Where the values come from
The characteristic snow load s_k (kN/m²) and the reference wind speed v_b (m/s) are read from the snow and wind zone polygons of Boverket's EKS 11, looked up at the house's latitude and longitude in a PostGIS table. Near a zone border the higher value is taken and the result is flagged near border, so the offer says check on site. When no polygon contains the point — no coordinates or no zone data — the kommun's values are used instead, from the kommun you or the homeowner picked, else from the kommun the geocoder returned. The kommun fallback counts as a suggestion only: it stays below the reliability threshold unless an admin has verified that row.
Every result carries a confidence — low, medium, high or verified — and the lower of the snow and wind confidence decides. Values at or above the threshold (medium by default) become facts on the estimate and the offer. Below it, the homeowner is asked for s_k and v_b, or can answer that the installer will enter them, and the offer card then asks you.
The inputs you or the client can change
Four inputs go into the calculation: terrain category 0 to IV (default III), building height 2.5 to 30 m (default the ridge height of the 3D model), safety class 2 or 3 (default 2) and whether there is a snow guard above the panels. On the offer card you can also enter s_k and v_b yourself; an entered pair always replaces the map values, the map values stay visible as the suggestion, and one value alone is not used. A homeowner who entered values on the estimate sends them with the request, marked as entered by the homeowner.
A zone diagram per roof face
Each face is cut into cells at every zone edge, and every cell shows the zone that governs it over all wind directions — wind on either eave and on either gable — the case with the highest design uplift at the cell's centre. A panel counts in the worst zone its area touches, so a panel drawn partly into an edge band is counted in that band, and the worst zone of the face governs the hooks. The diagram is drawn from the stored face: width, slope length, pitch, roof type, height and footprint.
Where the values go
On the public estimate the client sees the loads in their own pane. On your offer the loads are on the card and in the facts the package rules read, so a rule can pick the mounting per zone. The overrides live on the offer's requirement, inside your organisation only, and the project page shows the same values. The homepage map shows s_k and v_b for every place in Sweden; hover, tap or type a kommun or coordinates.
An estimate for the quote, Sweden only
This is an estimate for a quote, not a structural calculation: the zone values, the terrain category and the building height are inputs a person confirms, and the mounting system's own documentation sets what the roof and the hooks carry. The EKS method applies to Sweden only; an address outside Sweden gets no loads, no card and no facts.
