Problem: Siding deformation or displacement.
Persistent deformation will weaken siding and provide openings through which water can penetrate.
Cause: Direct installation over semi-rigid insulation
- Provide a stable backing for siding. Siding applied directly over semi-rigid insulation may deform and appear wavy because the insulation compresses when siding is installed to tightly. Use wall sheathing, strapping or furring for wood and hardboard siding. Use a backing that provides continuous support for vinyl and light metal siding. Heavier metals resist bending and may be spanned over furring strips. It is important to follow the manufacturer's instructions closely.
- Buckling at floor header assemblies.
- Shrinkage of header and trimmer joists can cause siding to deflect at the floor assemblies. Provide extra clearance at intersections and allow for the movement of siding installed above and below the assembly.