MCS Structural Evidence
The structural evidence on your installs, ready for the file.
At some point an MCS assessor, an auditor or a warranty provider asks the same question: what do you hold as the structural evidence behind this install? This page sets out what MIS 3002 V6.0 actually expects, the three forms the evidence can take, and what a defensible file looks like, roof by roof.
What MIS 3002 V6.0 actually requires
MIS 3002 V6.0 was issued on 18 March 2026 and became mandatory for MCS-certified solar PV installations on 18 June 2026. In substance, its universal structural requirement is this: before installation, the roof structure must be checked by a suitably competent person to confirm it can carry the system, and the outcome of that check belongs in the installation record. That baseline applies to every MCS install up to 50 kWp.
On top of the baseline, the standard is explicit that a qualified structural engineer must be involved in defined cases: where the roof is unusual or its capacity is in doubt (for example structural distress, past alteration, or configurations outside the standard's own tables), and for all flat-roof ballasted systems, where the engineer must confirm the roof can take the combined array and ballast load. Mounting systems are expected to be certified to MCS 012 and used inside their certified scope; where a mounting system is not MCS 012 certified, evidence of a structural assessment and wind loading calculation is required.
Full clause-level detail, including what changed from V5.0, is on our MIS 3002 V6.0 structural sign-off guide.
The three forms the evidence can take
Each is legitimate in the right place. The question for the file is not "did someone check the roof" but "can this evidence stand in front of an assessor, an auditor or a loss adjuster years after the install".
Form 1 · The minimum
Recorded competent-person check
The installer's own inspection of a standard, well-maintained pitched roof, using an MCS 012 certified mounting system inside its certified scope. Legitimate where the roof sits squarely within the standard's tables and shows no defects.
The limit: it is only evidence if it is recorded. Who checked, their basis of competence, what was considered, and the verdict. An unrecorded tick is the weakest position a file can be in, and it carries the installer's own liability with it.
Form 2 · The file-ready standard
Desktop Structural Roof Loading Report
A qualified structural engineer derives the site loads (wind to BS EN 1991-1-4, snow to BS EN 1991-1-3, PV uplift to BRE Digest 489), checks the roof against array and mounting, and signs the verdict. Produced from roof details, photographs and the array layout. From £130 per roof (residential and new build), from £150 (commercial), within a 48-hour benchmark.
The limit: a desktop report relies on the inputs being honest and the roof being inspectable from the information supplied. Where condition is uncertain, it escalates to Form 3. How the report works.
Form 3 · The full answer
On-site structural survey
A qualified structural engineer attends, measures and assesses the structure directly, with a signed report within 48 hours of the visit. From £600 per building. The expected route for ballasted flat roofs, older or altered structures, structural distress, and anything the desktop route flags.
The limit: cost and programme. Which is why the sensible sequence is desktop first, site visit only where the engineering says so. On-site surveys.
What the file needs, roof by roof
| Roof | Typical evidence the file needs | Why |
|---|---|---|
| Standard pitched, tiled or slated, good condition | Recorded competent-person check as a minimum; a signed desktop report where you want the file beyond argument. | Sits within the standard's tables if construction and condition are genuinely standard. The record is what makes it evidence. |
| Trapezoidal metal or built-up sheet (commercial) | Engineer-signed desktop report as the working minimum; on-site survey where purlin condition, fixings or past alterations are uncertain. | Fixing pull-out, purlin capacity and wind uplift are calculation questions, and commercial roofs routinely carry decades of alterations. |
| Flat roof, ballasted system | A qualified structural engineer's assessment of the combined array and ballast load. Not optional under MIS 3002 V6.0. | The one category where the standard names the engineer explicitly. Ballast concentrates load exactly where flat roofs are weakest. |
| Older, altered or distressed structures | On-site structural survey with a signed report; desktop only as a triage step. | Unusual roofs and roofs in doubt are an engineer-required category, and their real capacity is rarely visible from paperwork. |
| Array already installed (retrospective) | Retrospective engineer-signed assessment of the as-fitted system: dead load, fixings or ballast, uplift and snow. | Certification and warranty files can be completed after the fact, but only with evidence of the system as actually built. |
Above 50 kWp DC the install sits outside MIS 3002 V6.0 scope altogether and the structural case is made directly to the Eurocodes and Building Regulations, which is where most commercial portfolio work lives. The evidence logic in the file is the same; the specifier changes.
