Where a metal roof meets a brick wall, the flashing has to manage water moving across two very different materials. Metal panels shed water quickly, while brick and mortar can absorb moisture and expand or shift over time. A durable roof-to-wall connection uses layered flashing, sound underlayment, and a reliable path for water to drain away. The right design depends on the roof profile, wall construction, and local code requirements, but the core principles are consistent: direct water outward, allow for movement, and avoid relying on sealant alone.
Why Roof-to-Brick Flashing Matters
Flashing is the system of formed metal pieces and related waterproofing materials that protects joints and transitions. At a metal roof and brick wall, rain can run down the masonry and reach the roof edge, or wind can drive water upward beneath the panels. Without properly arranged flashing, water may enter the roof assembly and damage sheathing, insulation, framing, or interior finishes.
Brick is not necessarily a waterproof surface. Masonry can absorb rain, and water can travel through cracks, porous mortar, or gaps around openings. The roof-wall intersection therefore needs to manage both runoff from the roof and moisture that reaches the wall. A good installation directs water back onto the roof surface, where it can drain to the eave or gutter.
Flashing is a water-management system, not just a metal strip. Its success depends on the sequence of the parts, their connection to the wall and roof, and the condition of the materials behind them.
Common Flashing Components
Several components may be used at a metal roof-to-brick connection. The exact configuration varies with the roof panel system, wall details, and project design.
- Underlayment: A water-resistant layer installed over roof sheathing. At the wall, it should be integrated with flashing according to the roofing manufacturer’s instructions.
- Base flashing: A piece that bridges the roof and wall and directs water away from the joint. Its roof-side leg is formed to suit the metal panels.
- Counterflashing: A separate wall-side piece that covers the upper edge of base flashing. It is commonly set into a masonry joint or attached with a designed surface-mounted detail.
- Closure strips or closures: Profile-matched components used at panel ribs or edges when specified by the roof manufacturer. They help close gaps but do not replace properly designed flashing.
- Sealant: A compatible sealant may help seal a joint or fastener, but it should be a supporting component rather than the primary defense against water.
Some assemblies use a continuous apron-style flashing at a wall that runs across the roof slope. Others use a sidewall detail along a roof that meets the wall at an angle. A roof with raised seams, exposed fasteners, or a corrugated profile may require different formed parts. The roof manufacturer’s approved details should guide the selection.
How Base Flashing and Counterflashing Work Together
At a typical wall-side roof transition, base flashing lies over the roof-side drainage layer and turns up against the wall. Counterflashing then covers the top edge of the base flashing, protecting it from water running down the brick. The layers overlap so water flows outward and downward rather than behind the flashing.
At brick, counterflashing may be installed in a mortar joint, in a saw-cut reglet, or as part of a purpose-designed surface-mounted system. A reglet is a narrow cut or formed receiver in the masonry for the flashing’s upper edge. The receiver must be made without damaging the wall or creating an uncontrolled path for water. A qualified contractor should determine whether the masonry, mortar, and wall assembly can accommodate the selected method.
The base flashing and counterflashing should generally remain distinct parts. This arrangement helps accommodate movement between the roof and wall and makes future maintenance more practical. Rigidly bonding every layer together can concentrate stress at the joint, especially where the roof and masonry move differently with temperature and moisture changes.
Important Design Details for Metal Roofing
Match the flashing to the panel profile
Metal roof panels may have raised seams, ribs, corrugations, or flat sections. Flashing must fit the profile without leaving open channels beneath the panel. Manufacturer-approved closures or formed transitions can help address rib gaps, but improvised foam, excessive sealant, or crushed panel edges can create new problems. The panel system’s installation manual is the best starting point for compatible details.
Allow for thermal movement
Metal expands and contracts as temperatures change. A long panel run can move substantially over time, depending on its length, material, temperature range, and attachment system. Flashing and fasteners should not prevent movement in a way that distorts panels or opens seams. The roof system’s design determines where panels are fixed, how sliding clips are used, and how transitions are formed. Installers should follow the manufacturer’s movement and fastening requirements.
Use compatible metals and materials
Metal choice matters. Certain metals can corrode when they contact incompatible metals or are exposed to water runoff from other materials. Masonry can also be chemically aggressive to some metals, particularly when moisture is present. The selected flashing, fasteners, coatings, sealants, and roof panels should be compatible with one another and suitable for contact with masonry. Manufacturer guidance can identify approved combinations.
Integrate the layers in drainage order
Roof underlayment, base flashing, and wall weather-resistive layers need to overlap in a way that sheds water to the exterior. The exact sequence depends on the wall assembly and the roof detail. The important principle is that upper layers should lap over lower layers in the direction water naturally flows. A reverse lap can funnel water behind the flashing, even when the exposed metal appears neat.
Typical Installation Sequence
Installation details should be selected for the specific roof system and wall assembly. The following sequence describes common planning principles, not a substitute for project drawings or product instructions.
- Inspect the intersection. Identify the roof panel type, slope, sheathing condition, wall construction, mortar condition, and any existing flashing. Check for signs of water entry before covering the area.
