• What is a rainscreen
• How it works
• When a rainscreen is worth it
• Materials that benefit most
• The installation process
• Cost guide
• Timeline
• Do’s and don’ts
• Permits & inspections
• Choosing a contractor
• FAQ

What Is a Rainscreen?

A rainscreen is a ventilated air gap built between the siding and the wall’s water-resistant barrier, typically created with vertical furring strips or a manufactured drainage mat product. Rather than relying on the siding itself to be a perfect, unbroken seal against water, a rainscreen assumes that some moisture will eventually get behind the cladding — through a hairline crack, a failed seam, or wind-driven rain — and gives that moisture a clear path to drain out and dry, rather than sitting trapped against the sheathing.

It’s best understood as an upgrade layered onto a broader siding project rather than a standalone project type: a rainscreen gets built in during a full siding replacement, and in some cases during residing depending on the overlay system used, rather than added after the fact without disturbing the existing siding.

How a Rainscreen Works

• Drainage — the air gap gives any water that gets behind the siding a clear downward path, so it exits at the bottom of the wall instead of pooling against the barrier or sheathing.
• Ventilation — openings at the top and bottom of the gap allow air to move through it, actively drying out any residual moisture rather than leaving it to evaporate slowly against a sealed surface.
• Pressure equalization — in more advanced rainscreen designs, the gap helps equalize air pressure between the outside and the cavity, reducing the force that drives wind-driven rain through small gaps in the siding in the first place.
• Thermal benefit — as a secondary effect, the air gap can reduce heat transfer through the wall assembly and help siding dry faster after rain, extending the service life of moisture-sensitive materials.

Together, these functions mean a rainscreen doesn’t try to stop every drop of water from ever reaching the barrier — it accepts that some will get through and manages it, which is a fundamentally more resilient approach than depending on a perfect, gap-free installation over the life of the siding.

When a Rainscreen Is Worth It

Materials That Benefit Most

• Fiber cement is one of the strongest candidates for a rainscreen, since prolonged moisture contact at the back of the boards is a known contributor to premature failure, and a drainage gap directly addresses that risk.
• Natural wood siding benefits significantly, since wood is especially prone to rot and cupping when moisture is trapped against its back face for extended periods.
• Engineered wood also benefits, though somewhat less than natural wood, since most engineered products are manufactured with more consistent moisture resistance.
• Stucco increasingly uses a rainscreen approach in updated installations, since older direct-applied stucco systems were a common source of trapped-moisture failures.
• Vinyl and metal siding are less dependent on a rainscreen, since both materials are inherently more tolerant of occasional moisture contact, though a gap still offers some benefit in very wet climates.
• Brick and stone veneer typically uses its own dedicated air gap and weep system as a standard part of proper installation, functioning similarly to a rainscreen by design.

The Rainscreen Installation Process

1. Barrier installation. A water-resistant barrier is installed over the sheathing with properly lapped seams, forming the surface the rainscreen gap sits in front of.
2. Flashing integration. Flashing at windows, doors, and penetrations is installed and tied into the barrier before the gap is built out.
3. Furring strips or drainage mat installation. Vertical furring strips — or a manufactured three-dimensional drainage mat product — are fastened over the barrier, creating a consistent gap, typically 3/8 inch to 1 inch depending on the system and material.
4. Top and bottom venting. Openings are built in at the base and top of the wall (often behind vented trim or soffit details) so air can actually move through the gap rather than sitting stagnant.
5. Insect screening. Mesh screening is typically installed at the vent openings to keep pests out of the gap while still allowing airflow and drainage.
6. Siding installation over the gap. The chosen siding material is installed over the furring or drainage mat according to its manufacturer’s specifications.

Rainscreen Cost Guide

• Furring strips vs. drainage mat products — dimensional lumber furring strips are typically the lower-cost option, while manufactured drainage mat products cost more but can offer more consistent airflow and easier installation on complex wall shapes.
• Vent detailing — properly built top and bottom vents with insect screening add labor cost but are essential to the system functioning as intended.
• Wall complexity — extensive trim, multiple wall planes, and window and door density all add labor time to fitting furring strips or drainage mat around obstructions.
• Timing relative to the broader project — adding a rainscreen during a full replacement, when the wall is already stripped to the sheathing, costs meaningfully less than trying to retrofit one without removing existing siding.

Rainscreen Timeline

Because a rainscreen is built in as part of a larger siding project rather than installed on its own, it typically adds a modest amount of time to a full replacement — often one to a few extra days depending on wall complexity and the drainage system chosen — rather than extending the timeline significantly. Furring-strip systems are generally quicker to install than manufactured drainage mat products on straightforward wall shapes, while more complex trim and multiple wall planes can add time to either approach.

Rainscreen Do’s and Don’ts

Permits and Inspections

A rainscreen is typically installed as part of a larger permitted siding project — most often a full replacement — rather than pulled as its own separate permit. Because it sits directly over the water-resistant barrier and flashing, inspectors reviewing a replacement project will often want to see the furring or drainage mat system and vent detailing before it’s covered by the new siding. Confirming with the local building department how the rainscreen fits into the broader project’s inspection schedule avoids having to expose finished work later.

Choosing a Rainscreen Contractor

• Ask about their specific experience with rainscreen systems, since not every siding contractor installs them as a matter of course.
• Confirm the vent and insect screening details in writing, since these are the parts most likely to get skipped on a rushed job.
• Ask which gap depth and product they recommend for your climate and chosen siding material, and why.
• Check whether the rainscreen is itemized separately in the quote, so it’s clear what’s being added versus what’s included in standard installation.
• Ask how the rainscreen ties into flashing at windows, doors, and other penetrations, since a gap with poorly integrated flashing can undermine the whole system.

Rainscreen Installation FAQ

Do I need a rainscreen for my siding project?

It’s most strongly recommended in high-moisture climates and for materials like fiber cement and wood siding that are more sensitive to trapped moisture; it’s more discretionary for vinyl or metal siding in a moderate, dry climate.

Can a rainscreen be added without removing my existing siding?

Generally no — a rainscreen requires access to the water-resistant barrier, so it’s typically built in during a full siding replacement rather than added on top of existing siding.

How much does a rainscreen add to a siding project?

It varies by the system chosen — dimensional furring strips are generally the lower-cost option, while manufactured drainage mat products cost more but can offer more consistent performance, particularly on complex wall shapes.

Does a rainscreen replace the need for a water-resistant barrier?

No — a rainscreen works together with the barrier and flashing rather than replacing them; the air gap manages moisture that gets past the siding, while the barrier and flashing underneath remain the primary line of defense.

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