Stanford T1-11 Siding

T1-11 is grooved plywood or OSB panel siding hung vertically. It is inexpensive, quick to install, and gives a wall a clean, rhythmic, board-like pattern, which is why it shows up on so many postwar houses. It also depends on its paint. Once the coating lapses, the panel edges absorb water, swell, and start to come apart.

Around the Stanford campus, many mid-century faculty homes are built on vertical lines. Some wear T1-11 or similar grooved panels, original or added later, and many of those panels have now reached the swelling-and-flaking stage. Bay Area Siding Company is a siding and window contractor based in Larkspur. We replace tired T1-11 with new panels or with a more durable vertical-profile material. We also plan the job around the two approvals a Stanford exterior project usually requires.

Looking at soft or flaking panels? Request a bid or call (415) 619-5167. We'll assess the wall and walk you through your options.

What goes wrong with T1-11

T1-11 rarely fails across the whole wall at once. It fails at the edges and the low points first:

• Bottom edges near grade and hardscape. Splash-back and wet soil wick into the exposed panel ends, which then swell, fuzz, and soften.
• Horizontal joints. Where one panel stacks on another, the joint needs a Z-flashing. When that flashing is missing or has rusted out, water gets behind the upper panel.
• Delamination. Plywood plies separate and bubble, and OSB swells into a rough, grainy surface. Neither condition can be fixed with paint.
• Grooves that trap water. The routed channels hold moisture and wear through their coating before the flat faces do.
• Paint that won't stay on. If you have repainted and it peeled again within a season or two, the wood underneath is usually already compromised.

Stanford's climate won't cause these problems by itself. Summers are dry, winters are cool and wet, and rainfall is modest by Bay Area standards. But winter rain against panels with lapsed paint and open edges is enough to work on T1-11 year after year. The cause is maintenance and detailing, not anything unusual about the location.

Keep the look, or change the material?

Most Stanford homeowners we talk with want to keep the vertical, grooved character of the house. The real question is what material delivers that look. There are three honest paths:

1. Re-install T1-11. New grooved panels, properly primed and painted, with the edges sealed and correct Z-flashing at the joints.

• It is the lowest-cost way to keep the original look.
• Plywood-based panels generally tolerate moisture better than OSB, so we'll talk through which to use.
• The trade-off is unchanged: T1-11 needs faithful repainting and sealing, or you will be back where you started.
• This path makes sense on a budget, on secondary structures, or where exact continuity with the existing look matters most.

2. Engineered wood panels. LP SmartSide uses treated wood strands and offers vertical panel products.

• It has real-wood texture and is lighter and easier to work than fiber cement.
• It is designed to hold up better than untreated plywood or OSB, though it still needs periodic painting.
• For many homeowners it is the middle ground: a similar look with fewer of T1-11's weaknesses.

3. Fiber cement vertical panels or board-and-batten. Fiber cement, including James Hardie products, can recreate the vertical rhythm in panel or board-and-batten form.

• It is noncombustible and resists rot, pests, and moisture.
• It holds paint well.
• It costs more, is heavier, and needs a skilled crew.
• It is the right fit for homeowners who want to stop thinking about their siding for a long time. The Stanford James Hardie page covers that product choice in more depth.

On a post-and-beam or flat-roofed mid-century home, the groove spacing, panel reveal, and how the siding meets deep eaves and window walls matter as much as the material. We spec those details so the house still reads as itself. For a broader look at every material we install, including vinyl, CertainTeed, and wood, see the Stanford siding replacement page.

The part people don't expect: T1-11 is sometimes the wall

Here is a technical point that shapes the scope and the price. On a lot of homes, T1-11 was installed over separate sheathing, so it is only the cladding. On others, particularly some postwar construction, the T1-11 panels were nailed directly to the framing and serve as both siding and sheathing, including the wall's bracing.