- Prepare the roof edge and wall. Remove deteriorated materials as needed and repair underlying damage. Flashing should not be installed over loose mortar, wet sheathing, or a failing roof substrate.
- Plan the water path. Determine where roof runoff will go and how moisture draining down the wall will reach the roof surface. Include drainage to the eave, gutter, or other designed outlet.
- Install underlayment and wall layers. Extend and lap the water-control layers as required by the roof and wall manufacturers. Avoid punctures or reverse laps that could direct water behind the flashing.
- Fit the base flashing. Form it to the roof profile and wall junction. Provide the required overlap, attachment, and allowance for movement. Use only approved fastening locations and methods.
- Install counterflashing. Secure it using the specified masonry-joint, reglet, or surface-mounted detail. The counterflashing should cover the upper edge of the base flashing and direct water outward.
- Complete panel closures and sealant details. Install compatible closures, fasteners, and sealants where the approved system calls for them. Do not use exposed sealant as a substitute for correct laps and mechanical detailing.
- Inspect before the work is concealed. Confirm that flashing is continuous, drainage paths remain open, fasteners are correctly placed, and the metal has not been distorted.
Special Conditions That Need Attention
Roof slope and water volume
A low-slope roof may drain more slowly and can place greater demands on seams and transitions. The minimum slope permitted depends on the specific metal roof product and its installation method. Some systems require special seam treatments or underlayment at lower slopes. The roof manufacturer’s published requirements should be checked before the flashing detail is chosen.
Roof-to-wall intersections that run down the slope
Where a sloping roof meets a wall along its side, water must be guided down the intersection without escaping behind the panels. The detail may use continuous sidewall flashing, panel-specific closures, and a counterflashing connection at the brick. If the roof-wall junction ends above an eave, a kickout or diverter may be needed to send water away from the wall and into the gutter or onto the roof. The geometry and roof system determine the correct solution.
Chimneys and other masonry projections
A chimney creates multiple roof-to-wall intersections and often requires step flashing, counterflashing, and a cricket or saddle on the uphill side, depending on its size and configuration. A simple straight strip of flashing is generally not an adequate substitute for a complete chimney flashing system. Because these details are complex and difficult to repair once covered, they are often best handled by an experienced roofing or masonry contractor.
Existing walls and retrofit work
Retrofitting flashing into an existing brick wall can require cutting or removing mortar, which may affect the masonry. Surface-mounted systems may be appropriate in some cases, but the attachment and seal must be designed for the wall and exposure. A retrofit should not block existing drainage openings or conceal deteriorated brickwork. Repairs may also need to address the roof underlayment and wall water-control layers behind the visible surfaces.
Common Mistakes to Avoid
- Relying on caulk alone: Sealant deteriorates and cannot compensate for incorrect flashing laps or missing drainage paths.
- Using flat metal over a ribbed panel: A poor fit can leave channels where wind-driven rain can enter.
- Fastening through vulnerable areas: Fasteners placed where water flows or where the panel needs to move can create leaks or damage.
- Reversing the overlap: If the upper layer does not shed onto the lower layer, water can be directed into the roof or wall assembly.
- Ignoring brick condition: Cracked mortar, loose units, and open joints can undermine even well-made flashing.
- Blocking drainage: Sealant, mortar, or debris should not obstruct designed drainage gaps or wall weeps.
- Mixing incompatible materials: Unapproved metal, fastener, or sealant combinations can lead to corrosion or premature failure.
Inspection and Maintenance
Roof flashing should be checked as part of routine roof maintenance and after severe weather. From a safe viewing position, look for lifted or displaced metal, loose fasteners, cracked sealant, open mortar joints, rust, panel distortion, and debris that holds water at the wall. Inside the building, stains near the roofline, peeling paint, damp insulation, or a musty odor may indicate moisture entry, though leaks can travel before becoming visible.
Sealant inspection is useful, but repeated patching is not a durable repair if the underlying flashing is incorrectly shaped or layered. A qualified contractor can inspect concealed parts, identify whether the leak originates at the roof-wall junction, and determine whether repairs require removing roof panels or repairing masonry. Work on steep roofs, tall walls, or deteriorated masonry presents fall and structural hazards and should not be treated as a routine do-it-yourself task.
Codes, Product Instructions, and Contractor Questions
Building-code requirements vary by location and adopted code edition. The International Residential Code includes provisions for roof flashing and flashing at exterior wall openings, but a roof-to-brick detail must also account for the roof product, wall assembly, local amendments, and applicable manufacturer instructions. The local building department can clarify permit and inspection requirements.
Before work begins, a property owner can ask the contractor:
- What roof-manufacturer detail will be used at the brick wall?
- How will the base flashing and counterflashing overlap?
- How will the detail accommodate metal-panel movement?
- What materials and fasteners will contact the brick and roof panels?
- How will water drain at the eave or gutter, and will any kickout be needed?
- Will the work include inspection of the underlayment, sheathing, and mortar condition?
Written scope details and product documentation help verify that the proposed work is more than a surface patch. For technical guidance, useful references include the International Residential Code, the applicable metal roofing manufacturer’s installation manual, and guidance from the Metal Construction Association. Requirements differ among products and jurisdictions, so the project-specific instructions and local code official should take precedence.