How to Guide – Pitched Green Roof (Anti-Slip & Retention)
For sloped extensive & semi-extensive roofs (illustration only)
⚠️ Important Disclaimer: This guide is for illustration purposes only. It is not an installation manual and does not replace manufacturer data sheets, structural calculations, wind-uplift/fire design, or building regulations. Site conditions vary. Clever Shield Ltd accepts no liability for actions taken based on this information. Always follow current product documentation and consult competent professionals (including a structural engineer for loadings).
Pitched green roofs need the same core layers as flat systems, plus anti-slip retention to keep the growing medium and vegetation in place. This quick guide outlines the typical build for slopes above ~5° (low pitch) through to steeper roofs, using Wykamol components available from Clever Shield Ltd.
1) Check suitability
- Structure & loading: Verify saturated loads (layers + substrate + vegetation + rain/snow). Engineer sign-off recommended for pitched systems.
- Slope & access: Define safe access and fall protection for installation and maintenance.
- Drainage & overflows: Ensure free discharge to outlets/eaves; add inspection/access points where possible.
- Wind & fire: Design perimeter fire-breaks and wind-uplift restraint per project standards.
2) What you’ll need:
- Primary waterproofing: Wykamol Sureproof Waterproofing Membrane (self-adhesive Type A) where specified for the deck.
- Protection/filtration layer: Wykamol Geotexile Drainage & Protection Membrane (protection + filter for podium/roof build-ups).
- Drainage with bonded filter: Wykamol CM8 Geotextile Membrane 2m × 20m (preferred drainage layer on pitched systems).
- Higher void capacity (where designed): Wykamol CM20 Geotextile Membrane 2m × 10m.
- Edge restraint/terminations: Geotextile Membrane Profile Strip 2m for neat edges and to form perimeter gravel zones.
- Growing medium & planting: Certified lightweight green-roof substrate; sedum mats/trays or plugs/wildflower mix to specification.
- Retention aids (project-specific): Timber/aluminium battens or retention grids/strips fixed per design (spacing based on slope and load).
- Optional: Drip irrigation for semi-extensive mixes; outlet inspection boxes; eaves/gravel stop profiles.
3) Fast build sequence (illustration only)
- Prepare the roof: Repair defects; check fixings, eaves details and overflows. Confirm slopes.
- Primary waterproofing: Install/verify a continuous, tested membrane (e.g., Sureproof). Detail upstands, penetrations and eaves.
- Protection/filter layer: Loose-lay Geotex Drainage & Protection Membrane; lap/tape per data sheet. Turn up at upstands above finished level.
- Drainage layer: Roll out CM8 Geotextile (geotextile face up) from ridge to eaves; lap neatly and keep water paths clear to eaves/outlets. For higher capacity, use CM20 Geotextile where designed.
- Edge restraint & eaves details: Fix Profile Strips; form 300–500 mm gravel margins at perimeters, valleys and penetrations for fire breaks and maintenance.
- Install retention aids: Fit pitched-roof battens/grids on top of the drainage layer at designed centres across the slope to retain substrate. Seal any fixings through waterproofing with system-approved details.
- Substrate: Place certified lightweight substrate evenly to the specified depth (typ. extensive ~60–120 mm; semi-extensive ~100–200 mm), working uphill between retention rows. Do not block drainage at eaves.
- Vegetation: Lay sedum mats/trays tight to joints, or plant plugs/wildflower mixes per supplier rates. Water thoroughly.
- Final checks: Inspect retention rows, edges and eaves; confirm free drainage; record build-up, depths and retention spacing.
4) Indicative retention spacing (illustration only)
| Roof pitch (°) | Typical approach | Notes |
|---|---|---|
| 5–10° | Retention rows at wider centres | Substrate depth per planting; check wind/uplift details. |
| 10–20° | Closer retention centres; consider anti-slip grids | Irrigation advisable for semi-extensive mixes. |
| >20° | Engineered system (grids + anchors) | Engineer design required; enhanced edge/wind detailing. |
Spacing, fixings and component choice must be confirmed by the project designer/engineer and manufacturer data sheets.
5) Tips & common pitfalls
- Wrong layer order: Keep drainage with bonded geotextile above protection and below substrate. Do not bury inspection points.
- Insufficient retention: Increase retention rows as pitch increases; verify fixings and substrate depth.
- Blocked eaves: Maintain gravel margins and keep geotextile clear of outlets.
- Wind & fire: Use perimeter gravel/fire breaks and secure edge trims per guidance.
Product availability
Clever Shield Ltd supplies Wykamol Sureproof Waterproofing Membrane, Wykamol Geotex Drainage & Protection Membrane, Wykamol CM8 Geotextile Membrane, Wykamol CM20 Geotextile Membrane, and Geotextile Membrane Profile Strips, plus certified substrates, sedum mats/trays and retention accessories. Use the website search to select sizes and kits for your pitched roof project.
⚠️ Legal Notice: This content is a general, illustrative overview. It is not manufacturer guidance and may not suit all roofs. Requirements, regulations and recommended methods can change. Clever Shield Ltd provides this information “as-is” without warranty. Always follow current data sheets and consult qualified professionals before commencing work.