Ballasted vs. attached racking
Ballasted systems sit on the roof held down by concrete blocks, with few or no penetrations. They’re gentle on the membrane but add real weight, which needs a structural check. Attached systems anchor to the structure and weigh less, but every anchor is a penetration that has to be flashed correctly.
Colorado’s Front Range sees strong downslope winds, and mountain sites add heavy snow. Either can push a design toward attached racking or lower tilt angles. The engineering, not preference, picks the system.
The membrane question
Pulling an array off a flat roof to replace the membrane later is expensive, and we don’t do removal and reinstallation of existing arrays. So if your membrane is past the middle of its life, the smart sequence is to replace it first. Because we do roofing as well, we can handle both in one project.
Walkways, drains and scuppers need to stay clear. We lay out the array so water still reaches the drains and someone can service rooftop equipment.
Where flat roofs show up
On homes, flat roofs are common on modern infill in Denver and on some mid-century houses. On the commercial side, warehouses, retail boxes and self-storage buildings are mostly flat, which is part of why those buildings can carry large arrays.
What to do next
- 1Find out the age and type of your roof membrane if you can.
- 2We inspect the roof and check drainage, structure and equipment clearances.
- 3If the membrane is near the end of its life, we quote the roof and solar together.
- 4We choose ballasted or attached racking based on structural and wind/snow engineering.
FAQ
Questions we hear
Do panels on a flat roof lie flat?
Usually not. We tilt them a modest amount toward the south, which improves output and helps snow and dirt slide off. Tilt is balanced against wind load and row spacing so panels don’t shade each other.
Will a ballasted system damage my roof?
Properly installed, it protects the membrane with pads and adds no penetrations. The risk is weight — the structure has to be checked before anything goes up.
Can snow pile up behind a flat-roof array?
Yes, drifting can build up around rows, which adds load. That’s part of the structural review, especially at higher elevations.
Is a flat roof better or worse than a pitched one for solar?
Often better for production, since we control the angle and direction. Sometimes worse for cost, because of ballast or the structural work. It depends on the building.