Wall cladding materials should be 6-9 inches above grade to protect the cladding system and the structure from water damage. This means that we can see some of the foundations above grade and below the siding. Foundations are designed to withstand the moisture in the soil. People may not like the appearance of exposed foundations, but from a functional standpoint, we want to see them.
Masonry should usually be at least 6 inches above grade. There are exceptions because some bricks, for example, are designed for use at and below grade. Most other sidings, including wood, and wood-based products, stucco, metal, and vinyl, should be at least 8 inches above grade.
Siding materials too close to grade are typically the result of either poor original construction and landscaping, or the grade level changes during landscaping or surface water control work. It is possible that the siding is too close to grade because the building is settling, but there are bigger problems if this is the case.
Damage to wall cladding materials can include:
- Spalling (crumbling or flaking) and cracked brick and missing mortar
- obstructed weep holes in masonry veneer
- rotted wood
- Swollen, buckled, or cracking wood-based products
- Peeling paint
- Rusted fasteners
- Rusted lath and drip screed on stucco
In some cases, veneer walls with weep holes and flashings along the bottom course suffer dramatically if the weep hoes are below grade. Water won’t be able to drain out, air won’t be able to get in, and moisture may seep from the soil into the building through weep holes. Severe spalling can occur.
The more serious and concealed implications are the damage to the wall and floor structures behind the siding. This includes rot and insect damage at sheathing, studs, sill plates, headers, and floor joists. Damage to interior finishes and components is also possible. Sometimes damage is not visible until it is serious. This may be the first indication that there is a problem.
What remedies are available if this is the problem found during your home inspection?
An expensive and disruptive solution would be to raise the foundation. More practically, if the siding is too close to grade because the grade has been elevated to form a garden, for example, the solution may be to restore grade level to its original position. If the siding has simply been installed too low, the solution may be to remove the bottom few inches of siding. This is only practical if the foundation is tall enough.