sheets, but I would check the supporting structure can take the weight before even thinking about this.

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Thanks Ron for your kind response somewhat reassuring.  I had looked under reserach and saw refernces to new regulations possibly coming into force this year so thought it worth asking again.

On question 3, I was thinking that if you laid the canal tiles (i think that is the correct name) firstly in a concave manner in the channels of the grey sheets, you could then put a second layer of the same model tiles on top in a convex manner a bit like that seen improvised below.

mmmmmmmmmmmmmm - second layer of canal tiles overlap the first layer of canal tiles

uuuuuuuuuuuuuuuuuuuuuu - first layer of canal tiles sits in channels of corrugated grey sheet

wwwwwwwwwwwwwww - grey sheet at bottom

 

thanks

Ali


 

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I am about to have some re-roofing done using something called 'sous-tuiles' with canal tiles replaced on top. The sous tuiles are fibro-ciment. Are these the same animal that you have ?

I am not aware of any substantial timber support structure, but I could be wrong.

BTW do these things provide much by way of heat insulation ?

 

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Our boucher roof is exactly the same material and had been examined as part of the buying process. We were told that there is no problem with this material, unless it starts to deteriorate significantly ( a long, long time yet). As for support, the roofing timbers may well want beefing up. There's a helluva lot of weight going on.

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