Sill Plate Replacements: Material Selection and Installation methods

The sill plates, structural beams that lay where your concrete foundation meets the framing of your home, are prone to rotting and failure. Sill plate replacements can be a hairy fix if your foundation repair company isn’t equipped for proper installation methods.

Your sill plate is what anchors your home to your foundation. The correct, rot-resistant wood must be used to prevent wood rot, leaks and foundation problems. And your sill plate installation must be performed carefully to ensure your sill plate is securely attached to the foundation. Otherwise, you’ll find yourself quickly searching for sill plate replacement companies.

The sill plate is usually the first part of your flooring system to become subject to rot, but can quickly spread outward to your joists and vertical structural beams. Since your sill plate bears the compressive load of your home’s above-ground structure, wood rot can cause your sill to collapse.

This is why it is important to call a sill plate replacement contractor at the first sign of rot or structural damage. Sometimes, all we’ll need to do is fill the gaps with a foam sealant. Other times, your home will require a complete sill plate replacement.

At Helitech Waterproofing & Foundation Repair, we offer free consultations and estimates to homeowners like you. We’ll give you a fair and accurate estimate of the work it will take to get your home back into shape. We’ve been fixing foundations and performing sill plate installations for 30 years now, so you’ll know you’re getting some of the best repair services in the Midwest. Need more convincing? Check out this article on how to choose the best home improvement contractor for you.

How To Replace A Rotten Sill Plate

1. Install temporary supports
   First, we’ll install temporary supports to allow access to the sill plate for removal.
2. Measure twice, install once
   Your sill plate must be precisely installed to be flushed against the foundation. All gaps provide space for water to leak through into your foundation walls and structural beams, diminishing the structural integrity of your home.

Why is my sill plate rotting?

There are very specific guidelines as to how your sill plate should be installed. And if these guidelines are not followed, your home is vulnerable to wind uplift during storms and your sill plate is vulnerable to wood rot.

If your home was built prior to 1990, it is likely that non-treated wood was used in your sill plate installation, which can lead to premature wood rot. Nowadays, pressure-treated cedar or redwood is often recommended due to its rot- and water-resistant qualities. As an additional precaution against rot, sill plates must be installed about half a foot from the finished grade of your home to prevent the ground from soaking the sill plate, leaking into the house or promoting wood rot.

Sill plate gaskets—a material used to prevent air infiltration—must be placed between the sill plate and the concrete of your foundation. Your sill plate gasket serves two crucial functions:

1. creating an air-tight seam between the wooden sill plate and
2. protecting your sill plate from absorbing moisture from your concrete foundation.

In some cases, the sill plate is embedded directly into the concrete. This can, however, lead to premature rotting of your sill plate, so it might not be the best sill plate replacement or installation method.

The anchor bolts, which secure your sill plate to your foundation, must be installed strategically to prevent wind uplift. Typically, 1/2″ anchor bolts are attached about 8 feet apart, and always within 2 feet of each wall corner. In some areas, though, anchor bolts may be installed further apart or closer together—it depends on the area in which you live.