Follow a real Seattle craftsman home from severe moss damage discovery through complete roof replacement. Includes timeline, actual costs, and homeowner lessons.
This case study follows a real roof replacement project on a 1924 craftsman bungalow in Seattle's Ballard neighborhood. The homeowners discovered severe moss damage during a routine gutter cleaning, leading to a full roof replacement that transformed their home's protection and curb appeal.
The Problem
The homeowners had lived in the Ballard craftsman for 12 years. The roof was original to a 2004 renovation — 3-tab asphalt shingles that had reached the end of their lifespan in Seattle's wet climate. During fall gutter cleaning, the homeowner noticed:
- Thick moss covering 60% of the north-facing slope
- Shingles that crumbled when touched during moss removal
- Exposed underlayment in several areas
- Granules filling the gutters with every rain
A professional inspection revealed:
- Shingle integrity: Failed (widespread granule loss, brittleness, and moss root damage)
- Underlayment: Compromised in 3 locations
- Sheathing: Minor rot in two 4x4-foot sections near valleys
- Flashing: Corroded around chimney and one skylight
- Ventilation: Inadequate — original ridge vent was partially blocked
The Project
After getting 4 estimates (ranging from $11,800 to $18,500), the homeowners selected a mid-range option that included:
Scope of Work:
- Complete tear-off of existing shingles and underlayment
- Replacement of two sections of rotted OSB sheathing
- Installation of synthetic underlayment (full coverage)
- Ice and water shield in valleys and at eaves
- New GAF Timberline HDZ architectural shingles (Weathered Wood color)
- New step and counter flashing at chimney
- Skylight flashing replacement
- Continuous ridge vent installation
- New drip edge on all eaves and rakes
- Zinc strips for moss prevention
- Complete gutter cleaning and downspout flush
Timeline: 4 working days (Monday–Thursday)
Total Cost: $14,200 (including permits)
Day-by-Day Timeline
Day 1: Tear-Off and Discovery
Crew of 5 arrived at 7 AM. Complete tear-off of old shingles, underlayment, and damaged sheathing. Discovered additional minor sheathing damage near the chimney that required a small additional cost ($280). All debris removed to dumpster by end of day. Synthetic underlayment installed as temporary weather protection.
Day 2: Sheathing, Underlayment, and Flashing
New OSB sheathing installed. Full synthetic underlayment applied. Ice and water shield installed in valleys and at eaves. New chimney flashing (step and counter) and skylight flashing installed. Drip edge installed on all edges.
Day 3: Shingle Installation
Main shingle installation — starter strips, field shingles, hip and ridge caps. Standing seam ridge vent installed. Zinc moss prevention strips installed near ridge.
Day 4: Cleanup and Final Inspection
Remaining detail work, thorough cleanup with magnetic nail sweeper, gutter cleaning, and final walkthrough with homeowner. Seattle DCI inspection passed on first attempt.
Results
- Before: Moss-covered, deteriorating 3-tab shingles with active leaks in heavy rain
- After: Clean, modern architectural shingles with 30-year manufacturer warranty and 10-year workmanship warranty
- Curb Appeal: Dramatic improvement — neighbors commented immediately
- Energy Efficiency: Improved attic ventilation reduced summer attic temperatures by approximately 15°F
- Moss Prevention: Zinc strips provide ongoing moss inhibition without chemical treatments
Cost Breakdown
| Item | Cost |
|---|---|
| Tear-off and disposal | $2,100 |
| Sheathing repair | $680 |
| Underlayment and ice shield | $1,400 |
| Shingles (GAF Timberline HDZ) | $5,800 |
| Flashing (chimney + skylight) | $1,600 |
| Ridge vent + zinc strips | $750 |
| Drip edge and accessories | $450 |
| Labor (included in above) | — |
| Permit | $350 |
| Additional sheathing discovery | $280 |
| **Total** | **$14,200** |
Lessons Learned
- Don't wait for leaks — this roof was failing months before obvious interior leaks appeared
- Annual moss treatment would have extended the original roof's life by 5–10 years
- Get 4+ estimates — the range was $11,800–$18,500 for essentially the same scope
- Budget 10–15% extra for unexpected discoveries during tear-off
- Choose winter installation if your schedule allows — this project was done in November at a 15% seasonal discount
- Zinc strips are cheap insurance — $150 investment prevents thousands in future moss damage
This Ballard craftsman now has a roof system designed for 30+ years of Seattle weather protection. The investment in quality materials, proper flashing, and moss prevention means the homeowners can focus on enjoying their home instead of worrying about their roof.
Frequently Asked Questions
How long does a Seattle roof replacement take?
A typical residential roof replacement in Seattle takes 3–5 working days, depending on roof size, complexity, weather, and whether sheathing repairs are needed.
Do I need a permit for roof replacement in Seattle?
Yes. Seattle's Department of Construction & Inspections (DCI) requires a permit for full roof replacements. Your contractor should handle the permit application process.
Senior Roofing Inspector & Content Lead
20+ years of hands-on roofing experience across Western Washington. GAF Certified and NRCA-trained inspector specializing in residential and commercial roof systems.
