What's the difference between new-construction and replacement windows?

New-construction windows have a nailing fin and are installed into a framed, unfinished rough opening before siding goes on, giving full access to flash the opening properly. Replacement windows are designed to fit into an existing finished opening without disturbing the surrounding siding or trim. The two require different products and different install methods, so it matters which one your project actually needs.

How do I check that a window contractor is properly licensed and insured in Washington?

You can verify a contractor's license status and any complaint history directly through the Washington State Department of Labor & Industries' contractor lookup tool. Ask to see proof of current liability insurance and bonding before work starts, and get everything in writing. A legitimate local contractor won't hesitate to provide this.

Do vinyl, fiberglass, or wood-clad windows hold up differently this close to the water?

Vinyl and fiberglass frames generally handle salt air and moisture exposure with less maintenance than exposed wood, since there's no finish to maintain against the elements. Wood-clad windows can still be a good choice but the exposed wood components need a real maintenance plan in this climate. The right choice depends on your budget, style goals, and how much upkeep you want to commit to long-term.

What's a sill pan and why does it matter for my specific window order?

A sill pan is a shaped, waterproof liner installed at the bottom of the rough opening before the window goes in, with a raised back edge (a back-dam) that stops any water that gets past the window from reaching your subfloor or framing. Not every window package includes one — sometimes it's a separate accessory ordered specifically for the opening. It's one of the most important details on a coastal new-construction job and worth confirming is included before installation.

Does Semiahmoo's exposure to the Strait make window placement and orientation a real design factor?

Yes — walls facing west and northwest toward open water typically take more wind-driven rain than sheltered or inland-facing walls, which can affect flashing detail and product choice for those specific openings. This is worth discussing with your builder during the design phase, not after framing is done. It doesn't usually change which windows you can use, but it does affect how carefully certain openings need to be detailed.

Semiahmoo New-Construction Windows — Birch Bay Local Crew

Building New in Semiahmoo? The Windows Have to Be Right the First Time

Semiahmoo sits right up against the water, tucked in next to Birch Bay and Drayton Harbor, which means new construction here deals with a different mix of weather than a build fifteen miles inland in Whatcom County. Salt-laden air, wind-driven rain off the Strait, and a long gray moss season put real stress on window openings before the house has even had its first winter. On a new build, window installation isn't a retrofit problem you can quietly correct later — the rough openings, flashing sequence, and water-management layers get buried behind siding and trim, and whatever's wrong stays wrong for the life of the house. We install new-construction windows on Semiahmoo-area builds the way the local climate actually demands, not the way a generic spec sheet says is good enough somewhere drier.

This page covers new-construction window installation specifically — meaning windows going into a house during the framing/sheathing stage, before siding goes on — for homes in and around Semiahmoo. If you're dealing with an existing home and a window that's already failed, that's a different job with different fixes; ask us and we'll point you the right direction.

What Semiahmoo's Climate Actually Does to a Window Opening

A few things are true about this specific stretch of coastline that matter for how we build a window opening:

Salt air accelerates corrosion. Fasteners, flashing metal, and window hardware that would last decades inland can start showing problems years sooner this close to salt water. Material choice at the flashing and fastener level isn't optional here.
Driving rain comes sideways, not just down. Storms off the Strait of Georgia push rain horizontally against west- and northwest-facing walls. A window detail that only manages water falling straight down will let water in on a wind-driven storm.
Moss and organic growth season runs long. Whatcom County's wet stretch means sills, trim, and any horizontal surface near a window opening stay damp for months at a time. Anywhere water can pond or organic debris can collect becomes a slow leak path.
Temperature swings are modest but constant cycling matters. It's not extreme heat or cold that stresses a new-construction window opening here — it's the near-constant wet/dry, warm/cool cycling that works at any weak seal or gap over years.

None of this means new construction in Semiahmoo needs exotic materials. It means the ordinary steps — flashing order, sealant placement, drainage path — have to be done correctly, every time, with no shortcuts, because this location doesn't forgive a skipped step the way a drier inland site might for a while.

What a Correct New-Construction Window Install Actually Involves

The Rough Opening Comes First

Before a window ever gets set, the rough opening has to be square, correctly sized, and properly wrapped. We check the opening dimensions against the actual window unit (not just the plan spec), confirm the sill is level or has slight outward slope for drainage, and make sure the water-resistive barrier (house wrap) is lapped correctly before the window goes anywhere near the opening.

Flashing Sequence — This Is Where Most Failures Start

New-construction window flashing has to follow shingle-lap order: sill pan first, then the window unit, then jamb flashing, then head flashing last, each layer overlapping the one below it so water sheds downward and outward, never inward. On a Semiahmoo build we pay particular attention to:

A proper sill pan with back-dam, so any water that gets past the window has somewhere to go besides your subfloor
Head flashing that ties into the drainage plane above the window, not just caulked over the top
Corner and end-dam details at the sill, since that's the spot most likely to leak on a wind-driven rain event

Sealant and Fastening

We use sealants and fasteners rated for coastal/marine-adjacent exposure rather than whatever is cheapest at the yard, and we don't rely on sealant alone to do a flashing detail's job — sealant is backup, not the primary water management layer. Fastener corrosion resistance matters more here than most Whatcom County builds fifteen minutes off the water, and we spec accordingly.

