Facilities managers are rightly more worried about the roof than about the panels. Warranty, structural loading, fire and asbestos all come before savings. The survey deals with those first, and everything it measures is the reason a quotation is a real number rather than a rate card.
no fee / the document is yours / half a day on site
A roof survey before installing solar panels is a structural and condition assessment that establishes what a commercial roof can carry, whether the covering has the service life to justify an array, and whether anything up there rules out the mounting system a designer would otherwise assume.
On a commercial building the answer is therefore yes. Most solar installers will not put a firm price on an industrial roof without one, and the ones who will are pricing a set of assumptions rather than your building.
The benefits of running the survey before solar installation are mostly financial. A survey before installing solar panels finds the asbestos cement sheet, the corroded gutter line and the purlin spacing that would otherwise arrive as variations halfway through the work. It also leaves you with a document you can put in front of more than one contractor, so you are comparing prices for the same scope rather than comparing assumptions.
There is a third reason to survey before installing. Roof condition assessment evidence is what your insurer and your landlord ask for, and gathering it once the panels are on the roof is considerably harder than gathering it now. Commercial roofs on industrial estates are also rarely as they were drawn, because plant, mezzanines and earlier repairs accumulate, and every one of those changes the design.
Structural loading is the permanent dead load an array adds to a building, plus the wind uplift it catches on a flat roof, where the array is also a sail.
The survey records the structural arrangement we can see and gathers what is needed for an engineer to check it: purlin spacing and section, sheet span, the rafter or portal frame layout, and any earlier alterations such as added plant, mezzanines or roof penetrations. Purlin centres are the spacing between the steel members that carry the roof sheet, and they decide where a mounting rail can be fixed at all.
That package goes to a structural engineer alongside the solar panel mounting manufacturer's published dead load, with wind and snow actions taken from the Eurocodes, BS EN 1991-1-4 and BS EN 1991-1-3. Two outcomes are common and both are useful. Either the frame takes the proposed system, in which case the design proceeds, or it takes a lighter or smaller one, in which case you know the real usable capacity of the building before anyone has quoted for something it cannot carry.
Schematic and not to scale. The array is a permanent dead load, the wind action can act upward as suction at the edges of the array, and the snow action loads the sheet between purlins. All three are checked together, which is why a mounting weight on its own never answers the question.
The cladding profile is the shape and fixing system of the roof covering, and it decides the mounting method before any other factor does. It is the first thing we identify on site.
Standing seam is a metal roof system whose sheets are joined by a raised upstand. Solar panel clamps grip that seam, so the array is fixed without a penetration through the sheet. It is the cleanest case for the weathertightness of the roof and often the easiest one to reconcile with a manufacturer warranty.
Trapezoidal profiled sheet is the ridged metal cladding most warehouses are built with. Rails fix into the crown of the profile with sealing washers, set out to land above purlins. Profile geometry, sheet gauge and the condition of the coating all feed into the fixing pattern and the number of fixings per rail.
Usually a ballasted frame on protection mats, tilted and spaced so the rows do not shade each other. Ballast weight is what holds it down, so this is the case where structural headroom matters most.
Insulated composite panels behave differently again, and the fixing has to reach the supporting structure rather than relying on the outer skin. We record the panel type and its thickness rather than guessing from the profile.
Asbestos cement sheet is a fragile fibre reinforced roof covering that a large share of UK industrial stock built before the mid 1980s still carries, as roof sheet or as gutter lining.
It cannot be walked on, and work on it is regulated. The Control of Asbestos Regulations 2012 place a duty to manage asbestos on whoever controls the building, and any drilling or fixing into the material has to be planned and carried out under those regulations rather than treated as ordinary roof work.
We ask for the asbestos register at the point of booking, and if there is not one that is itself a finding. Where a survey identifies asbestos cement, there are normally three honest options: re-sheet the roof through a commercial roofing contractor and mount on the new covering, install on a structure that does not load the sheet, or leave the roof alone. On an older covering the re-sheet option is often better value than it first looks, because it resets the service life of the roof under an array that will be there for decades. We set out what each route does to the cost on the cost and payback page.
RC62 is the RISCAuthority guidance on fire safety with photovoltaic panel installations, and it is the document UK commercial property insurers most often reference when they are asked to accept a rooftop array.
A rooftop array is a DC electrical installation covering a large area of a building your insurer has already priced. It is not building regulations, but on a warehouse it can matter more, because the insurer can decline or load the cover.
The themes it deals with are the ones we look for on the survey: how DC cabling is routed and protected, where isolation sits and whether it can be reached safely, keeping the array clear of compartment walls so it does not bridge a fire separation line, leaving access routes and clear zones for the fire service, and the documentation handed over at completion. Large single compartment sheds and buildings storing high calorific value goods attract the most scrutiny. Telling your insurer early, and designing to what they say, costs nothing. Finding out afterwards is expensive.
