Planted basins for roof and driveway runoff
Practical sizing methods, soil specifications, and native plant palettes for shallow infiltration gardens in Polish conditions — from clay-heavy soils to sandy outwash.
Core Topics
What this site covers
Three areas of rain garden design relevant to Polish residential and light commercial contexts, each with specific sizing calculations, soil guidance, and plant references.
Sizing for roof area
How to calculate basin volume based on catchment area, local rainfall intensity, and target infiltration rate. Includes worked examples for 80 m² and 150 m² roofs.
Soil mix specifications
Layer composition — topsoil blend, aggregate transition, and gravel underdrain. Adapted for Poland's range of native soils from Poznań loams to Masovian sands.
Plant palettes
Species tolerant of periodic inundation and summer drought, selected from plants native to central Poland. Grouped by basin zone: inflow, central, and edge.
Downspout disconnection
Methods for directing gutter discharge into a planted basin, including splash pad design, overflow routing, and bypass provisions for high-intensity events.
Driveway runoff
Lateral swale geometry and curb-cut sizing for driveways draining 40–120 m² of impervious surface into a roadside or front-yard basin.
Polish climate context
Design-relevant rainfall data from IMGW stations. Reference intensities for 10-year return periods across Warsaw, Kraków, Wrocław, and Trójmiasto.
How it works
Basin sizing in three steps
A simplified sequence for estimating rain garden dimensions when the primary goal is managing a single downspout or a small driveway apron.
| Step | Input | Calculation | Typical result |
|---|---|---|---|
| 1. Determine runoff volume | Roof or driveway area (m²) | Area × design rainfall depth (mm) × runoff coefficient | 0.6–2.0 m³ for 100 m² catchment |
| 2. Select infiltration rate | Soil texture, percolation test | Match to soil class; apply 50% safety factor | 25–80 mm/hr for Polish loam soils |
| 3. Size basin surface | Runoff volume, drain-down time | Volume ÷ (infiltration rate × target hours) | 8–20 m² basin for 100 m² roof |
Articles
In-depth guides
Detailed reference material on specific aspects of rain garden design for Polish conditions.
How to Size a Rain Garden for Roof Runoff
Step-by-step sizing calculations using catchment area, Polish rainfall data, and soil percolation rates.
Read article →
Soil Mix and Plant Palettes for Polish Rain Gardens
Layer specifications and species lists for basins in central Poland, grouped by inundation tolerance and soil zone.
Read article →
Managing Driveway Runoff with Shallow Planted Basins
Swale geometry, curb-cut sizing, and overflow design for driveways discharging into front-yard or roadside basins.
Read article →Reference Data
Design rainfall — selected Polish cities
10-year return period rainfall intensities from IMGW stations, commonly used as the design storm for residential rain garden sizing in Poland.
| City | Region | 10-yr, 15-min (mm/hr) | 10-yr, 60-min (mm/hr) | Dominant soil type |
|---|---|---|---|---|
| Warsaw | Masovia | ~60–70 | ~25–30 | Loamy sand / sand |
| Kraków | Lesser Poland | ~65–75 | ~28–34 | Clay loam |
| Wrocław | Lower Silesia | ~55–65 | ~22–28 | Silty clay |
| Gdańsk | Pomerania | ~55–65 | ~22–28 | Sandy loam |
| Poznań | Greater Poland | ~50–60 | ~20–25 | Loam |
Values are indicative ranges based on publicly available IMGW station data. Site-specific analysis requires local station records.
Contact
Send a question
Use this form to submit a question about rain garden design, site conditions, or specific plant queries. No sales or solicitation.