Why Every Siding Assembly Needs a Rainscreen
A rainscreen is a critical component of modern wall assemblies, creating a ventilated cavity between the cladding and the water resistive barrier that wraps the building. This gap allows the siding to breathe from the back side and provides a drainage plane for any moisture that gets past the cladding. In the Fine Homebuilding House in New York, builder Jon Beer demonstrated how products from Cor-A-Vent make the ventilated rainscreen installation straightforward for both horizontal and vertical siding orientations. Understanding the materials and methods for each orientation is essential for achieving a durable, long lasting wall assembly.
Without a rainscreen, water that penetrates the siding whether through wind driven rain, capillary action, or condensation becomes trapped against the weather resistive barrier. This trapped moisture cannot evaporate readily, leading to rot, mold, and degradation of the sheathing and framing over time. The building science behind rainscreens is well established: a ventilated cavity behind cladding dramatically reduces the moisture load on the wall structure by allowing both drainage and evaporation to occur continuously. Studies have shown that walls with rainscreens dry out multiple times faster than walls without them, even when both assemblies start with the same initial moisture content.
A properly designed rainscreen eliminates these risks by maintaining continuous drainage and airflow behind the cladding. The cavity depth typically ranges from 3/8 inch to 1 inch depending on the siding type and local climate conditions. For wood siding in wet climates, a deeper cavity of at least 3/4 inch is recommended to prevent the back side of the siding from absorbing moisture through capillary bridging. For fiber cement or engineered wood siding, the minimum cavity depth is usually 3/8 inch, though deeper is always better for ventilation performance.
Rainscreen Components for Horizontal Siding
Horizontal siding, such as hemlock lap siding or cedar bevel siding, requires vertical furring strips to create the drainage cavity. These strips run perpendicular to the siding boards, allowing water to flow downward and air to circulate upward behind the cladding. For the FHB House New York project, the crew used a combination of two Cor-A-Vent products to build the rainscreen for the horizontally oriented wood hemlock siding on the shop.
The SV-3 Ventilation Strip with Bug Screen
The installation began with the SV-3 strip at the bottom of each wall section. This product is a corrugated plastic strip with an integrated bug screen made of mesh glued directly to the plastic. The integrated bug screen saves significant installation time because it eliminates the separate step of installing mesh or insect screening at the base of the wall. Without this product, a typical rainscreen installation requires first installing a furring strip, then cutting and stapling a piece of insect mesh to prevent bugs from entering the wall cavity. The SV-3 accomplishes both tasks in a single piece.
The crew worked the SV-3 all the way around the perimeter at the base of the walls before moving upward. Key installation tips for the SV-3 include:
- Cut strips to length with a utility knife no power tools needed for the corrugated plastic material
- Butt joints tightly at corners and along long runs to maintain continuous bug protection
- Fasten with corrosion resistant nails or staples at each stud location
- Ensure the strip sits flush against the water resistive barrier for proper drainage
Sturdi-Strips for the Vertical Cavity
Above the SV-3 starter strip, the crew installed Sturdi-Strips at regular intervals across the wall. These vertical furring strips create the continuous air gap behind the horizontal siding. Spacing between strips should match the stud layout, typically 16 inches on center, to provide adequate nailing support for the siding boards. The goal was to complete the entire rainscreen framework across the wall before any siding was installed. This approach ensures that the drainage plane is continuous and uninterrupted, with no gaps that could trap moisture against the wall assembly.
The Sturdi-Strips are made from the same corrugated plastic material as the SV-3, providing consistent performance across the assembly. They are lightweight, easy to handle, and can be cut on site with a utility knife. A single box of strips can be carried up in a lift alongside the siding material, allowing the installer to work on the rainscreen and the siding in the same trip. The termination at the top of the wall also uses an SV-3 strip, which provides both ventilation exit and prevents insects from entering the cavity from above. This top and bottom ventilation strategy creates a natural convection chimney effect that continuously draws air through the cavity, accelerating drying after wet weather events.
