Green Roofs
K Pendlebury & Sons installs green roofs on commercial buildings across the North West. A green roof adds a living planted layer above the waterproofing, which manages rainwater run-off, improves the thermal performance of the building and supports biodiversity, and we install the complete build-up that makes it work.
What a green roof does for a building
A green roof holds rainwater in its growing layer and releases it slowly, which reduces the peak run-off that drainage systems and planning conditions increasingly have to deal with. The planted layer also shields the waterproofing from ultraviolet light and temperature extremes, and shading the membrane extends its life because UV and thermal cycling are what age a flat roof. Added mass and insulation improve the building's thermal performance, and the vegetation supports biodiversity, which is why green roofs feature in planning requirements on many new commercial developments.
The waterproofing underneath is what matters
A green roof is only as good as the waterproofing below it, because once the planting is established, getting back to the membrane is disruptive and expensive. That is why the membrane under a green roof must be root-resistant and installed exactly to the manufacturer specification before a single tray of sedum goes down.
This is where a specialist flat roofing contractor earns its place on a green roof project. We are accredited contractors for manufacturers including Bauder, whose green roof systems are among the most widely specified in the UK, and we install the full build-up: waterproofing, root barrier, drainage and filtration layers, growing medium and planting.
New build and refurbishment
Green roofs suit new build projects where the structure is designed for the load from the start, and refurbishments where the client wants the replacement roof to give the building more than waterproofing. Our free survey establishes whether the existing structure can take a green roof build-up, and what the waterproofing and drainage design needs to look like underneath it.
What a green roof build-up includes
- ✓Root-resistant waterproofing membrane installed to specification
- ✓Root barrier, drainage and filtration layers
- ✓Growing medium and planting appropriate to the roof
- ✓Rainwater run-off attenuation for drainage and planning
- ✓Protection of the membrane from UV and temperature extremes
- ✓Manufacturer-backed system guarantees through accredited installation
Frequently asked questions
Can my existing flat roof be converted to a green roof?+
Only if the structure can carry the extra weight and the waterproofing is suitable, because a saturated green roof build-up is significantly heavier than a standard membrane. Our free survey assesses the structure and tells you what is possible before any commitment.
Does a green roof damage the waterproofing over time?+
No, the opposite, provided the membrane is root-resistant and correctly installed. The planted layer shields the membrane from UV and temperature swings, which are the main causes of membrane ageing, so the covered membrane is protected rather than threatened.
How much maintenance does a green roof need?+
Less than a garden but more than a bare membrane. Typical maintenance covers inspecting outlets and borders, removing unwanted growth and checking the planting, and the frequency depends on the system specified. We will set out the maintenance requirement for the specific build-up we propose.
Why do planners ask for green roofs?+
Because green roofs reduce peak rainwater run-off and add biodiversity, both of which feature in planning policy for commercial developments. A green roof can therefore help a scheme meet drainage and ecology conditions while also insulating the building.
Accredited by the bodies that matter in commercial roofing
How can we help you with your new project?
Surveys, budgets and reports are free of charge for all clients, new and existing. Tell us about your roof and we will advise on the right system.