Is step flashing better than continuous flashing?

Flashing is an important aspect of exterior lighting design. It serves to make structures more visible and to communicate information. There are two main types of flashing: step flashing and continuous flashing. Determining which is better depends on the specific application.

What is Step Flashing?

Step flashing is a type of flashing where individual pieces overlap in a stair-step pattern. Each piece overlaps the piece below it to allow water to drain down the wall. Step flashing is commonly used on chimneys, walls, and other vertical surfaces.

Some key features of step flashing:

• Each piece is typically 4-8 inches wide
• Pieces overlap each other by 2-4 inches
• Made from galvanized steel, copper, aluminum, or other durable materials
• Installed shingle-style up the vertical surface

Step flashing provides a broken, segmented flashing surface. This allows for greater flexibility and movement. The overlapping pieces can shift slightly without compromising the flashing. Step flashing is the traditional method used with masonry construction.

What is Continuous Flashing?

Continuous flashing utilizes long, single pieces that run up the full height of the surface. Instead of overlapping segments, continuous flashing is one unified piece. This creates an unbroken barrier against water intrusion.

Some key features of continuous flashing:

• Comes in lengths up to 50 feet
• Made from sheet metal, rubber, or flexible vinyl
• Installed in single sections with watertight seams
• Used on chimneys, walls, roofs, and other surfaces

Continuous flashing provides a single monolithic surface. It is less prone to leakage since there are fewer joints. Continuous flashing also allows for simpler installation in many cases since only one main piece needs to be integrated.

Step Flashing vs. Continuous Flashing

So which type of flashing is better? There is no universally superior option. Here is a comparison of the two types:

Factor	Step Flashing	Continuous Flashing
Flexibility	More flexible since pieces can shift individually	Less flexible as one whole unit
Durability	Vulnerable to leakage at overlaps	Fewer seams make it more leak resistant
Cost	Lower material cost overall	Higher material cost
Installation	More difficult with multiple pieces	Easier with fewer pieces
Appearance	Overlap can be visible	Provides a clean, smooth facade
Use with Masonry	Traditional method, works well	Challenging, requires fasteners

As shown in the table, each type of flashing has its own strengths and weaknesses. Step flashing allows for greater flexibility and movement, while continuous flashing provides better water resistance. Continuous flashing costs more upfront but requires less labor to install. The appearance with step flashing may show visible joints.

Best Uses for Step Flashing

Step flashing excels in these types of applications:

• Masonry chimneys – The traditional flashing method used with brick or stone.
• Walls with uneven surfaces – Allows for variations and movement.
• Roof-to-wall transitions – Provides flexibility at the juncture.
• Frequent maintenance areas – Pieces can be easily replaced or repaired.
• Cost-sensitive projects – Less expensive than continuous flashing.

Step flashing is the go-to choice for masonry elements like chimneys and brick walls. The segmented pieces conform well to uneven surfaces. Step flashing holds up well in high movement areas thanks to the flexibility. It works great in areas that require frequent maintenance too.

Best Uses for Continuous Flashing

Continuous flashing is optimal for these applications:

• Tall vertical runs – Long sections minimize seams.
• Smooth facades – Gives a clean, unbroken look.
• Watertight structures – Minimizes leakage.
• Metal panel systems – Integrates well with large metal sheets.
• Highly exposed areas – Wind, rain, and weather resistances.

The long single pieces of continuous flashing make it perfect for uninterrupted, tall runs. Continuous flashing delivers superior water tightness, which is ideal for exposed rooftops and walls vulnerable to heavy rain. It provides very sleek lines on modern structures where smooth facades are desired.

Continuous Flashing Installation Tips

To properly install continuous flashing:

• Inspect the surface for smoothness and proper preparation.
• Measure the area to find the exact length needed.
• Cut the flashing to the measured length.
• Secure the top edge using termination bars, sealant or other methods.
• Roll the flashing out and press it firmly to the surface.
• Secure the lower edge in the same manner as the top.
• Seal any seams, penetrations, and edges completely.
• Test water tightness and make any necessary repairs.

Having the right length is critical so measure twice and cut once. Get a good tight seal along the top and bottom edges. Lap seams at least 6 inches and seal the laps. Avoid wrinkles and buckling since they can create pockets for leakage. Use caulk, sealant or adhesive strips at lap joints.

Step Flashing Installation Tips

To properly install step flashing:

• Inspect, clean and prepare the surface.
• Cut individual flashing pieces to size.
• Insert the first piece under the roof covering.
• Lay the next piece over the top, overlapping the piece below.
• Repeat up the surface, overlapping pieces shingle style.
• Secure pieces with nails, fasteners or sealant.
• Maintain 2-4 inches of overlap between each piece.
• Bend pieces as needed to fit surface contours.
• Seal any gaps, seams or penetrations.

Work up the wall in the proper shingle style overlap. Bend pieces to adapt to irregular shapes. Stagger seams so they do not line up. Check for proper overhang into gutters or drip edges. Caulk seams for improved water resistance.

Flashing Options for Various Materials

Here are common flashing material options for different construction types:

Wood: Aluminum, galvanized steel, copper, sheet lead

Vinyl: Vinyl, aluminum, galvanized steel

Brick and Stone Masonry: Copper, stainless steel, galvanized steel

Concrete: EPDM rubber, sheet metal, aluminum, bituthane polymer

Stucco: Copper, galvanized steel, aluminum

Metal Panels: Zinc, stainless steel, copper, aluminum

Sheet metal is commonly used for flashing. Copper offers exceptional durability but higher cost. For masonry, avoid harder metals like stainless steel that can scrape off the edges over time. Match flashing materials to the main building materials for best compatibility.

Key Flashing Design Principles

Follow these guidelines for effective flashing design:

• Overlap seams – Overlapping joints prevents leakage.
• Direct water flow – Flashings should shed water down and outward.
• Seal penetrations – Any screws, anchors or pipes need sealed.
• Allow for expansion – Gaps let the flashing expand and contract.
• Use compatible materials – Prevent corrosion from mismatched metals.
• Minimize ledger boards – These interrupt the flashing plane.
• Install kickouts – Help divert water from wall intersections.

Also ensure proper integration with the water resistive barrier beneath the exterior facade. Following best practices for overlap, drainage, seals and material selection will lead to effective, durable flashing.

Stepped Retrofit Flashing

Stepped retrofit flashings allow upgrading the flashing on existing structures. Sections fit shingle-style over the old step flashings. The new pieces integrate over the aged flashing. This provides improved protection without removing the old flashing.

Some key advantages of retrofit flashings:

• Avoids damage from full flashing replacement
• Less labor compared to traditional replacement
• Maintains flexibility of step flashing system
• Can be done alongside repointing or repairs
• Suitable for chimneys, walls, parapets and other areas

The retrofit pieces come in tapered segments for easy watertight installation. They install quickly without needing to detach the old flashing. This approach prevents disruption to surrounding materials. It provides substantial improvements at a reasonable cost.

Conclusion

In summary, step flashing and continuous flashing each have advantages depending on the specific building conditions and requirements. Step flashing provides flexibility, easier maintenance and lower cost. Continuous flashing delivers better water tightness, sleeker appearance and easier installation. Proper overlap and drainage principles remain important for either approach. Consider the structure design, materials and cost when selecting between step flashing and continuous flashing. With good fundamental detailing, both methods can provide lasting water protection.