In the logistics of steel structures, there is a critical threshold: 24 feet wide. Below 24 feet (standard 1-Car and 2-Car Carports), the engineering is straightforward. The trusses are simple bows. But once you cross into 26-foot to 30-foot widths—the territory of the 3-Car Carport or “Triple Wide”—the physics change completely.
As the Supply Chain Director, I authorize the release of these structures daily. I also see the warranty claims from customers who bought a non-certified Triple Wide from a budget competitor and watched it buckle under 6 inches of wet snow.
A 3-Car Carport acts as a massive sail in the wind and a giant catchment basin for snow. You cannot simply “scale up” a small carport design. You need a different structural system entirely. This guide is your “Engineering 101” for Triple Wide planning. We will move past the aesthetics and look at the raw numbers: Truss strength, Anchor pull-out ratings, and Wind Load limits.
1. The “Triple Wide” Definition: Understanding the Scale
First, let’s define what we are building. In our inventory system, a “Triple Wide” is any clear-span structure between 26 feet and 30 feet wide. Unlike commercial clear-span buildings (which use massive I-beams), Triple Wides use a reinforced tubular steel truss system to keep costs reasonable for residential use.
Table 1: Triple Wide Dimensions & Capacity Logistics
| Largeur | Typical Use Case | Vehicle Capacity | Recommended Minimum Length |
|---|---|---|---|
| 26 Feet | 3 Compact Cars OR 2 Full-Size Trucks + ATV | Tight fit for 3 daily drivers. | 21 Feet (Bare Minimum) |
| 28 Feet | 3 SUVs / Sedans | Comfortable fit; doors can open freely. | 26 Feet (Standard) |
| 30 Feet | 3 Full-Size Trucks OR 2 Cars + Boat | Maximum residential width. | 31 Feet or 36 Feet |
Director’s Note: Never buy a 26-foot wide carport for three full-size American pickup trucks (e.g., F-150s). You will not be able to open the doors. For three trucks, you need the full 30-foot width.
2. The Truss System: The Backbone of the Beast
This is where the supply chain quality matters most. On a standard 18-foot carport, the roof bow is a simple bent tube. On a 30-foot Abri de voiture triple largeur, a simple tube would sag under its own weight.
We use a Webbed Truss design for all Triple Wides. This means every roof bow is actually two steel tubes welded together with a zig-zag webbing pattern in between. This creates a bridge-like structure capable of spanning the distance without interior columns.
Table 2: Truss Engineering Specifications
| Feature | Standard Carport (12′-24′) | Triple Wide Carport (26′-30′) | Why It Matters? |
|---|---|---|---|
| Truss Design | Single Tube Bow | Welded Web Truss | Prevents roof sagging in the middle. |
| Corner Bracing | 2-3 Foot Braces | 4-Foot or Full Web Bracing | Prevents the structure from “racking” (leaning) in wind. |
| Leg Spacing | Up to 5 Feet | 4 Feet Maximum | Tighter leg spacing supports the heavier roof weight. |
| Steel Gauge | 14-Gauge Standard | 14-Gauge (Standard) or 12-Gauge (Heavy) | We highly recommend upgrading to 12-Gauge for 30′ spans. |
3. Wind Load Dynamics: Managing the “Sail Effect”
Imagine holding a 30-foot wide sheet of plywood in a windstorm. That is essentially what your carport roof is. Wind load isn’t just about the wind blowing against the side; the bigger danger for Triple Wides is Uplift. Wind gets under the large canopy and tries to lift the entire structure out of the ground like a kite.
To combat this, our Certified Triple Wide units are engineered to withstand winds up to 140 mph (and higher in coastal zones).
Table 3: Wind Rating vs. Structural Requirements
| Wind Speed Rating | Structural Requirement | Anchoring Requirement | Supply Chain Rec |
|---|---|---|---|
| 100 mph (Non-Certified) | Standard spacing (5′ on center). | Standard Rebar Anchors. | NOT RECOMMENDED for Triple Wides. Too risky. |
| 130 mph (Certified) | Tighter spacing (4′ on center). | Mobile Home Augers (Earth) or Wedges (Concrete). | The Minimum Standard for most US states. |
| 150+ mph (High Wind) | 12-Gauge Steel + Extra Bracing. | Cemented Anchors + High-Wind pattern. | Mandatory for FL and Coastal TX/SC. |
Director’s Warning: If you live in an open area (farm, field) where wind accelerates without obstruction, do not buy a non-certified 3-Car Carport. The cost difference is minimal compared to the cost of your carport flying into your neighbor’s living room.
4. Snow Load Logistics: The Weight of Winter
Snow is heavy. Wet snow can weigh 20 pounds per square foot (PSF). On a 30′ x 40′ Triple Wide Carport, that is 1,200 square feet of roof. If you get 1 foot of wet snow (20 PSF), your carport is holding 24,000 POUNDS of weight. That is the equivalent of parking four Ford F-250s on the roof.
This is why roof style is critical.
Table 4: Roof Style Performance for 3-Car Units
| Style de toit | Description | Suitability for Triple Wide | Snow Load Risk |
|---|---|---|---|
| Regular (Rounded) | Horizontal Panels. | POOR. | High. Snow sticks to the ridges. Structure may bow. |
| Boxed-Eave (A-Frame) | Horizontal Panels. | FAIR. | Moderate. Better look, but snow still doesn’t slide off easily. |
| Toit vertical | Vertical Panels. | EXCELLENT. | Low. Snow slides off immediately. Hat-channel purlins add strength. |
The Supply Chain Rule: We strongly discourage selling Regular or Boxed-Eave styles on 30-foot wide units in snow zones. The risk of collapse is too high. Always upgrade to the Toit vertical for a 3-Car Carport. The vertical orientation adds structural cross-bracing (purlins) that horizontal roofs lack.