That difference changes what removal involves:

• Over sheathing. Tearing off the panels exposes the sheathing and substrate so we can inspect and renew the water-resistive barrier (WRB) and flashing. This is a conventional re-side.
• As the only layer. Taking the panels off exposes the framing. The new assembly then needs structural sheathing or a panel rated to do that job, plus a WRB and proper flashing that may never have existed.

We identify which condition your house has during the assessment, before we price anything, so the scope isn't a surprise halfway through the job. Either way, we don't recommend nailing new siding over failing T1-11. Doing so hides swollen or rotted material, adds weight, and can trap moisture against the wall.

Approvals for a Stanford re-side

Most Stanford homes sit on land leased from the university, so a panel replacement usually involves two separate sign-offs.

The building permit. A re-side is a permitted alteration.

• On unincorporated land, the Santa Clara County Department of Planning and Development's Building Division issues the permit.
• A few faculty-housing pockets fall within Palo Alto or Menlo Park city limits, where the city building department is the authority instead.
• We confirm which applies to your parcel rather than assume.

The Stanford Faculty and Staff Housing (FSH) review. For homes on a Stanford lease, FSH must approve home-improvement projects before work begins.

• The review calls for a project application with drawings, photos, and product spec sheets, along with an application fee.
• Homes fifty years and older need added time for historic review.
• Each lease area has its own building regulations to check against, including San Juan, Olmsted Terrace, University Terrace, and the Palo Alto and Menlo Park pockets.

Because FSH looks at exterior appearance, a like-for-like vertical profile is often the smoothest submission. If you're switching to fiber cement or engineered wood, documenting the new panel's groove pattern and finish clearly helps the review.

On fire code: Stanford sits low and flat near the valley floor and is not one of the designated Very High Fire Hazard Severity Zones that drive noncombustible-material rules in the hills. Fire requirements don't usually decide the T1-11 question here. We still confirm parcel-specific requirements with the AHJ at permit time.

How a T1-11 job typically runs

1. We assess the walls, confirm whether the panels are cladding or structural, and talk through the three material paths.
2. We prepare the permit application and the FSH package together.
3. We remove the old panels, repair any damaged substrate or sheathing, and install a new WRB and flashing. Windows and panel joints get particular attention.
4. We install the new siding, seal the edges, add trim, and paint as specified.
5. We finish with a walkthrough.

If your windows are due too, it is efficient to flash them in during the same job. See Stanford window replacement.

What drives the cost

We don't quote online. The main variables are:

• The square footage of wall area.
• Whether the T1-11 is cladding or the structural layer, since the latter adds sheathing.
• How much substrate or framing damage turns up.
• The replacement material: T1-11, engineered wood, or fiber cement.
• Paint and finish.
• Trim and detailing around glass-heavy elevations.
• Access.
• The front-end work of clearing both the permit and FSH review.

FAQs

Can I just replace the bad panels instead of the whole wall? Sometimes, yes. If the damage is limited to a few panels and the rest are sound, spot replacement with matched grooves and fresh flashing at the joints can buy time. Once swelling and delamination show up across several elevations, a full replacement is usually the better investment.

Does my Stanford home need FSH approval just to replace T1-11 with T1-11? Homes on a Stanford lease generally need FSH review for home-improvement projects before work begins, and a re-side falls in that category. A like-for-like material may make the review simpler, but we plan for the review either way. You'll also need a building permit from the county or the relevant city.

Is plywood T1-11 better than OSB? Plywood panels are generally more forgiving of moisture than OSB, which swells when it gets wet. Both need sealed edges and consistent paint maintenance. If you want the look without that upkeep, engineered wood or fiber cement is the stronger move.

Will switching away from T1-11 change how my Eichler or mid-century home looks? Not if the new material is specified carefully. Both fiber cement and engineered wood come in vertical formats, and matching the groove spacing and reveal keeps the home's lines intact. You can see examples of our work on the projects page.

Ready to deal with that failing T1-11? Request a bid or call (415) 619-5167. We serve Stanford and the surrounding Peninsula communities.