Deck Waterproofing & Flashing in Lake Forest Park, WA
Waterproofing and flashing repair for decks, balconies, windows and roof-to-wall joints. When coatings wear through or flashing is missing at doors and walls, the leak often shows up far from where water gets in. We trace it to the source, replace any wet framing, correct slope and flashing, and finish with a walkable surface that drains away from the house. We serve homeowners across Lake Forest Park and nearby Kenmore and Shoreline.
Before
AfterNew siding and trim around the window
Why waterproofing comes up so often in Lake Forest Park
With water coming from the sky and from uphill, flashing details matter in Lake Forest Park. Decks attached to the house need ledger flashing that actually sheds water, roof-to-wall joints need kick-out flashing, and windows on shaded walls need sill pans. Many homes here were built before those details were standard. We open the problem areas, replace rotted framing as needed, and install membranes, ledger flashing, kick-outs and pans that carry water out and away from the walls.
Lake Forest Park was laid out as a residential community on the hills above the north end of Lake Washington, and it still feels like a neighborhood built into a forest. Homes range from a few older cottages and 1920s to 1940s houses near the lake to mid-century ramblers, split-levels and contemporaries from the 1950s through the 70s on steep, winding streets. Lots are large and irregular, often sloping sharply toward a creek or the road. Cedar lap siding, board-and-batten and vertical panel siding are common, and many homes have multi-level decks built out over the slope.
Tree cover is the defining condition in Lake Forest Park. Tall firs, cedars and maples shade roofs, siding and decks so heavily that some walls never dry between November and April. Needles and leaves pile into gutters and onto deck boards, and moss grows on anything horizontal. Steep lots send groundwater and surface runoff toward the uphill side of houses, so lower siding and sill plates stay wet. Homes near Lake Washington add morning fog and lake moisture to the mix.
Our crew comes out from our Woodinville office, and we also work in nearby Kenmore, Shoreline, Seattle and Bothell.
When to call about waterproofing in Lake Forest Park
- Water pooling against the house after rain
- Streaks down the wall below a roof edge
- A deck that slopes toward the house
- Stains or drips on the ceiling below a deck or balcony
- Cracked, peeling or soft deck coating
Our waterproofing process, step by step
Trace the leak
Moisture readings, inspection openings and photos to find the real source.
Repair the substrate
Rotted plywood, joists or sheathing are replaced before sealing.
Correct slope and details
Proper slope, sill pans and flashing at every edge and door.
Apply the system
Primer, membrane and walkable top coat applied in layers.
Water test
We test the problem areas and show you the finished details.
Recent waterproofing projects near Lake Forest Park
What we do in Lake Forest Park
Slope correction
Fix flat or back-sloped decks so water drains away from the wall.
Walkable deck coatings
Waterproof coating systems for decks and balconies over living space.
Leak investigation
We trace leaks to the source before anything is sealed.
Window head flashing
Flashing and tape around windows to stop leaks into the wall.
Kick-out flashing
Diverts roof water away from the wall at roof-to-wall joints.
Door and sill pans
Pan flashing under doors, where many balcony leaks start.
Neighborhoods and permits in Lake Forest Park
Sheridan Heights and Horizon View sit higher on the hills, with steep lots, view decks and wind on the exposed edges. Brookside and homes along Lyon Creek and McAleer Creek sit lower in wooded ravines where shade, moss and runoff dominate. Properties near the Town Center and along Bothell Way are flatter and closer to the lake, with more fog and less slope. Uphill walls on almost any lot here tend to be the wettest side of the house.
Like-for-like repairs on a small scale often don’t need a permit, but structural work, new decks and larger replacements usually do. The City of Lake Forest Park issues building permits, and work near creeks or steep slopes may get extra review. We check with the City of Lake Forest Park before starting so there are no surprises mid-project.
Deck and balcony surface options
| System | Best for | Expected life | Maintenance |
|---|---|---|---|
| Recoat existing membrane | Sound surface with a worn top coat | A few years per top coat | Keep drains clear, recoat when worn |
| New walkable membrane | Decks and balconies over living space | 10–15+ years | Top coat every few years |
| Membrane under decking | Dry space under a deck with a wood or composite surface | 15+ years | Keep gaps and drains clear |
| Rebuild, slope and membrane | Wet or rotted plywood, flat or back-sloped deck | 15+ years | Top coat every few years |
What waterproofing typically costs in Lake Forest Park
| Project | Typical scope | Price range | Timeline |
|---|---|---|---|
| Flashing repair | Kick-out, head flashing or a door pan at one spot | $600 – $2,500 | 1 day |
| Recoat a balcony | Prep and top coat over a sound membrane | $1,500 – $4,500 | 2–3 days |
| New walkable membrane | Full membrane system on a deck or balcony | $5,000 – $14,000 | 4–7 days |
| Rebuild and waterproof | New plywood, slope correction, flashing and membrane | $12,000 – $30,000+ | 1–3 weeks |
These are typical 2026 ranges we see for waterproofing in Lake Forest Park and nearby cities. Your price depends on what we find once the area is open, access and height, and the materials you choose. Every estimate is free, in writing and based on an on-site inspection with photos.
Waterproofing in Lake Forest Park: cost and timing
Most common causes
Missing kick-out flashing
Roof water runs down the wall instead of into the gutter and soaks the siding and framing.
Decks that slope toward the house
Flat or back-sloped surfaces push water against the wall and door thresholds.
Doors without sill pans
Water that gets under a threshold runs into the subfloor and the room below.
What drives the price in Lake Forest Park
Waterproofing in Lake Forest Park depends on the size of the deck or balcony, how much substrate has to be replaced, slope correction and how many doors and walls need new flashing. Recoating a sound surface costs far less than rebuilding a wet one. You get a written price after we trace the leak.
Typical timeline
A recoat over a sound deck usually takes a few days including cure time. Rebuilding plywood, slope and flashing takes about one to two weeks, depending on weather.
Backed by a 24-month workmanship warranty
Written scope
You know exactly what is included before work starts, with photos of what we found.
Our own crew
The people who quote your job are the people who do it, start to finish.
Clean site daily
Debris is hauled away and your yard is left the way we found it.
24 months covered
If our workmanship fails within two years, we come back and make it right.
What homeowners near Lake Forest Park say
“One of my windows leaked after I had them cleaned and so I called Eco Home Repair to take a look. I really appreciated the thorough inspection - they determined the leak was unique to the aggressive window washing and wouldn't happen in regular rain (it had…”
“Very professional, quick to respond, and able to schedule the work on short notice they treated our home and deck with care and did an excellent job. I would definitely hire them again for a future project.”
“I hired Eco Home Repair to do a leak repair under my balcony, deck waterproofing and slope correction, and underlying rot repair. They were professional, quick, and fairly priced; kept me in the loop throughout the whole process and was honest about what…”
5.0 average from 106 reviews on Google, Thumbtack, Angi, HomeAdvisor and Yelp. Read our reviews on Google.
Questions Lake Forest Park homeowners ask about waterproofing
Can you repair a tall hillside deck in Lake Forest Park?
Can you coat over my existing deck in Lake Forest Park?
Do you fix leaks around windows?
What is kick-out flashing?
How often should a deck coating be recoated?
More from our crew in Lake Forest Park
Waterproofing near Lake Forest Park
Tell us about your waterproofing project in Lake Forest Park
- Licensed, bonded & insured
- Free on-site estimates
- 24-month workmanship warranty
Book a free waterproofing inspection in Lake Forest Park
We inspect the damage on-site, show you photos of what we find and give you a written price before any work starts.