Soffit, Fascia & Exterior Trim Systems

Aluminum Soffit, Fascia Capping and Exterior Trim

Soffit, fascia and trim are the edges of a Calgary exterior: the underside of the eaves, the board the eavestrough hangs on, and the corners, bands and window surrounds that frame the siding. They are small in area but they ventilate the attic, protect the roof edge and decide whether new siding looks finished. This page explains how the three services differ and when to do them with, or without, a re-side.

Looking up at a house eave with white perforated aluminum soffit panels and smooth white aluminum fascia below the roof edge.

How These Systems Differ

Soffit is the panel under the roof overhang, and on most Calgary houses it is also the attic’s air intake. The building code requires attic vents with unobstructed area of at least 1/300 of the insulated ceiling area, 1/150 on low-slope roofs, with at least 25% of the openings low and 25% high. Vented soffit usually provides those low openings, and insulation must not block the airflow behind it. Aluminum soffit comes in vented and solid panels, and prefinished aluminum siding, soffit and fascia are made to CAN/CGSB-93.2-M. Net free vent area varies by product, so we check the panel against the attic rather than assuming. Near property lines the rules tighten: the City of Calgary does not permit roof soffits within 0.45 m of the property line, and soffits within 1.2 m must have no openings.

Fascia is the vertical board at the roof edge. On many older Calgary homes it is painted wood, and aluminum fascia capping covers it with prefinished coil, in standard or heavy-duty thickness, bent to fit so it no longer needs repainting. The catch is the same as with window capping: capping over rotten sub-fascia hides the rot, and water that gets behind the metal stays there. So the wood is checked and repaired first, and the capping is lapped to shed water rather than hold it. The eavestrough attaches through this board, so fascia work and gutter condition are always looked at together.

Exterior trim and mouldings are the corner boards, frieze boards, band boards and window surrounds that give siding clean edges. Cellular PVC and composite trim boards do not rot and take paint, but they move with temperature, so joints are detailed for expansion. HardieTrim fibre cement boards are the other main option and pair naturally with Hardie siding. Horizontal band boards need flashing above them, because a flat ledge in the middle of a wall is exactly where water collects. Trim on a non-combustible wall can remain a minor combustible element under the code, provided it is spread out rather than concentrated.

Soffit & Fascia Services

Close view up at the underside of a roof overhang lined with white perforated aluminum soffit panels.

Vented & Solid Aluminum Soffit Installation

Vented and solid aluminum soffit for attic airflow, hail repairs and sagging eaves.

How it works

A roof corner seen from below, with a brown eavestrough and downspout along the shingle edge over brown aluminum fascia and vented soffit.

Custom Aluminum Fascia Capping

Prefinished aluminum bent over sound wood fascia to end peeling paint and rot.

How it works

A white frieze board and crown moulding run beneath the eave of a house above pale grey lap siding.

Decorative Exterior Trim & Mouldings

Corner, frieze and band boards, window surrounds and built-up crown details.

How it works

Choosing Between Them

Aluminum soffit for most eaves: Choose aluminum soffit when panels are sagging, dented by hail or not venting the attic. Use vented panels where the attic needs intake, and solid, unvented panels where the eave is close to a property line.
Fascia capping over sound wood: Choose aluminum fascia capping when the wood fascia is structurally sound and you are tired of repainting it. If boards are soft or the roof edge sags, the wood is replaced before any metal goes on.
Trim and mouldings to finish a re-side: Choose exterior trim and mouldings when new siding needs corners, frieze lines and window surrounds that suit its style. Pick PVC or composite for painted detail work, or fibre cement where the siding is Hardie.
HardieSoffit for an all-Hardie house: If the whole exterior is going to James Hardie fibre cement, HardieSoffit panels, covered in our Hardie category, keep the eaves in the same material and finish.

Why It Matters in Calgary

Hail does not only hit walls. Soffit panels and aluminum fascia are often damaged alongside siding, so on homes in the northern communities hit by the June 2020 and August 2024 storms, the eaves belong in any damage inspection. Separately, wood fascia and trim are typical of 1980s and 1990s homes in communities such as Castleridge, Falconridge, Martindale, Edgemont and Citadel, and that wood is now a common candidate for capping or replacement.

Calgary’s narrow side yards add a code question that surprises owners. On many suburban lots and inner-city infills, an eave on the side of the house sits within 1.2 m of the property line, where the soffit must be unvented and built from a listed material such as sheet steel or unvented aluminum. We confirm the distance on site before specifying panels for those eaves.

Soffit & Fascia: Common Questions

Should soffit and fascia be replaced with the siding?

Often, yes. When siding comes off, the top of the wall meets the soffit, and new siding has to be trimmed into it. Replacing soffit and fascia at the same time means one colour scheme, one set of details at the roof edge, and no second scaffold or ladder setup later. If your soffit and fascia are sound and match the new siding, keeping them is reasonable, and we will say so. After hail, it is worth having all three inspected together, because damage to one is often a sign of damage to the others.

Can soffit, fascia and trim be done without new siding?

Yes. Soffit, fascia capping and many trim pieces can be replaced on their own, for example after hail dents the eaves, when attic ventilation is poor, or when wood fascia needs painting again. The limits are where trim is tucked under existing siding, such as some corner boards and window surrounds; replacing those can disturb the siding around them. We look at how the existing pieces are installed before quoting a stand-alone job, so you know whether any siding has to be lifted.

Aluminum or fibre cement for soffit and trim?

Aluminum soffit and capping are light, prefinished and quick to replace, and suit vinyl, aluminum and most mixed exteriors. Fibre cement soffit and HardieTrim boards are heavier and need painting or a ColorPlus finish, but they match a Hardie exterior in material and texture. Vented HardieSoffit panels 12 to 24 inches wide provide 5 square inches of net free ventilation per lineal foot, according to James Hardie’s Canadian instructions. On a house clad in fibre cement, matching edges usually look better; on a vinyl house, aluminum is the practical choice.

Other Siding & Exterior Services

Hardie Board

Vinyl & SmartSide

Metal, Cedar & Stone

Envelope & Insulation

Repair & Hail Damage

Talk to Us About Soffit & Fascia

Tell us about the house and what is going wrong with the walls. We will recommend the system that fits, including when a cheaper one will do.

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