Cutting duct into roof

[mrpaint]

Hi.

I need to cut a 300m duct into the workshop roof ..... the roof is made of cement asbestos corrugate roof panels .


The plan was to mark the hole then cut the hole by using a air saw and spraying the area of the cut with soapy water...will be suited and booted using my painting mask and coveralls

after the hole is cut and the 300mm ducting is trial fitted ....what is the best method for sealing to the roof ?

our initial thoughts were to secure ducting from inside by bracing of the roof beams ...then either use fibre glass and resin (marine spec) or use a polyurethane sealant ? there will also be guy wires supporting the pipe from the outside


Thanks

Tommy

 

[ree]

Old Asbstos cement will be very fragile and could split while you are cutting a hole. I've never used an air saw however.

Some kind of custom 300mm circumference boot flashing would be a manufacturer's, or supplier, of asbestos cement roofing item.

How to fix and secure from below would require pics and info ref the "duct" or pipe.

I personally have no experience in the above kind of work.

 

[mrpaint]

thanks any other advise please

 

[catlad]

If I was fitting this ducting then I would place it near were the sheets over lap and then I could slide the flexable slate back under the sheet.