Deck Waterproofing & Flashing in Mountlake Terrace, 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 Mountlake Terrace and nearby Lynnwood and Edmonds.
Before
AfterFlashed and rebuilt
Why waterproofing comes up so often in Mountlake Terrace
Flashing gaps at additions are the most common waterproofing issue in Mountlake Terrace. Where a newer roof meets an older wall, kick-out flashing is often missing, and runoff soaks into the siding and framing below. Low-pitch roofs on additions and carport conversions can leak at their edges. Decks attached without ledger flashing let water behind the siding. We install kick-outs, step and ledger flashing, Z-flashing at siding transitions, and sill pans at doors. On decks or flat roofs over living space, we apply membranes with flashed edges so the assembly sheds water properly.
Mountlake Terrace was built quickly after World War II as an affordable planned community, and its core is still made up of modest 1950s ramblers on regular grid lots. Most started as small single-story homes on crawlspaces or slabs, with cedar or plywood siding and simple gable roofs. Over the decades, owners added bedrooms, second stories, converted carports and back decks, so many houses now combine original walls with several generations of additions. Around Town Center and the light rail station, newer townhomes and apartment buildings are going up, while the Lake Ballinger area includes some larger and newer homes.
Mountlake Terrace sits on flat to gently rolling ground east of Edmonds, away from direct Sound exposure but within reach of the convergence zone showers that often settle over south Snohomish County. Rain falls steadily through fall and winter, and the low, flat terrain does not always drain quickly. Homes near Lake Ballinger and along creek corridors deal with a higher water table and occasional flooding. Ramblers built close to grade suffer from splashback, and additions tied into older walls create seams where water finds its way in.
Our crew comes out from our Woodinville office, and we also work in nearby Lynnwood, Edmonds, Shoreline and Bothell.
When to call about waterproofing in Mountlake Terrace
- A deck that slopes toward the house
- Streaks down the wall below a roof edge
- Rot or stains under windows and doors
- Stains or drips on the ceiling below a deck or balcony
- Water pooling against the house after rain
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 Mountlake Terrace
What we do in Mountlake Terrace
Leak investigation
We trace leaks to the source before anything is sealed.
Walkable deck coatings
Waterproof coating systems for decks and balconies over living space.
Door and sill pans
Pan flashing under doors, where many balcony leaks start.
Slope correction
Fix flat or back-sloped decks so water drains away from the wall.
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.
Neighborhoods and permits in Mountlake Terrace
Around Lake Ballinger, low ground and higher groundwater keep crawlspaces and lower walls damp. Near Town Center, older ramblers sit beside new construction, and changes in grading can redirect runoff toward neighboring lots. Terrace Creek Park and the streets around it are more wooded, keeping roofs and decks shaded. Along Cedar Way and the I-5 corridor, many homes have had multiple additions, and the seams between old and new walls are where leaks usually start.
Small in-kind repairs, like replacing a few boards or a section of trim, frequently need no permit. Structural work, new decks, additions and larger siding replacements usually do, and properties near Lake Ballinger or creek corridors may involve extra review. Our crew checks with the City of Mountlake Terrace up front and files for a permit whenever one applies.
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 Mountlake Terrace
| 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 Mountlake Terrace 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 Mountlake Terrace: 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.
Worn deck coatings
Coatings wear through first at doors, edges and posts, and water reaches the plywood underneath.
Decks that slope toward the house
Flat or back-sloped surfaces push water against the wall and door thresholds.
What drives the price in Mountlake Terrace
Waterproofing in Mountlake Terrace 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 Mountlake Terrace say
“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 had a great experience working with Eco Home Repair on a water damage project. Water was leaking into the house through the chimney, which caused mold and water damage issues. Eco Home Repair handled everything smoothly and professionally. They replaced the…”
“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…”
5.0 average from 106 reviews on Google, Thumbtack, Angi, HomeAdvisor and Yelp. Read our reviews on Google.
Questions Mountlake Terrace homeowners ask about waterproofing
Can you repair original siding on a 1950s Mountlake Terrace rambler?
Can you coat over my existing deck in Mountlake Terrace?
What is kick-out flashing?
Why is water leaking under my deck or balcony?
Why does my ceiling leak only in heavy rain?
More from our crew in Mountlake Terrace
Waterproofing near Mountlake Terrace
Tell us about your waterproofing project in Mountlake Terrace
- Licensed, bonded & insured
- Free on-site estimates
- 24-month workmanship warranty
Book a free waterproofing inspection in Mountlake Terrace
We inspect the damage on-site, show you photos of what we find and give you a written price before any work starts.