Where files fall down
From the structural queries and non-conformities that reach our desk, the same weaknesses recur. None of them is exotic; all of them are avoidable at the point of install.
No record of who checked the roof. The check may well have happened. If the file cannot say who, when and on what basis of competence, it did not happen as far as an assessor is concerned.
A verdict with no load basis. "Roof is fine" with nothing on dead load, wind uplift or snow. The moment anyone asks how the conclusion was reached, the file has no answer.
A ballasted flat roof with no engineer. The clearest gap of all, because this is the category where MIS 3002 V6.0 requires a qualified structural engineer by name.
Visible condition issues left unaddressed. Sagging, cracked or repaired members visible in the survey photos, with no comment anywhere in the evidence. Assessors read photographs too.
A mounting system used outside its certified scope. MCS 012 certification covers defined roof types, fixings and spans. Evidence that assumes the certificate covers a configuration it does not is worse than no evidence.
The five questions a defensible file answers
Strip the standard back to what an assessor, auditor or loss adjuster will actually probe, and the structural evidence on any install needs to answer five questions:
- Which roof, when, against which layout? Site address, date of the check, and the array and mounting layout it was checked against. Evidence for a different layout is evidence for a different install.
- Who checked it, and why are they competent? Name, role, and the basis of competence. Where that person is a qualified structural engineer, say so; it is the strongest single line in the file.
- What loads were considered, and how were they derived? Dead load of the system, wind uplift and snow for the site, and the method behind them (the Eurocodes and BRE Digest 489 for PV uplift).
- Is the mounting certified and inside its scope? The MCS 012 certificate, and confirmation the roof type, fixings and spacings sit within what it certifies, with the fixing schedule recorded.
- What was the verdict, and were conditions closed? Pass, pass with conditions, or action required, and evidence that any conditions were dealt with before panels went on.
A signed Desktop Structural Roof Loading Report answers all five in one document, which is the point of it. If you want the roof sense-checked before committing to anything, the free structural pre-check takes two minutes.
MCS structural evidence questions
What structural evidence does MCS require for solar PV?
MIS 3002 V6.0, mandatory from 18 June 2026, requires that before any MCS-certified solar PV installation up to 50 kWp the roof structure is checked by a suitably competent person to confirm it can carry the system, and that the outcome is evidenced in the installation record. A qualified structural engineer must be consulted for unusual roofs and for all flat-roof ballasted systems.
Does the structural evidence have to come from a structural engineer?
Not on every roof. The universal baseline is a check by a suitably competent person, and the standard does not define that person as a structural engineer. A qualified structural engineer is the expected standard for unusual roofs, for roofs showing distress or past alteration, and for all flat-roof ballasted systems. Our position as a structural practice is that confirming a specific, ageing roof can carry a 25-year PV load is a structural engineering judgement, so on any commercial roof the competent person should be a structural engineer.
Is the installer's own roof check enough for the file?
On a standard, well-maintained pitched roof with an MCS 012 certified mounting system used inside its certified scope, it can be, provided the check is recorded: who checked it, on what basis they are competent, what loads were considered and what the verdict was. An unrecorded check is the weakest position a file can be in. Where the roof is older, altered, ballasted or in any doubt, an engineer-signed report is the defensible route.
What does a Desktop Structural Roof Loading Report contain?
The imposed loads from the array and mounting system, wind uplift to BS EN 1991-1-4 and snow loading to BS EN 1991-1-3 derived for the site, PV uplift checked against BRE Digest 489, an assessment of the roof structure against those loads, and a clear verdict, signed by a qualified structural engineer. It is produced from roof details, photographs and the array layout, from £130 per roof within a 48-hour benchmark, and it drops straight into the MCS evidence file.
What happens if an MCS assessor raises a structural non-conformity?
The close-out is evidence: a structural engineer's review or report that addresses the specific point raised, on headed paper the assessor can file. Depending on the query that can be a desktop review of the documentation and photographs, a full desktop structural roof loading report, or an on-site survey. We handle these regularly and turn the desktop cases around quickly.
The array is already installed. Can the structural evidence be produced retrospectively?
Yes. A retrospective assessment verifies the as-fitted system: dead load, fixings or ballast, wind uplift and snow to the Eurocodes, against the roof as built. Straightforward cases can be handled as a desktop report from the as-fitted documentation and photographs; anything unusual gets an on-site structural survey. The signed report then completes the file.
Need the evidence on file? A signed report, from £130, within the 48-hour benchmark.