Roofing & Exterior
T1-11 Doesn't Fail Randomly. It Fails at the Bottom Edge.
Grooved plywood siding was everywhere from the '70s through the '90s, and it's all reaching failure age at once — usually rot from the ground up, at the seams, and behind the paint.
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Signs to watch
Is this you?
The bottom edge is soft, dark, or delaminating
T1-11 wicks water at its lower edge, especially where it was installed too close to grade or a deck. The plies separate and rot from the bottom up, long before the face looks bad.
Paint is peeling faster than you can keep up
When a sanded and primed panel won't hold paint for more than a few years, moisture is moving through the plywood from behind. You're painting the symptom, not the cause.
Swollen seams and lifting grooves
The vertical grooves and butt seams are where water gets in. Swelling, cupping, and a spongy feel under a screwdriver tip mean the panel has taken on water it can't release.
Woodpecker holes or visible ply separation
Birds find soft, rotting plywood. Once you can see the layers peeling apart or daylight at a seam, the moisture story behind the wall is usually further along than the surface shows.
Your options
Repair what's genuinely repairable — replace what isn't
Isolated damage from a specific leak can sometimes be cut out and patched, and we'll do that when the surrounding panels are sound. But when the plywood is failing from age and clearance problems, patching chases the rot around the wall. Where replacement is the honest call, we tear off, correct the ground and deck clearances that caused it, add a proper weather-resistive barrier, and re-side. Modern alternatives — fiber cement like James Hardie, or engineered wood like LP SmartSide — give you the T1-11 look without the T1-11 failure mode. We'll show you both paths and let you decide.
The method
How we do it
- 01
Probe and map the damage
We check the lower edges, seams, and penetrations with a probe, not just our eyes, and photograph what we find so you see the real extent before any decision.
- 02
Fix the cause, not just the panel
Where we replace, we correct the clearances and drainage that rotted the original, then install a weather-resistive barrier and flashing behind the new siding.
- 03
Re-side and document
New panels or a modern alternative, fastened and clearance-set to spec, with before-and-after photos for your records.
Straight numbers
Repair or replace — the math
A localized T1-11 repair is a modest job when the rest of the wall is sound. Full replacement scales with square footage, stories, and what we find behind the old panels. When scattered repairs start approaching a meaningful share of a full re-side — or when the rot is clearly age-driven rather than from one fixable leak — we'll lay out both numbers so the decision is yours, not a guess. No fabricated prices over the phone; we quote from the actual wall.
Where we do this work
T1-11 & Plywood Siding Replacement: straight answers
Can my T1-11 be repaired, or does it all need to go?
It depends on why it's failing. Damage from a single leak or a bad flashing detail can often be cut out and patched. But when the panels are rotting from age and improper clearances, repairs just move the problem down the wall — and that's when replacement is the honest answer.
Why does T1-11 always rot at the bottom first?
Plywood wicks water at its cut edges, and the lower edge is closest to splashback, grade, and deck ledgers. When it was installed too close to the ground — which was common — the bottom takes on water it can't dry out, and the plies delaminate from there up.
Should I replace T1-11 with the same thing?
You can, and new plywood siding installed with correct clearances and a weather barrier will outlast the original. But most homeowners choose a modern alternative like fiber cement or engineered wood that gives a similar look without the same edge-rot vulnerability. We'll price both.
What causes T1-11 to fail so predictably in this region?
A lot of it went up across the inland Northwest in the same two decades, often with too little ground clearance and paint as the only moisture defense. Combine that with our wet season and it's all reaching the end of its service life on roughly the same timeline.
Get the t1-11 & plywood siding replacement conversation started.
Free 20-minute inspection. Photo report you keep either way. Zero pressure.