Metal roofing over shingles: what to check first.

Keeping the shingles or removing them

A roof recover installs a new covering over an existing one. A tear-off removes the old covering before the replacement is installed. Neither choice should be made from a photograph or the roof's age alone.

Removing the existing covering can expose the roof deck for inspection and repairs. A recover leaves more of the existing assembly in place, so its condition and suitability need to be established before that work is approved.

Start with what is already there

Give the contractor any history of leaks, storm damage, repairs or earlier replacements. The assessment should consider the existing covering, underlying materials, roof deck and number of roof layers.

Water damage, deterioration or an unsuitable deck can change the scope. A new metal covering should not be treated as a substitute for assessing and addressing those conditions. Ask what needs to be repaired or removed, and have that work described in the quote.

Choose a complete roof system

Metal roofing is more than the visible panels. The proposed assembly needs appropriate support, attachment and details for the building and site. Ask how the supporting structure will be assessed and whether the project needs engineering.

Different roofing systems use different recover methods. A detail designed for one panel or purpose-built recover system is not a universal instruction for another. The chosen manufacturer's requirements should guide the compatible components, preparation and installation method.

This is why a generic article cannot give you a reliable fastener length, spacing pattern or underlayment specification for your home.

Ask about moisture and roof details

The roof still needs a plan for moisture and ventilation. Ask how the proposed assembly handles condensation and how it works with the building's insulation and ventilation. Do not assume that adding metal automatically solves an existing moisture problem.

Also ask how the work addresses edges, valleys, chimneys, pipes and other transitions. Existing surface unevenness, flashing and drainage details can affect the proposed installation. Make sure the quote explains which existing components stay and which are replaced.

Check the requirements for your address

Requirements can differ between cities and properties. Ask which building rules, permits and inspections apply to the actual job address, and who is responsible for confirming and handling them. The fact that a recover was suitable on another property does not establish that yours qualifies.

Compare the written scope before the price

Two quotes can describe very different work. Before choosing, ask:

• What did the roof assessment find, and why is recover or tear-off proposed?
• Which roof system and installation requirements apply?
• What repairs, preparation, flashing and drainage work are included?
• How will moisture and ventilation be addressed?
• Who handles any required permits and inspections?
• What is excluded, and how would additional work be agreed?
• Which product and workmanship warranties apply to this installation?

The useful answer is a suitable roof with a clear scope, rather than an assumption that keeping the shingles is always the quicker or less expensive choice.