Flat roof double carport plans

This step by step diy woodworking project is about flat roof double carport plans. If you want to learn how to build a double car carport with a flat roof, we recommend you to pay attention to the instructions described in the article and to check out the related projects. There are many storage projects featured on our site, so don’t be afraid to browse through the rest of the woodworking plans.

Before starting the actual construction project, we recommend you to plan everything, as to save money and to keep the costs under control. Adjust the size and the design of the wooden carport to suit your needs. In addition, we recommend you to invest in high-quality materials, such as pine, redwood or cedar, as they have a nice finish and are highly durable, especially in a humid environment.

It is essential to invest in high quality materials, that are also water-resistant, such as pressure-treated lumber. Cut the components at the right size by using a circular saw and smooth the cut edges with a sand block. Don’t forget to ask a skilled friend to assist you during the project, especially if you don’t have a large expertise in the field. You need someone to hold the components into place, while you drive the screws in. See all my Premium Plans in the Shop.

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Flat roof double carport plans

Building a flat roof double carport

Materials

• A – 2 pieces of 4×4 lumber – 132″ long, 2 pieces –  140 1/4″ long, 2 pieces – 148 1/2″ long POSTS
• B – 2 piece of 4×4 lumber – 42 1/2″ long, 2 pieces – 47 1/2″ long, 2 pieces – 55″ long, 2 pieces – 59″ long BRACES
• C – 4 pieces of 2×6 lumber – 265 3/4″ long SUPPORT BEAMS
• D – 12 piece of 2×6 lumber – 243″ long RAFTERS
• D – 2 piece of 2×6 lumber – 246″ long, 2 pieces – 265 3/4″ long RIM RAFTERS
• E – 10 pieces of 3/4″ plywood – 48″x96″ long, 5 pieces – 48″x73 3/4″ long, 2 pieces – 3″x96″ long, 1 piece – 3″x73 3/4″ long ROOFING SHEETS
• F – 600 sq ft tar paper, 600 sq ft asphalt shingles ROOFING

• 4 pieces of 4×4 lumber – 12 ft
• 2 pieces of 4×4 lumber – 14 ft
• 2 pieces of 4×4 lumber – 8 ft
• 2 pieces of 4×4 lumber – 10 ft
• 6 pieces of 2×6 lumber – 24 ft
• 14 pieces of 2×6 lumber – 22 ft
• 16 pieces of 3/4″ plywood – 4’x8′
• 600 sq ft tar paper, 600 sq ft asphalt shingles
• (roofing felt, asphalt shingles)
• 6 pieces of tube form
• 6 pieces of concrete bags
• 1000 pieces of 1 5/8″ screws
• 50 pieces of 5 1/2″ screws
• 2 boxes of 1 1/2″ structural screws
• 12 pieces of  7″ carriage bolt with nuts and washers
• 24 pieces of rafter ties

Tools

• Safety gloves, glasses
• Miter saw, jigsaw
• Chalk line, tape measure, spirit level, carpentry pencil
• Drill machinery and drill bits

Tips

• Use a good miter saw to make the angle cuts
• Drill pilot holes before inserting the screws

Time

• One Week

Related

• Free carport plans
• Double carport building plans

Building a flat roof double carport

Laying out the carport

The first step of the woodworking project is to lay out the carport in a professional manner. Therefore, we recommend you to use batter boards and string to make sure the posts will be properly placed. Apply the 3-4-5 rule to each corner of the layout in order to check if they are perfectly square. In addition, make sure the diagonals are perfectly equal before setting the posts into place.

Building the posts

Next, you need to cut the posts at the right size, making sure you need to fit them about 3′ into the ground, before adjusting their dimensions.

Fitting the posts

Setting the posts in concrete is essential for the rigidity of the carport. As you can easily notice in the diagram, we recommend you to dig 3′ deep holes and to pour 2″ gravel on the bottom. Install the tube forms to the holes. Secure the posts with braces before filling the forms with concrete.

Fitting the support beams

Next, install the 2×6 support beams to the top of the posts. Use clamps to secure the beams to the top of the posts. Drill pilot holes through both the support beams and through the posts before inserting the 7-8″ carriage bolts. Leave no gaps between the components and lock the components together tightly.

