Here’s a technical note on the sheathing under the roof shingles, based on a Gibsons home inspection.
When you open the hatch to the attic, look up at the plywood or OSB sheathing. Sometimes there is a gap between the sheathing, created by metal spacers. These spacers are referred to as `H-clips`.This product serves two purposes:
- braces unsupported sheathing edges
- provides a 1/8″ gap for shrinkage and expansion of roof sheathing
For the majority of inspections I do not comment whether they are installed or not because their use is dictated by code or designer or contractor practice or roof truss spacing or sheathing thickness. Using the H-clips can increase the load bearing capacity of the roof 4-fold.
However when they are not present but should have been used it becomes obvious because the roof is in distress. This shows up as:
- Unacceptable spring in the sheathing when walking on the roof
- Warping of sheathing when viewed from the attic space
There is very little opportunity, if any, to remedy the situation. If the roof does not leak then it`s best to just leave it alone. However do keep it in mind when purchasing your next property.