Rainscreen Systems Seattle — Ventilated Drainage Gap Installation by GP General Corp
British Columbia mandated rainscreen installation after the 1990s envelope crisis destroyed thousands of homes in a climate identical to Seattle’s. Washington hasn’t — but we install them anyway. Every project, no exceptions.
WA License #GPGENGC830KDHydroGap Standard SpecHat-Channel or Drainage MatInsect Screen TerminationEvery ProjectGP General Corp builds ventilated rainscreen wall systems across Seattle, the Eastside, and Snohomish County — furring and cross-batten cavities, drainable WRB, and vented terminations behind cedar, Hardie, metal, or thermally-modified wood. WA license GPGENGC830KD, MBAKS member, rated 5.0 on Google. Real installed rates on our pricing page; free written quote after an on-site assessment.
By Paul Gubenya — Owner, James Hardie Certified Installer · WA License #GPGENGC830KD · MBAKS Member · Rated 5.0 on Google · (425) 344-9635
What Homeowners Say
Real reviews from our Google profile — unedited, from real projects.
“We recently had Paul with GP General repair a damaged corner protector and sidings. His estimate was reasonable, his availability was timely, and his job was excellent. Our home hadn’t been re-painted in a while and the paint had considerably faded, yet he was able to match the color perfectly. Now we know who to turn to when in need of another repair work.”
“GP General replaced LP siding on our garage. Paul was very thorough when he came out to do the estimate; he listened to my concerns and was able to work out solutions on the spot. His crew did a great job and were very courteous. They also were careful about cleaning up (I didn’t find any nails!). Really happy with the job and can recommend GP General.”
“I highly recommend GP General Corp for siding replacement. We recently had our wood siding replaced with James Hardie lap siding, and Paul and his team did an excellent job.”
Rainscreen Drainage: Standard Practice, Not an Upsell
GP General has opened up walls on dozens of Seattle-area homes during siding replacement projects — see our rainscreen builds in Seattle for documented examples.
Any water that infiltrates behind the siding has a vertical path to drain down and out of the wall assembly. Without a gap, that water is trapped between siding and WRB.
Air circulation in the gap lets wetting events dry between rain events.
Hat-channel metal furring or HydroGap 6mm drainage mat — we select the drainage layer based on exposure conditions.
Ready to talk about your project?
Free walk-through with Paul. No-pressure quote. Honest assessment of what your home needs.
What Is a Rainscreen System?
A rainscreen is a ventilated drainage gap installed between the exterior siding and the water-resistive barrier (WRB) on your home’s wall.
Recent rainscreen projects:
- Mercer Island reside with 1×4 furring rainscreen over R-5 continuous insulation →
- Bellevue modern new construction with rainscreen →
- Bellevue mixed Hardie lap & panel with rainscreen →
Why Seattle and the PNW Need Rainscreen Systems
The PNW’s envelope problem isn’t primarily about the total volume of rain — it’s about extended wet periods with limited solar drying, wind-driven rain, and sustained humidity.
- Extended wet periods with limited solar drying. Seattle’s wet season runs October through April.
- Wind-driven rain. Prevailing southwest winds drive rain at angles that penetrate siding lap joints.
- Sustained humidity. Ambient outdoor RH keeps wall materials at elevated moisture content.
British Columbia’s building code response was mandatory rainscreen installation on all new construction. Washington hasn’t followed formally, but the physics are the same on both sides of the border.
How GP General Installs Rainscreen Systems in Seattle
Sheathing Inspection and Repair
Old siding removed. We inspect all sheathing for moisture damage. See our dry rot restoration page.
HydroGap® WRB Installation
HydroGap drainable housewrap installed horizontally from bottom to top, with correct lapping and all seams taped.
Window and Door Flashing
Every opening gets membrane flashing — sill pan, jamb, and head — integrated with the WRB.
Rainscreen Drainage Layer
One of two options depending on the project: HydroGap 6mm drainage mat (premium) or Hat-channel metal furring.
Siding Installation
Siding is fastened through the drainage layer into the sheathing and framing.
Bottom Drainage Gap Termination
The drainage cavity is open at the bottom for water exit and air entry — protected with a J-metal insect screen.
Rainscreen System Cost in Seattle
| Scope | Add-On Cost / Sq. Ft. |
|---|---|
| Hat-channel furring rainscreen | $1.50–$2.50 |
| HydroGap 6mm drainage mat rainscreen | $2.00–$3.50 |
| WRB upgrade (HydroGap housewrap) | $2.00–$3.00 (separate add-on) |
| Full system: WRB + rainscreen drainage layer | $3.50–$6.00 combined |
Rainscreen add-on cost on a typical 2,000 sq. ft. home: $3,000–$7,000 depending on WRB product and drainage layer type.
Not sure where to start?
We’ll come out, look at your siding, and give you a straight answer — even if the answer is “you don’t need us yet.”
Rainscreen Systems Seattle — Frequently Asked Questions
What exactly is a rainscreen and how does it work?
Is rainscreen required by code in Seattle / Washington State?
Do I need a rainscreen with James Hardie siding?
Can insects or rodents get into the rainscreen gap?
How much does adding a rainscreen cost on a re-side project in Seattle?
What size gap does a proper rainscreen cavity need?
Will a rainscreen system void my James Hardie warranty?
Rainscreen Installation — Across Seattle Neighborhoods
Schedule a Free Rainscreen & Siding Assessment
Paul will assess your home’s current moisture management, identify whether you have a drainage gap behind your siding, and provide a written estimate.
WA License #GPGENGC830KD — Verify · James Hardie Certified Installer · King & Snohomish Counties
Rainscreen systems Seattle — see the work
Real projects from our crew — photos, specs, and the problems they solved.