Deck Waterproofing & Flashing in Redmond, WA
Walkable waterproof coatings, slope fixes and flashing that keep water out of your walls and ceilings. 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 Redmond and nearby Sammamish and Woodinville.
Before
AfterNew siding and trim around the window
Why waterproofing comes up so often in Redmond
Many Redmond houses went up before builders routinely installed kick-out flashing, sill pans and metal ledger flashing, and that gap shows up today as rot at predictable locations. Townhomes downtown and in Overlake bring their own issues: balconies over living space and complex wall intersections. We add kick-outs where roofs die into walls, metal flashing at deck ledgers, and self-adhered membranes at window and door openings. Any deck that sits over a room gets a full sloped membrane system. We often combine this work with rot repair in Redmond so the fix lasts.
Redmond grew quickly from the 1970s onward, and its housing reflects that. Education Hill and Grass Lawn are full of 1970s and 80s two-story homes and split-levels, many with cedar or hardboard lap siding and attached wood decks. Idylwood and the slopes toward Lake Sammamish have a mix of older cabins converted to year-round homes and newer view houses. Bear Creek and the hills to the east have larger 1980s through 2000s homes on wooded lots. Downtown and Overlake have added many townhomes and apartments in the last two decades, often with small balconies and mixed siding materials.
The Sammamish River valley runs through the middle of Redmond, and cool air and fog settle there on winter mornings, keeping lower walls and decks wet longer. The surrounding hills, especially Education Hill and the Bear Creek area, are heavily wooded, so many homes sit in shade for most of the day. Rain comes in long, steady stretches rather than short bursts. Wood that never fully dries between storms is the pattern behind much of the rot we find, along with moss on roof edges and decks.
Our crew comes out from our Woodinville office, and we also work in nearby Sammamish, Woodinville, Kirkland and Bellevue.
When to call about waterproofing in Redmond
- Stains or drips on the ceiling below a deck or balcony
- Streaks down the wall below a roof edge
- Cracked, peeling or soft deck coating
- A deck that slopes toward the house
- 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 Redmond
What we do in Redmond
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.
Door and sill pans
Pan flashing under doors, where many balcony leaks start.
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.
Kick-out flashing
Diverts roof water away from the wall at roof-to-wall joints.
Neighborhoods and permits in Redmond
Education Hill homes stay shaded under big trees, and the damage concentrates at north walls, fascia and decks. Grass Lawn and Overlake have more sun but older flashing details, so window sills and roof-to-wall joints fail first. Idylwood, close to Lake Sammamish, sees moisture at lower siding and docks or stairs near the water. Out toward Bear Creek, larger homes with tall walls and big decks carry the most exposed surface.
Swapping out a few rotted siding boards or a small section of trim like-for-like often doesn’t need a permit. Replacing joists, posts or wall framing, building a new deck, or residing a large wall is a different story. Our office contacts the City of Redmond ahead of time, files what is required, and lines up inspections so the homeowner isn’t stuck chasing paperwork.
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 Redmond
| 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 Redmond 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 Redmond: cost and timing
Most common causes
Doors without sill pans
Water that gets under a threshold runs into the subfloor and the room below.
Worn deck coatings
Coatings wear through first at doors, edges and posts, and water reaches the plywood underneath.
Missing kick-out flashing
Roof water runs down the wall instead of into the gutter and soaks the siding and framing.
What drives the price in Redmond
Waterproofing in Redmond 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 Redmond say
“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…”
“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 Redmond homeowners ask about waterproofing
Is fog in the Sammamish Valley part of Redmond really a problem for siding?
Can you coat over my existing deck in Redmond?
What is kick-out flashing?
How long does a deck coating last?
Why does my ceiling leak only in heavy rain?
More from our crew in Redmond
Waterproofing near Redmond
Tell us about your waterproofing project in Redmond
- Licensed, bonded & insured
- Free on-site estimates
- 24-month workmanship warranty
Book a free waterproofing inspection in Redmond
We inspect the damage on-site, show you photos of what we find and give you a written price before any work starts.