I remember my first encounter with T1-11 siding back in the late ’70s. A homeowner had called me out to take a look at their relatively new ranch-style house. From a distance, the vertical grooves of the siding gave the home a clean, rustic look. But up close, the story was different — swelling edges, peeling paint, and soft spots where water had worked its way in.
That was my introduction to T1-11, and like many builders and homeowners since, I learned it’s a product with strengths — and some serious weaknesses.
What Exactly Is T1-11 Siding?
T1-11 (often written T111) is a type of plywood or oriented strand board (OSB) siding that became popular in the 1960s and ’70s. It’s recognizable by its vertical grooves, which give the impression of board-and-batten siding.
Here’s why it caught on:
Affordability: Much cheaper than solid wood siding.
Ease of installation: Comes in large 4×8 panels that go up quickly.
Rustic look: The grooves mimic traditional wood siding without the labor of individual boards.
For budget-conscious builders, it was a dream come true — a fast, inexpensive way to cover a house.
The Advantages of T1-11
Before we get into its flaws, it’s fair to mention what made T1-11 popular in the first place:
Cost-effective: At the time, it was one of the cheapest siding materials on the market.
Versatile: Worked well for sheds, cabins, and homes alike.
Customizable: Could be painted or stained for different looks.
Structural strength: In some cases, it doubled as sheathing, saving builders another step.
When brand new and freshly painted, it really did look good. That’s why entire neighborhoods popped up clad in T1-11 siding during its heyday.
The Problem: Moisture
The Achilles’ heel of T1-11 siding is water. Both plywood and OSB versions are highly vulnerable to moisture. When exposed to rain or humidity:
Edges swell and delaminate (layers peel apart).
Surface warps or buckles.
Paint peels quickly, leaving the wood unprotected.
Rot sets in, especially near the bottom edges where splashback from the ground is common.
In damp climates, these problems can show up in as little as 5–10 years if maintenance isn’t meticulous.
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Why It Often Fails Over Time
High Maintenance Needs
T1-11 requires frequent painting or staining — usually every 3–5 years. Skip it, and the panels soak up water like a sponge.Installation Shortcuts
Many builders installed panels too close to the ground, where they absorbed moisture from soil and landscaping. Without proper flashing or spacing, failure was almost guaranteed.Climate Challenges
In dry regions, T1-11 can last decades. But in humid or rainy areas, it deteriorates much faster.Material Limitations
OSB versions of T1-11, while cheaper, are even more prone to swelling and breakdown than plywood.
Real-World Example
On one job, I helped a family with a 1985 home clad in T1-11. The siding had looked fine for the first 15 years. But by year 20, large sections near the foundation were rotted through. We replaced it with fiber cement siding, which not only solved the water issues but gave the house a fresh, updated look.
That’s a story I’ve seen play out countless times: T1-11 starts strong, but without near-constant upkeep, it simply doesn’t stand the test of time.
Alternatives to T1-11 Siding
If you’re considering new siding today, you’ve got far better options:
Fiber Cement (e.g., James Hardie): Incredibly durable, resistant to moisture, pests, and fire. Low maintenance. See our James Hardie siding project in Oakland, CA.
Engineered Wood (e.g., LP SmartSide): Mimics wood’s look but with added weather resistance.
Vinyl Siding: Affordable, low-maintenance, and available in countless styles.
Natural Wood (cedar, redwood): More expensive and requires care, but beautiful and long-lasting when maintained.
Each of these solves the moisture problem that plagues T1-11. For more, explore The Ultimate Guide to James Hardie Siding.
What to Do If You Have T1-11
If your home still has T1-11 siding, here’s how to stretch its lifespan:
Inspect regularly for swelling, peeling, or soft spots.
Repaint or reseal every few years.
Make sure panels are at least 6–8 inches above the ground.
Add flashing where needed to prevent water intrusion.
But understand this: even with diligent care, T1-11 rarely lasts as long as modern alternatives. Planning for eventual replacement is wise.
Final Thoughts
So, what is T1-11 siding? It’s a budget-friendly plywood or OSB siding that gave homes a rustic look and builders a quick solution. But over time, its vulnerability to water has made it one of the most failure-prone siding materials out there.
If your house has T1-11, stay on top of maintenance and start thinking about longer-lasting options. Materials like fiber cement and engineered wood cost more upfront but will save you money, time, and headaches in the long run.
At America’s Dream HomeWorks, we’ve helped countless homeowners replace T1-11 with siding that’s built to last. Explore our exterior remodeling services and inspiration projects to see what’s possible.
✨ Ready to trade high maintenance for long-lasting beauty? Contact us today — let’s find the perfect siding solution for your home.
