WALLS + INSULATION

How to Retrofit Walls Safely in Pacific Northwest Homes

What Homeowners Usually Think

“If the walls feel cold, we should just add insulation. More insulation = better.”

What Actually Happens

In older Pacific Northwest homes, simply stuffing insulation into existing walls can actually cause moisture problems.
Our climate is wet, our siding often stores water, and older wall assemblies dry slowly.
When insulation is added without the correct moisture strategy, walls can trap condensation, grow mold, and rot from the inside out.

Why Walls Fail in the PNW

1. Older Homes Weren’t Designed for Insulation

Pre-1980 walls relied on air movement and heat loss to stay dry.
When insulation is added, drying slows down—so any moisture that gets in tends to stay in.

2. Reservoir Claddings Soak Up Rain

Materials like:

  • stucco

  • brick

  • fiber cement

  • cedar siding

…hold moisture and push it inward when warmed by the sun ("solar vapor drive").
Without a rainscreen gap, the wall assembly can stay wet for months.

3. No Drainage Plane Behind the Siding

Most older homes have siding installed directly against sheathing with no air gap.
This traps moisture behind the cladding.

4. Air Leaks Carry Moisture Into Wall Cavities

Warm indoor air leaks into cold wall cavities, hits the dew point, and condenses inside the insulation.

5. Poor Insulation Choices

Fiberglass batts and blown-in cellulose store moisture and collapse when wet.
This leads to mold, odor, and structural damage.

Signs of a Wall Moisture Problem

  • Peeling paint or bubbling exterior paint

  • Musty smell indoors

  • Cold spots or damp walls

  • Mold at baseboards or behind furniture

  • Staining around outlets

  • Warped trim or cupped flooring

  • Visible rot when siding is removed

Best Practices for Wall Retrofits in the Pacific Northwest

Retrofitting walls safely requires a balance of water control, vapor control, air control, and insulation.

1. Fix Exterior Water First

  • Gutters and downspouts functioning

  • Siding in good condition

  • Window flashing corrected

  • Penetrations sealed

If bulk water gets in, the assembly will fail no matter what insulation you use.

2. Add a Rainscreen Gap (When Residing)

A rainscreen provides:

  • Drainage

  • Airflow

  • Faster drying

  • Protection against solar vapor drive

This is the single biggest upgrade you can make during a siding replacement.

3. Choose the Right Insulation

For retrofits, the safest options are:

  • Blown-in fiberglass (dense pack) — only when drying paths are safe

  • Exterior rigid insulation — excellent for older homes

  • Closed-cell spray foam in targeted areas — creates air and vapor control where needed

Avoid cellulose in older walls unless a rainscreen is added.

4. Control Air Leakage

We seal the top plates, bottom plates, electrical penetrations, and rim joists to prevent moist indoor air from entering the wall cavity.

5. Use a Smart Vapor Retarder (When Appropriate)

These membranes tighten in winter and loosen in summer, allowing seasonal drying.
They’re ideal when interior drying is needed.

6. Address the Rim Joist and Transitional Areas

The rim joist is one of the highest-risk condensation zones.
Closed-cell foam or rigid insulation is best here.

How Emerald State Contracting Retrofits Walls Safely

1. Assess the Existing Assembly

We determine the age, cladding type, ventilation paths, vapor profile, and drying potential of your walls.
No two houses are the same.

2. Identify Moisture Risks

We look for:

  • reservoir claddings

  • failed flashing

  • air leaks

  • previous insulation mistakes

  • interior humidity sources

3. Evaluate the Safest Insulation Method

Based on your wall type, we choose the option with the lowest moisture risk and highest comfort gain.

4. Correct Water and Air Pathways

We fix penetrations, flashing, vents, and drainage issues so the wall can safely stay dry.

5. Install Insulation Properly

We use methods that maintain a drying path and prevent condensation.

6. Upgrade Siding Assemblies (When Needed)

If a full siding replacement is planned, we install:

  • rainscreen battens

  • drainage wrap

  • exterior rigid insulation

  • smart vapor control assembly

This dramatically improves durability.

Why This Matters

A wall is a moisture system, not just a place to put insulation.
Done wrong, insulation traps moisture and causes hidden mold and structural damage.
Done right, it improves comfort, lowers energy bills, and protects the home for decades.

When to Call a Professional

You should have your walls evaluated if:

  • You notice peeling interior or exterior paint

  • Your home gets musty in winter

  • You see condensation on windows

  • You’re planning a siding replacement

  • You want to add insulation to an older home

  • You have brick, stucco, or fiber cement siding

  • You’ve had a previous moisture issue