Door face, top and bottom
ANSI/BHMA A156.16 · NFPA 80 · IBC 1010
Maryland, DC & Northern Virginia
A surface bolt is a sliding steel bolt that mounts on the face of a door. When you push it up or down, the bolt drops into a strike in the frame head or floor. Most businesses use surface bolts to hold the inactive leaf of a pair of doors closed. They are common on storage rooms, loading areas, mechanical closets, and gates. Because nothing is cut into the door, surface bolts work on metal and wood doors where a mortise is hard or costly.
Surface bolts mount with screws or thru-bolts, so we can secure your door without major cutting.
Long steel throws and strong springs keep the inactive leaf locked tight against pushing and prying.
Staff can see at a glance whether each bolt is thrown, which simplifies nightly lockup checks.
King Locksmith And Doors Inc. is a commercial locksmith and door company serving Maryland, Washington DC, and Northern Virginia. Our skilled technicians install, repair, and replace door hardware for small businesses, government agencies, hospitals, hotels, and large enterprises. We supply grade-rated surface bolts, match strikes to your frame and floor, and check each opening against local code. From one storeroom to a full campus, we deliver clean installs, clear written quotes, and fast, friendly response.
The right surface bolt depends on the door, the frame, the floor, and the code rules for that opening. Use this guide to compare your options before you buy new hardware or schedule an installation.
Surface bolts range from small 3-inch models to heavy units over 12 inches long. Short bolts suit cabinets and light gates. Most commercial doors need 8-inch or 12-inch bolts at the top and bottom of the inactive leaf.
Throw matters just as much. A longer throw sends more steel into the strike, so the door resists prying and flexing. For storerooms and rear service doors, we suggest a throw of about one inch or more.
The strike is where the bolt lands, and a poor strike is a common weak point. Top bolts use a frame strike or a universal strike plate. Bottom bolts need a floor strike or a mortised hole.
On concrete or tile, we often add a dustproof strike. It keeps dirt out of the hole, so the bolt drops every time and nobody trips on an open socket. We match every strike to your floor finish.
Building codes limit manual surface bolts on exit doors. Under the IBC, they are generally allowed on the inactive leaf only in limited cases, such as storage or equipment rooms and some small business occupancies.
Fire-rated pairs need labeled bolts and approval from the authority having jurisdiction, often the local fire marshal. Hospital corridor doors usually need automatic flush bolts instead of manual bolts. We review each opening against current code before we install anything.
Look for commercial surface bolts tested to ANSI/BHMA A156.16, the standard for auxiliary hardware. Higher grades suit heavier traffic. Heavy steel bars and strong springs stop the bolt from creeping out of the strike.
Finish affects looks and life span. Satin chrome and stainless resist wear indoors. For gates, garages, and coastal sites, choose stainless steel or a coated finish that stands up to moisture and salt. We stock finishes that match your existing hardware.
Many surface bolt problems start small and cost little to fix. A bolt that sticks, sags, or misses the strike can often be fixed by realigning the strike, tightening loose screws, or replacing worn springs.
Replace the bolt when the bar is bent, the housing is cracked, or the door has been forced open. We also upgrade light residential bolts to heavy-duty commercial models when a storeroom or closet holds valuable stock or sensitive records.
Surface bolts and flush bolts both secure the inactive leaf of a pair of doors. The simple table below shows where surface bolts give your facility a clear, practical advantage.
Consideration
Surface Bolts
Flush Bolts
Screws to the door face, minimal cutting
Requires mortising the door edge or stile
Works on existing doors without new preps
Often needs a factory door prep
Bolt position is visible from the room
Hidden lever makes status harder to see
Parts swap quickly with basic tools
Repairs may require removing the door
Leaves the door edge fully intact
Edge cutouts can weaken wood doors
Surface bolts take a beating on busy service and storage doors. Most failures come from wear, misalignment, or damage, and each can leave your inactive leaf open to forced entry.
We mount top and bottom bolts, set the strikes, and test the leaf for smooth, secure engagement.
We free sticking bolts, replace worn springs, and realign strikes so each bolt throws fully every time.
We swap light-duty slide bolts for commercial-grade steel units with longer throws, stronger springs, and thru-bolt mounting.
We install new frame strikes, floor strikes, and dustproof sockets on concrete, tile, terrazzo, and wood floors.
We check each pair against IBC egress rules and NFPA 80, then recommend the right compliant option.
We maintain surface bolts across offices, clinics, hotels, and agency buildings with scheduled inspections and fast repairs.
Tell us about your doors. We will assess every opening, recommend code-ready surface bolts, and send a clear, free quote.
