Two inches. That is the margin between an RV carport that protects your investment and one that cannot fit the rig it was built for. Unlike most home improvement purchases, a metal carport ordered to ...
Two inches. That is the margin between an RV carport that protects your investment and one that cannot fit the rig it was built for. Unlike most home improvement purchases, a metal carport ordered to the wrong dimensions is a permanent, non-returnable mistake, and resizing after installation is rarely a simple fix. Most buyers approach RV carport sizing as a generic checklist: pick a width, pick a length, check a box. The problem is that a Class A diesel pusher, a fifth wheel, and a travel trailer each demand fundamentally different clearances, and treating them the same way is exactly how costly post-purchase regret happens. This guide treats sizing as the vehicle-class problem it actually is. You will find dimension reference tables organized by RV type, a clear explanation of why eave height and true clearance are not the same number, a step-by-step measurement methodology, and a breakdown of the most common sizing mistakes buyers make before they order. You will also learn how to size your structure for the rig you plan to own next, not just the one sitting in your driveway today. Why RV Carport Sizing Is a Vehicle-Class Problem, Not a Generic Checklist A metal RV carport is not a scaled-up car carport. A Class A diesel pusher, a fifth wheel, and a travel trailer have fundamentally different geometry, and a single size recommendation fails all three. Getting this wrong means ordering a permanent steel structure that cannot do its job. Four dimensions drive the problem, and each one hides a common mistake. Height is where most sizing errors begin. The eave height listed in a carport specification is the sidewall height where the roof panel meets the leg. It is not the usable vertical clearance above your rig. The roof pitch adds height above the eave at the peak, but the eave is the constraint that determines whether your RV clears the structure at the sides. Confusing these two numbers is one of the most frequently cited sources of post-purchase regret in the RV shelter category. Width is rarely just the body of the rig. Slide-outs, tow mirrors, and rooftop antenna mounts can collectively add significantly beyond the manufacturer's listed width. A Class A with dual slide-outs fully extended can measure substantially wider than the listed body width when extended. Order to the spec sheet, and the carport becomes unusable the moment you park normally. Length carries its own trap for fifth wheel and travel trailer owners. The RV manufacturer's listed length stops at the trailer body. It does not include the hitch receiver, tow ball overhang at the rear, or the cab of the pickup truck if the carport will shelter the entire rig combination. The total occupied footprint is consistently longer than the spec sheet suggests. Tolerance is the final variable, and the least forgiving. A metal RV carport ordered even two inches too narrow or too low is a non-returnable custom structure. There is no correction after delivery. That reality makes accurate pre-order measurement the single most consequential step in the entire buying process, more important than roof style, gauge selection, or color. Each of these dimensions requires a class-specific answer. The sections that follow address them one at a time. Eave Height vs. True Clearance: The Number That Actually Matters Of all the dimensions in a carport specification, eave height is the one most frequently misread, and that misreading is where costly sizing mistakes are born. Eave height is the measurement from the ground to the point where the sidewall meets the roof panel. It is not the peak height, and it is not the usable clearance at the center of the structure. On a boxed-eave or vertical-roof carport, the roof panels rise above the eave line, so the structural peak sits higher than the listed eave height. That extra height is useful for water and snow shedding, but it does not help the RV parked below. What matters for clearance is the lowest point inside the structure that the vehicle must pass under, which on most configurations is near the eave line, not the peak. This distinction drives the standard sizing rule: add adequate clearance above the tallest point on your RV to determine your minimum safe eave height. That tallest point is rarely the bare roofline. Rooftop air conditioning units, antennas, vents, and satellite dishes all extend above the manufacturer's listed height, sometimes by several inches combined. Measure to the highest fixed object on the roof, then apply the buffer. For Class A motorhomes specifically, the math is straightforward. Most Class A coaches stand tall enough that a 14-foot eave is a widely recommended starting point for Class A configurations based on owner experience and community guidance. On the low end of the height spectrum, Cardinal Carports configures eave height through custom leg height orders, allowing the structure to be matched precisely to the measured clearance requirement rather than forcing a compromise. RV Carport Dimensions by Vehicle Class: Reference Tables With eave height logic established, the next step is matching those numbers to your specific vehicle class. Each class has a distinct size envelope, and the table below gives you concrete starting points. Class A Motorhomes (Gas and Diesel Pushers) Class A coaches vary by manufacturer; measure your specific rig. For carport configuration, plan at minimum 45 feet long with a 14-foot eave; width should reflect your extended-slide measurement. For a 40-foot diesel pusher specifically, a 25x45 with a 13-foot eave is a functional starting point, though a 14-foot eave is safer when rooftop AC units are present. Class C Motorhomes Class C motorhomes vary by manufacturer; measure your specific rig. A 14-foot-wide carport in the 30-to-35-foot range with eave height matched to your measured rig clearance covers most Class C configurations with room to spare on all three dimensions. Fifth Wheels Fifth wheels introduce a geometry problem no other class shares. The raised front gooseneck section sits noticeably higher than the main trailer body. Because the carport must clear the highest point, size to that front peak. A 14-to-16-foot-wide carport in the 40-foot range, with eave height sized to the gooseneck peak , handles most fifth wheel configurations. Always measure the gooseneck height separately before ordering. Travel Trailers Travel trailers vary by manufacturer; measure your specific rig. A 12-foot-wide carport in the 30-foot range with eave height matched to the trailer's measured height fits most mid-range trailers. Larger units warrant a 14x40 configuration. Owners currently running a 28-foot trailer but planning a future Class A upgrade should look at a 35x25 with a 13-foot eave to avoid ordering twice. Toy Haulers Toy haulers need their own row in your planning. Toy haulers often stand taller than other classes due to rooftop features and rear ramp doors; treat them as the tallest vehicle in your fleet when specifying eave height and add generous overhead clearance above the manufacturer's listed height before ordering. How to Measure Your RV for a Metal Carport Before You Order Those reference tables give you the target dimensions for your vehicle class. Now you need to confirm your specific rig's actual numbers before placing an order. Here is the five-step process. Step 1: Measure actual height. Use a tape measure from the ground to the highest fixed point on the roof. That is typically a rooftop AC unit, not the roofline itself. Manufacturer spec sheets frequently exclude aftermarket additions like cellular boosters, satellite dishes, and ladder mounts, which can add potentially significant additional height above the published figure. Your tape measure is the only number that matters here. Step 2: Measure width with slide-outs fully extended. Park the rig on level ground, extend every slide-out completely, then measure side to side at the widest point. A Class A with dual slides is…