Roof tie-ins for additions and dormers in Vancouver, WA

Additions, dormers and bump-outs add space, but they also add the hardest part of roofing: the tie-in. That is the line where a new roof meets an existing one, or where a dormer cuts through an old slope. Water flowing down the old roof has to pass over or around the new section without finding a gap. Valleys, saddles, step flashing and headwall flashing all need to be built so the layers lap in the right order.

We roof second-story additions, shed and gable dormers, kitchen bump-outs, sunroom roofs and garage conversions that add living space. Sometimes we work for the general contractor building the addition, and sometimes for the homeowner directly. Either way, we look at the existing roof first, because a new section tied into an old, worn roof can push the old roof into early failure if no one plans for it.

Where addition roofs go wrong

The most common problem we fix on additions is a tie-in that was laid on top of the old roof instead of woven under it. Water runs down the old shingles and straight into the joint. Another frequent issue is a valley that is too shallow or too short, so heavy rain overshoots it and soaks the wall below. Dormers built without proper step flashing along the sides leak behind the siding, sometimes for years before the drywall shows a stain.

Mismatched slopes cause trouble too. When a new low-pitch roof meets a steep older one, shingles may be the wrong material for the flatter section. Some additions end up with a low-slope area that really needs a membrane rather than shingles. We look at the pitch of every new plane and pick the right covering for each, rather than forcing one product across all of them, even if it means two materials on one job.

What our addition and dormer roofing includes

Each job starts with a plan for how water will travel across the old and new roofs. We mark the tie-in line, decide how far back to open the old roof, and choose whether the valleys will be open metal or closed-cut shingles. Then we build the new roof and fold it into the old one in the order that keeps every lap pointing downhill, then check each joint before moving on.

• Weaving new underlayment under existing shingles
• New valleys at addition and dormer tie-ins
• Step flashing along dormer side walls
• Saddles and crickets behind wide wall sections
• Matching shingle line and color where possible
• Membrane for low-slope sections of the addition

Matching an older roof

Owners usually want the addition to look like it was always part of the house. Shingle lines and colors change over the years, and even the same color from the same maker can look different next to shingles that have weathered for a decade. We bring samples and check them against the existing roof in daylight. Where a close match is not available, we look for a natural break line, such as a valley or ridge, so the change in color is less noticeable.

In some cases the smartest move is to re-roof the whole slope or the whole house at the same time. If the existing roof has only a few years left, tying a new addition into it means tearing into that tie-in again soon. Replacing it together costs more today but avoids a second disruption and gives every section the same age and the same manufacturer warranty terms. It also means one crew handles the whole roof at once.

Protecting the house during an addition

An addition opens the existing house to weather, often for days at a time. We plan the roof opening so as little of the old roof is exposed as possible, and we cover the open areas with underlayment and secured tarps every night. In the October to May rain season that matters even more. We stay in touch with the builder about framing dates so our crew is ready the moment the new structure is sheathed, rather than leaving it under plastic.