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At Arizona General Contractor, Inc. in Tucson, we take siding and exterior material choices seriously because they impact not only your home’s curb appeal—but also its structural integrity and safety. Over the years, one product that has come under intense scrutiny is T1-11 siding.

Although once widely used due to its affordability and ease of installation, the truth is that T1-11’s design and material flaws have led to widespread problems for homeowners, contractors, and even manufacturers. In this article, we’ll break down:

What Is T1-11 Siding?

T1-11 is a type of plywood or OSB (oriented strand board) siding that became popular in the 1970s and 1980s as a low-cost exterior sheathing option. It’s often used on sheds, barns, and budget-conscious residential construction. The surface is grooved to give the look of vertical planks and it can be painted or stained.

Despite its initial popularity, T1-11 is now considered outdated and problematic—especially in the harsh weather conditions of Arizona and the Southwest.

The Installation Flaw: A Hidden Design Problem

How T1-11 Is Installed

In many homes, T1-11 siding is installed directly onto wall framing with little to no weather-resistant barrier underneath. This can allow water to get behind the panels during rainstorms or from irrigation systems.

One of the biggest flaws in T1-11’s installation method is the inadequate moisture drainage system. Water that gets behind the panels is not directed away from the structure. Instead, it drips down the backside of the panels, pooling at the bottom edge.

The Consequences of Poor Drainage

This leads to a silent but destructive process:

This means homeowners may not realize their siding is failing until it’s far too late, resulting in expensive repairs and even structural damage.

Mold, Rot, and Health Risks

Arizona’s dry climate doesn’t make us immune to mold—especially when moisture is trapped between siding and framing. Once mold forms on the backside of T1-11 siding, it can spread to interior wall cavities, affecting insulation, drywall, and eventually indoor air quality.

Many homeowners report musty smells, respiratory issues, and allergies long before they discover the source is their deteriorating siding.

T1-11’s Flammability Risk

One of the more alarming concerns with T1-11 is its higher-than-expected flammability.

Why T1-11 Burns So Easily

Unlike solid hardwood siding, T1-11 is made from layers of thin wood or OSB pressed together with adhesives. These adhesives are combustible and, under high heat or flame, can cause T1-11 to ignite and spread flames rapidly.

In some cases, homes clad in T1-11 burned faster than those with untreated cedar or redwood siding, both of which are considered more natural and slightly more flame-resistant.

This has led many fire safety experts to question why T1-11 continued to be marketed as a safe residential product for so many years.

Lawsuits and Industry Backlash

Who Was Involved in Legal Action?

Over the years, several lawsuits have been filed against the manufacturers of T1-11 siding products, especially during the 1990s and early 2000s.

Some of the major manufacturers facing lawsuits included:

Key Legal Claims

These class-action lawsuits alleged that the manufacturers:

Many of these suits resulted in multi-million dollar settlements, requiring companies to compensate homeowners for siding replacement, mold remediation, and associated home repairs.

Unfortunately, many homeowners missed the claims deadlines or were unaware they were even eligible for compensation. As a result, thousands were left footing the bill for costly siding replacement out of pocket.

Why T1-11 Failed the Test of Time

Despite being inexpensive, T1-11 ultimately proved to be a “cheap now, expensive later” solution. Between moisture damage, high maintenance requirements, flammability, and poor long-term performance, it failed to meet modern standards for exterior siding.

Arizona General Contractor, Inc. has seen firsthand how devastating the damage can be after just a few short years of exposure to Tucson’s sun, monsoon rains, and daily temperature fluctuations.

Better Alternatives to T1-11 Siding

We no longer recommend T1-11 for residential use and instead suggest higher-performing alternatives:

1. Fiber Cement Siding (e.g., James Hardie)

2. Stucco with Elastomeric Coating

3. Engineered Wood Siding (e.g., LP SmartSide)

4. Vinyl Siding (for budget projects)

Why Choose Arizona General Contractor, Inc.?

We’ve spent years helping homeowners throughout Tucson and Phoenix replace outdated or failing T1-11 siding with modern, reliable materials that will last for decades. Our licensed, bonded, and insured team ensures:

Whether you’re doing a full exterior remodel or addressing water damage from failing siding, Arizona General Contractor, Inc. is your trusted partner in getting the job done right.

Final Thoughts

T1-11 siding may have been an affordable solution in its day, but its inherent design flaws, moisture vulnerability, and fire risks have made it a product of the past. Combined with multiple lawsuits and widespread dissatisfaction, it’s no longer a recommended siding material for any residential application—especially not in Arizona’s demanding climate.

If your home still has T1-11 siding, don’t wait for hidden mold or structural damage to appear. Contact Arizona General Contractor, Inc. today for a free inspection and siding upgrade consultation.

Let us protect your home, boost its value, and give it a modern, durable exterior you can rely on.