Lesson 2 of 3

Read the spec sheet.
Then read the warranty.

A door comes with an NFRC sticker, sometimes a fire label, sometimes a pressure rating, and a warranty with a table in it. None of it is hard. All of it is written to be skimmed. Here is how to read it slowly, with a real warranty as the example.

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The label and the ratings

Four numbers, and which ones apply to your opening.

The NFRC label on a door is the same sticker as on a window, and the two numbers mean the same thing: U-factor for heat through the whole unit and SHGC for sun through the glass, lower is better on both. The twist on a door is glass area. An opaque foam-core door posts a very low U-factor. Add a half-lite and it climbs; go full-lite and it climbs again. That is why ENERGY STAR publishes separate limits for opaque, half-lite, and more-than-half-lite doors, and why the number on the quote has to be for the exact door and lite you are ordering, not the line. Therma-Tru and Masonite both publish ENERGY STAR options and both put the NFRC numbers on the unit. We covered the climate-zone-4 side of this once, in the windows lesson on reading the label; it applies here without change.

The fire rating matters on one opening in most houses: garage to house. Most residential codes call for a 20-minute rated door there, or a solid door of a stated thickness. A rated door carries a metal label on the edge from the certifier (Intertek Warnock Hersey on Therma-Tru's), and the rating depends on the frame and hardware it was tested with. Remove the label, paint over it, or hang the slab in a different frame and the rating is gone.

The impact rating is a coastal code item and an optional upgrade here. The test fires a 2-by-4 at the door (the large-missile test) and then cycles pressure on it. Therma-Tru's impact doors carry a 24-gauge steel plate inside the slab and laminated glass. The DP rating is the wind-load number for the whole unit, tested under AAMA/NAFS in pounds per square foot. Slabs do not get a DP; units do.

Ask

Show me the NFRC numbers for this door at this lite. Which opening needs the fire label, and is the frame on the quote the one it was tested in. If the house is exposed on a hill, what is the unit's DP.

Rating	Test	What it tells you	Look for
U-factor	NFRC 100	Heat through the whole door, frame and glass	The number for this exact lite; lower is better; ENERGY STAR mark for zone 4
SHGC	NFRC 200	Sun's heat through the glass	Matters on full-lite and west-facing doors; lower is cooler
Fire	20-minute positive pressure (UL 10C / NFPA 252)	Holds fire back 20 minutes in the tested frame	A metal edge label from the certifier, on the garage-to-house door
Impact	ASTM E1886 / E1996 large missile	Survives debris and pressure cycling	Laminated glass and a steel-plate slab; optional here
Design pressure	AAMA/NAFS (ASTM E330)	Wind load the whole unit held	A plus and minus number in psf for the unit, not the slab
Forced entry	AAMA 1304	Resistance to a push and pry on the lock side	Therma-Tru publishes 300 pounds on its door systems

The tell

A rating with a test standard and a label behind it is a spec. "Energy efficient" and "secure" on a brochure are claims. Ask for the label.

The warranty: a worked example

"Lifetime" has a table. Here is Therma-Tru's.

Therma-Tru's residential limited warranty is a four-page document, and it is a fair example of how every entry door warranty is built. The headline on fiberglass is Lifetime. The table under it says lifetime means as long as the original owner owns and lives in the house, and it applies to Classic Craft, Fiber-Classic, Smooth-Star, and Pulse fiberglass slabs. The steel lines are in the same table with their own clocks: 10 years on Profiles, 5 years on Traditions, 15 years on the fire-rated steel-edge door.

Then the rows. Hinges, weatherstrip, sweep, sill, corner seal pads, and Therma-Tru's own rot-resistant frame parts are covered. Multi-point lock mechanicals are covered on fiberglass doors and specifically not on steel. Glass has its own row for seal failure and fogging. Pine jambs and pine brickmould are named as not covered, which is the frame most doors are hung in. Hinges within five miles of salt water are out. Labor to remove, reinstall, or refinish is out on every row.

Three lines decide whether any of it pays. Finishing: fiberglass doors must be finished within six months of installation, steel within days, all six sides; bare wood frame parts within two weeks. Installation: coverage assumes the unit was assembled from genuine parts and installed per the maker's instructions, and rot in a frame that is not Therma-Tru's rot-resistant frame is excluded. Transfer: the standard warranty is not transferable. The published exception is Classic Craft, which transfers once to the next owner, and its 10-year PrismaGuard factory finish warranty transfers with it.

None of that is a criticism. It is a strong warranty and it is typical of the category. Masonite's reads the same way: fiberglass lifetime for the original occupant, Sta-Tru steel 20 years, insulated glass 20 years, factory finish 2 to 5 years, not transferable, finish within 45 days, no labor. Steves: lifetime on its top fiberglass lines, 25 years on the next, 10 on steel, 1 year on wood, original owner only. The wrapper says lifetime. The table says original owner, finish it on time, hang it in our frame, and we do not pay labor. Both are the same document, and the table is the one that pays.

