Design decision
Why this idea works
A lean-to uses an existing wall for shelter and warmth, and a small potting court gives it the working surface it needs right at the door. The concrete keeps the potting zone firm and clean while the wall does structural and thermal work, making an efficient growing spot in a compact footprint.
- The tradeoff
- The layout sets a clear direction, but it also commits the project to fixed relationships. Slope the court away from the wall and keep the threshold flush.
- How to measure it
- Conceptual range: the potting court measured to the working area in front of the lean-to.
On your property
Plan it for your site
Keep the court a grippy, rinseable surface sloped to drain, and detail the junction with the wall so water sheds away from it. Keep the threshold flush so trays and carts move between court and greenhouse cleanly.
- Slope the court away from the supporting wall so water does not collect against it.
- Keep the threshold flush so trays and carts move cleanly.
- Size the court to the potting and staging the lean-to needs.
Before forms are set
Build implications
- Confirm before estimating Drainage directed away from the wall.
- Confirm before estimating A flush threshold at the greenhouse.
- Confirm before estimating A court sized to real potting work.
- Measure the site and establish elevations Record boundaries, thresholds, grade changes, utilities, and the dimensions of vehicles, furniture, equipment, or structures that affect the layout.
- Test how the space will be used Check walking routes, turning paths, door swings, working clearances, maintenance access, and the route back to the house or street.
- Resolve drainage, services, and structural support Decide where water goes and coordinate drains, conduit, irrigation, fuel, electrical work, footings, and independent supports before forms are set.
- Define and estimate each concrete element Confirm the slab or footing section, base, joints, edges, and finish, then estimate simple measurable fields separately from steps, walls, drains, and supported features.
Prevent these problems
- Matching the wall footprint exactlyA small dry perimeter can improve the threshold, door clearance, maintenance access, and runoff control.
- Using one uniform thin sectionBearing walls, anchors, heavier storage, or manufacturer requirements may call for thickened edges or a footing.
- Allowing wet soil against the slabPoor grading, mulch, and irrigation can keep the pad edge damp and undermine the base or the structure above.
Next step
Turn the idea into your estimate
Enter measurements from the property. The conceptual image does not provide a takeoff.
Estimate a similar shed padQuestions this idea raises
What is a lean-to greenhouse?
One built against an existing wall, which provides shelter and some thermal mass, making it efficient in a compact footprint. A potting court in front gives it a firm working surface.
How do I protect the wall from the court’s water?
Slope the court away from the wall so runoff sheds toward the garden, not against the structure. Plan that fall into the pour.
- Best when
- Greenhouse pads
- Reconsider when
- Reconsider the idea if base preparation, bearing edges, anchors, drainage, and building-manufacturer requirements cannot be resolved on the property.
- Verify first
- Slope the court away from the wall and keep the threshold flush.
- Professional input
- Concrete contractor; verify the building manufacturer’s foundation requirements
Sources and further reading
- American Concrete InstituteTechnical references for small slab-on-grade pours and thickened edges.
- NRMCA CIP 6: Joints in Concrete Slabs on GradeUseful when a longer garden or greenhouse pad needs planned crack control.
- ICC model code portalCheck whether an accessory building or its slab needs a permit or setback in your area.
