Fiberglass, Steel or Wood Entry Door: What Each Warranty Covers When the Door Fails

Material decides the length of the warranty more than the definition of a failure. In the four manufacturer warranties we opened for this article, fiberglass door slabs are covered for the life of the original owner’s occupancy, Masonite’s Sta-Tru steel doors for 20 years, and Simpson’s wood exterior doors for one year in most cases. The rules that decide most claims are nearly the same across all of them: warp under 1/4 inch is not a defect, a warp claim can be put on hold for up to 12 months, every face and edge must be finished on time, and labor and refinishing are largely the owner’s cost.

These are each manufacturer’s own terms, quoted from the documents listed under Sources. Your door’s warranty is the one that applies to it, and terms change by product line and purchase date.

Simpson Door Company’s warranty, updated October 28, 2024, gives most exterior wood doors one year from shipment, and only for doors “hung in a location protected from exposure to direct sun or rain under normal conditions.” Longer terms belong to specific lines: five years for its Performance Series doors with UltraBlock technology (stiles and bottom rails, in a protected location), and, under its heading for exterior doors with no overhang protection, five years for Performance Series doors with WaterBarrier technology and ten years for Nantucket Collection doors.

The conditions are where wood claims are won or lost. Simpson requires that “all edges must be sealed within 72 hours after fitting and hanging,” excludes doors exposed to direct sun or rain, excludes defects caused by inadequate overhang, and excludes damage from heat build-up behind a storm door or under a dark paint or stain (with an exception for dark paint on Accoya Nantucket doors). Surface checking of hardwoods, panel shrinkage and expansion of the bottom rail are listed as natural characteristics, not defects.

Warp has a sliding limit. Simpson does not treat warp as a defect up to 1/4 inch in the plane of the door for doors up to 3 feet 6 inches wide or 7 feet high, or up to 3/8 inch for doors up to 5 feet wide or 10 feet high, and warp is excluded entirely on larger doors. It may defer a warp claim for up to 12 months so the door can acclimate.

Therma-Tru’s warranty for Fiber-Classic and Smooth-Star fiberglass doors bought on or after June 1, 2024 gives a lifetime limited warranty on “all door slabs and sidelite slabs” and on insulated glass against seal failure, for the original purchaser of a single-family home. Masonite’s Exterior Door & Glass Limited Warranty, for products shipped after August 1, 2019, gives its fiberglass doors lifetime coverage, defined as “as long as the original owner occupies the residential home.” Pella’s warranty for its fiberglass or steel entry doors bought on or after February 24, 2020 is a limited lifetime warranty on nonglass materials and workmanship for as long as the homeowner owns and occupies the home.

The finish is a separate, shorter warranty. Therma-Tru warrants its pre-colored factory finish for ten years and its pre-stained wood-grain finish for five, against cracking, peeling, checking, chalking, blistering and flaking. Masonite’s factory finish coverage on fiberglass is two years, and Pella’s factory-applied paint and stain on fiberglass or steel panels is also two years. A finish applied in the field is not covered by any of them: Therma-Tru states that “finishes applied by anyone other than Therma-Tru are not covered.”

Therma-Tru spells out how warp is measured: a straight edge on the suspected concave face of the door, measuring the greatest distance between the straight edge and the face, “accounting for panels and glazing recess.” Warp is not a defect unless it exceeds 1/4 inch, and action on a warp claim may be deferred for up to 12 months.

In the Masonite and Pella warranties, steel and fiberglass doors share one document, and the difference shows up in the coverage table. Masonite’s warranty gives Sta-Tru steel doors 20 years with five years of factory finish coverage, HD Steel Edge doors 15 years, and utility steel doors one year, against lifetime coverage for its fiberglass lines. Pella’s entry door warranty covers fiberglass and steel panels under the same limited lifetime terms.

Neither document we read lists a failure that applies only to steel. The exclusions that tend to matter for any door, including steel, are general ones: Masonite excludes “impact by foreign objects,” improper finishing, and damage from a non-vented storm door or a dark finish; Pella excludes accidents, misuse and abuse.

The 1/4-inch warp line. Simpson, Therma-Tru and Masonite each set warp at 1/4 inch before it counts as a defect on a standard-size door, and Pella excludes “warping less than 1/4 inch.” Masonite measures it “across the plane of the door in a section no greater than 3-6 x 7-0” on a 1-3/4-inch door. Before assuming the slab is the problem, check the frame: a door that looks warped is often hanging in jambs that are not on the same plane, which these warranties do not treat as a door defect. How to tell the two apart.

The 12-month wait. All four allow the manufacturer to defer action on a warp claim for up to 12 months while the door adjusts to local temperature and humidity. Masonite adds that the wait “often remedies the issue.”

Finishing every surface, on time. The deadline differs: 72 hours after hanging for Simpson’s edges, 30 days of installation for Pella, 45 days from shipment for Masonite, and before exposure to weather for Therma-Tru (including doors stored more than 30 days). Masonite names all sides, front, back and all edges; Pella names every panel, sidelight, transom, molding, light rim and frame surface, and the jambs. The faces you see are not enough.

Coastal homes. Masonite cuts lifetime and 15-year-plus terms to ten years within 5 miles of salt water, and halves its other terms. Therma-Tru excludes multi-point locks and hinges installed within 5 miles of salt water, and damage from “substantial exposure to sun, salt spray, or airborne pollutants.” Pella excludes salt spray, “including exposure to coastal weather conditions.”

Labor and refinishing. Pella includes the cost of labor only when the claim is made within two years of the date of sale. Masonite states it will not be liable for “labor, rehanging charges, painting/staining, installation.” Therma-Tru is not responsible for installing or reinstalling a door system, and Simpson is not responsible for “the installation or finishing of replacement door or door components.”

Door slabs that have warped, bowed or delaminated appear in 18% of the 246,000+ door and window work orders with a written request in UTS ServicePros’ field record, January 2008 to September 2026. Frames, jambs and mulls appear in 21%. The record is classified from the request text and is not split by door material, so it cannot say whether fiberglass, steel or wood slabs fail more often.

What it does show is that the slab and the frame around it come up about as often as each other. That is why the inspection measures the door and the opening before anyone decides the slab has failed.

UTS ServicePros does not paint or refinish doors, so a finish claim such as fading, chalking or peeling is outside its scope. It does replace components, including the door slab itself, where the manufacturer warrants that remedy. A delaminated slab is a replacement job, not a refinishing job. We are bound by what the manufacturer deems warranted: the contractor inspects and documents, and the manufacturer decides the remedy. What we repair.

If your door is under warranty, start with the manufacturer or the dealer or builder who sold it; Therma-Tru and Masonite both direct claims there first. If the manufacturer covers the part but not the labor, or the door is out of warranty, request a repair quote. If a contractor is coming to your home on the manufacturer’s behalf, here is what to expect. Questions first? Contact the team.