For horizontal siding installations, completing the full rainscreen grid before starting the siding work is strongly recommended. This sequence allows the crew to inspect the entire drainage plane for continuity and address any gaps or obstructions before the cladding covers everything up. It also ensures that the fastening pattern for the siding is consistent and well supported across every stud bay.
| Product | Application | Orientation | Key Feature |
|---|---|---|---|
| SV-3 | Top and bottom of wall | Horizontal runs | Integrated bug screen mesh |
| Sturdi-Strip | Vertical furring for horizontal siding | Vertical runs | Lightweight corrugated plastic |
| Sturdi-Batten | Horizontal furring for vertical siding | Horizontal runs | Vertically oriented drainage holes |
Rainscreen Details for Vertical Siding
Vertical siding, such as board and batten or shiplap installed vertically, presents a different challenge for rainscreen design. Because the siding runs vertically, the furring strips must run horizontally to provide continuous support across the stud cavities. The rainscreen cavity still needs to drain vertically, which requires a product designed to allow water to flow through or around the horizontal furring.
Using Sturdi-Batten for Horizontal Furring
For the house portion of the FHB House New York project, where the siding is vertically oriented, the crew switched from Sturdi-Strips to Sturdi-Batten. The Sturdi-Batten is a horizontal furring strip made from corrugated plastic, but unlike the Sturdi-Strip, its internal channels are oriented so that the holes run vertically even though the strip itself is installed horizontally. This clever design maintains a continuous drainage plane for water to escape, while allowing air to circulate behind the vertical siding boards.
The Sturdi-Batten installation sequence differed slightly from the horizontal siding approach. The SV-3 strips at the top and bottom of the wall were installed concurrently with the siding rather than ahead of it. This method works well for vertical siding because the horizontal furring strips create a ladder like framework that the siding boards attach to directly.
Installation Sequence for Vertical Siding Rainscreens
- Install the water resistive barrier over the sheathing, following manufacturer specifications for laps and flashing
- Install SV-3 strips horizontally at the base of the wall with the bug screen facing outward
- Install Sturdi-Batten strips horizontally at regular intervals across the wall, typically at 16 inch or 24 inch on center spacing
- Install SV-3 strips horizontally at the top of the wall to provide ventilation exit and bug protection
- Attach the vertical siding boards to the Sturdi-Batten strips using corrosion resistant fasteners
The board and batten siding modern materials installation techniques work particularly well with this rainscreen approach, as the horizontal furring provides robust nailing surfaces for every vertical board. Similarly, a open joint siding rain screen battens material selection and installation guide provides additional details for achieving optimal results with vertical siding patterns.
Material Benefits and Installation Efficiency
One of the most compelling advantages of working with corrugated plastic rainscreen products is the ease of installation. The material brings several practical benefits to the jobsite that translate into real time savings and improved assembly performance.
Lightweight and Portable
The Sturdi-Strips and Sturdi-Batten strips are only 4 ft long and weigh very little compared to traditional wood furring strips. A full box can be carried up in a lift alongside the siding material, eliminating the need for separate material handling trips. This efficiency is especially valuable on larger projects where multiple elevation changes or scaffolding setups would otherwise consume significant labor time.
On Site Cutting Without Power Tools
Corrugated plastic cuts cleanly with a utility knife, which means no sawdust, no extension cords, and no blade changes. The installer can cut strips to exact length at the point of installation, trimming around windows, doors, and other penetrations without returning to a cutting station. This on the spot flexibility reduces waste and keeps the workflow moving.
Durability and Drainage Performance
The plastic material does not rot, warp, or absorb moisture, unlike wood furring strips that can deteriorate over time if exposed to chronic dampness. The corrugated design creates continuous air channels that promote drying, and the integrated bug screen on the SV-3 ensures that the cavity remains free of insects and debris. For long term performance, combining the rainscreen with drainable rainscreen membranes for high performance wall assemblies provides an additional layer of moisture management that further protects the structure.
Simultaneous Rainscreen and Siding Installation
Because the strips are lightweight and easy to handle, an experienced installer can install the rainscreen and the siding in the same workflow. For horizontal siding, completing the full rainscreen grid first is recommended. For vertical siding, installing the SV-3 at the top and bottom during the siding process works well because the horizontal Sturdi-Batten strips provide a natural framework for the vertical siding boards. In both cases, the integrated design of the Cor-A-Vent system reduces the total number of steps compared to traditional furring strip and mesh installations.
A well executed rainscreen is one of the most important investments a builder can make in the longevity of a wall assembly. Whether the siding runs horizontally or vertically, products like the SV-3, Sturdi-Strip, and Sturdi-Batten make the job faster, more consistent, and more reliable. The combination of proper ventilation, continuous drainage, and bug protection ensures that the siding performs as intended for decades, keeping the structure dry and durable through every season.