An exterior door has to do five jobs at once: keep out weather, keep out intruders, insulate a 20-square-foot hole in your wall, swing smoothly ten thousand times a year, and look good doing it. That’s why the price range is so wide — $200 for a basic steel slab to $10,000+ for a custom mahogany entry system. This guide walks through the three materials that matter, the styles and configurations, the energy labels worth reading, and the prehung-versus-slab decision that trips up most first-time buyers.
Steel vs Fiberglass vs Wood
Steel is the budget and security champion. A 24-gauge steel skin over a polyurethane foam core insulates roughly five times better than solid wood and won’t warp, crack, or rot. Prices start around $200 to $600 for the slab. The downsides: steel dents and the dents don’t come out, scratches can rust if not touched up, the surface gets hot in direct sun, and even embossed “woodgrain” steel looks like painted metal up close. Best for side and back entries, rentals, and budget builds. Buy 24-gauge or heavier — big-box 26/28-gauge doors feel tinny and dent easily.
Fiberglass is the mainstream sweet spot and the fastest-growing segment. Molded fiberglass skins over a foam core deliver the same thermal performance as steel (R-5 to R-6 for the slab) with far better durability: no dents, no rust, no rot, minimal expansion. Premium lines from Therma-Tru, Masonite, and Provia mold genuine wood-grain texture and accept gel stains convincingly enough to fool most visitors. Expect $300 to $1,200 for common slabs and $2,000 to $5,000 for high-end stained entry systems with sidelites. If you want one default recommendation for a front door, this is it.
Wood remains the beauty benchmark — real stile-and-rail construction in mahogany, fir, knotty alder, or oak, with detail no molding process matches. It’s also the highest-maintenance option: expect to refinish every 2 to 5 years (annually on unprotected south/west exposures), and expect seasonal movement. Solid wood runs $600 to $4,000+, custom work well beyond. Wood makes sense under a porch roof or deep overhang; fully exposed to sun and rain, it punishes owners who skip maintenance.
| Factor | Steel | Fiberglass | Wood |
|---|---|---|---|
| Slab cost | $200–$600 | $300–$1,200 | $600–$4,000+ |
| Insulation (slab R-value) | R-5–R-6 | R-5–R-6 | R-2–R-3 |
| Maintenance | Touch-up paint | Minimal | Refinish every 2–5 yrs |
| Weakness | Dents, rust at scratches | Can crack on hard impact | Warping, rot, upkeep |
| Lifespan | 20–30 yrs | 30–50 yrs | 30–100 yrs w/ care |
Styles and Configurations
Panel count and glass define the look. Classic 6-panel and craftsman 3-panel-with-shelf styles suit traditional homes; flush or narrow-lite designs suit modern builds. Glass options run from small decorative lites to 3/4-lite and full-lite doors — remember every square foot of glass cuts thermal performance and, unless it’s laminated, security. Configuration choices:
- Single door: Standard 36″ x 80″; 30″ and 32″ widths for secondary entries.
- Door with sidelites: Fixed glass panels one or both sides; adds light and presence, adds $800 to $2,500.
- Double doors: Grand but harder to seal; the inactive leaf secures with flush bolts that loosen over time.
- Door with transom: Glass above for tall entries.
- Patio configurations: Sliding and French doors are their own category with different hardware and glazing priorities. If the project includes an outdoor living upgrade, coordinate finishes with structures like a covered patio or pergola so the entry reads as one design.
Energy Ratings: What the Stickers Mean
Look for the NFRC label and two numbers. U-factor measures heat transfer — lower is better; ENERGY STAR requires roughly 0.30 or lower for opaque doors in northern climates (glass doors get looser limits, around 0.23 to 0.32 depending on glazing area). Solar Heat Gain Coefficient (SHGC) matters mainly for doors with glass — low (0.25 or under) for hot climates, higher is acceptable or even helpful in cold ones. A foam-core steel or fiberglass door with quality weatherstripping outperforms any wood door thermally, but honestly, the biggest energy leaks are around the door, not through it: worn sweeps, compressed weatherstrip, and un-insulated rough openings. If drafts are your motivator, audit the whole envelope — our window insulation guide covers the companion fixes that usually pay back faster.
