New to this? Five steps
Work down the page in order. Everything on the right updates as you go, and that right hand panel is the bit you turn round and show the customer.
- Measure the roof from above. Trace it in Google Earth, or measure length and width on site. Enter the flat footprint and let the calculator handle the slope.
- Set the pitch. Most roofs are 8/12 to 12/12. Pick off the shaded fan, or work it back from the ridge height.
- Choose the work. Clean only, or clean plus sealer.
- Price the conditions. Anything awkward about access, then any add-ons.
- Apply a discount if you are offering one, then print the estimate and hand it over.
Roof sections
Add a section for each separate roof plane. A simple house is usually one section. Add more for extensions, garages and porches.
Measuring tip. Google Earth and similar tools give you the roof as seen from above, which is the footprint. The real surface is bigger because the roof slopes, and the calculator handles that for you.
Pitch calculator
Enter any one value and the rest follow. Pick from the fan or the table if you know the pitch by eye. Whatever you set here applies to the roof section highlighted above.
Rule of thumb. Around 80% of roofs come in between 8/12 and 12/12, which is 33.7 to 45 degrees. That band is shaded on the fan and highlighted in the table, so start there if you are working from a photograph or a distance. Check the tile type before committing though: low pitch interlocking concrete tiles sit lower, often 4/12 to 7/12.
Work it back from a measurement
Not sure how?
Pitch is rise divided by run. On a gable or hip the run is half the width of the building, not the full span.
Pitch, angle and multiplier table
The multiplier is what turns a footprint into the real roof surface. A 100 m² footprint at 7/12 is 115.8 m² of roof to clean and treat.
The work
Access
Tick anything that will make the job harder to set up or work safely, and price it.
Add-ons
Optional extras, priced as fixed amounts.
Discount
Comes off the whole job and shows on the customer’s estimate as a saving.
- Footprint
- 0m²
- Roof surface
- 0m²
What is included
This is an estimate based on the measurements above. The final price is confirmed after a survey, once we have seen the roof condition and access for ourselves.
Rates not confirmed yet. The figures in this build are placeholders so you can see the calculator working. Set your real numbers under Your rates before quoting anyone.