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Rotten Fascia Repair in Ontario: What Hides Under Old Aluminum, How the Wood Got Wet, What the Carpentry Costs at $18 a Foot, and What to Do When the Rafter Tails Are Gone Too
Exterior Finishes
Rotten Fascia: The Aluminum Looks Fine Because Aluminum Always Looks Fine, and the Wood Behind It Has Been Wet Since 2009
Fascia rot is the surprise on almost every eaves job on a house over 25 years old, and the reason it is a surprise is the capping. Aluminum does not rot, stain, or sag, so the fascia looks perfect from the driveway while the 1×8 behind it turns to wet cardboard. You find out the day the old trough comes down and the installer pushes a screwdriver into the board up to the handle. At $18 a foot of carpentry it is not a disaster if it is in the quote as a unit rate. It is a fight if the quote said “replace eavestroughs, $2,800” and nothing else.
How to find it before the ladder goes up
- Look at the hangers. A trough that sags between hangers, or hangs away from the fascia at one end, has pulled its screws or spikes out of wood that no longer holds them. That stretch of fascia is soft.
- Look at the bottom lip of the capping. Aluminum fascia cover is bent under the bottom of the board. If that lip is wavy, bulged, or has a dark line of staining along it, the board behind it is swollen with water.
- Look at the soffit panels under the trough. Rust streaks, drips, or a panel that has dropped out of its channel in one spot means water has been running down the back of the fascia into the soffit for years.
- Push on it. From a ladder, a thumb or the handle of a screwdriver against the fascia just under the trough, every few feet. Sound wood is hard. Rot gives like a loaf of bread.
- Check the corners and the valleys first. Water concentrates where two roof planes meet and where the trough turns a corner, and those are the first 4 ft to go.
That walk takes twenty minutes and tells you whether to budget 10 ft of rot or 100. Put the number in the quote request, so the installer prices a known quantity instead of guessing low and finding it on day one.
The four ways the water got there
The trough overflowed behind itself. An eavestrough that is plugged, or set with no slope, or too small for the valley above it, fills and spills over the back edge, which is the fascia. The roof drip edge is supposed to lap into the trough so this water goes where it should; on a lot of houses the drip edge stops short, or there is none, and the back of the trough sits an inch below the shingle edge with a gap between. Every heavy rain runs down the fascia in that gap. The sizing page is the fix for the first half of this; a strip of drip-edge flashing tucked under the shingles and over the back of the new trough is the fix for the second.
Ice dams. Melt from a warm attic refreezes at the eave, builds a ridge, and the water behind the ridge backs up under the shingles and down the fascia. Replacing the fascia without fixing the attic means doing it again in fifteen years; the ice dam page and the vented soffit page are the real repair.
The capping sealed it in. Aluminum fascia cover is nailed at the top, under the drip edge, and bent under at the bottom. Water that gets in at the top, from any of the causes above, has nowhere to dry to. A bare wood fascia that gets wet dries out in a week of sun; a capped one stays wet, and wet wood at 10 to 20 C grows the fungus that eats it. Capping is not the cause of the rot. Capping is why rot that would have been a stain became a replacement.
Spikes through the front. The old 7 in. eavestrough spike went through the trough, the capping, and 5 in. into the fascia and the rafter tail behind it. Every spike is a hole in the capping with a steel rod in it, and every rod wicks water into the end grain of the board. Where you see a row of spike heads, the wood behind each one is the first to go.
What the carpentry costs
| Repair | Rate | What is done |
|---|---|---|
| Rotten fascia or rafter-tail repair, carpentry only | $18 per lf | Old capping off, soft board cut out to sound wood, new fascia board fitted, sistering at a soft rafter tail, sub-fascia replaced where needed. Priced per foot of fascia affected, not per foot of house. |
| New wood fascia board plus aluminum cover | $24 per lf | Where the whole run is being replaced anyway: new 1×6 or 1×8 fastened to the tails, then capped. Compare with $13 for cover alone over sound wood. |
| Aluminum soffit and fascia package, to 24 in. | $25 per lf | The re-cover after the carpentry, on the soffit and fascia cost page. The rot line is added to this; it is not inside it. |
| New eavestrough with hidden hangers | $13 / $16 per lf | The trough goes back on after the fascia is sound. Hangers screwed into new wood hold; hangers screwed into rot do not, which is why the order matters. |
Minimum job $900. Rot repair found on an eaves job is priced in the eaves quote; rot that has run back into the roof sheathing or the top plate is a roofing or framing quote, not an eaves line.
