Commercial Door Sizing: The Mistakes We See on Every Project

hotian
February 9, 2026
11:41 am

We see the same door sizing mistakes on nearly every commercial project. Contractor orders 3′-0″ doors when code requires 36″ clear width—doesn’t realize the frame eats 2″ of that. Developer specs standard 8 ft patio opening for a restaurant, discovers after opening that server traffic doesn’t flow. GC frames the rough opening (RO) before getting manufacturer’s actual dimensions, ends up with doors that don’t fit.

These aren’t product problems. They’re specification and coordination problems that happen months before installation. Here’s what actually goes wrong and how to avoid it.

The “36 Inch Door” Problem

When code says “36” clear width,” contractors often spec a 3′-0″ door. But here’s what they miss: that’s nominal door size. Actual clear width after frame and door thickness? 33.5-34 inches. Fails ADA (per IBC/ADA standards).

You need 38-40″ nominal door to get 36″ clear width. This catches people constantly on restaurant ADA entry access, hotel accessible rooms, office suite entries. Double doors compound it: two 36″ doors for “6 ft clear”? Actually 5′-2″ to 5′-4″ after center post and thickness—too tight for service carts or luggage.

Quick fix: Always ask manufacturer “what’s clear width at 90° open” before ordering. Don’t calculate yourself. Hotian provides verified clear width for all configurations during quoting—we’ve seen this mistake too many times.

Restaurant Patio Doors: Why 8-10 Feet Never Works

Standard residential patio = 6-8 ft. Fine for homeowners. But restaurant developers spec 8-10 ft commercial openings, thinking “bigger than residential, should suffice.” Nope. Math that matters: server with tray needs 3 ft; two customers: 5 ft; simultaneous = 8 ft minimum.

8 ft is uncomfortable at peak (150 covers Saturday night). Aim 12-16 ft for smooth flow. Cost: 8→16 ft adds $10-15K, but +8-12 patio seats = $600-800 extra revenue per weekend service. Pays back in 6-8 weeks.

Mistake: sizing for “fit” not “performance.” When developers say “10 ft patio,” Hotian recommends 14-16 ft—not upselling, but from watching undersized patios bottleneck for 15 years.

The RO Coordination Sequence Nobody Follows

What should happen:

Decide door config/size
Get RO dims from manufacturer
Engineer designs header for loads
Frame RO
Order doors

What happens: Architect sketches door; framer guesses “standard” RO; doors ordered later—don’t fit/header undersized/no bi-fold stack space.

Root: RO specs too late. Fix: Get manufacturer RO in design phase, pre-framing. Reframing costs 10x more. Critical for >8 ft/custom: 12 ft patio may need 12′-3″ RO + 800 lb header load. Engineer needs real data, not assumptions. Seen $15K beam sistering post-install—early coord prevents.

Hotian sends RO dims/header loads early—even pre-order.

Custom vs Standard: When It Actually Matters

Standard = cheaper/faster (8-10 wk lead). Custom = +10-15% cost, +2-3 wks.

Standard fine for:

Office terraces (8 ft sliders adequate)
Hotel balconies (6-8 ft standards)
Budget projects

Custom worth it for:

Restaurant patios (traffic optimization)
Retrofits (fit existing RO)
Aesthetic modules

Contractors default “standard saves”—right 60%. Other 40%: 20-yr performance hit for $3K upfront save. Ask: “Does standard compromise function?” Ex: Hotel 14′-6″ legacy RO—12 ft wastes space (odd look), 16 ft needs $20K mods; custom 14′-6″ +$4K solves clean.

Scenario	Standard Size	Custom Benefit	Hotian Cost/Lead
Restaurant Patio	8-10 ft	14-16 ft no bottleneck	+$10-15K, 12-14 wk
Hotel Balcony	6-8 ft	Exact RO fit	+10%, no MOQ
Office Terrace	8 ft slider	Module aesthetics	8-10 wk

What to Actually Provide Manufacturers

Minimum:

Application (restaurant patio/hotel balcony/office terrace)
Desired clear opening (e.g., “8 ft clear fully open,” not “8 ft door”)
RO if framed
Timeline

Better for recs:

Traffic volume/pattern
Budget priorities
Integrations (access/fire rating)

No-app quote? Red flag. Good ones ask traffic—8 ft slider vs 12 ft bi-fold depends. Hotian details to avoid mismatches.

Swing Doors vs Patio Doors: Different Sizing Logic

Swing (entry/office/restroom): Standardized 32″/36″/42″ x 80″/84″—code-driven, simple.

Patio/storefront: Sized to needed opening, not list. Restaurant 16 ft for traffic; office 10 ft for module. Mistake: Treat patio like swing—”standard commercial patio size”? None. Function/architecture drives; hence more early coord need.

Working with Hotian: Standard & Custom Commercial Doors

Hotian builds for restaurants/hotels/offices/retail—standard/custom.

Capabilities:

Patio: 6-20 ft (slider/bi-fold/French)
Entry swings: std/custom
No MOQ (single to multi-building)
Custom +10-15%, 12-14 wk

Early deliverables:

RO dims/header loads
Traffic-based configs
ADA clear width verify
System integration

Ex: 120-seat restaurant 10 ft patio initial; we rec 14 ft for peak (2 servers+guests). +$8K doors, but top revenue patio Season 1—no bottlenecks. Adequate vs optimized.