Make sure the carport has appropriate overhangs, in order to allow the water to drain properly. Use at least 2 bolts for each joint.

Fitting the braces

If you live in a windy area, you should install 4×4 braces to the flat roof carport. Cut both ends of the braces at 45 degrees and secure them to the structure, as described in the diagram. Drill pilot holes before inserting the screws and leave no gaps between the components, for a professional result. Insert at least two 5 1/2″ screws for each joint.

Fitting the support beams

Install the support beams to the other side of the carport, using the same techniques described above. It is essential to make sure the beams are at the same level, otherwise the roof won’t be level.

Fitting the rafters

Build the rafters out of 2×6 lumber. Cut the components at the right size and smooth the edges with sandpaper.

Cutting the rafters

Make notches at both ends of the rafters, using the information from the diagram. Make parallel cuts inside the marked area and remove the excess material with a chisel. Smooth the cut edges with fine-grit sandpaper and remove the residues with a damp cloth.

Fitting the rafters

Place the rafters equally-spaced and and secure them to the support beams using rafter ties and 1 1/2″ structural screws. Align the rafters at both ends before inserting the screws, to get a professional result.

Fitting the rim rafters

One of the last steps of the project, is to fit the 2×6 trims to the exterior of the rafters. The top edge of the rim rafters should be 3/4″ over the rafters, in order to get a professional result. Secure the trims to the frame of the carport using 5 1/2″ screws, every 8″. Use a spirit level to make sure the bottom and the top trims are horizontal.

Build the roof out of 3/4″ plywood sheets and lay them to the rafters, as described in the diagram.  Align the sheets at both ends and lock them to the rafters with 1 5/8″ nails or screws, every 6-8″. It is essential to close the gaps between the sheets, if you want to get the job done as a professional. Make sure the surface is even and the screws are not protruding.

Fitting the roofing

You could fit asphalt shingles to protect the carport, as it is a straight forward solution. Therefore, install roofing felt over the roofing sheets, making sure the strips overlap at least 2″. Secure the tar paper to the plywood sheets with roofing staples. Fit the side drip edges over the roofing felt, while the bottom drip edges should be fit under. Place a starting course at the bottom of the roof, before installing the asphalt shingles. Always read the manufacturing instructions before starting the installation, as there are several aspects that differ.

Flat roof carport plans

The flat roof carport has a neat appearance so that it can match the style of any home.

Flat roof carport plans

Last but not least, we recommend you to take care of the finishing touches. Fill the holes with wood filler and let it to dry out for several hours. Check out the rest of the outdoor projects, to see more ways to improve the look of your garden.

If you want to download the plans. just click on the GET PDF PLANS button bellow.

My best tips on building a double flat roof carport:

A double flat roof carport provides ample space for two vehicles while offering a clean, modern look. It’s a functional and stylish addition to any home, protecting your cars from sun, rain, and snow. With its simple design, a flat roof carport is easier to build than other types, making it a great DIY project. Here are my best tips for building a strong, durable double flat roof carport.

1. Plan and Design the Carport

• Determine the Carport Size: A double carport typically measures around 20-24 feet wide and 20 feet long, providing enough space for two vehicles. Adjust the size according to your needs and available space.
• Flat Roof Design Considerations: A flat roof is easy to construct and maintains a low profile, but it still needs a slight pitch for water drainage. Plan for a slope of about 1/4 inch per foot to direct water away from the roof.
• Location and Orientation: Choose a spot with level ground, ideally close to your driveway or garage for convenience. Ensure the location has proper drainage and isn’t prone to pooling water.
• Check Local Building Codes: Before starting, check your local building codes and obtain any necessary permits. Some areas may have rules about the size, height, or placement of carports, especially if they are close to property lines or utility easements.

2. Gather Materials and Tools

• Pressure-Treated Lumber or Metal Posts: Pressure-treated wood is affordable and durable for outdoor structures. For a more contemporary look, consider steel or aluminum posts and beams.
• Roofing Material: For a flat roof, corrugated metal sheets, polycarbonate panels, or rolled roofing are excellent choices for durability and weather resistance. Choose materials that are lightweight but strong enough to withstand wind and rain.
• Concrete for Post Anchors: Use concrete footings to securely anchor the posts in the ground. This ensures the carport remains stable and strong.
• Tools: You’ll need tools such as a saw, drill, hammer, post-hole digger, level, measuring tape, and ladder for the construction process.

