Backyard Concrete Demolition + Garden

1

Get plan cadastral for the abri de jardin You

Download from cadastre.gouv.fr or request at Saint-Germain mairie. Need the parcelle showing the abri de jardin that's cadastré. This is required for the permis de démolir application.

2

File permis de démolir You

Cerfa 13405 at Saint-Germain mairie. Required because abri de jardin is cadastré (registered on cadastre = likely >5m² footprint). Include site plan + photos + demolition description. Délai: 2-3 months. This is the long pole — start immediately.

3

Measure + inspect access path You

Three things to check: (1) Alley width at narrowest point - need 60cm+ for Yanmar SV08, 66cm+ for Kubota K008. (2) Wooden steps in the alley - shallow terraced drops (0.5-1m) with 3-4m flat runs between. Screwdriver-test every step for rot. Solid wood on trackway panels = fine. Soft/rotten = no machine. (3) Stone walkways - flagstones likely sand-set, need trackway panels (caillebotis) or plywood to prevent displacement. Front stone stairs from street are car-rated granite, not a concern.

4

Estimate concrete volume You

Surface area (m2) × thickness (cm). "Two parking spaces worth of 15cm slab" is enough detail. This drives cost more than anything.

5

Decide garden vision You

Lawn? Flower beds? Trees? Vegetables? Determines topsoil depth needed (30-40cm standard, more for trees). If trees are desired, placement must be planned before backfilling so pits can be dug through the concrete.

6

Request benne authorization from mairie You

Autorisation d'occupation du domaine public from Saint-Germain mairie. Allows placing a skip on the narrow street. Request early - can take 1-2 weeks. Smaller benne (10m3) for tight street.

7

Research + call démolition "accès difficile" companies Alfred

Find 2-3 companies in Yvelines that specialize in difficult-access demolition. They come do a site visit and tell you what method they'd use. Not quotable over phone.

8

Get site visits + devis from 2-3 démolition companies You

Show them the access (stairs, alley, narrow street). Ask about: mini-pelle (Yanmar SV08 / Kubota K008) + trackway, tapis convoyeur option, break-and-bury approach. Compare quotes.

9

Phase 1: Demolition + earthworks (requires permis de démolir approved) Contractor

Break concrete in place. Leave rubble as drainage base. Lay geotextile membrane (feutre jardin). Bring in topsoil (30-40cm). Level. Haul out only excess rubble via alley + stairs to benne.

10

File cadastre modification (within 90 days of demolition) You

Cerfa 12210 (déclaration de modification des éléments d'évaluation). Stops taxe foncière on the demolished abri. File within 90 days of completing demolition, otherwise you keep paying tax on a building that no longer exists.

11

Research + call paysagistes Alfred

Find 2-3 local landscapers. They work on the prepared base. This phase starts after demolition is complete.

12

Get devis from 2-3 paysagistes You

Present garden vision, review their proposals, choose. Quality matters here more than price - look at previous work.

13

Phase 2: Garden build Contractor

Planting, finishing, paths, any structures. Done on the prepared base from Phase 1.

Planning phase

What: Existing concrete in backyard needs to go. Bring in topsoil, build a garden.
Property: Saint-Germain-en-Laye house with difficult backyard access.
Scale: "Serious" demolition (exact volume TBD).

This is the defining challenge of the project. Standard "mini-pelle + benne" won't work without creative solutions.

Front access: Solid stone stairs (likely granite) from street-level raised parking area. Same structure holds two cars (3-4t). Structurally sound for mini-pelle (0.8-1.3t). Easy part.
Garden alley terrain: Shallow terraced path down the hill. Small drops (0.5-1m) with 3-4m flat runs between them. Not steep stairs. Timber ramps (scaffold planks / railway sleepers) bridge each drop. Mini-pelle crawls down at ~10-15° angle. Standard for démolition crews.
Alley surfaces: Mix of wooden steps and stone walkways. Wood needs screwdriver test for rot. Stone is likely flagstone in sand/thin mortar, needs trackway panels (caillebotis) or thick plywood to prevent dislodging.
Two side alleys, both with plants/trees: Don't want to remove vegetation. Mini-pelle on trackway panels protects roots from compaction. Width is the question (need 60cm+ for Yanmar SV08).
Narrow street out front: Benne placement needs mairie authorization. Smaller skip (10m3) likely required.

