Aluminum capping
Aluminum capping means wrapping formed aluminum around the exposed wood pieces of a building: fascia, window and door surrounds, trim, bands, porch columns. The sheet metal is bent to measurements taken on site, then fixed over the existing piece. The wood stops being in direct contact with rain, sun and frost, and painting drops off the maintenance list for those surfaces. The result depends entirely on what’s underneath — Gouttières et Revêtements Synergy, based in Lavaltrie, approaches every capping project by checking the wood’s condition before the finish.
Why cap instead of repaint
Painted exterior wood follows the same cycle every time. The paint cracks, water gets in through the crack, the wood swells and dries, the paint peels further. Every freeze-thaw cycle widens the opening. On a second-floor fascia or a window surround up high, that cycle means climbing back up to scrape, prime and repaint.
Aluminum doesn’t rot. Its factory finish takes UV exposure without flaking the way paint on wood does. Once a piece is properly capped, the painting maintenance stops there. That’s the real reason to cap — removing a recurring task, not just changing the look.
The critical point: capping rotten wood makes things worse
This is where a lot of jobs go wrong. Putting aluminum over already-rotten wood doesn’t fix anything — it hides it.
Aluminum is watertight, and that’s exactly the problem in this case. Moisture already in the fibre, or moisture still getting in through a failed joint higher up, gets trapped between the sheet metal and the wood. It stops drying. Rot that was at least progressing in open air, and staying visible, now progresses out of sight in a constantly damp environment. By the time someone opens it up, there’s often not enough material left to hold a screw, and the repair becomes structural rather than a simple board replacement.
Our rule doesn’t move: the wood is probed before the first piece of aluminum goes on. Soft, spongy, blackened or crumbly wood comes out. It gets replaced, the base gets rebuilt, then it gets capped. If the inspection shows damage extending beyond the visible piece, we say so and the replacement shows up in the quote. We don’t put aluminum over dead wood to make things look good for a sale.
The pieces most often capped
Fascia and rake boards
The most exposed piece: it takes roof water, overflow and ice. It also carries the gutters, so its condition affects how well they hold.
Window and door surrounds
Casings, sills and trim. Water collects in inside corners and on horizontal surfaces — exactly where paint fails first.
Columns, bands and exposed beams
Porch columns, plates, roof returns. High or hard-to-reach pieces, so they rarely get repainted at the right time.
Fascia capping and attic ventilation
Capping a fascia should never close off ventilation. Cold air enters through perforated soffits and exits at the ridge. If the fascia’s aluminum blocks that air intake, or if solid soffits are installed at the same time without keeping the openings, the attic starts holding moisture. A paint problem gets traded for a condensation and ice problem. Fascia capping and soffit and fascia work should therefore be planned together, not one after the other.
Caulking is part of the job
Capping isn’t watertight by magic — it’s watertight because of its folds, overlaps and joints. Surfaces overlap in the direction water flows, so water runs over the piece below rather than behind it. Sealant then closes the top and side joints.
The bottom stays open. A joint sealed on all four sides traps condensation and any infiltration, exactly like capping installed over damp wood. Caulking needs to go in the right spots only, with a product compatible with aluminum and material movement.
What capping doesn’t fix
It doesn’t straighten a crooked piece or reinforce a weakened structure — the sheet metal follows the shape of whatever it covers. It doesn’t replace exterior siding at the end of its life. It doesn’t stop an infiltration coming from the roof or from a gutter overflowing behind the fascia — in that case, the cause gets corrected first, through a gutter repair or roof work. And it doesn’t seal a window whose frame is already finished.
Our process
Site visit and wood probing, piece by piece. Replacement of anything affected. Measurements taken, aluminum bent, installation with overlaps oriented in the direction of water flow. Discreet fasteners, sealant at top and side joints, drainage left open. Verification that nothing blocks ventilation.
Gouttières et Revêtements Synergy holds RBQ licence 5723-4940-01, is an Alu-Rex ÉLITE installer, recommended by CAA-Quebec and APCHQ certified. We serve Lanaudière, the Laurentians, the North Shore, Laval and Montreal, from 580 chemin de Lavaltrie, suite 103, in Lavaltrie.