Read for	Where it hides	What a strong answer looks like
What "lifetime" means	The definitions, first page	Stated: original owner, while they occupy the house
The slab's years	The summary table, by line	You know which column your door is in before you sign
The frame	The exclusions list	The jamb on the quote is one the warranty names as covered
Glass seal	Its own row	Years stated for fogging and seal failure
Finish	A separate warranty, in years	Factory finish with its years stated, or a site finish date on the schedule
Finishing deadline	Notes under the table	Somebody owns that date
Transfer	One sentence, usually in capitals	Transferable, and you know the deadline and the paperwork
Labor	The remedies section	You planned for it

Ask

Which column of the table is this door in. Is the frame on the quote one the warranty covers. Who finishes it, and by when. If you are building to sell, does it transfer.

Before You Price a Door

Know what you are hanging.

Three short reads on entry doors: fiberglass, steel, and wood. Written for the builder who has to answer to the money, and for the money.

Lesson 1 What you are paying for The slab, frame and sill, glass, and hardware. What separates an entry door that lasts from one that looks the same on the truck. Each one you can check on a sample. Read it → Lesson 2 Read the spec sheet The NFRC sticker on a door, the 20-minute fire label, impact and pressure ratings, and what "lifetime" means once you read the table. A real door warranty as the worked example. You are here Lesson 3 The second door is the expensive one An entry door is priced by the opening and paid for by the year. Run your own two quotes per door, with the upkeep, against the years you will own the house. Read it →

Frequently Asked

Door ratings and warranties, answered.

What does a lifetime warranty on a fiberglass door actually cover?

Read the table, not the headline. On Therma-Tru's residential warranty, "lifetime" means as long as the original owner owns and lives in the house, and it covers the slab against defects in material and workmanship. Steel lines in the same document get 10 years, 5 years, or 15 years depending on the line. Labor to remove, reinstall, or refinish is excluded. Pine jambs and brickmould are excluded. Hinges near salt water are excluded. It is a good warranty, and it is typical of the category; the point is that the table is the part that pays.

Is a door warranty transferable when I sell the house?

Usually not, and it is one sentence in the document. Masonite's residential exterior door warranty says in capitals that it is not transferable. Steves warrants the original owner only. Therma-Tru's standard warranty is not transferable either, with one published exception: Classic Craft, where the lifetime slab warranty transfers one time to the next owner and the balance of the 10-year factory finish warranty transfers with it. If you are building to sell, that one line is worth the difference.

What does "finished within" mean on a door warranty?

Every entry door warranty makes coverage depend on finishing the door on time and on all six sides. Therma-Tru gives fiberglass doors six months from installation and steel doors a matter of days; bare wood frame parts get two weeks. Masonite gives 45 days from shipment. Steves says 30 days from delivery. Miss it and the warranty is gone before the house is done. Factory-finished doors, like Therma-Tru's PrismaGuard, take that job off the site schedule.

What is a 20-minute fire-rated door and where do I need one?

A door tested to hold back fire for 20 minutes under positive pressure and labeled by a certifier like Intertek Warnock Hersey. Most residential codes require one, or an equivalent solid door, between an attached garage and the house. Therma-Tru builds 20-minute fire-rated doors in both fiberglass and steel; Woodgrain builds fire-rated wood doors with an intumescent core. The label is a metal tag on the door edge, and if it is removed the rating is gone. Ask your inspector which opening needs one.

What do U-factor and SHGC mean on an entry door?

The same as on a window, and the NFRC label is the same sticker. U-factor is how much heat gets through the whole door, frame and glass; lower is better. SHGC is how much of the sun's heat comes through the glass; lower is cooler in August. Middle Tennessee is climate zone 4. An opaque door has a very low U-factor because foam beats glass; the more glass in the door, the higher the number climbs, which is why ENERGY STAR sets different limits for opaque, half-lite, and full-lite doors. Our windows lesson on reading the label covers the zone-4 numbers.

What is a DP rating on a door?

Design pressure, tested under the AAMA/NAFS standard, is how much wind load the whole door unit held in a lab before it failed, in pounds per square foot, plus and minus. It is a unit rating, not a slab rating: the frame, sill, hinges, and lock all count. Masonite publishes DP up to plus and minus 76 for its HD steel-edge unit as an example of the kind of number to look for. A slab with no DP number has not been tested as a door.

Come See It

Put your hands on it first.

Specs only tell you so much. Come walk the yard and the showroom.
119 Cumberland St, Ashland City. The coffee’s on.

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Read the spec sheet.Then read the warranty.