Interior Air Sealing

A window opening also has to be air-sealed on the interior side with a compatible low-expansion foam or sealant, insulated properly around the frame without over-packing (which can bow the frame and cause the sash to bind), and left with room for the window to expand and contract seasonally.

Window Product Considerations for a Semiahmoo Build

We're not a single-brand shop and we don't push one manufacturer as the answer for every project. What we do steer builders and homeowners toward, for a home this close to salt water, is:

Factor	Why It Matters Here
Frame material corrosion resistance	Salt air is harder on unprotected metal hardware and fasteners; frame and hardware finish matters more here than inland
Cladding vs. bare wood exposure	Any exterior wood left unclad or unfinished needs a maintenance plan for this climate — bare wood in driving rain and long wet seasons doesn't hold up without upkeep
Warranty structure on coastal installs	Some manufacturer warranties carve out reduced coverage within a certain distance of salt water — worth checking before you commit to a product
Drainage design of the window unit itself	Weep holes and internal drainage paths that stay clear matter more where moss, debris, and prolonged damp are a factor

We'll walk through specific product lines and their trade-offs once we know your build's orientation, budget, and how exposed the walls are to prevailing weather — that's a conversation better had against your actual plans than in general terms on a webpage.

Our Process for New-Construction Window Jobs in Semiahmoo

Plan review. We look at your window schedule, rough opening sizes, and wall assembly before we ever show up, so we're not solving problems on site that should've been caught on paper.
Coordination with your builder or GC. New-construction windows are a sequenced trade — we need house wrap on and rough openings ready before we start, and siding/trim crews need us finished before they can close things up. We coordinate timing so nobody's waiting on anybody.
Install per manufacturer instructions plus our coastal-climate details. Manufacturer install guides are the baseline; we layer on the flashing and drainage details this location specifically needs.
Photo documentation at each flashing stage. Since these details get buried behind siding, we document sill pan, flashing laps, and sealant placement before cover-up — useful for your records and for warranty purposes down the line.
Final walk-through. We check operation, seal integrity, and trim readiness before we call the opening complete.

Why a Crew That Already Works Semiahmoo Matters

New-construction window installation isn't exotic work, but doing it correctly for this specific stretch of coastline takes local judgment a crew only builds by working here repeatedly. We know which orientations on a Semiahmoo lot take the worst of the wind-driven rain, we know what a wet Whatcom County winter does to an opening that was flashed even slightly wrong, and we've seen what happens years later when a corner was cut during framing that nobody caught until siding came off for a repair. That's knowledge that doesn't show up in a manufacturer's install manual — it comes from doing this work, on this coastline, over and over.

We also know the local building department's expectations for water-resistive barrier and flashing inspections, which keeps your build moving instead of getting flagged and delayed.

Common Mistakes We See on Coastal New-Construction Window Jobs

Caulk used as the primary flashing strategy instead of a proper lapped sequence
No sill pan or back-dam, leaving no path for incidental water to drain out
Fasteners not rated for coastal exposure, corroding years before the rest of the assembly
Rough openings cut oversized "to be safe," leaving gaps that get filled with excess sealant instead of properly sized and shimmed
Head flashing tucked under house wrap incorrectly, directing water behind the barrier instead of over it

Every one of these is fixable at the time of install for the cost of doing it right the first time. After siding goes on, the same fix means opening the wall back up.

What This Typically Costs

New-construction window installation pricing depends on the number of openings, window size and type, wall assembly complexity, and how many stories you're working at. As a broad range, expect new-construction window installation labor (not including the window units themselves) to run from a few hundred to over a thousand dollars per opening depending on size and access — the only way to get a real number is a look at your plans or the framed structure itself. We'll give you a written estimate before any work starts, with no pressure to sign on the spot.

Questions to Ask Before You Hire for This Kind of Work

Do they install a sill pan with a back-dam on every opening, or only when asked?
Can they explain their flashing lap sequence in plain language, not just "we follow code"?
Do they document flashing details with photos before the opening gets covered by siding?
Are they specifying fasteners and flashing metal rated for coastal/salt-air exposure?
Have they worked new construction in Whatcom County's coastal zone before, not just inland builds?

If a contractor can't answer these clearly, that's worth knowing before your rough openings get buried.

If you're planning a new build in Semiahmoo or elsewhere around Birch Bay, we're happy to look at your window schedule and plans and give you a straightforward, no-pressure estimate — reach out through the form below and we'll get back to you.