3. Mark and Prepare the Site

• Mark the Carport’s Footprint: Use stakes and string to outline the carport’s footprint, ensuring it’s square and aligned with your home or driveway. Measure carefully to avoid alignment issues during construction.
• Clear the Area: Remove grass, plants, or debris from the marked area. Depending on your preference, you can pour a concrete slab or use gravel as the carport’s floor. A flat, solid base is important for long-term stability.

4. Set the Support Posts

• Dig Post Holes: Using a post-hole digger, dig holes for the corner and intermediate support posts. Each hole should be at least 2-3 feet deep to ensure the posts are securely anchored in the ground. The depth may vary depending on your region’s frost line.
• Set the Posts in Concrete: Place the posts into the holes and pour concrete around them. Use a level to ensure the posts are plumb (vertically straight) and brace them with temporary supports while the concrete cures. Allow the concrete to set for at least 24-48 hours.
• Spacing Between Posts: For a double carport, space the posts evenly—usually 8-10 feet apart—along the perimeter for adequate support.

5. Attach the Horizontal Beams

• Install the Main Support Beams: Once the posts are set, attach horizontal beams across the tops of the posts. These beams will support the flat roof. Use galvanized carriage bolts or lag screws to securely fasten the beams to the posts.
• Ensure Level Alignment: Check that the beams are level across the structure, as this will ensure a flat roof that drains properly. You can use shims if necessary to adjust the alignment.

6. Install Roof Joists

• Install Roof Joists Across the Beams: Measure and cut roof joists to span the width of the carport. Space them 16-24 inches apart along the beams to provide support for the roofing material.
• Slight Pitch for Drainage: Even though it’s a flat roof, create a slight pitch by attaching one side of the joists slightly higher than the other. A 1/4-inch slope per foot is typically enough for water drainage.
• Secure the Joists: Attach the joists to the beams using joist hangers or screws. Ensure the joists are evenly spaced and aligned for proper roof support.

7. Install the Roofing Material

• Lay Down the Roofing Sheets: Starting at the low end of the slope, install the roofing material (corrugated metal sheets, polycarbonate panels, or rolled roofing) across the joists. Overlap the sheets according to the manufacturer’s guidelines to prevent leaks.
• Secure the Roofing Material: Use screws with rubber washers to fasten the roofing sheets to the joists. This will ensure a watertight seal and prevent water from seeping through.
• Install Flashing (Optional): If the carport is attached to your house or garage, install flashing along the edges where the roof meets the wall. This will prevent water from getting into the seams.

8. Add Finishing Touches

• Install Gutters (Optional): To manage water runoff, consider installing gutters and downspouts along the edges of the carport roof. This will protect the area below from water pooling and help direct rainwater away from the foundation.
• Paint or Stain the Wood: If you’ve used wooden posts and beams, consider painting or staining the wood to protect it from the elements and give it a finished look. Use a weather-resistant sealant for added protection.
• Add Privacy Panels or Lattice (Optional): If you want more protection from wind or sunlight, consider adding side panels, lattice, or even trellises along one or more sides of the carport.

9. Anchor the Carport for Stability

• Anchor the Posts for Extra Stability: In windy areas, it’s essential to securely anchor the posts to the ground or concrete slab using metal brackets or additional concrete footings. This will prevent the carport from shifting or lifting in strong winds.
• Install Cross Bracing: For added strength, install diagonal cross braces between the posts and beams. This will help prevent the structure from swaying or collapsing in bad weather.

10. Maintain Your Carport

• Inspect Regularly: Check the carport periodically for any signs of wear or damage, such as loose bolts, rusted screws, or cracks in the roofing material. Tighten or replace any damaged components as needed.
• Clean the Roof: Regularly clear the roof of leaves, dirt, and debris to prevent water buildup and ensure the roof’s longevity.

Building a double flat roof carport is a practical and rewarding DIY project that offers plenty of space for protecting two vehicles. By following these tips and using quality materials, you’ll create a sturdy, functional carport that complements your home and provides reliable shelter for years to come. Whether you’re looking for a simple design or something more elaborate, the flat roof carport is a versatile and stylish addition to any property.

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