“New roof” can mean different things in different quotations. Ask what will happen beneath the tiles or slates, rather than assuming the visible covering tells you the full scope.
Ask what is being stripped
For a complete replacement, the quotation should explain which layers will be removed and which, if any, will remain. Ask how the exposed structure will be assessed and how any additional timber work will be agreed. We do not agree to conceal known defective work under a new covering to make the job quicker.
What underlay and battens contribute
The covering, underlay, battens, fixings and ventilation need to work as a suitable arrangement. Marley describes these as components of a roof system rather than unrelated products. The proposed specification should explain the components being used and how they suit the roof.
A correction we have actually carried out
One of our project reports records a roof with poor overlapping and older roofing left underneath the later work. The correction involved stripping, renewing felt and battens, and carrying out new leadwork. It is a useful reminder that a tidy-looking surface can hide work that still needs attention.
What you should receive before booking
Ask whether the quote includes removal, disposal, underlay, battens and the relevant finishing details. Find out how concealed defects will be recorded and priced. Do not compare a covering-only proposal with a full strip and replacement as if they were identical. Our priority is an agreed scope we can stand behind, even when that costs more time than a shortcut.
Technical reference: Marley: the components of a roof system. The requirements for an individual roof need checking against its actual specification.