Tar Paper vs. Tyvek vs. Blueskin: What’s Best for Your Building Envelope?
When it comes to protecting your home from the elements, what you wrap it in matters — especially in BC’s wet climate. Tar paper, Tyvek, and Blueskin are three common materials used across the Lower Mainland — but each serves a different role, and using the wrong one (or installing it wrong) can trap moisture, rot your walls, and kill insulation performance.
Climate Matters — Especially in BC
Vancouver and the Fraser Valley experience high rainfall and mild temperatures, meaning buildings are exposed to heavy wetting with limited drying potential. Even in winter, temperatures stay warm enough to support fungal growth, while walls often stay damp if they can't breathe.
BC Housing warns: in our climate, even airtight walls can fail if moisture is trapped and can't dry out.
1. Tar Paper (Building Felt)
What it is: Old-school asphalt-saturated paper. Still widely used as a basic layer under siding.
Pros:
Cheap and easy to get
Allows vapor to escape (somewhat breathable)
Sheds water decently
Cons:
Tears easily during install
Breaks down in sunlight and moisture
Not an air barrier
Best used as a temporary or budget-friendly WRB — good in dry conditions, but not airtight or high-performance.
2. Tyvek (Housewrap / WRB)
What it is: A synthetic housewrap that sheds bulk water while allowing vapor to escape from inside the wall.
Pros:
Breathable
Lightweight, easy to wrap
Can reduce air leakage if seams are sealed tightly
Cons:
Easily punctured
Fails as an air barrier if seams or penetrations are missed
Needs careful flashing and overlap
Best used as a water-resistive barrier (WRB) in standard construction — works well if installed correctly.
3. Blueskin (Peel-and-Stick Membrane)
What it is: A fully adhered rubberized membrane used to create airtight, waterproof seals.
Pros:
Excellent air and moisture barrier
Great around windows, doors, decks
Very durable
Cons:
Not breathable — moisture must not get trapped behind it
Must be sequenced perfectly
Costs more than typical wraps
Best for high-risk areas: balconies, sill pans, decks, and full Passive House-style air-sealed builds.
Don’t Confuse Air Barriers with Moisture Barriers
A WRB (like Tyvek) sheds water but may not stop air.
An air barrier (like Blueskin) stops air but might trap moisture.
Moisture barriers = keep water out, let vapor out
Air barriers = stop drafts and heat loss
Tar paper = does neither very well
Why Condensation Is a Silent Killer
Even if rain doesn’t get in, condensation inside your wall can quietly destroy it from within. BC Housing outlines three conditions for this to happen:
A source of moisture (like interior humidity or wet construction materials)
A cold surface (like sheathing in winter)
A path (typically air leakage)
Even a 1-inch hole in drywall leaks 100 times more moisture through air than through vapor diffusion. That’s why airtightness is critical.
Smart strategy: Seal your wrap completely, reduce thermal bridging, and use continuous exterior insulation where possible.
Don’t Trap Moisture in Walls
Blueskin and other peel-and-stick membranes are vapor impermeable — great for waterproofing, but dangerous if your framing is wet.
Once sealed in, wet wood can’t dry outward. And with interior poly or drywall acting as a vapor barrier, it can't dry inward either. That’s a recipe for rot, mold, and trapped decay.
Solution: Ventilate your cladding, avoid double vapor barriers, and let your wall assembly dry in at least one direction.
Other Building Wraps Worth Knowing
Typar®
Like Tyvek but stronger
Slightly less breathable
Delta-Vent / Delta-Dry
Advanced breathable membranes for Passive House/Net Zero
Delta-Dry includes rainscreen drainage
Zip System®
Sheathing + WRB in one panel
Growing in high-performance custom builds
Liquid Membranes
Roll-on or spray-on
Great for tricky shapes and ICF construction
6-Mil Polyethylene
Interior vapor barrier
May trap moisture if exterior wrap is also non-breathable
📊 Product Comparison Summary
Tyvek / Typar
• Role: Water-Resistive Barrier (WRB)
• Breathable? Yes
• Typical Use: Behind siding
Tar Paper
• Role: WRB
• Breathable? Somewhat
• Typical Use: Budget-friendly or temporary moisture barrier
Blueskin
• Role: Air + Moisture Barrier
• Breathable? No
• Typical Use: Windows, decks, Passive House builds
Delta-Vent
• Role: Air + WRB
• Breathable? Yes
• Typical Use: High-performance and Net Zero homes
Zip System
• Role: Sheathing + WRB
• Breathable? Yes
• Typical Use: Modern airtight homes, fast installs
Liquid Membranes
• Role: Air + Moisture Barrier
• Breathable? Depends on product
• Typical Use: Custom builds, ICFs, complex transitions
Final Word from the Specialist
A poor wrap job — or the wrong product in the wrong spot — causes:
Trapped condensation from daily humidity or rain
Mold, rot, and sheathing delamination
Peeling paint or warped siding
Energy loss from air leaks and cold bridging
Even the best product fails if installed wrong. BC Housing recommends wall assemblies that can:
Breathe
Dry in at least one direction
Seal against air leaks
Avoid major thermal bridging
Want to avoid expensive damage and future repairs?
Alantra Construction is based in Maple Ridge and serves Mission, Pitt Meadows, and the Fraser Valley. We specialize in smart, code-compliant building envelope solutions built for BC’s climate.
💬 Need an expert opinion before wrapping up your reno? Call or email — I’m happy to help.