How To Install Sidewall Flashing For A Metal Roof. Step By Step Guide

If you have a vertical wall on the gable side of your corrugated metal roof, you’re going to need to install sidewall. It will keep the water from dripping down the wall and leaking into the roof.

This step by step installation article specifically covers sidewall flashing installation for an exposed fastener panel such as: ⅞” Corrugated. It is not intended for installation of standing seam panels.

At Western States Metal Roofing, our objective is to make the installation of your metal roofing project simple and stress-free. To help you visualize the installation process, please check out our sidewall flashing detail in conjunction with this guide and our sidewall installation video.

To begin, please note that if your roof has a sidewall condition, all sidewall trim must be installed prior to fastening the endwall.

Installing sidewall flashing for a metal roof doesn’t have to be a difficult process. In our step-by-step guide here, we will show cover:

• What Is Sidewall Flashing?
• How Much Does Sidewall Flashing Cost?
• Prepare your sidewall at endwall
• Prepare sidewall at eave
• Overlap sidewall
• Install foam closures
• Fasten the sidewall

What Is Sidewall Flashing On A Metal Roof?

Sidewall flashing for a metal roof is the metal that’s installed on a vertical wall along the gable side of the metal roof. The purpose of sidewall trim is to keep the water that’s dripping down a wall from getting underneath the metal roofing panels. Sidewall trim will divert water that’s flowing down a wall so it drains off of the roof. It must be installed prior to endwall flashing.

How Much Does Sidewall Flashing Cost?

The cost of the sidewall flashing will depend upon the gauge and type of paint finish. On average sidewall flashing will cost $1.25 to $2.50 per lineal foot.

How To Cut And Finish Sidewall Trim At The Endwall

This is the toughest part of the trim installation and we suggest watching our sidewall installation video in conjunction with this guide to installing sidewall flashing on a metal roof. Keep in mind that the sidewall flashing should be installed prior to fastening endwall flashing.

1. Start by marking the pitch angle of your roof on the top edge of your sidewall starting at the corner of the trim.
2. Make a parallel line 1” from your first mark
3. On the lower section of the sidewall flashing, mark a straight line across from your angled 1” line.
4. Using metal cutting snips, remove the sections marked with an “X”.
5. Fold the remaining tab inwards 90 degrees with a hand seamer.

When you are finished with this step, your sidewall should be flush to your corner and have the tab bent backwards on the endwall.

How To Cut And Finish Sidewall Trim At The Eave Ends

1. At the eave end, measure the length of sidewall needed and add an additional inch.
2. Mark the top section of the sidewall 3” inward from this mark. Please note for this installation we had a 3” overhang. Your measurements will differ based upon the size of the overhang.
3. Using metal cutting snips, cut along the outline.
4. With your hand seamer, fold the remaining tab downwards 90 degrees.

When you are finished with this step, the tab should fall flush with the roofing panels as shown here:

How To Overlap Sidewall Trim

Note: Overlaps should be a minimum of 3”

1. Mark the hem of your sidewall by 3”.
2. Using metal cutting snips, cut off ⅛” from your hem to your 3” mark.
3. Slightly pry open the hem of the adjacent trim to help the piece slide into the trimmed hem section.
4. Silicone sealant should be placed where the sidewall trim overlaps.
5. The section that was pried open should slide into the cut section as shown here:

Foam Closures and Double Sided Butyl Tape

1. Before installing your sidewall, double sided butyl tape should be laid across the path of your endwall 1” from the edge of the endwall.
2. Foam closures should be placed on top of the double sided butyl tape along the path of the endwall.
3. A strip of double sided butyl tape should be laid along the first high seam of the roofing panel and along the sidewall trim path.
4. Silicone Sealant should be placed on top of the foam closures.

How To Fasten Sidewall Trim

Note: For easier installation, pre-drill your holes prior to fastening the trim. Place holes on the top edge 1” from the edge and 12” apart on center.

1. Begin to secure your sidewall using pancake screws along the top section of trim 12” apart.
2. Lap screws should then be placed 12” apart on the lower section of sidewall along the 1st high seam of your roofing panel. Make sure your screws penetrate through the double sided butyl tape.
3. After the sidewall is in place, install the endwall.

It’s important to clean off all metal shavings to avoid them rusting overnight and staining your roof.

If the siding is corrugated panels, your panels will overlap as shown here:

If you’re using another material like stucco, you will need to install a reglet. You can find a step-by-step installation guide for reglet installation on our YouTube channel.

Buy Factory Direct And Save Money On Your Metal Roofing Panels

Looking to save money on your metal roofing project? Western States Metal Roofing is a manufacturer that sells directly to the public and to contractors. This can help you save 15% to 50% percent on all of the metal roofing materials you’ll need for your house.

Go to the Western States Metal Roofing website to see our catalog and request a quote or metal color sample as there are hundreds of colors to choose from.

Looking for more homeowner guides and step-by-step installation help? You can find everything you need at the Western States Metal Roofing Learning Center to help you have an easy and successful installation.