Roofing & Solar

Re-roofing and going solar look like separate projects, but they share one number: the roof area. Measure it properly — from the ground, using the footprint and the pitch, exactly the way roofers do it — and both takeoffs follow from the same figure. That's why this hub puts measurement first and treats materials, gutters, panels and batteries as four answers to one question.

The sequence runs: measure the roof, total the covering and drainage, check what fits and what it produces, then size storage. Each step has a calculator and a guide behind it, and the numbers stay planning-grade — roofers count in squares, solar yield depends on local irradiance and shading, and both trades will verify on site. What these tools do is get you into the right order of magnitude before anyone climbs a ladder, and let you hold a conversation with an installer that doesn't start from zero.

Because it needs saying early: this hub plans from the ground. Roof work at height is genuinely dangerous, and solar and battery systems add high-voltage DC to the mix — the safety section below marks where planning ends and qualified installers begin.

1. Measure the roof. Footprint length times width at ground level, then the pitch multiplier for the slope — a 12 × 6 m footprint at a 6-in-12 pitch gives about 80 m² (roughly 8.6 squares). The guide covers multipliers and the squares convention.
2. Total the materials. Covering area plus waste — typically 10–15%, more on cut-up roofs with valleys and dormers — plus underlayment and fixings. The calculator converts squares to bundles.
3. Size the gutters and downpipes. Eave run and catchment area set the gutter length and the downpipe count — a typical planning figure is around 50 m² of roof per downpipe for 100 mm half-round in moderate rainfall, varying with gutter size and rainfall intensity.
4. Check the solar fit. Usable area — minus margins, obstructions and orientation limits — becomes a panel count at roughly 2 m² per modern panel, then a system size.
5. Do the energy maths. Daily energy use against expected production turns the panel count into an answer to “what will this actually cover?” — the honest question in every solar conversation.
6. Size the storage. Daily use, backup days, depth of discharge and inverter efficiency give a battery bank in kWh and amp-hours at the system voltage.
7. Hand it to qualified installers. Grid connection, permits and the installation itself — roof-side and electrical — are professional work. The plan's job is to make you an informed client, not a roofer.