Roof, siding, windows, gutters and paint: what order to do exterior projects

A house exterior is a set of layers that shed water downhill. University of Minnesota Extension's rule for a drainage plane is that every layer must lap out and over the layer below it. That one rule sets most of the sequence: the parts that sit higher, or that tuck behind other parts, go in first.

Where a roof meets a wall — a dormer, a second-story wall above a porch, a garage roof against the house — the roof is flashed with step flashing that runs up the wall behind the siding. Wisconsin's Uniform Dwelling Code requires flashing at wall and roof intersections, and it requires the end of the roof flashing at an eave that meets a sidewall to divert water away from the wall and onto the roof or into the gutter. That piece is usually called kickout flashing. Chimneys must be flashed and counter-flashed.

Siding manufacturers build their instructions around those details. James Hardie's best-practice guide calls for 2 in. of clearance where siding meets a roof and for kickout flashing at roof-to-wall ends. LP SmartSide's instructions call for 1 in. of clearance from roofing, step flashing with an upper leg of at least 4 in., and kickout flashing.

If the siding goes on first and the roof is replaced a year later, the roofer has two poor choices: reuse old step flashing, or cut and remove new siding to replace it. Doing the roof first lets the siding crew finish over new flashing with the right clearances. Roof work is also hard on walls — tear-off debris, ladders and foot traffic mark new siding and new paint.

A new-construction window with a nailing flange is flashed into the wall: the water-resistive barrier and flashing tapes lap so that water running down the wall is carried out over the window head and past the sill. The UDC requires flashing at the tops of doors and windows. University of Minnesota Extension adds a detail that matters: don't caulk the bottom flange of a window, because that traps water that needs to drain out.

That lapping only works if the window goes in before the siding covers the barrier. Replacing flanged windows after new siding means cutting back siding and trim, and patching the barrier around each opening. If both projects are coming, do windows and doors first or with the siding.

Insert replacement windows, which fit inside the existing frame and leave the exterior trim in place, are less tied to the siding schedule. Even then, trim that will be wrapped or replaced with the siding is best finished once, after the windows are in.

Gutters hang on the fascia, below the drip edge at the roof's lower edge. The drip edge goes on with the roof, and fascia repairs or wraps usually happen with the siding and trim. Hanging new gutters before either is finished means taking them down again.

The siding details point the same way. James Hardie and LP both call for a 1 in. gap between the end of a gutter and the siding, and the kickout flashing the UDC calls for is there to direct water into the gutter rather than down the wall. Those pieces fit together best when the roof edge and wall are already finished.

Downspouts finish the job. University of Minnesota Extension recommends discharging them at least 4 ft from the foundation. New gutters are the last step of water management, not the first.

Paint is the finish on everything else, so it goes on after rotted trim and siding boards are replaced, after joints are caulked, and after the roofers, window installers and gutter crew are done leaning ladders on the walls.

Two product rules affect the timing. Sherwin-Williams' Duration Exterior data sheet says standard latex primers cannot be used below 50°F, so new or bare wood needs a warm enough window to be primed. And primed fiber cement and engineered wood have a clock: James Hardie's instructions require painting within 180 days, and LP's say as soon as possible or within 180 days. A fall siding job on primed product can be painted the following spring, but not left for years.

If new siding is factory-finished, the paint phase may shrink to trim, doors and any wood that stays. See when you can paint an exterior here for the weather side of the schedule, and exterior painting for what the work includes.

Fix the source of water before fixing what it damaged. A ceiling stained by a roof leak or an ice dam should wait until the roof and attic are fixed and the materials have dried; then drywall repair and interior painting can be done once. The same goes for interior trim and paint around new windows — install the windows first.

Few households do everything in one year. When the work has to be split, rank it by water risk, then plan each phase so it leaves a clean connection for the next.

Separate specialists can each be excellent at their trade. The risk is at the connections — step flashing behind siding, window flashing into the barrier, gutter ends at the wall — where each trade can reasonably assume the other one owns the detail. One firm handling several trades has fewer handoffs, but should still be able to explain every connection.

Either way, ask each contractor who is responsible for the flashing at the transitions, and get that in the written scope. C&L Property Improvements does roofing, windows and doors, siding, gutters and exterior painting, provides free estimates, and puts the sequence and the scope in writing.