RE-ROOFING, OVERCLADDING AND STRENGTHENING
Structural engineering for roof refurbishment answers one question before the contractor prices the job: can the existing structure carry what is about to go on it? Overcladding adds a second roof to purlins and frames that were sized for the first. Stripping and replacing changes the covering, the fixings and often the insulation the purlins must carry. Solar PV adds its own weight and wind uplift. Solar Surveys measures the structure as built, checks it for each option, and designs the strengthening and the new roof structure where they are needed: with solar PV, without it, or with PV planned for later.
THE BUILDINGS
Older roofs, often with no drawings
The buildings that come to us for refurbishment are mostly steel or timber framed sheds that are decades old: factories, warehouses, workshops, depots and farm buildings. Many are roofed in asbestos cement or fibre cement sheets, others in early profiled metal. The drawings have usually been lost, and the structure has often been altered, with plant hung from the purlins, openings cut or a second covering added.
In our published UK Roof Plane Dataset 2026, a visible condition issue was photographed on 83% of fibre cement roofs. Corrosion at purlin cleats, bearings and frame connections is common, so the survey records every connection it can reach, not only the main members.
WHO INSTRUCTS US
- Roofing and cladding contractors pricing a scheme
- Estate owners and asset managers
- Building surveyors and project managers
- Farm and rural estate owners
- Solar developers whose roof needs work first
THE OPTIONS
Overclad, strip and replace, or refurbish
Overcladding leaves the existing sheets in place and builds a new roof above them on a support system fixed back to the existing purlins. Nothing is removed, so the purlins and the frame carry the old roof and the new one together.
Strip and replace removes the old sheets and fits new ones, usually insulated. The weight on the structure changes, and the new sheets and their fixings have to suit purlins that were spaced for the original covering.
Refurbishment in place, such as a coating or local repair, adds little weight but leaves the structure and the fixings as they are. It still needs a view on whether the roof beneath is sound enough to keep.
Solar PV can be added to any of the three. It brings weight and wind uplift at the fixings, so it is checked together with the roof option, not after it.
WHAT WE COMPARE
- The weight of each option on the purlins and the frame
- Wind uplift on the new covering and its fixings
- Snow load and drift for the site
- Solar PV now, later or not at all
- The members that need strengthening or replacement
TWO STAGES
Appraise first, then design
Stage 1 tells you what the structure can take and what each option would need. Stage 2 is priced on those findings.
STAGE 1: SURVEY AND APPRAISAL
A site inspection and measured survey of trusses, rafters, purlins, bearings, columns and bracing, with a photographic record of the coverings. A register of corrosion and defects by connection and member. Capacities checked on the measured sections, the options compared, and a clear recommendation. One report per building, written for a contractor to price from. The programme is agreed at quote, depending on the size and complexity of the building.
STAGE 2: DESIGN
Design basis, purlins and secondary steelwork, cleats and connections, and truss or rafter nodes under the revised loading. Remedial and strengthening design, drawings and specification. The overclad support and fixing layout, or the replacement roof structure, with PV loading included where panels are planned. Technical queries answered during construction, and an inspection of the completed works with a report and sign off.
WHAT STAYS WITH YOU
You keep the roof, the client and the programme. We do not install, supply roofing or remove asbestos. We work alongside the roofing contractor and the asbestos contractor, and our report is written for them to build from.
WHAT WE NEED TO QUOTE
The site address; photographs of the roof and of the frame inside; any drawings or previous surveys; the asbestos survey if one exists; the proposed roof system if it has been chosen; and the PV layout if known. We aim to return a quote within 24 hours.
ASBESTOS CEMENT
The asbestos stays with the specialists
Asbestos cement and fibre cement roofs are fragile. We do not sample, disturb or remove asbestos cement, and our work starts from the asbestos survey or register where one exists. We go onto a roof only when proper safety measures are in place. Otherwise we inspect the frame from inside and from safe access, and record the coverings from the air.
In Great Britain, work with asbestos is governed by the Control of Asbestos Regulations 2012, and in Northern Ireland by the Control of Asbestos Regulations (Northern Ireland) 2012. The duty to manage it sits with whoever is responsible for the maintenance and repair of the building.
Our part is the structure: what the frame and purlins can carry once the sheets are overclad or removed, and what has to be strengthened first.
WHERE WE FIT
- Asbestos survey and removal: the asbestos contractor
- Roof system supply and installation: the roofing contractor
- Structure, loads, strengthening and sign off: Solar Surveys
- Solar PV layout: the installer, with our fixing zones
WHY SOLAR SURVEYS
What you get from us
Measured, not assumed
The structure is measured on site, member by member and connection by connection. Nothing is taken from a typical building of the same type.
Options compared first
Overcladding, replacement and refurbishment are checked side by side, with and without PV, before money is committed to one of them.
One team throughout
The engineers who survey the building design the strengthening, answer queries during construction and inspect the finished work.
Solar included from the start
Roofs for solar PV are our core work, so panel loads and fixing zones are part of the appraisal, not a second commission.
FREQUENTLY ASKED QUESTIONS
Questions we are asked about re-roofing and overcladding
Do I need a structural engineer to overclad a roof?
Overcladding adds a second roof to a structure that was designed for one, so someone has to confirm that the purlins, frame and connections can carry both, with the wind and snow loads for the site. On an older building with no drawings that means measuring the structure. A structural appraisal gives the contractor and the owner that answer before the system is ordered.
Can an asbestos cement roof be overclad?
Overcladding is widely used on asbestos cement and fibre cement roofs in the UK and Ireland because the old sheets stay in place. Whether it suits a particular building depends on the structure beneath, which then carries the weight of the old roof and the new one together. We check that, and compare it with stripping and replacing the sheets.
Can solar panels go on after a roof is overclad or replaced?
Yes, and it is best decided at the start. Solar PV adds weight and wind uplift at the fixings, so we include it in the appraisal and in the design, whether the panels go on with the new roof or later.
What does the appraisal report contain?
The measured structure, a register of corrosion and defects by connection and member, the capacity of the members checked on their measured sections, a comparison of the realistic options with and without solar PV, and a recommendation with the members that need strengthening or replacement. One report per building, written for a contractor to price from.
How long does it take, and what does it cost?
Both depend on the size and number of buildings and how much of the structure can be reached, so the programme is agreed when we quote. Desktop structural reports carry our 48-hour delivery target from commission; site surveys and design are programmed when we quote. Send the address, photographs of the roof and of the frame inside, any drawings and the asbestos survey if there is one, and we aim to return a quote within 24 hours.
Do you remove asbestos or install roofing?
No. We do not sample, disturb or remove asbestos, and we do not supply or install roofing. Those stay with the asbestos contractor and the roofing contractor. Our part is the structure: what it can carry, what has to be strengthened, and the design and sign off of that work.
Which areas do you cover?
The whole of the UK and Ireland. Sites in the Republic of Ireland are designed to the Eurocodes with the Irish National Annexes. For farm buildings under the TAMS reroofing scheme, our report is set out to cover what the scheme's reroofing specification asks for. Chartered sign-off is available where a grant scheme, funder or insurer requires it. See structural surveys in Ireland and Northern Ireland.
COMMISSION AN APPRAISAL
Ready to Proceed?
Send us the site address, photographs of the roof and of the frame inside, any drawings and the asbestos survey if there is one. We aim to confirm scope and return a quote within 24 hours.