Building a sidewall flare on your exterior walls helps protect your home’s foundation while adding a distinct architectural touch. This gradual, wave-like roll at the bottom of a wall helps to direct water away from trim features below.
In this guide, This Old House general contractor Tom Silva demonstrates an innovative method for creating a sidewall flare that includes flashing and drainage excellent for wet climates.
What Are Sidewall Flares?
Sidewall flares are architectural features where the lower section of a home’s exterior flares outward at the bottom, creating a curve that helps send water away from the home’s foundation, offering better protection to the underlying structure.
They’re typically located at the bottom of a wall, just above the water table trim and drip cap near the foundation. However, they can also be placed higher up the wall to mark a transition between different siding materials, such as clapboards to shingles.
Sidewall flares are common in craftsman, colonial, and other traditional architectural styles and are often paired with specific siding or shingle treatments to create a visually appealing and functional detail.
Silva’s method for creating a sidewall flare allows for a more precise and customizable curve, giving you the flexibility to achieve the desired look. The method also allows for the addition of crown molding below the flare, integrating the flare with the rest of the home’s exterior.
Tools and Materials to Build a Sidewall Flare
You’ll need the following tools and materials to build and install your sidewall flares.
Tools
- Clamps (for securing pieces)
- Drill
- Hammer (for nailing shingles)
- Jigsaw
- Level
- Measuring tape
- Pencil
- Router
- Screwdriver
- Utility knife (for trimming shingles)
Materials
- 2x material (for template and curved studs)
- 1/4-inch to 3/8-inch plywood (for shingle nailing)
- Exterior-grade screws
- High-quality, rot-resistant cedar shingles
- Stainless steel or hot-dipped galvanized nails
- Wood glue
- 3/4-inch plywood (base for mounting curved studs)
Creating a Sidewall Flare Pattern
Follow the instructions below to create your sidewall flare pattern.
Step 1: Create a Template
A template will help you cut every piece of the support the same way, creating an even sidewall flare.
- Determine the desired length and depth of the flare.
- Cut a curved stud template from 2x material.
- Include a notch in the back for mounting to plywood.
- Make sure that the template has the proper spring angle for crown molding installation.
Step 2: Cut the Curved Studs
Using that template, you’ll shape the actual sidewall flare supports.
- Trace the template onto 2x material.
- Use a jigsaw to rough-cut the pieces. Cut enough pieces to create a 16-inch on-center layout along the flare’s length.
- Secure the template and rough-cut piece together.
- Use a bottom-bearing flush-cut bit on a router.
- Add 2x material around the pieces for a flat router base.
- Hold the router firmly and move slowly for precise cuts.
Step 3: Mount Curved Studs to Plywood
Attaching the studs to a piece of plywood makes it significantly easier to install on the house.
- Use 3/4-inch plywood as a base.
- Space the curved studs 16 inches apart on center.
- Apply glue to the back of the studs.
- Screw the studs in place from the back of the plywood.
Step 4: Install the Flare Unit
Mount the assembled unit to the wall using exterior-grade screws. Add a layer of 1/4-inch to 3/8-inch plywood on top for shingle nailing.
Install Shingles on the Flare
Sidewall flares can be used with a variety of siding materials, but they’re particularly common in homes with shingle siding. After assembling the flare structures, you can begin installing the shingles to the flares.
Before installing shingles, make sure the plywood surface is clean, dry, and free of any protruding nails or screws. This will provide a smooth base for the shingles. Then, begin the shingle installation:
- Start with a starter course at the bottom of the flare.
- Hang the starter course slightly lower than subsequent courses.
- Install the first full course, verifying the joints don’t line up with the starter course.
- Push shingles down to follow the curve of the flare.
- Nail through the filler pieces to secure shingles.
- Continue up the flare, maintaining proper reveal between courses.
We recommend using high-quality, rot-resistant cedar shingles and maintaining consistent spacing to create a uniform appearance. Proper overlap prevents water infiltration and protects the structure from moisture damage. Finally, opt for stainless steel or hot-dipped galvanized nails to avoid rust stains and improve durability.
Adding Crown Molding Below the Sidewall Flare
You can add crown molding below the flare for a more elaborate look. To complement your home’s style, choose a crown molding profile proportionate to the flare’s size. For exterior applications, use cedar or another rot-resistant material to improve longevity and durability against the elements.
Install Crown Molding
Follow the steps below to install your crown molding:
- Cut the crown molding to fit the length of the flare.
- Install a small fascia board below the flare to support the crown.
- Secure the crown molding to the fascia and curved studs.
- Caulk and paint as needed to protect from moisture.
Considerations for Different Siding Materials
Although we focus on shingle siding for this project, you can adapt the flare technique to various siding materials. We’ve outlined other options below.
- Clapboard siding: To create a flare for clapboard siding, gradually increase the reveal of the bottom few courses. This method forms a subtle outward curve without requiring complex framing.
- Vinyl siding: Due to its rigid nature, vinyl siding requires a different approach. Special curved starter strips and J-channels can be used to create a flared effect at the bottom of the wall.
- Fiber cement siding: Installing fiber cement siding is similar to working with wood clapboards, with a gradual increase in reveal at the bottom. However, extra care is needed to prevent cracking the material when bending it to follow the curve.
Maintenance and Care To Prevent Flare Damage
Use these recommended maintenance tips to prevent flare damage and keep them in excellent condition.
Regular Inspections
Perform regular inspections to keep your sidewall flare in good condition:
- Check for signs of water damage or rot.
- Verify proper drainage away from the flare.
- Inspect caulking and repaint as needed.
Cleaning
Cleaning your sidewall flare regularly will help maintain its appearance and prevent damage:
- Gently wash the flare and siding annually.
- Use a soft brush and mild detergent solution.
- Avoid high-pressure washing, which can damage shingles or force water behind the siding.
Seasonal Care
Seasonal care helps prevent damage from weather changes. In winter, inspect for ice dams, and in spring, check for any damage from snow or ice. Summer and fall are good times for cleaning and performing any necessary touch-ups.
