What causes wood rot on Calgary homes?

Wood rot on Calgary homes is caused by moisture penetrating painted or sealed wood surfaces, enabling wood-decay fungi to establish. Calgary-specific contributors: (1) Freeze-thaw cycling — paint film contracts and expands with temperature swings from -40°C to +30°C, eventually cracking. Once cracked, water enters behind the paint and into the wood fibres. (2) End-grain moisture absorption — exposed end grain (cut ends of fascia boards, window sill ends, deck post bottoms) absorbs water 200 to 400 times faster than face grain. End grain in contact with moisture rots faster than any other wood orientation. (3) Failed caulk at window and door frames — caulk cracks in Calgary winters; water enters the joint, saturates the wood behind the frame, and rot develops in the concealed wood over multiple seasons. (4) Ice dams — when snow melts off a warm roof, refreezes at the eaves, and backs up under shingles, water penetrates soffit and fascia boards.

What is the difference between soft rot and hard rot on exterior wood in Calgary?

Wood rot is technically caused by fungi and occurs in two forms that affect Calgary homes: (1) Brown rot (also called dry rot in common usage) — breaks down the cellulose in wood while leaving the lignin. Wood turns dark brown and breaks into cube-like chunks. Often appears dry to the touch even when active. Most common on deck boards, fence boards, and window sills in Calgary where wood dries between wet cycles. (2) White rot — breaks down both cellulose and lignin. Wood turns whitish and stringy, becoming fibrous and soft. Less common in Calgary's dry climate but can occur in constantly wet conditions (soffit above a drippy eave, deck boards that do not drain). For repair purposes: soft or spongy wood of any color that compresses when pressed with a screwdriver is structurally compromised and needs to be addressed — epoxy consolidant for surface rot, replacement for rot that has penetrated deeper than the repair layer.

Can wood rot be repaired with epoxy, or does the wood need to be replaced?

Epoxy wood repair products (Abatron WoodEpox, PC-Woody, Bondo Wood Filler) are suitable for Calgary exterior wood rot repairs when: (1) The rot is surface-level — within the outer 25-30% of the wood thickness. (2) The structural integrity of the board or post is not compromised — the wood beneath the rot is still sound. (3) The moisture source has been addressed — if the rot returned because of failed caulk or a drainage problem, fixing the source is prerequisite to repair. Wood replacement is the right call when: rot has penetrated the full thickness of a board, the wood is a structural member (deck post, joist, load-bearing framing), or the rot area covers more than 50% of the member's cross-section. Deck posts that have rotted at their base — the most common Calgary deck post failure point — must be replaced, not patched.

How do I find hidden wood rot on a Calgary home?

Probing for rot — use a screwdriver or awl and probe the suspect area with moderate pressure. Sound wood does not compress and the tip will not penetrate. Rotten wood compresses easily or the probe penetrates with little resistance. Probe these high-risk areas on a Calgary home: (1) Window sill ends — where the sill meets the trim or brick mould. (2) Fascia board ends — particularly at the roofline corners where two fascia boards meet. (3) Deck post bases — at or just above grade level, where the post meets the concrete pier or gravel base. (4) Door sill (threshold) ends — the bottom corners of exterior door frames. (5) Soffit boards at drippy eave locations. Visual cues before probing: paint bubbling or peeling without an obvious source, discoloration or darkening of wood, visible cracking or checking of wood grain on a painted surface.

How much does wood rot repair cost in Calgary?

Calgary wood rot repair pricing depends on extent and access: Window sill rot repair (epoxy consolidant + filler + paint): from $95. Window sill replacement (including paint): from $145. Fascia board section repair (epoxy consolidant + paint): from $95. Fascia board section replacement (1.2m section): from $125. Door frame rot repair (bottom corner of exterior frame): from $95. Deck post base rot assessment and replacement quote: from $65 (assessment) to $350+ (full post replacement including concrete work). Most minor rot repairs on window trim and fascia are completed in a single visit.

Wood Rot Repair Calgary | Steve Balakshii

High-risk rot locations on a Calgary home

Location	Why Calgary risk is high	What to probe
Window sill ends	End grain exposed at each end; caulk fails in freeze-thaw	Press screwdriver tip into sill ends
Fascia board ends	Roofline corners where boards meet; paint film fails first	Probe fascia corners and board ends
Door frame base (exterior)	Bottom corner absorbs splash-back from rain and snowmelt	Press corners of exterior door frame at ground level
Deck post bases	Post bottom in contact with concrete/moisture; freeze-thaw wicks water up end grain	Probe post base at grade level on all four sides
Soffit at drippy eaves	Water backs up behind ice dams in winter; saturates soffit wood	Look for paint bubbling; probe behind visible paint failures
Window sill beneath AC unit	AC condensate drips onto sill constantly in summer	Probe the sill beneath window AC unit mounting

Epoxy consolidant repair vs. replacement

Factor	Use epoxy repair	Replace the wood
Rot depth	Surface only (outer 25% of thickness)	Through more than 25-50% of thickness
Structural role	Non-structural (trim, sill, fascia face)	Structural (deck post, beam, joist)
Moisture source	Source identified and fixed	Source ongoing or unknown
Wood condition below rot	Sound — probe confirms solid wood beneath	Soft throughout when probed
Cost comparison	Lower — typically 40-60% of replacement cost	Higher — but correct for structural rot
Lifespan (properly done)	10-15+ years if moisture source is addressed	As long as the new wood lasts

The epoxy consolidant repair process

The two-part epoxy repair method used for surface-level exterior wood rot:

Remove all soft wood — use a chisel, oscillating tool, or wire brush to remove all deteriorated wood until you reach sound wood. Do not skim over soft spots — the epoxy consolidant will not bond to active rot.
Apply epoxy consolidant liquid (Part 1) — brush the liquid consolidant into all exposed wood surfaces. It penetrates the remaining wood fibres and hardens them. Allow to cure per product instructions (typically 4-8 hours).
Apply epoxy wood filler (Part 2) — mix the two-part filler and build up the repair to the original shape. The filler can be carved and shaped while workable, then sanded after curing.
Sand and prime — sand smooth, apply exterior primer (epoxy repairs accept paint well), and paint to match.
Address the moisture source — recaulk the window frame, repair the drainage issue, or seal the end grain with oil-based end grain sealer.

Rot repair pricing in Calgary

Scope	Starting price
Window sill rot repair (epoxy + prime + paint)	From $95
Window sill replacement	From $145
Fascia board section repair (epoxy + paint)	From $95
Fascia board section replacement (1.2m section)	From $125
Exterior door frame corner repair	From $95
Deck post rot assessment	From $65 (credited on repair booking)
Exterior rot inspection (full perimeter)	From $65

Wood rot repair in Calgary

Send a photo of the suspect area — we can usually assess repair vs. replacement remotely and provide a quote before booking. Most exterior trim rot repairs are completed in a single visit.

View deck and fence repair service →Request a wood rot repair quote

Steve serves all Calgary areas