Water doesn’t need much of an opening to cause serious damage. A gap the width of a credit card between your roofline and an exterior wall can let moisture work its way into the sheathing, wall framing, and insulation over months before you see a single stain on the ceiling. In North Charleston, where summer storms can dump two inches of rain in under an hour and humidity sits high most of the year, proper flashing installation at wall-to-roof intersections isn’t optional — it’s the difference between a roof that lasts 25 years and one that needs emergency repairs in year seven.
Wando Roofing Charleston handles this type of work regularly across North Charleston and the surrounding Lowcountry, and the details below reflect what actually works in this climate — not just what the textbook says.
How to Install Roof Flashing Against a Wall in North Charleston?
Installing step flashing — the correct method for a sloped roof running alongside a vertical wall — requires you to work shingle-by-shingle up the slope rather than sliding one long piece of metal under everything at once. Here’s how it goes, done properly.
Start with the right materials. For North Charleston conditions, 26-gauge galvanized steel or aluminum step flashing works well. Each piece should be at least 10 inches tall (the portion going up the wall) and 10 inches long (the portion lying on the roof deck). Pre-bent pieces from a roofing supply house are faster, but sheet metal cut on-site gives you more flexibility around uneven walls.
Prepare the wall surface. Remove siding down to the sheathing for at least 6 inches above the roof line. You’ll be integrating the flashing with the wall’s water-resistive barrier — typically felt paper or a house wrap product — and that barrier needs to lap over the top of the finished flashing, not underneath it. Getting this sequence wrong is one of the most common errors we see on DIY jobs and contractor re-dos alike.
Set the first piece of step flashing. The bottom piece goes in at the eave before you start laying shingles. Apply a small amount of roofing sealant along the deck where the flashing will sit, press it flat, and nail it once through the top portion into the wall sheathing. Never nail through the horizontal leg lying on the roof — thermal expansion will crack sealant and lift shingles if the metal can’t move.
Work up course by course. Lay one shingle. Set one piece of step flashing over it, offset so the front edge of the flashing aligns with the front edge of the shingle below. Nail once at the top of the vertical leg. Lay the next shingle over the flashing’s horizontal portion. Repeat until you reach the top of the wall. Each piece overlaps the one below by at least 2 inches. If your slope is steeper than 6:12, check that your overlaps are sufficient — steeper pitches move water faster and reduce the margin for error.
Install the counter flashing (kickout at the bottom, cap at the top). At the bottom of the wall-to-roof intersection, a kickout flashing diverts water away from the siding face and into the gutter. This small piece is frequently skipped and is responsible for a disproportionate number of rot claims in this region. At the top of the run, install a piece of cap or head flashing that tucks under the siding and laps over the last step flashing piece.
Seal and re-side. Bring the wall’s water-resistive barrier down over the vertical legs of the step flashing, then reinstall or replace the siding. The siding should end at least 1 inch above the shingle surface — not touching it — to prevent wicking.
For roof installation in Charleston SC, the South Carolina Residential Code follows the IRC, which requires flashing at all roof-wall intersections. The 2024 IRC (adopted in SC) specifies corrosion-resistant flashing materials and minimum lap dimensions. You can review the SC Building Codes Council’s current adopted codes to confirm local requirements before pulling a permit.
Why the Kickout Piece Matters More Than People Think?
Walk around almost any neighborhood in North Charleston and look at the bottom of every chimney or dormer wall that meets a sloped roof. A significant number will be missing kickout flashing. Without it, water running down the wall surface hits the top of the gutter or the shingle apron and gets directed sideways — straight into the gap between the siding and the sheathing.
We repaired a home on Montague Avenue a couple of years back where the homeowner had no idea there was a problem until paint started peeling in a second-floor bedroom. The actual damage was three feet of rotted OSB sheathing and two wall studs that had to be sistered. Total repair: close to $4,200. The kickout piece that would have prevented it costs about $6 in materials and 20 minutes to install correctly.
GAF Roofing, one of the major manufacturers whose products we use, publishes detailed flashing installation guidelines that align with this sequencing. Owens Corning also covers flashing requirements in their installation documentation. Both reinforce the kickout requirement at the eave-wall junction.
Choosing the Right Flashing Material for This Climate
Galvanized steel is the most forgiving choice here. It bonds well with most sealants, doesn’t react badly with asphalt roofs, and holds up against the salt air that drifts inland from Charleston Harbor. Aluminum is lighter and easier to cut on-site, but it does react with some masonry — if you’re flashing against a brick chimney or stucco wall, stick with galvanized or go with lead-coated copper for long-term durability.
Copper is the premium option and pairs well with slate roofs. It outlasts the roof itself in most cases and develops a patina that actually improves its weather resistance over time. The tradeoff is cost — copper step flashing can run three to four times the price of galvanized. For most residential jobs in North Charleston, galvanized is the right call.
Avoid using sheet metal flashing with exposed lap sealant as your only moisture barrier. Sealant fails. It dries out, cracks, and loses adhesion — sometimes within five years in this heat. The physical overlap and proper sequencing of materials is what keeps water out. Sealant is a supplement, not a substitute.
The National Roofing Contractors Association maintains technical guidance on flashing installation that’s worth reviewing if you’re managing a project yourself. The Insurance Institute for Business & Home Safety also publishes research on water intrusion failures specific to the Southeast that’s directly relevant to Lowcountry homes.
When to Call a Roofer Instead of DIY?
Flashing a straightforward shed dormer or a simple gable wall addition is manageable for an experienced DIYer with the right tools and patience for the sequencing. But a few situations call for professional installation.
If the wall is brick or stucco, you’ll need to cut a reglet (a slot in the mortar joint or surface) to embed the counter flashing, which requires a grinder and some experience reading masonry. If the roof pitch is above 9:12, working safely at the wall intersection requires staging or fall protection. If there’s any existing rot or water damage at the junction, you need to address the framing before the flashing goes on — putting new metal over damaged wood just hides the problem.
Roof repair in Charleston SC that involves flashing also often turns up surprises once you pull the old material. Previous improperly installed or missing flashing can mean several courses of damaged decking that have to come out before anything new goes on.
Our about our team page covers the background and credentials we bring to this work. If you want to see what North Charleston homeowners have said about our flashing and installation work, check our client reviews — most of the feedback covers exactly these kinds of detail-oriented repair and installation jobs.
For common questions about materials, permits, and timelines, our roofing FAQs page is a practical starting point.
Get the Flashing Right Before the Next Storm
Flashing failures are quiet — they don’t announce themselves the way a missing shingle does. But they’re responsible for a large share of the interior water damage claims filed after summer storm seasons in the Lowcountry. Getting it done correctly the first time, with the right materials and proper sequencing, protects your wall framing, your insulation, and your interior finishes for the life of the roof.
If you’d like a professional to handle the installation or inspect an existing wall-to-roof junction, contact us to schedule a time. You can also call us directly at (843)-442-7656 or stop by our office at 4721 Lysa Ave, North Charleston, SC 29405. Wando Roofing Charleston serves homeowners throughout North Charleston and the broader Charleston area — we’re familiar with the building stock, the weather patterns, and what it takes to keep a roof tight in this part of South Carolina.