Siding in Pittsburgh, PA

Old siding comes off first, and that is when problems that were hidden for years finally show themselves, soft sheathing around windows, old caulk that failed, insulation that got wet and never dried. Once the walls are exposed, any damaged sheathing gets replaced and a weather resistant barrier goes up before a single piece of new siding is hung. From there it is starter strip along the bottom, J channel around windows and doors, and panels working up the wall in straight, level courses.

Vinyl siding that looks fine at installation can fail within a few years if it was hung wrong. Vinyl expands and contracts with temperature, so panels nailed too tight will buckle and wave once summer heat hits them. Skipping the house wrap or flashing tape around window and door openings lets water get behind the siding, where it sits against the sheathing and causes rot that nobody sees until the siding is pulled off again.

Ask what is going behind the new siding, not just what the siding itself looks like. A proper weather barrier, correctly lapped and taped around openings, is what actually keeps water out of the wall. The siding itself is mostly there to shed water and protect that barrier from sun and weather.