How Long Does a Commercial Re-Roof Take?

The biggest factor is the area, followed by the roof system. A roof with a single large membrane laid over a clean deck moves quickly. A roof with many rooflights, plant bases, upstands and gutters takes much longer, because every detail is made by hand. Stripping the old covering first adds time, particularly if it is heavy or has to be sorted for disposal.

Insulation is the next factor. New boards must be laid, fixed and sealed before the membrane goes on, and falls may need to be built up with tapered boards. Metal profile roofs follow a different rhythm again, with sheets lifted into place by hoist or crane.

Weather matters because most flat roof systems need dry conditions to bond or weld properly. Rain, damp mornings and low temperatures can stop work for the day or lead to a part-finished roof being made watertight overnight. We never uncover more roof than we can close before the end of the working day.

For these reasons we give no fixed number of days from the outside. After the survey we state the expected programme in the written quote, and we tell you what could extend it.

On an occupied building we usually work in sections, finishing one area completely before opening the next. That keeps the part of the roof that is open to the weather small, and it lets the business keep trading below. It adds days to the total but avoids shutting the premises. We talk through delivery times, noise, access routes and parking with you at the start, and we keep customers and staff clear of the work area.

Some businesses need quiet or clear periods, such as stock-taking, a seasonal peak or a lease deadline. Mention them when we survey and we build the programme around them where we can. Our answer on roof repairs while the business is open goes through the arrangements in more detail.

Daily updates are part of how we run a site. You are told what is being done that day, what comes next and how the forecast affects the plan, and the roof and yard are made secure and cleared before each shift ends, with waste taken away.

Some delays can be seen coming. A scaffold standing on the road or pavement outside needs a licence from the highway authority, and arranging one takes time. West Sussex requires at least 10 working days' notice, and Surrey asks for 10 working days before the planned start. Kent County Council's page puts the scaffolding company in the applicant's seat. Elsewhere, ask who applies and allow for the lead time.

Within 6 km of Gatwick, lifting with a crane or other tall equipment calls for an airport permit, unless the kit is under 10 m or surrounded by trees or structures taller than it. Raise it early if heavy materials have to go up.

Asbestos is the delay that can change everything. HSE's advice for pre-2000 buildings, whether built or refurbished then, is to presume asbestos, and it calls asbestos cement roofing fragile every time. If testing finds it, the removal method decides the timetable, and the work may need notifying before it starts.

Last come the surprises. Wet insulation or soft decking uncovered once the old layer comes off must be put right before the new one goes on. We photograph what we find and tell you at once.

A good plan starts with the survey. We look at the roof, the access, the neighbours and the services that cross the roof, and we find out what the business needs. Then we can offer a start window and an estimate of how long the work will occupy the site, in writing, together with the one total price.

Materials have their own lead times. A specialist membrane, rooflights or metal sheets cut to length may have to be ordered, so the date for ordering often comes before the date for starting. Ask for it in the programme. If a contractor promises a start next week on a large roof without a survey, ask what they are assuming.

To get things moving, send us the building address, a rough roof size and any earlier surveys or asbestos reports. Our guide to commercial roof condition surveys explains what we record. For a Crawley example of access and working practice on an industrial estate, see roof repairs at Manor Royal, and for the full list of services, our commercial roofing page.