new sheeting over old on garage roof

[olly330]

Hi all

Need to repair a garage which is outlying from the house, the roof is made from very old asbestos sheet roofing and we have a few leaks in the garage.

Im thinking of just going over the old roof sheeting with new sheeting, but am not sure how the new sheets should be secured down. Would a product like gripfill do the job or just blow away? Or should I nail the new sheets through the old sheets and into the roof battens?

Also, I have seen some good value seconds of roof sheeting on ebay, but it appears this is ideally for proper sloping roofs. Can anyone see any problems if I was to use this on the garage roof bearing in mind the slope on the garage roof is minimal. These are the sheets im looking at:

Thanks for any advice or tips

 

[olly330]

Another thing I was thinking, would it be possible to felt over the old roof? Give it a good clean and then felt it, sticking down with felt adhesive and nailing with clout nails?

 

[flameport]

To put anything over the existing will add significantly to the weight, which the roof structure may not be able to support.
Would also require that all the moss and whatever else is removed first.

Using sheets of material outside of their intended use may well result in leaks, all depends on what is used and how it's installed.

Sticking felt over the top of what is there will be a total disaster, and banging 100s of clout nails in will just ensure it leaks like a sieve.

In summary, if the roof needs replacement, the only sensible option is to remove the existing one and fit new.

 

[olly330]

Thanks for that.

I am trying to avoid removing the whole roof as it contains asbestos and so would be a messy and costly job. Hoping to do a middle of the road repair to make it last around 2/3 years as we are moving in around that time frame.


How does this sound, brush off all the moss and pressure wash with bleach.

Then use flashing /leak repair tape along all the joins, and go over the lot with a thick coat of bitumen paint.


Or the other way im thinking, brush off all the moss then use galvanised roofing sheets to cover the whole roof, but I am not certain how these should be tied down?