Moisture barriers · Redmond, WA
Stop ground moisture under your Redmond home
In Redmond's valley and lakeside neighborhoods, soil moisture rises into crawl spaces all winter. We lay a heavy, sealed barrier that keeps it out of your floor framing.
- White bloom and efflorescence on foundation walls
- Crushed or shifted old plastic
- Gaps where the barrier stops short of the walls
Moisture barriers for Redmond homes · Kent, WARedmond homes
Moisture barriers built around Redmond houses
Soil under Redmond homes near the Sammamish River, Bear Creek and the north end of Lake Sammamish stays damp for much of the year. Even without visible puddles, that soil releases water vapor constantly into the crawl space. Without a solid ground cover, the vapor condenses on cool joists, subfloor and ducts, and floor insulation slowly takes on water. In Idylwood and the streets around Marymoor, homes near the water often show this as musty air in lower rooms and a white bloom on the foundation walls. Older barriers in these homes have usually been crushed, shifted or buried by years of foot traffic.
We fit the barrier to the conditions. On wet sites, that means a thicker reinforced liner, wide overlaps at every seam, taped joints, and edges run up the foundation wall and fastened, so vapor can't escape around the sides. Piers and posts get wrapped and sealed. If water is pooling on the ground, we point out the cause, such as downspouts discharging at the foundation or low spots in the yard, and recommend dealing with it so the barrier isn't holding a pond underneath. Afterward you get photos of the full crawl space floor, so you can see that every seam and edge is closed.
- White bloom and efflorescence on foundation walls
- Crushed or shifted old plastic
- Gaps where the barrier stops short of the walls
- Downspouts discharging next to the foundation
Local conditions
What Redmond throws at attics and crawl spaces
The houses
Redmond's housing climbs from the Sammamish River valley up onto the hills around it. Education Hill and Grass Lawn have 1960s and 1970s split-levels and ramblers, mostly on vented crawl spaces. Idylwood, near the north end of Lake Sammamish, mixes older lake homes with remodels. North Redmond and Bear Creek filled in through the 1980s, 1990s and 2000s with two-story homes on larger lots, many with crawl spaces, ducts running through the attic and roofs with several sections. Overlake and Downtown Redmond add townhomes and apartments. The older homes often still have their original ductwork and first-generation insulation.
The weather
The Sammamish River valley floor is flat, low and wet. Cold air settles there on clear winter nights, bringing fog and frost while the hillsides stay a little milder. Bear Creek and Evans Creek feed the valley, and the ground near them stays saturated through the October-to-May rain. Up on Education Hill and in North Redmond, tall second-growth firs shade roofs and drop needles that fill gutters.
The wildlife
Marymoor Park, the Sammamish River Trail, Bear Creek and the remaining farm fields in the Sammamish Valley give rodents plenty of habitat next to homes. Norway rats follow the river and creek banks and burrow under sheds and decks. Roof rats use wooded hillsides and fence lines to reach rooflines. Mice move indoors as fields are cut and nights get cold.
Typical results
What moisture barriers looks like
BeforeAfterHow it works
Same crew, same standard, in Redmond
- 01
Inspect inside and out
- 02
Trace each water source
- 03
Fix the barrier and the vents
- 04
Get roof water away
- 05
Recheck and photos
FAQ
Moisture barriers in Redmond: FAQ
Still unsure? Call (800) 674-4933 and talk it through with us.
How thick should a crawl space vapor barrier be?
Code sets a minimum, but on wetter Redmond sites we generally recommend a heavier, reinforced liner that stands up to foot traffic from plumbers and cable installers. Thickness matters less than coverage, though. A thick barrier with open seams and gaps at the walls still lets vapor through. We focus on full, sealed coverage.
Can a moisture barrier fix standing water?
No. A barrier stops vapor rising from damp soil. It won't stop water flowing into the crawl space from outside. If we see standing water, we show you where it's coming from, such as downspouts, grading or a high water table, so it can be dealt with first or alongside the new barrier.
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Free moisture barriers inspection in Redmond.
Book a free inspection. We'll photograph your attic and crawl space and walk you through what we find, before you decide anything.