Prior to roof replacement, your contractor will do a thorough inspection to estimate repair needs. However, a second inspection may be necessary after the roof is torn off, as not all damage can be found before the work commences. These are a few issues that may be uncovered once teardown and replacement have begun.
1. Decking Damages
Although the underside of the decking can be inspected via the attic, the topside condition is unknown until the old shingles are torn off. Sometimes mold and the first stages of wood rot may be on the top surface of the decking. When this happens, the damaged piece must be removed and new decking will be put down.
2. Blocked Roof Vents
Most roofs have vents in the eaves and along the peak. There may also be vents midway up the roof slope or in the gable end walls. If the attic is inaccessible due to heavy insulation, then the condition of the vents may not be completely known until after work begins. It's not uncommon for vents to be blocked due to damage or spray foam insulation incursion. Replacement vents will be necessary.
3. Rotten Eaves
Much like decking, only the exterior of the eaves can be inspected before teardown. Once the roof is off, water damage in the interior may become apparent. Wood eaves are more likely to have interior damage, as metal and vinyl damage like rust or cracking is visible from the outside. Damaged eaves must be replaced before the roof installation can proceed.
4. Weak Trusses
Many newer homes have metal trusses supporting the roof, while older homes usually have wood trusses. Most of the trusswork will be inspected before replacement begins, as they are usually visible in the attic. What may not be apparent until after work begins is if a truss has missing or loose hardware, such as hurricane strapping and support brackets.
5. Seal Failure
Rubber boots are used to seal where round vent stacks connect to the roof, and aluminum flashing is used for a similar purpose around square vents and chimneys. The footing of these seals is shingled-over and sealed with roofing tar. When the shingles and tar are torn off for replacement, damages to these hidden parts of the seal may be found. Replacement of the boot or flashing must be completed to avoid future leaks.
Fortunately, your home roof installation contractor can handle any problem that is uncovered after the initial teardown.