How long does a commercial re-roof take?

Anyone who gives you a fixed number of days for a commercial roof before seeing it is guessing. Four things set the length of the job, and we measure each of them at the survey.

• Area and complexity. A plain rectangle takes less time to cover than a roof broken up by upstands, plant, rooflights and box gutters, because every junction is hand-detailed.
• The system. Laying a single-ply membrane, torching on built-up felt, fixing metal sheets and installing insulated panels each move at a different pace and are affected by weather in different ways.
• Strip or overlay. Taking the old covering off, sorting out the deck underneath and disposing of the waste is often the longest phase, so an overlay can shorten the programme.
• Access. Where the scaffold, hoist and skips can stand decides how fast materials reach the roof and the old covering leaves it.

On the valley sites around Stroud, narrow service yards and units that back onto lanes or the canal can slow deliveries. We record that on the survey sheet and allow time for it from the outset, rather than explaining a delay later.

Most commercial re-roofs follow the same sequence, whatever the covering. Knowing it helps you see where time goes.

Before anyone is on the roof

A survey opens the job, and our photographs show you the roof as we found it. After that we issue a written quote, and once it is accepted there is a lead-in: ordering materials, booking the scaffold and, where work is notifiable, dealing with the Building Regulations side. Materials for a made-to-order system such as profiled sheets or insulated panels may sit on a longer lead time than a roll of membrane, so we order as early as we can.

Strip, repair and prepare

We lift the old covering a section at a time and close each section before leaving site. The deck is then checked. Rotten boards, corroded purlins and failed fixings are dealt with before the new layer goes on, and this is the part of a job where a survey can only predict, not promise.

Lay, detail and test

The new system is laid, then the upstands, flashings, outlets and rooflight kerbs are finished by hand. Last come the clean-up, removal of waste and a walk-round with you. At handover you receive our written 10-year workmanship guarantee.

A big roof is rarely stripped in one go. Working in bays means only one section is exposed at a time, and each bay is sealed against rain before we open the next one. The same method lets a warehouse keep stock moving or a workshop keep its machines running underneath. It does add working days compared with stripping the whole roof at once, but the cost of lost trading often outweighs them.

Phasing also follows the building. A roof over a shop front, an office and a store room may need three different start dates, because noise or access matters in one area and not another. You and we settle the sequence ahead of the start date, and we keep it flexible so that an urgent trading period can be worked around. Our answer on repairing a commercial roof while you trade covers protection and out-of-hours work in more detail.

If funds arrive in stages, the same logic applies. Phase one can be the worst-leaking bays, with the rest following when the budget is released. The written quote describes the work phase by phase, so the programme is clear. For the money side, the guide to commercial roof costs sets out the sourced flat roof ranges.

Weather is the most obvious cause. A flat roof system cannot be laid on a wet deck, and some adhesives, liquid coatings and torch-applied layers have conditions that must be met before work starts. The sequence is arranged so that a wet day moves the programme without leaving any bay exposed. Winter work is possible with some systems and not others; our answer on replacing commercial roofs in winter explains which.

Other delays are in the building itself.

• Hidden deck damage. Timber or steel that seems fine from underneath may prove soft or corroded once the covering is lifted.
• Asbestos cement. If old sheets are present, the HSE treats careful, unbroken removal as non-licensed, and work that breaks the sheets up substantially as notifiable, with notice given before the work starts. That is a step on the programme, not an optional extra.
• Services on the roof. Air handling units, flues and solar fixings must be isolated, moved or worked around.
• Late changes. Changing the specification after the order is placed can mean waiting for new materials.

You can shorten the real disruption by deciding a few things early. Tell us your busiest weeks and your quietest, and we will aim the noisiest phases at the quiet ones. Tell us who else needs access to the yard, because a delivery lorry and a hoist cannot always share the same space. If you are a tenant, check who is allowed to authorise roof works before you book anything, as our answer on who repairs the roof on a leased unit explains. And if VAT matters to your cash flow, our answer on VAT on commercial roofing covers how the quote shows it.

The most useful thing you can do is send us a few photographs, the approximate floor area and any drawings you hold. We will give you a realistic window after the survey, written into the quote, with the reasons it might move. To begin, use the enquiry form at the foot of this page or message us on WhatsApp. More on the service itself is on our commercial roofing page.