Introduction:
Here is our pictorial guide for the establishment of our simple green roof system. The intention is to give a step by step account of how to install the Wildflower Turf roof system. Our turf is suitable for any green roof project using any manufacturers product.Before starting:
Ensure that the roof structure is of sufficient strength and suitably designed to support the combined saturated weight of the turf, substrate and irrigation system. If unsure, it is advisable to consult a structural engineer, architect, or specialist contractor.
Safety Note:
Please ensure that it is safe to work on the roof. If in doubt please refer to the Health & Safety Executive web site for further guidance and availability of publications.1. Waterproof Membrane
Lay a waterproof membrane over the entire roof area. Consult a roofing contractor for an appropriate system. Pay attention to sealing around roof lights, vent stacks and other similar features where there is a higher risk of water ingress. The whole roof must be watertight. Take care not to puncture the membrane.
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One manufacturers product using a single ply membrane |
2. Substrate Retention
When using loose substrate, and in particular on steeply pitched roofs, provision must be made for a retaining system at the eaves and sides of the roof. This can be in the form of a wooden batten/barge board with accompanying fixing brackets or an engineered metal L shaped strip attached to the roof structure. Your architect or roofing contractor should advise you on the design and construction of this feature. Attention should be made to the water-tightness of fixing points. |
Engineered metal L shaped retaining profile |
In addition to eaves retention it is advisable to install a line of our woven substrate sacks around the perimeter of the roof which provides the initial containment of the loose substrate whilst the turf establishes a root system.
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Eaves and ridge substrate sacks |
3. Drainage
Adequate provision must be made for drainage at the bottom of the roof slopes. This can be achieved by leaving a small gap in the retention feature, or a strip back-filled with gravel or similar material.
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Barge board and gutter system |
If rainwater collection is desirable, a gutter can be installed draining to a suitable collection point. |
Gravel and open gutter system |
4. Substrate Layer Options
Option 1 - Loose substrate
Lay a strip of geo-textile permeable membrane along the inside of the barge board to allow water to drain without washing out any substrate/soil in the process.
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Permeable retaining material |
Fill area with substrate laid evenly at 100mm depth. Remember to allow 10% extra for settlement.
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Spreading loose substrate |
Option 2 - Mixed - Loose substrate and Substrate sacks
Using our 600x460x100mm woven substrate sacks, allow 3.8 sacks per m². Lay two lines of sacks around the perimeter of the roof and along the ridge. Backfill the remainder of the area with loose substrate to the same level as the sacks allowing 10% extra for settlement. |
Mixed substrate - bagged and loose substrate combination. |
Use some of the loose substrate to fill in the small spaces between the substrate sacks.
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Fully screeded |
Option 3 - Substrate layer using sacks only
Using our 600x460x100mm woven substrate sacks (allowing 3.8 sacks per m²) cover the whole roof area. Using sacks helps to give permanent structural strength. |
Substrate sacks |
Using loose substrate, apply a screed layer of substrate over the substrate sacks and brush in to ensure any gaps are properly filled. |
Sacks and Screed |
5. Irrigation (optional, but recommended)
Lay drip irrigation system, if required (recommended). Pipes should be laid across the gradient of the roof slope with T joints to a vertical supply/feeder pipe. Please request information about our irrigation kits. |
Drip irrigation kit installed |
6. Laying Turf
Lay the turf paying attention to abutting turf joints and ensuring turf roots are in contact with the substrate. Any gaps should be filled with loose substrate. |
Turf laying in progress |
7. Completed Project
The completed Green Roof project at Cardiff Castle. |
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The completed Green Roof project at Paultons Park. |
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8. Watering
Water turf daily (if it does not rain) until the roots have established (allow two weeks minimum). Do not flood the turf when watering but ensure the substrate is damp. Once established revert to occasional watering as per the maintenance sheet. |
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9. After Care
For aftercare after the green roof is established please refer to our maintenance sheet.