5. Anchoring 101: Keeping It Grounded
You have the heavy truss, you have the vertical roof. Now, how do we keep it on the ground? Anchoring a Triple Wide is not a DIY job with a tent stake. The sheer surface area requires industrial holding power.
Table 5: Anchor Types and Pull-Out Strength
| Anchor Type | Surface Application | Pull-Out Resistance (Approx) | Notes |
|---|---|---|---|
| Rebar Pin (30″) | Dirt / Asphalt | ~400 lbs | Temporary only. Never rely on this for a 3-Car unit. |
| Mobile Home Auger (30″) | Dirt / Gravel | ~2,500 – 3,500 lbs | Standard for Certified ground installs. Screws deep into earth. |
| Asphalt Anchor | Asphalt Driveway | ~1,500 lbs | Specialized barb design. |
| Wedge Anchor (5/8″ x 6″) | Dalle de béton | ~5,000+ lbs | The Gold Standard. Expands inside the concrete. |
Logistics Tip: If you are installing on dirt, we typically install auger anchors every 8 to 10 feet. On a high-wind certified unit, we may install them on every leg.
6. Foundation Requirements: The Concrete Slab
While you can install a Triple Wide on dirt or gravel, most customers investing in a 3-car structure choose to pour a concrete slab. Because the legs of a 30-foot truss exert significant downward pressure (point load), the slab edges must be reinforced.
Table 6: Concrete Slab Specifications for Triple Wides
| Spec | Recommendation | Why? |
|---|---|---|
| Slab Thickness | 4 Inches (Minimum) | Standard vehicle weight support. |
| PSI Rating | 3000 – 4000 PSI | Prevents cracking under heavy trucks. |
| Edge Footing (Turndown) | 12″ Deep x 12″ Wide | Critical. The perimeter carries the weight of the building. |
| Width Sizing | Exact Width or +2 Inches | Do not pour the slab exactly 30′ wide if the frame is 30′ wide; give yourself a 2″ margin for error. |
| Length Sizing | Length + 1 Foot | E.g., for a 31′ carport, pour a 32′ slab. |
Common Mistake: Customers pour a slab exactly 30′ x 30′ for a 30′ x 30′ building. If the concrete form bowed slightly during pouring, one leg might hang off the edge. Always pour the slab 1 foot wider and longer than the frame.
7. The Cost Efficiency of Triple Wides
From a supply chain perspective, buying one Abri de voiture triple largeur is significantly cheaper than buying a Abri pour 2 voitures plus a separate 1-Car Carport. You save on logistics (one delivery truck), installation labor (one crew trip), and materials (sharing the center support structure).
Table 7: Cost Efficiency Analysis (Estimated)
| Option | Approximate Cost | Pour | Cons |
|---|---|---|---|
| (1) 30′ x 26′ Triple Wide | $4,500 – $6,000 | Cheapest per sq. ft.; Open floor plan. | Needs a massive clear space. |
| (1) 20′ x 26′ + (1) 12′ x 26′ | $6,500 – $8,500 | Can separate vehicles (e.g., boat vs. car). | Higher cost; Wasted space between units. |
| (1) 20′ x 26′ with Lean-To | $5,000 – $6,500 | Good for zoning restrictions. | Lean-to side has lower height. |
8. Permitting and Inspection: The Paper Trail
Because Triple Wides are substantial structures (often exceeding 800 sq. ft.), they almost always trigger local building permits. When you order a 3-Car Carport from us, you need to request the Generic Engineering Plans (Blueprints).
- Wind Load Calculation: Your permit office will want to see that the engineer has calculated the uplift on a 30-foot span.
- Snow Load Calculation: In the north, they need to verify the truss can handle the specific ground snow load (e.g., 40 PSF).
- Truss Details: The inspector will check the weld spacing on the web trusses.
Supply Chain Director’s Advice: Do not try to fly under the radar with a Triple Wide. It is too big to hide behind a fence. Get the permit. We provide the engineering drawings to back you up.
Conclusion: Build It Wide, Build It Strong
A 3-Car Carport is a fantastic investment. It covers your daily drivers and your weekend toys in one cohesive structure. It adds significant appraisal value to your property.
But please, respect the physics.
- Don’t skimp on the width (go for 28′ or 30′ if you have trucks).
- Don’t skip the Vertical Roof (especially if you ever see snow).
- Don’t ignore the foundation (reinforce those slab edges).
We have the trusses in stock, welded and ready to ship. We have the logistics network to deliver 30-foot spans directly to your job site. When you are ready to build big, build it right.
Frequently Asked Questions (FAQ)
Q: Can I install a garage door on a Triple Wide later? A: Yes, but you need to plan for leg height. If you want to install standard 8-foot tall garage doors later, you should order the carport with at least 9-foot or 10-foot legs now. You need room for the door tracks and the roll-up header.
Q: Does a Triple Wide require a center post? A: No! That is the beauty of the Webbed Truss. It is a “Clear Span” structure. You have 30 feet of open space with no annoying poles to hit with your car door.
Q: What is the maximum height for a Triple Wide? A: We can engineer them up to 16 feet tall (side leg height). This is popular for Abris pour véhicules de loisirs or combining an RV spot with two car spots. However, once you go above 12 feet, we strongly
