Shingle roofs
Shingle roofs mounting systems fix photovoltaic modules to a bitumen shingle covering laid over a solid boarded deck, carrying the array load past the shingles into the rafters below. There is no tile to lift, so watertightness rests entirely on the seal at each penetration: hanger bolts with EPDM washers, or flashed brackets dressed under the course above. Finish with rail profiles and clamps from the pitched roof range. Guide
Related shingle roof categories
- Hanger bolts and flashings
- Bitumen felt roofs
- Rail profiles and clamps
- Pitched roof systems
- Roof solar panels
Shingle roofs: a sealed hole in a solid deck
Asphalt shingle is a flexible covering nailed to a continuous boarded or OSB deck, and that changes the fixing logic compared with tile. There is no gap between courses to reach through, so the fixing is a hanger bolt or flashed plate driven straight through covering and deck into the rafter. The deck carries nothing useful in tension: 22 mm of boarding will not hold a screw against wind uplift, so the wood thread has to be fully seated in the rafter. Because the shingle is never lifted back over the fixing, every hole is permanent, and the EPDM sealing washer or flashing is the only thing keeping water out for twenty-five years.
FROM THE FIELD
"On shingle I mark every rafter from inside the loft before I touch the roof. You cannot see a rafter through shingle and you only get one honest attempt at each hole. A bolt driven into a gap between rafters leaves you with a leak and a plugged hole, and the shingle will not simply be lifted back off to hide it."
Ladislav Proc · Mounting systems specialist, ONSA Plus
How to choose a shingle roof mounting system
Two questions decide the kit: where the rafters run under the deck, and whether you seal the penetration with a washer at the stud or with a metal flashing worked into the shingle courses. Rails, clamps and splices follow from the fixing spacing those answers give you.
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Finding the rafters under the deck
A continuous deck hides the structure completely, and a bolt that misses the rafter has no pull-out resistance at all, because uplift loads a photovoltaic fixing in tension rather than shear.
- Measure from inside: find two rafters in the loft, take the centre spacing, then transfer the grid to the outside from a fixed reference such as the gable. European timber roofs typically sit between 0.6 and 1.0 m centres, but never assume the figure.
- Probe before you drill: a fine pilot hole tells you whether you have found solid timber. A pilot hole in the wrong place is patched with sealant, a 10 mm bolt hole is not.
- Layout follows the rafters: the rafter grid sets the fixing spacing and therefore the rail span. If the array wants a fixing where there is no rafter, change the layout, not the fixing.
Hanger bolt or flashed bracket
Both are correct on shingle and they seal in completely different ways. A hanger bolt is a double-threaded stud, wood thread into the rafter and metric thread up to the rail foot, sealed at deck level by a bonded EPDM washer compressed once to a specified torque. A flashed bracket sits on a metal plate slid up under the shingle course above, so water running down the roof passes over the flashing rather than reaching the fastener. Flashings are more work, but they give a mechanical water path rather than relying on an elastomer alone.
Tip from practice
Do not work on shingle in the heat of the day. Bitumen softens well below the surface temperature a dark roof reaches in summer, the shingle tears under a knee or a ladder hook, and a washer bedded into soft bitumen relaxes as the roof cools. Fit in the morning.
Hanger bolt against flashed bracket
| Property | Hanger bolt with EPDM washer | Flashed mounting bracket |
|---|---|---|
| How it seals | Compressed elastomer washer at the stud | Metal flashing tucked under the course above |
| Installation time | Fast, one hole per fixing | Slower, shingle courses must be lifted and refixed |
| Main risk | Torque error or ageing of the washer | Flashing dressed the wrong way round the water path |
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Frequently asked questions about shingle roof mounting
How are solar panels fixed to a bitumen shingle roof?
With hanger bolts or flashed brackets driven through the shingle and the boarded deck into the rafter underneath. Each penetration is sealed with a bonded EPDM washer or a metal flashing, then rails and module clamps are built on top.
Can I screw into the boarding instead of the rafter?
No. Boarding or OSB of 20 to 25 mm has very little pull-out resistance, and wind uplift loads the fixing in tension. The wood thread must be fully seated in a rafter, with the deck thickness treated as dead length rather than anchorage.
How do I find the rafters through the shingle?
Measure the rafter centres from inside the loft and transfer the grid to the roof from a fixed reference such as the gable. Confirm each position with a fine pilot hole before drilling: a pilot hole is easy to repair, a misplaced bolt hole is not.
Will mounting on shingle make the roof leak?
Only if the seal is wrong. Unlike tile, nothing is laid back over the fixing, so watertightness depends entirely on the EPDM washer compressed to the correct torque, or on a flashing dressed under the course above.
Does hot weather affect a shingle installation?
Yes. Bitumen softens on a hot dark roof, so shingles tear under foot traffic and washers bedded into soft bitumen relax as the roof cools. Work in the morning and avoid loading fresh sealed penetrations the same afternoon.
Can I mount panels on an old shingle roof?
Check the covering first. If the shingles are curling, losing granules or brittle at the edges, re-cover before mounting: the array will outlive the roof, and removing it later costs more than re-shingling now. The same applies to bitumen felt roofs.
Watertightness on a shingle roof depends entirely on the seal at each penetration, so the fixing detail must match the covering.
About ONSA Plus
Why installers across Europe order roof fixings from us
ONSA Plus is a European B2B distributor of photovoltaics, battery storage, heat pumps and EV charging stations. In our own EU warehouses we keep over 1,500 products from 25+ brands, including Huawei, Solis, SolaX and Dyness.
We are not just a trading company. We design and service energy systems ourselves, so we answer questions on shingle roof fixings and sealing from engineering practice, not from a catalogue. You handle a warranty claim directly with us and you buy per job.
