Warranty/Guarantee period for warm roof installation

[fiveminutejob]

What would be a typical/reasonable period for guaranteeing roofer's workmanship on a new warm roof? [As distinct from any manufacturers' guarantees for any of the materials used].

If it matters, in our case it would be to an existing flat roof extension about 6x4 metres, with one long side attached to sound brickwork of our house and taking water from part of main roof - and topped with something like Polyglass felt, or similar.

Thanks.

 

[Xenon]

Labour should be guaranteed unconditionally.

 

[fiveminutejob]

Thanks Xenon.