Sequencing a Roof, Siding, and Window Project in Skagit, Island, and Whatcom Counties

Updated August 2026 · Alpine Exteriors · WA contractor license ALPINI751OW

The Short Answer: Roof First, Then Windows, Then Siding

If you're replacing all three at once, the roof goes first, windows go in second, and siding goes on last, because siding is supposed to close over new window flanges and a finished roofline, not the other way around. Get the order backwards and you'll likely pay to pull off and redo trim, flashing, or siding a second time. There's one common exception: if your roof is sound and only needs a few more years, windows still go before siding for the same reason — flashing continuity.

The Detail Behind the Order

A roof and its flashing details — valleys, step flashing along dormers and chimney chases, and especially kickout flashing where a roof edge meets a sidewall — need to be finished before siding is installed tight against those transitions. Kickout flashing is a small L-shaped piece that directs roof runoff away from the wall instead of behind it, and it's one of the most common failure points on homes we see in this region, particularly on additions and dormers built without one. If siding goes on first, that flashing either gets skipped or installed after the fact by cutting into finished siding, which rarely seals as well as doing it in the right order.

Windows come next because the window flange has to integrate with the weather-resistive barrier (WRB) wrapped on the wall sheathing, and siding trim — whether it's lap siding, cedar shakes, board-and-batten, or fiber cement — is cut and flashed to die into that window opening. Install siding first and a window installer either has to cut siding away sloppily or leave gaps that get caulked instead of properly flashed. Caulk is a maintenance item, not a waterproofing detail, and in a climate that sees rain for months at a stretch, that difference shows up as rot within a handful of years, not decades.

Gutters usually follow the roof, since fascia work and drip edge placement affect how the gutter hangs, but whether gutters go before or after siding depends on whether the fascia is being wrapped in metal or replaced — that's a detail worth confirming with whoever is running the job. Painting, caulking, and trim touch-up are always last, after every other trade has had a chance to scuff, drill, or bump the finished surfaces.

What Makes This Region Different

Sequencing rules aren't just theory here — the Skagit, Island, and Whatcom county climate punishes shortcuts faster than a drier region would.

• Heavy winter rain: The lowland stretch from Burlington through Mount Vernon to Bellingham gets a long, wet rainy season roughly October through March. An open building envelope — roof off, sheathing exposed — is a real liability during that window, so timing matters as much as order.
• Moss on shaded roofs: Homes tucked under conifer canopy around Sedro-Woolley, the Bellingham foothills, and wooded lots on Camano Island tend to grow moss on north-facing roof slopes. That's a roofing-stage issue — proper ventilation, and in some cases zinc or copper strips, help slow regrowth — and it needs to be addressed before the roof is buttoned up, not patched later.
• Wind off the Skagit flats and the Strait: The open farmland between Mount Vernon and Burlington funnels wind with little to break it, and waterfront exposure in Anacortes, La Conner, and Camano Island adds more. Fastening schedules for both roofing and siding matter more here than they would on a sheltered inland lot.
• Salt air on the islands: Camano Island, Anacortes, and the La Conner waterfront sit close enough to saltwater that corrosion becomes a real factor. Fasteners and flashing that aren't stainless or properly hot-dip galvanized can start rusting within a few years, which is a detail worth specifying up front rather than discovering later.
• Occasional ice and snow in the foothills: Properties closer to the Cascade foothills, including parts of Sedro-Woolley, see occasional cold snaps and light snow that lowland areas mostly avoid. Ice-and-water shield at eaves and valleys is worth confirming on those roofs specifically.
• Washington State Energy Code: Window replacements in this state generally have to meet current U-factor requirements under the Washington State Energy Code, and inspectors sometimes want to see flashing and insulation continuity before it's covered by siding. That's another reason not to close in the wall assembly before windows are set and inspected.

What the Homeowner Should Actually Do

Start by deciding whether you actually need all three trades now or whether staggering them over a couple of years makes more financial sense. Staggering isn't wrong — plenty of homeowners replace a roof one year and siding and windows a couple of years later — but it does mean paying for mobilization, cleanup, and material minimums more than once, and it can leave a mismatch between old and new trim details in the meantime.

If you're doing a combined project, it's worth having one contractor either perform or closely coordinate all three trades rather than hiring three separate specialty contractors on independent schedules. Hand-offs between separate crews are exactly where kickout flashing gets forgotten and where nobody takes responsibility for a leak that shows up two winters later. Alpine Exteriors runs roofing, siding, windows, and gutters as one crew for this reason — it removes the finger-pointing that happens when three companies each installed one piece of the same wall assembly.

Ask directly about kickout flashing at roof-to-wall intersections, what fastener material is being used if you're on Camano Island, Anacortes, or anywhere near saltwater, and whether ice-and-water shield is included if you're closer to the foothills. Try to schedule envelope-opening work — tear-off, sheathing repairs, window swaps — outside the heaviest rain months when your project timeline allows it, though a good crew can manage a wet-season job with proper temporary protection if that's the only window you have.

Finally, confirm permits and inspections before work starts. Skagit, Island, and Whatcom counties and their cities each have their own permitting requirements, and some inspections are timed to see flashing or insulation before it's covered — scheduling those inspections into the sequence, rather than around it, avoids delays that leave a wall open longer than it should be.

FAQ

Can I do siding first if my roof is only a few years old?

Yes — if your roof is genuinely sound and not part of the current project, siding can be installed against the existing roofline without a problem, since the flashing at those transitions is already in place. The sequencing concern only applies when the roof itself is also being replaced as part of the same project.

Do I need new flashing if I'm only replacing windows, not the roof or siding?

Usually yes, at least at the window openings themselves. Window flashing tape and pan flashing at the sill are typically replaced as part of any proper window installation, even if the siding around the opening stays untouched and just gets carefully reattached or patched.

How long does a combined roof, siding, and window project take in this area?

It depends heavily on house size and weather, but a full roof-siding-window project on a typical single-family home often runs several weeks when sequenced properly, with the roof phase usually the fastest and siding the longest. Wet-season scheduling can add time if work needs to pause during heavy rain.

Will replacing my windows trigger an energy code inspection?

In most jurisdictions here, yes — window replacements generally need to meet current Washington State Energy Code U-factor requirements and may require a permit and inspection, even on a like-for-like swap. Your contractor should confirm this with the specific county or city before work starts.

Plan Your Project With Alpine Exteriors

Getting the order right on a roof, siding, and window project is mostly about avoiding rework and keeping the wall assembly weathertight through a wet Pacific Northwest winter. Alpine Exteriors, WA contractor license ALPINI751OW, handles roofing, siding, windows, and gutters for homeowners across Mount Vernon, Anacortes, Burlington, Sedro-Woolley, La Conner, Stanwood, Camano Island, and Bellingham, and can walk through a sequencing plan specific to your house, its exposure, and its budget before any tear-off starts. Reach out to talk through what your home actually needs and in what order.