Prehung vs Slab
A slab is the door alone. A prehung unit arrives already hinged into a frame with weatherstripping, sill, and machined lockset bores. Buy a slab only when your existing frame is sound, square, and rot-free and you’re comfortable mortising hinges to match — a genuinely fussy job where a 1/16-inch error means a binding door. For everyone else, prehung is the right call: you get a fresh frame, fresh seals, and a factory-fit door for $50 to $250 over the slab price. Replacement is a half-day job for a pro: pull the old frame, dry-fit, shim plumb and square, foam and flash the gap, and adjust the sill. Expect $300 to $800 in labor for a standard single door, more for sidelite units or masonry openings.
Security and Hardware
Most break-ins defeat the jamb, not the door. Whatever slab you buy: a Grade 1 or Grade 2 deadbolt with a 1-inch throw, a heavy strike plate fastened with 3-inch screws that reach the wall framing, and hinge screws upgraded the same way. On glass-adjacent doors, use a double-cylinder deadbolt where code allows or laminated glass so a broken pane doesn’t expose the thumbturn. Smart locks are fine — just buy ones with a mechanical key backup and check they clear your storm door.
Budgeting the Whole Project
Realistic installed totals: steel prehung entry $600 to $1,500; fiberglass prehung $1,200 to $3,500; fiberglass entry system with sidelites $3,000 to $7,000; solid wood custom $4,000 to $12,000+. Add $150 to $400 for quality lockset hardware and $100 to $300 if the opening needs framing or rot repair — common on older homes where decades of splashback rotted the sill framing. Fall (September–November) often brings the best contractor availability and promotions before the winter rush.
Measuring and Ordering Without Mistakes
More door projects go sideways at the tape measure than at the install. For a prehung replacement, you need three sets of numbers. First, the slab size: width and height of the existing door itself (standard is 36 x 80 inches, but 1920s-to-1950s homes are full of 32 x 79s and other odd sizes). Second, the rough opening: the framed hole behind the trim, which should run about 2 to 2.5 inches wider and taller than the slab — pull a piece of interior casing to verify rather than guessing. Third, the jamb depth: measure the wall thickness from interior drywall face to exterior sheathing face; 4-9/16 inches suits standard 2×4 walls with 1/2-inch drywall, 6-9/16 for 2×6 walls. Order the wrong jamb depth and you’ll be ripping extension jambs on install day.
Note the swing while you’re there — stand on the outside; hinges on the right means a right-hand inswing — and count it twice, because handing errors are the most common special-order mistake and handed doors are rarely returnable. Check the sill condition and floor height too: if new flooring went in since the door did, the replacement may need a taller sill or a trimmed slab bottom to clear rugs. Photograph the existing brickmold and threshold before ordering so the new unit’s exterior trim matches or improves on it. Special-order doors run 2 to 6 weeks; measure early, order once.
Exterior Door FAQ
Which is better, steel or fiberglass? Fiberglass for a front entry — better durability and looks for modest extra cost. Steel for budget-driven or secondary doors.
How long does installation take? 3 to 5 hours for a straightforward prehung swap; a full day with sidelites or framing repair.
Can I paint a fiberglass door? Yes — acrylic latex over a proper cleaner/primer; premium skins also take gel stain for a wood look.
Do I need a storm door? Helpful over wood doors and in harsh climates; skip full-glass storm doors over dark-painted doors in direct sun — trapped heat can hit 180°F and warp the slab or void warranties.
Choose the material for your exposure and maintenance appetite, buy prehung unless you have a specific reason not to, and spend the leftover budget on hardware and installation quality. A well-hung mid-range door beats a premium door in a leaky frame every single winter.
