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A roof mounting system has one job and it lasts longer than anything else on the project: holding the array to the building for the design life. It is also the item most often bought as if it were a commodity, which is why roof leaks, loose clamps and cracked module frames are the three failures that show up years after handover rather than during commissioning.
This page covers the roof system as supplied: how the roof covering decides the attachment method, what the structural calculation is based on, and what has to be settled before it ships.
How the roof covering decides the method
The first question is not which rail to buy. It is what is on the building, because the covering decides whether penetrations are allowed at all.
- Standing-seam metal may accept non-penetrating clamps for approved seam profiles. Confirm the seam, panel gauge, clamp test data and roof-manufacturer approval; a non-penetrating attachment does not automatically preserve the roof warranty.
- Asphalt shingle takes a flashed penetrating attachment. The flashing detail matters more than the bracket, and it is the part that fails when it is improvised.
- Tile roofs take a hook that replaces a tile, or a tile cut with a flashing. Cutting tile on site without the right detail is the most common source of a leak claim.
- Flat membrane takes a ballasted tray at a low tilt, with no penetration. The ballast is calculated, not estimated.
Where the roof is under warranty, get the manufacturer position in writing before the method is fixed. A method the roof manufacturer does not sanction is a claim waiting to happen.
Specifications
Configuration reference
Swipe horizontally to view all columns →
| Parameter | Typical value | What it depends on |
|---|---|---|
| Suitable roof types | Asphalt shingle, tile, standing-seam metal, flat membrane | What is on the building now |
| Attachment method | Penetrating hooks and rails, non-penetrating seam clamps, or ballasted tray | Roof covering and the roof warranty position |
| Material | Anodised aluminium 6063-T5, hot-dip galvanised steel, or stainless steel | Load, weight limit and corrosion class |
| Rail length | Stocked lengths, cut to the layout where required | Module dimensions and rail span |
| Module layout | Portrait or landscape, clamp mid or end | Module frame height and rail position |
| Tilt | Roof-following on pitched roofs; 5 to 10 degrees on flat roofs | Roof pitch or ballasted design |
| Wind load | Calculated per roof zone to ASCE 7 or EN 1991-1-4 | Building height, terrain and roof zone |
| Snow load | Calculated from ground snow load and roof factors | Local code and roof geometry |
| Corrosion class | C3 to C5 to ISO 9223 | Distance from the coast and the site environment |
| Fixings | Stainless steel, with torque values supplied | Frame material and coating compatibility |
| Documentation | Confirm calculation, layout, torque and maintenance document scope | Project inputs, selected system and local engineering requirements |
| Warranty | Confirm structural, coating and component warranty terms for the selected system | Selected model and written order terms |
Figures are selection references. Confirm the final ratings, dimensions, available certifications and warranty against the current datasheet and written proposal for the selected model or system.
What arrives in a typical order
- Rails, clamps, hooks or seam clamps, and the fixings for the roof covering specified.
- Torque specifications for every connection, and the maintenance notes.
- Site-specific structural calculation for the wind and snow region of the building.
- Layout drawing with rail spans, clamp positions and the ballast schedule where applicable.
- Packing list and delivery documentation.
Where a roof system usually goes
- Commercial and industrial pitched roofs, where the roof-following layout is the cheapest way to get array onto the building.
- Flat commercial roofs with ballasted trays, where penetrations are not permitted.
- Standing-seam metal roofs on warehouses and distribution centres, where non-penetrating clamps protect the warranty.
- Multi-building sites where one system across every roof keeps the spares and the torque values identical.
Sizing notes before you order
- Ballast is calculated by roof zone. Corners and edges carry several times the uplift of the field, so one figure across the whole roof will be wrong somewhere.
- Assess atmospheric exposure, local contaminants, material compatibility and any manufacturer limits before selecting coatings and fixings. Distance from salt water alone is not a complete corrosion classification.
- Check the rail span and clamp positions against the selected module installation manual and load rating. Unapproved support arrangements can affect structural performance and warranty coverage.
- Use the specified clamp torque and installation method. Over-tightening can damage frames or fasteners and may affect warranty coverage under the selected manufacturer terms.
Packaging, minimum order and delivery
- Minimum order: one project kit; stocked components can be ordered by the pallet.
- Packaging: bundled and palletised, with the layout drawing referenced on the packing list so the kit can be issued by roof block.
- Delivery: U.S. domestic freight to your site or yard, from U.S. warehouse inventory with dispatch timing confirmed for the selected model and delivery address for stocked configurations.
Documentation to confirm for your order
- Site-specific structural calculation for the wind speed, snow load, building height and roof covering.
- Layout drawing with rail spans, clamp positions and the ballast schedule.
- Torque specifications and maintenance notes.
- Material certificates for the aluminium, coating or steel specified.
- Packing list and delivery documentation.
Questions buyers ask
Can we avoid penetrating the roof?
On standing-seam metal, usually yes, with clamps that grip the seam. On shingle and tile roofs some penetration is normally required, and the flashing detail is what decides whether it leaks. On flat membrane roofs a ballasted tray avoids penetrations entirely.
How is the ballast calculated?
From the wind uplift at each roof zone, the building height and the surrounding terrain. Corners and edges take several times the field load, so the schedule differs across the roof rather than being one number.
Aluminium or galvanised steel?
Aluminium is lighter and suits weight-limited roofs. Galvanised steel carries higher loads and suits ground-mount and carport structures. On a roof the weight limit and the corrosion class usually decide it before cost does.
Do we get a structural calculation?
Project-specific design support can be scoped from the roof covering, building geometry, module layout and local wind and snow inputs. Confirm the calculation, drawing and any locally required engineer review included in the quotation.
What happens if a clamp is over-torqued?
Over-tightening can damage the frame or connection. Follow the selected clamp and module installation manuals; any warranty consequence depends on the manufacturer terms and the assessed cause of damage.
What to send us
Send the roof covering, the building height and location for wind and snow, the module model you are using, and the array size. We return the attachment method, the layout and the structural calculation for that building.
EXPLORE FURTHER
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Send the roof covering and the wind speed
With the roof covering and pitch, purlin spacing, wind speed and snow load, and the module dimensions, we issue a structural calculation for that roof rather than a generic fixing pattern.
Send your requirementsOr reach us directly: +86 136 7367 3267 · sales@gtpsolar.com