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LEARNING HUB
Site Requirements
& Common Issues
Learn the main biosolar site requirements, installation risks and common issues involving waterproofing, drainage, mounting stability, access, cables and trade coordination.
How a Biosolar Installation Works
A biosolar installation combines roofing, green roof and solar works within the same roof area.
Because several trades are working around the waterproofing, drainage, mounting system and planting zones, site logistics and sequencing need more coordination than on a conventional standalone roof or PV installation.
Good site control helps prevent damage, reduces rework and makes the completed roof easier to inspect and maintain.
In Simple Terms:
Protect the Roof
Keep the waterproofing and completed roof layers protected throughout the works.
Control the Work Area
Plan access, storage and trade sequencing before installation begins.
Keep Critical Routes Clear
Maintain drainage, fire zones, cable routes and maintenance access at all times.
Site Readiness
01
Safe Roof Access
Confirm safe access, lifting and fall protection before work begins.
02
Waterproofing Ready
The membrane should be complete, inspected and protected before biosolar installation works begin.
03
Approved Layout
The latest coordinated roof, mounting, drainage and access layout should be available on site.
04
Material Storage
Define safe loading and storage areas that do not overload or damage completed roof sections.
05
Trade Responsibilities
Confirm who is responsible for roofing, green roof, mounting, solar and shared interface works.
06
Weather Planning
Consider wind and rainfall when planning lifting, mounting, substrate and exposed roof activities.
Waterproofing Damage & Site Traffic
01
Heavy foot traffic, dragged materials and repeated access can damage the waterproofing before the roof is fully covered.
Once the biosolar build-up is installed, locating and repairing membrane damage can become significantly more difficult.
How to Prevent It
-
Use designated access routes and temporary protection
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Lift components rather than dragging them
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Avoid concentrated material storage on completed areas
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Keep the working area clean and free from sharp debris
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Inspect exposed waterproofing as installation progresses
Blocked Drainage & Fire Zones
02
Substrate, fleece, vegetation, mounting components or stored materials can accidentally obstruct drainage outlets or required separation zones.
These areas need to remain clear throughout installation, not simply be corrected at the end.
How to Prevent It
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Keep outlets, gutters and overflows visible
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Maintain the designed drainage routes
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Protect required fire and separation zones
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Prevent substrate and vegetation bridging clear areas
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Inspect critical zones before they are covered
Mounting Stability & Build-Up Depth
03
Some biosolar mounting systems rely on ballast, substrate or proprietary load-distribution components to achieve the required stability.
Changing specified quantities, depths or component positions can mean the installed system no longer matches the approved structural and wind design.
How to Prevent It
-
Follow the project-specific mounting design
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Maintain specified substrate or ballast quantities
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Check mounting alignment before later layers are installed
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Do not substitute components without approval
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Recheck affected areas after heavy site traffic
Cables, Access & Future Maintenance
04
Poor cable routing or equipment positioning can create inaccessible areas, interfere with vegetation and make future maintenance unnecessarily difficult.
The completed installation should remain practical to inspect and service throughout its working life.
How to Prevent It
-
Keep cables supported, protected and organised
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Avoid loose cabling within growing media
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Keep isolators and equipment accessible
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Preserve maintenance routes to PV and green roof areas
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Coordinate cable routes before planting is completed
Do Not Improvise the Layout
Small site changes can affect several parts of a biosolar design at once.
Changes to module spacing, mounting positions, substrate depth, drainage routes or fire-zone layouts can affect wind loading, energy performance, access and warranty requirements.
If the installed arrangement differs from the approved design, stop and confirm the change before continuing.
Who Does What on Site?
01
Roofing Team
Typically responsible for:
-
Waterproofing installation and detailing
-
Relevant roof inspections
-
Membrane protection requirements
-
Roofing warranty requirements
02
Green Roof Team
Typically responsible for:
-
Green roof build-up
-
Growing substrate
-
Vegetation installation
-
Establishment requirements
03
Solar / Biosolar Team
Typically responsible for:
-
PV mounting within their package
-
Solar PV modules
-
Electrical installation
-
Testing and commissioning
Shared Responsibility
The critical issue is the interface between trades.
Responsibility for mounting components, waterproofing protection, drainage, substrate levels, cable routes and final sign-off should be agreed before work begins.
Site Checks Before Handover
Responsibility varies between contracts and manufacturers, so these should be treated as typical roles rather than fixed rules.
-
Drainage outlets remain clear
-
Required fire zones are maintained
-
Substrate matches the specified depth
-
Vegetation is correctly established
-
Maintenance routes remain accessible
Roof & Green Roof
-
Mounting system is complete and aligned
-
PV modules and fixings are secure
-
Cable routes are supported and accessible
-
Electrical equipment remains serviceable
-
The approved layout has been followed
Solar & Mounting
Stop and Review If You See
Blocked
Outlet
Drainage water cannot reach the intended outlet freely.
Membrane
Damage
Cuts, punctures or visible damage appear in exposed waterproofing.
Mounting
Movement
Frames, supports or mounting components move unexpectedly.
Changed
Substrate Depth
Installed substrate no longer matches the required build-up.
Loose
Cabling
Cables sit unsupported within planting or drainage areas.
Unapproved
Layout Changes
Installed positions differ from the latest approved design.
WHERE TO GO NEXT
To understand how biosolar compares with other combined roof systems, continue to Biosolar vs Green Roof Solar.
If you’d like to explore what a biosolar roof can achieve in terms of energy performance, biodiversity value, and planning outcomes, visit Key Benefits.
For policy drivers and regulatory context, the Biosolar and Planning / Policy page provides a concise overview of current UK guidance.
If you’re seeking a specialist contractor to deliver a biosolar roof system visit PV Plus
