Journey to Sucess Project Management

Roof Appraisal

When CPS Evaluation is Acceptable

For standard roof types (e.g. trussed rafters or simple gable-ended cut timber roofs) you can use calculation methods published in the standards:

Trussed rafter roofs – Method 1 or Method 2 calculations:

Method 1 assumes a design dead load of 0.785 kN/m², then deduct the load of the existing roof covering to give the residual load available for the solar array.

Method 2 (not for roofs >60° pitch) assumes a design imposed load of 0.75 kN/m², then deducts the snow load for the site (from Eurocode-1 BS EN 1991-1) to give the residual load.

Traditional cut roofs (gable-ended) – calculate the maximum dead load for rafters and purlins using TRADA span tables, deduct existing covering load, and check the residual capacity .

If you follow these prescribed calculation routes, a CPS-registered installer can sign off the structural adequacy without needing a surveyor.

When a Structural Surveyor/Engineer is Required

You must consult a structural engineer where the roof structure is:

Unusual or complex, such as:

Traditional cut roofs with hips/valleys

Asymmetric duo-pitched roofs

Roofs showing signs of distress or modification (e.g. timbers cut, heavier coverings added)

Very shallow-pitched roofs ( Less than 30° Pitch)

Roofs with increased snow build-up potential (dormers, valleys, parapets, etc.)

Flat roofs with ballasted systems – a structural engineer must confirm the roof can withstand both the array and ballast loads .

Any situation of doubt about structural capacity.

What Needs to Be Documented Under CPS

If relying on CPS rather than a surveyor, you need:

Documented calculations showing residual load available vs. array load (using dead load and imposed/snow load methods).

Reference to TRADA span tables for timber cut roofs.

Evidence of methodology used (e.g. Eurocode-1 snow loads, BRE Digest coefficients for flat/ballasted).

Clear record in project files that a CPS-approved competent person performed and validated the calculations.

✅ Summary:

Use CPS calculations for standard trussed rafter or simple gable roofs, with documented load checks.

Bring in a surveyor/engineer for unusual, modified, complex, or flat/ballasted roof structures, or if there is any doubt.

EIC Certificate

The Electrical Installation Certificate (EIC) must be issued and signed by the competent electrician who actually carries out the design, installation, inspection and testing of the electrical work.

MCS installation standards require that:

The person(s) responsible for the design, construction, inspection and testing of the installation sign the certificate.

Where work is done under a Competent Person Scheme (CPS), only the registered electrician/organisation can self-certify Building Regulations compliance and issue the EIC.

The MCS Contractor (the NTP in Paperclip) is responsible overall for ensuring compliance, keeping records, and handing the EIC to the customer in the handover pack.

👉 In practice:

The electrician who installs and tests the system wiring (whether employed directly by the NTP or subcontracted) issues and signs the EIC.

The NTP/installer must then provide that EIC to the customer alongside the MCS certificate, Building Regulations notification, and DNO approval (where required).

✅ Summary:

The electrician issues the EIC.

The NTP/installer ensures it is obtained, retained, and passed on as part of compliance and handover.