House Wrap and Rain Screens: The Invisible Upgrade That Matters
Why what goes under your siding is as important as the siding itself.
The materials between your siding and your sheathing — house wrap, flashing, and (increasingly) rain screens — determine whether your wall assembly stays dry. They cost a small fraction of the siding itself but have an outsized impact on longevity.
House wrap basics
Modern house wraps (Tyvek, Typar, ZipWall) provide a secondary water barrier behind the siding and allow vapor to escape from interior to exterior. Required by every modern building code for siding installation.
Tape every seam. Properly flash all window and door openings. Skipping these steps — common on lowball siding bids — guarantees leaks within 5-10 years.
Rain screens
A rain screen creates a vented air gap between the house wrap and the siding using furring strips or proprietary mats. This allows any moisture that penetrates the siding to drain and evaporate rather than soaking into the sheathing.
Adds $1.50-$3.50 per sq ft to install but doubles or triples wall assembly life. Required by code in some Pacific Northwest jurisdictions and increasingly common in any wet climate.