Alley is viable for mini-pelle. Shallow terraced drops (0.5-1m) with 3-4m flat runs are easy terrain for a tracked machine. Timber ramps bridge each drop. No winch needed at these angles. Démolition crew brings the planks. Main unknowns: alley width (60cm+ needed) and wood step condition (rot check).

Before machine descent: Screwdriver-test every wooden step in the alley. Solid hardwood on concrete/stringers = fine. Soft/rotten = no machine through that section. Lay trackway panels over stone walkways to prevent flagstone displacement.

Break-and-bury (primary strategy): Break concrete in place with marteau piqueur, leave rubble as drainage base, lay geotextile, top with 30-40cm topsoil. Only haul out excess volume. Cuts removal problem by 50-70%.

Two phases, two contractors:

Phase	Who	Scope
1. Demolition + earthworks	Entreprise de démolition (accès difficile specialist)	Break concrete, bury rubble in place as drainage base, geotextile, bring in topsoil, level. Haul out only excess rubble via alley (wheelbarrow or mini conveyor).
2. Garden build	Paysagiste	Plant selection, planting, finishing. Works on prepared base. Lawn, beds, paths, etc.

Machine options (if alley allows):

Machine	Width	Weight	Notes
Yanmar SV08-1	59 cm	0.8 t	Smallest in the world. Fits through a garden gate. Needs wooden trackway (caillebotis) over planted alley. 0.8t is ~20% of what the parking area holds daily.
Kubota K008-3	66 cm	1.3 t	Fits through standard doorframe (80cm). Ride-on with an arm. Common in Paris apartment renos.
Kubota U10-3	75 cm	~1.2 t	Articulating undercarriage narrows further. Slightly more reach and power.

Machine constraints beyond width:

Weight on alley: Even 0.8t on rubber tracks compacts soil and crushes roots. Lay wooden trackway panels.
Stairs: Structurally fine (holds car weight). Operational concern: machine tipping/sliding on descent. Needs winch or ramp. Many operators will do it with proper setup.
Turning room: If backyard is small, a mini-pelle that can't turn isn't much better than manual labor.

Fallback if no machine fits: Full manual. Marteau piqueur (rent from Kiloutou/Lebon), sledgehammer, fill big bags (1m3, ~1t each), wheelbarrow out through alley. Slow but viable.

Concrete is inert (cement + sand + gravel). Doesn't leach toxins. Basically rocks. In Île-de-France, native soil is already slightly alkaline (calcareous), so pH drift from concrete is less of an issue than in acidic regions.

pH drift: Concrete is alkaline, can slowly raise soil pH. Mitigate: 5cm clean crushed gravel drainage layer + geotextile membrane (feutre jardin) + topsoil.
Geotextile prevents migration: Stops concrete fragments from working up through soil via freeze-thaw cycles.
Drainage improves: Broken concrete under soil drains better than compacted clay. Net positive.
Depth for plants: 30-40cm topsoil is enough for lawn, perennials, most shrubs. Not enough for deep-rooted trees. If you want a tree, dig a pit through the concrete for it specifically.

Bottom line: Break-and-bury is standard practice in French garden renos ("démolition sur place + remblai + terre végétale"). Soil risk is manageable with geotextile. Don't let this concern block the approach.

Exact alley width? Need measurement at narrowest point.
Stair dimensions? Step count, tread depth, width. Visual inspection for loose/cracked steps.
Concrete volume? Surface area and thickness. Old patio? Foundations? Pathways?
Garden vision? What do you want growing back there?
Any trees in the plan? Changes the soil depth requirement.
Timeline? Before winter? Next spring? Affects plant selection and scheduling.

🌿 Backyard Demolition + Garden

✅ Action Plan - Step by Step

📋 Situation

🚧 Access Constraints

🏗️ Recommended Approach

🌱 Soil Composition: Break-and-Bury Concerns

❓ Open Questions