A worked example. The 156 lf hip-roof bungalow is getting new aluminum soffit and fascia and new eaves. The walk-around finds 20 ft of soft fascia on the north side under the valley and 12 ft at the back corner where a downspout was missing: 32 lf of rot. Carpentry 32 at $18 is $576. The package 156 at $25 is $3,900. Trough 156 at $13 is $2,028, four downspouts 40 lf at $12 is $480, removal 156 at $2 is $312. Total $7,296 before HST, $948.48 of HST, $8,244.48. The rot was 8% of the job. On a quote with no rot line it would have been a $576 change order on the first morning, which is the same money with an argument attached.
When the rafter tails are gone
The fascia is nailed to the ends of the rafters or trusses, the tails. Water that sits in the fascia long enough gets into the end grain of the tails, and a soft tail will not hold a fascia nail or a hanger screw. The fix is to sister a short piece of 2×4 or 2×6 alongside each soft tail, screwed into the sound wood further up the rafter, and nail the new fascia to the sisters. That is still carpentry at the $18 a foot rate when it is one tail in four; a crew with a nail gun and a box of structural screws does it as they go.
When every tail along a run is gone past the wall line, or the rot has reached the roof sheathing above or the top plate of the wall below, it is no longer an eaves job. The roof edge has to be opened from above, the sheathing cut back, the tails rebuilt and the shingles redone along that edge, and the person doing that is a roofer or a framing carpenter, priced per job. The eaves installer should stop, show you, and tell you to call one, and a good one will. The roof inspection checklist covers what the edge should look like when that work is done, before the new fascia hides it again.
What a quote has to say
Three things. A unit rate for rot per linear foot, written down before anyone climbs. An agreement that the installer stops and shows you the wood before covering it, with a photograph. And a line that says what happens if the tails are gone: a roofing referral, not a capping job over it. “Depends on the job” is the honest answer to how much rot there is, and the honest way to price it is per foot of what comes off. The exterior renovation hub has the contract wording.
Questions people ask
How much does it cost to repair rotten fascia?
$18 a linear foot of affected fascia for the carpentry, under the new capping or trough, with a $900 minimum job. A typical find on an older house is 20 to 40 ft, $360 to $720. A whole run replaced new with cover is $24 a foot.
Can you put new aluminum over rotten fascia?
You can and people do, and it is the reason the next owner finds rafter tails you can pull apart by hand. The rot comes out to sound wood first. Capping does not stop rot; it hides it and keeps it wet.
Why did my fascia rot behind the aluminum?
Water got in at the top, from a trough overflowing behind itself, a missing drip edge, an ice dam or old spike holes, and the capping kept it from drying out. Fix the water path or the new board goes the same way.
Do I need a roofer or an eaves installer?
An eaves installer for fascia and sub-fascia and the odd soft rafter tail. A roofer or framing carpenter when the tails are gone along a run, or the roof sheathing or the wall top plate is soft; that is a roof-edge rebuild, not trim.
How do I check my fascia for rot without a ladder?
Look for a sagging or pulled-away trough, a wavy or stained bottom lip on the capping, rust streaks on the soffit, and, in February, icicles along one stretch of eave. Any of those marks the spot to probe.
Get your own number
The soffit, fascia and eavestrough calculator carries the rot allowance as its own line, so you can put your walk-around count in and see what it does to the total before the quotes arrive. If the quotes have already arrived and none of them has a rot rate, the $99 review will say which one is going to be a change order.
Sources and further reading
- Addressing moisture and mould in your home: Health Canada: what to do when the sheathing under the siding turns out wet.
- Canada Mortgage and Housing Corporation: the Canadian wall-assembly and moisture research behind rainscreens and the second plane of protection.
- Tarion warranty coverage: what a new-home warranty covers for cladding, stucco cracks, masonry and water penetration in years one, two and seven.
