Washington State Energy Code Requirements for Insulation
Gus Koedding • January 23, 2025
The Washington State Energy Code (WSEC) sets specific insulation requirements to enhance energy efficiency in residential buildings. As of July 1, 2023, the state adopted the 2021 WSEC, which includes updated insulation standards.
Key Insulation Requirements:
- Ceilings (Attic/Roof):
- R-Value Requirement: Increased from R-49 to R-60. Insulation Institute
- U-Factor Equivalent: U-0.024.
- Wood Frame Walls:
- R-Value Options:
- R-20 cavity insulation plus R-5 continuous insulation (ci).
- R-13 cavity insulation plus R-10 ci.
- U-Factor Equivalent: U-0.056.
- Basement Walls:
- R-Value Requirement: 10/15/21 + 5 TB.
- This denotes R-10 continuous insulation on the exterior, R-15 continuous insulation on the interior, or R-21 cavity insulation plus a thermal break between the slab and the basement wall.
- U-Factor Equivalents:
- U-0.042 at 2 feet.
- U-0.040 at 3.5 feet.
- U-0.035 at 7 feet.
- Slab-on-Grade Floors:
- R-Value Requirement: R-10 insulation extending 4 feet.
- F-Factor: 0.54.
- Fenestration (Windows):
- U-Factor Requirement: U-0.30.
Additional Considerations:
- Climate Zones:
- Washington State primarily falls within Climate Zone 5 and Marine 4, influencing specific insulation requirements.
- Air Leakage:
- The code mandates a maximum air leakage rate of 5 air changes per hour at 50 Pascals (ACH50), emphasizing the importance of proper air sealing in conjunction with insulation.
- Additional Energy Efficiency Credits:
- The WSEC requires residential buildings to achieve a certain number of energy efficiency credits based on building size and type. These credits can be obtained through various measures, including enhanced insulation levels, high-efficiency HVAC systems, or renewable energy installations.
Compliance and Implementation:
Builders and homeowners should consult the full 2021 Washington State Energy Code - Residential Provisions for comprehensive details.
It's also advisable to check with local building departments, as some jurisdictions may have additional requirements or amendments to the state code.By adhering to these updated insulation standards, homeowners can enhance energy efficiency, reduce utility costs, and contribute to Washington State's sustainability goals.
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Attic mold foggers might sound like a quick-fix miracle in a can—but the truth is, they’re often more smoke than solution. Here’s a straight-up breakdown of the shortcomings of mold foggers when it comes to attic mold : 🚫 1. They Don’t Eliminate the Source Mold grows because of moisture and poor ventilation . Foggers don’t fix: Roof leaks Bathroom fans dumping into the attic Blocked soffits Air leaks from the home into the attic No matter how much fog you pump up there, the mold’s coming back if the conditions stay the same. ⚠️ 2. No Physical Mold Removal Foggers do not scrub, lift, or remove mold colonies . They only coat surfaces. Mold still needs to be: Brushed off Vacuumed with a HEPA system Treated with antimicrobial agents Dead mold spores can still trigger allergies and health issues—so leaving them there isn’t a win. 🪵 3. Poor Penetration on Porous Surfaces Attics are full of raw, porous wood —rafters, sheathing, joists. Foggers often can’t penetrate deep enough into the wood grain where mold roots have taken hold. That means: Spores may survive inside the wood Regrowth is likely, especially in humid climates 🧴 4. Short-Term Fix, No Residual Protection Most over-the-counter foggers don’t leave behind a long-lasting antimicrobial barrier. Unlike encapsulation with mold-killing primers , foggers offer: No surface sealing No moisture resistance No long-term protection 🧯 5. False Sense of Security Because foggers leave a scent and the mold "looks better," homeowners may think the problem is solved—but the underlying issue remains . This delays real remediation and can lead to much worse (and more expensive) problems later. 💸 6. Cost vs. Effectiveness For DIYers, foggers aren’t cheap—and they don’t replace: Proper insulation removal Real mold remediation Ventilation correction So you're spending money to mask the problem rather than fix it. ✅ Bottom Line: Foggers may help with odor control or surface disinfecting, but they’re not a standalone solution for attic mold. Real mold remediation requires: Source control (leaks, ventilation) Physical removal Disinfection with EPA-registered products Sealing with mold-resistant primers Insulation replacement if contaminated
Mold remediation isn't just spraying bleach and walking away. It's a multi-step process that requires proper containment, safety, treatment, and restoration. Here's a deep dive into the phases of mold remediation. 🧰 1. Inspection & Moisture Source Identification What’s involved: Visual attic inspection Moisture readings (IR cameras or moisture meters) Identifying leak sources, venting issues, insulation saturation 🔒 2. Containment & Setup What’s involved: Sealing off the work area with plastic sheeting Creating negative air pressure (HEPA fan) Floor protection and access control 🧼 3. Insulation Removal (if contaminated) What’s involved: Attic vacuum system for blown-in or batt insulation Bagging and disposal of contaminated material 🧪 4. Mold Cleaning & Disinfection What’s involved: Applying EPA-registered products (e.g., Vital Oxide , Benefect, Concrobium) Brushing/scrubbing visible mold HEPA vacuuming all surfaces 🎨 5. Encapsulation What’s involved: Spraying mold-resistant primer/sealant (e.g., Zinsser Perma-White , Fiberlock Aftershock) Covering all exposed wood (rafters, decking, joists) 🌬️ 6. Ventilation Correction & Air Sealing What’s involved: Bathroom fan rerouting to exterior Unclogging soffits Installing baffles Sealing light can penetrations, top plates, pipes 🧱 7. Insulation Reinstallation What’s involved: Installing new blown-in cellulose (often R-49 or greater) Final prep, air sealing touch-ups ⚠️ Notes on Pricing: Emergency jobs (flood/mold after storms) = higher labor rate Crawlspaces or tight attics increase time and hazard pay Licensed mold remediation companies often include limited warranties, which may increase overhead