Usable area is the roof area left once everything that cannot carry an array, or would shade one, has been taken out, and it is always smaller than gross roof area.
Rooflight strips, smoke vents, plant, air handling units, walkways, safety line runs and edge exclusion zones all come out first. So does anything that casts a shadow across the day: parapets, adjacent taller industrial units, flues and lift overruns.
Older glass reinforced plastic rooflights are a safety matter in their own right, since they degrade and are fragile long before they look it, and they need covering or protecting for the duration of the works. What is left after all of that is the usable area, and it is the only figure worth converting into kWp, the kilowatt peak rating of an array under standard test conditions. The modelled yield we apply to it comes from EU PVGIS v5.2 for your latitude, pitch and orientation, and the locations index carries the figure we use for each county.
Remaining sheet life is the number of years a roof covering has left before it needs replacing, and it has to outlast the array bolted to it.
A modern array has a working life measured in decades. A roof covering two thirds of the way through its own life does not, and removing and refitting an array to re-sheet underneath it is a cost nobody budgets for at the outset. We record coating condition, corrosion at fixings and laps, gutter and flashing condition, and any signs of water ingress, then say plainly how much life we think the covering has left. That condition assessment is the finding that most often changes the order of the work.
Where a manufacturer or membrane warranty is still running, its terms usually govern what may be fixed to the roof and who may do it. Sending us the warranty documentation at the start means the mounting method is chosen around it. If the roof is close to end of life, re-sheeting and then mounting is frequently the cheaper sequence over the life of the asset, and it is worth testing that against the funding routes on the finance and PPA page, because a longer lived roof supports a longer agreement.
An export limit is the maximum output a distribution network operator will allow your system to put onto the local network, and it is agreed before the design is fixed rather than after.
The last item on the survey is therefore not on the roof at all. We record the incoming supply, the MPAN, which is the unique reference number for your electricity supply point, the existing switchgear and the available headroom, and identify the distribution network operator for your area. Smaller systems connect under G98 by notification. Larger ones need a G99 application, the formal route for a generator the network has to assess, and an agreed export limit before the design is fixed. Knowing which applies, and what limit is realistic for your area, stops a scheme being sized on a roof plan and then cut back months later.
All of that lands in one pack of reports with the roof plan, the usable area, the array size in kWp, the modelled generation against your half hourly consumption, and the constraints we found. It is free and it is yours to keep, whoever installs.
A rooftop solar design needs a short stack of surveys rather than a single one, and on an industrial building knowing which of them you already hold saves time and money. People say roof survey as though it were one document.
The order is not arbitrary. Nothing above the structural step is worth measuring if the frame will not take the load, which is why the structural item is the one that usually sets the timetable. The connection enquiry goes in while the report is being written rather than after it, because that answer takes the longest to come back.
A commercial solar roof survey produces documents rather than opinions.
These are the reports that come out of it, and the reports a funder, an insurer or competing solar installers will ask to see before anyone commits to the work.
Those reports travel together in one pack. Once it exists, repeat surveys are rarely needed, and the same reports serve the insurer, the funder and whoever installs. We survey warehouses, cold stores, manufacturing units and trade counters across most industrial sectors, and the format stays the same across sectors so that a reader who has seen one pack can read every other one quickly.
Permitted development is the planning route most rooftop solar on an industrial or commercial building in England takes, under Schedule 2, Part 14 of the Town and Country Planning (General Permitted Development) (England) Order 2015 and subject to the limits and conditions that order sets out.
That is not the same as needing nothing. Listed buildings, conservation areas, sites carrying planning conditions that restrict roof alterations, and arrays that fall outside those limits all need a planning application, and some cases need prior approval instead.
The survey captures what a planning case would need if one turns out to be required: the roof plan, the array outline, the height above the covering and the visibility from the highway. Planning officers and insurers ask for exactly these drawings, and having them ready is the difference between a fortnight and a quarter.
Compliance runs alongside planning rather than after it. The regulatory items that touch a commercial roofing project of this kind are the Control of Asbestos Regulations 2012, the structural Eurocodes BS EN 1991-1-4 and BS EN 1991-1-3, the Building Regulations where structural alteration is involved, the distribution network operator process under G98 or G99, and your insurer's own requirements, which on commercial roofing work usually means RC62. We record the compliance position for each of them in the survey so nothing is discovered late.
Send the postcode, the rough footprint and anything you already know about the covering. If you have an asbestos register, a roof warranty or recent condition reports, those shorten the whole process considerably.
Lenzie Consulting Ltd arranges the survey, the design and the installation through an MCS-certified partner, and passes your details to them so they can quote. No survey fee, no obligation to proceed.