FMCSA Sleeper Berth Size Under 49 CFR 393.76

The dimensions depend on when the berth was installed

Section 393.76(a) is a table, not a single modern number. A sleeper berth installed before January 1, 1953 must be at least 72 inches long, 18 inches wide, and 18 inches high. A berth installed after December 31, 1952 and before October 1, 1975 must be at least 75 inches long, 21 inches wide, and 21 inches high. A berth installed after September 30, 1975 must be at least 75 inches long, 24 inches wide, and 24 inches high. Almost every truck you will buy used or new falls in the last row. The older rows matter when someone is arguing about a very old installation, not when they are selling you a current condo sleeper.

The column headers are the measurement instructions. Length is measured on the centerline of the longitudinal axis. Width is measured on the centerline of the transverse axis. Height is measured from the highest point of the top of the mattress. A footnote says that if the berth uses an adjustable mechanical suspension, the required clearance can be measured when the suspension is adjusted to the height to which it would settle when occupied by a driver. You do not get to measure a suspended bunk in the fully raised, empty position and call the extra air legal clearance.

Shape is separate from size. A berth installed on or after January 1, 1953 must be generally rectangular. Horizontal corners and roof corners may be rounded to radii not exceeding 10 and one-half inches. A berth that is mostly a tube, or a corner that eats the rectangle past that radius, is a shape failure even if a tape in the middle of the bunk hits 75 inches.

How an inspector can make a legal-looking bunk fail

OEM sleeper names, mid-roof inches, and the inches a salesman quotes from the outside of the cab are not the three centerline measurements in the table. A bunk can be advertised as larger than 75 inches and still lose width where a cabinet cuts the centerline, or lose height where the mattress plus a low roof leaves less than 24 inches at the highest point of that mattress. Measure the space a body occupies, on the axes the rule names, with the mattress that is actually in the truck.

Access is its own sentence. The berth must be constructed so that an occupant's ready entrance and exit are not unduly hindered. A bunk you can only enter by climbing over a refrigerator, or a curtain track that drops into the opening, is an access problem even when the tape meets 75, 24, and 24. Ready entrance is not a decoration.

Factory dimension charts are useful when you are comparing cabs as products. They are not 393.76. The product comparison lives on sleeper cab dimensions. Use it to shop. Use this page to know the legal floor those brochures are not allowed to undercut, and the other subsections a big bunk can still miss.

Where the berth is allowed to be

Location is 393.76(b). A sleeper berth must not be installed in or on a semitrailer or a full trailer other than a house trailer. A box behind the cab, a custom cabin built into a van trailer, or a berth bolted to a flatbed trailer is not a sleeper berth under this section, whatever you call it at the truck stop. A house trailer is the exception the sentence itself writes. A freight trailer is not a house trailer because someone put a mattress in it.

A sleeper berth located within the cargo space of a motor vehicle must be securely compartmentalized from the remainder of the cargo space. A berth installed on or after January 1, 1953 must be located in the cab or immediately adjacent to the cab and must be securely fixed in relation to the cab. Immediately adjacent and securely fixed are the answers to a loose box slid into a cargo area. If it is not in the cab or immediately adjacent, and fixed, it is not the installation the date row is describing.

If the berth is not located within the driver's compartment and has no direct entrance into that compartment, 393.76(d) requires a means of communication between the occupant and the driver. The rule lists a telephone, speaker tube, buzzer, pull cord, or other mechanical or electrical device. A shout through a wall is not on that list.

Exit, bedding, ventilation, exhaust, and the restraint

There must be a direct and ready means of exit from the berth into the driver's seat or compartment. If the berth was installed on or after January 1, 1963, the exit must be a doorway or opening at least 18 inches high and 36 inches wide. Older installations have different exit geometry, including an ellipse of 24 inches by 16 inches for some pre-1963 berths, and a two-exit alternative for berths installed before 1953. On a truck you are buying now, plan on the 18-by-36 opening. A curtain does not shrink that opening into legality. The opening is the hole, not the fabric.

Equipment is 393.76(e). The berth must be properly equipped for sleeping. That includes adequate bedclothing and blankets, and one of the mattress types the rule lists: springs and a mattress, an innerspring mattress, a cellular rubber or flexible foam mattress at least four inches thick, or a mattress filled with a fluid and thick enough when filled to prevent bottoming-out when occupied while the vehicle is in motion. A thin pad on plywood fails the foam sentence if it is under four inches and it is not one of the other types. Bottoming-out is written into the fluid-mattress option on purpose. The bunk has to still be a bed when the truck is moving.

Ventilation, 393.76(f), requires louvers or another means of adequate ventilation, and the berth must be reasonably tight against dust and rain. A sleeper that fills with water or dust is not reasonably tight, even if the tape hits 75 inches.

Exhaust and fuel, 393.76(g), require the berth to be located so that leaks in the exhaust system or the fuel system do not permit fuel, fuel-system gases, or exhaust gases to enter the berth. It must also be located so that it will not be overheated or damaged by proximity to the exhaust. A stack or a pipe routed so the bunk heats up, or a fuel-line leak that can reach the sleeper, is a placement failure. It is not a comfort complaint.

Occupant restraint, 393.76(h), applies to a motor vehicle manufactured on or after July 1, 1971 and equipped with a sleeper berth. There must be a means of preventing ejection of the occupant during deceleration. The restraint must be designed, installed, and maintained to withstand a minimum total force of 6,000 pounds applied toward the front of the vehicle and parallel to the longitudinal axis. A net that is unclipped, a bar that is missing, or a restraint that was never installed is a maintenance failure of that sentence, not a style choice. The rule does not say the occupant has to like the restraint. It says the vehicle must have one that meets the force figure and that it must be maintained.

What fails when someone is looking at the bunk

• Less than 75 by 24 by 24 on a post-September 30, 1975 installation, measured on the centerlines and from the top of the mattress.
• Height measured with an adjustable bunk raised, instead of at the settled occupied height.
• Corners rounded past a 10 and one-half inch radius, or a shape that is not generally rectangular.
• An exit installed in 1963 or later that is under 18 inches high or under 36 inches wide, or an exit that does not give a direct ready path into the driver's compartment.
• A berth in or on a freight trailer, or a cargo-space berth that is not compartmentalized and not fixed in or immediately adjacent to the cab.
• No adequate bedding, or a foam mattress under four inches when that is the type you are relying on.
• Dust, rain, exhaust, fuel vapor, or exhaust heat reaching the berth.
• No restraint, or a restraint that is not maintained, on a vehicle manufactured on or after July 1, 1971.

This page does not invent a fine for those failures. 393.76 is the specification. The citation, if one is written, is for the defect the officer finds. The fix is to make the bunk match the subsection, not to negotiate the inches.

This is not the sleeper split

Hours-of-service rules let a driver pair sleeper periods in ways people shorthand as 7/3 or 8/2. Those provisions assume you are resting in a sleeper berth. They do not define how long the bunk is. A berth that fails 393.76 is a parts-and-accessories problem. A split that fails the hours rule is a different problem, written up on sleeper berth rules and the split-sleeper guide. Do not answer an inspector's tape measure with a speech about the split, and do not answer a log question with the mattress thickness.

A day cab has no sleeper berth. You do not create one by reclining the seat, and you do not create one by putting a mattress in the trailer. If the operation needs a legal berth, the berth has to be the installation 393.76 describes. If the operation needs the hours split, it needs both a legal berth and a legal log. One does not substitute for the other.

O Trucking does not measure bunks and does not certify restraints. The tape, the exit, the mattress, and the restraint hardware are on the truck. The numbers they have to meet are the ones in 393.76, read on the eCFR the week of this draft.

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