gap between floor and wall - mud sill failure

Pier & Beam Problems: Gaps Between Your Floors and Exterior Walls

You’ve got gaps going on between your floors and the exterior walls of your home. This is a pier and beam home, by the way. You know, the kind with a concrete beam around the perimeter but it’s not a slab, it’s a crawl space foundation. Yeah, that kind . . . 

You’ve got a special problem that is only found in pier and beam homes. It can only be solved with a special type of sill beam called a mud sill.

Anchor Foundation Repair Bryan College Station

At Anchor Foundation Repair, we have been repairing pier and beam problems for 35+ years in Bryan, College Station, and the surrounding Brazos Valley communities like Caldwell and Brenham. We’ve seen these gaps more than a time or two and can tell you what the problem is and how we fix it. 

This article will explain your gapping problem and what to do to solve it when we’re doing house leveling repairs on your pier and beam home. We’ll talk about the purpose of a mud sill and how it helps create the structure of your home. Let’s get started filling these gaps in your knowledge!

Where Do Sills Fit Into Crawl Space Foundation Structure?

Just in case you need this general info, it’s helpful to make sure you’re oriented to the terms and basic structure of your home. If you’ve already got a handle on these *foundational* facts about crawl space foundations, feel free to skip to the next section.

pier and beam foundation structure

Your pier and beam foundation is built layer by layer in the beginning . . . On a pier and beam home (unlike other types of crawl space homes), a concrete perimeter beam does double duty, serving in the role of the pier and sill beam at the same time. It does get a little confusing, we made a video about pier and beam structure, terminology, and damage here

I’m sure we’ve got pictures around here too.

Your foundation structure is kinda like one of the stacked sandwiches with lots of layers – it’s almost lunchtime as I am writing this so maybe I’m a little hungry – From the ground up, the sandwi . . . I mean layers go like this:

  1. Dirt/Soil/Ground
  2. Piers that elevate the home and transition up from the ground to the sill beams,
  • For a pier and beam home, individual piers are only found under the middle of the home, not on the perimeter. In a way, the concrete beam fills a pier’s role along the perimeter. Actually, there are often small piers underneath and attached to the perimeter beam, but you wouldn’t know if they were there or not.
  1. Shims are inserted between the sill and piers to make small elevation adjustments and keep things as level as possible,
  2. Sill beams that hold up and support the floor joists 
  • Concrete perimeter beam with mud sill on top, standard wood sill beams with piers under load-bearing walls through the middle of the home,
mud sill in construction
Mud sill during construction
  1. Floor joists that support the subfloor and the home structure,
  2. Subfloor that serves as an underlayment for your finished flooring surface, and
  3. Floor transitioning to framing and walls.

Sills fall in the middle of these layers and there are a few different types of sills that all serve different purposes or solve certain problems. In general, sills are large, long, and strong beams (typically made from wood on this home type) that help carry and distribute the weight of your home. 

What all types of foundation sills *do* is allow the structure to move from vertically oriented support with the stacked piers to a horizontal orientation by bridging the gaps between piers. Mud sills are a little different than the other types and we’ll talk about that in the next section.

What Is a Mud Sill and What Is Its Role in My Home?

new mud sill in place

Like other sill types, mud sills help transition your home structure from the horizontal orientation of a concrete perimeter beam to vertical, but there’s more to it. Instead of bridging the gaps between individual piers as a main sill does, a mud sill is laid on top of the beam to not only move from horizontal to vertical but to allow the structure to move from concrete to wood material.

Additionally, mud sills help to smooth out any irregularities in the concrete beam by providing an even surface to begin attaching the house framing. A mud sill is laid flat and attached to the concrete beam by anchor bolts. I sure like the sound of those bolts for some reason . . .

Your floor joists are then laid on top of the mud sill and the rest of the structure continues in the layers described above. The floor joists are also attached to the mud sill, and it’s a lot easier to attach the wooden joists to the wooden mud sill rather than trying to attach each joist to a concrete beam. So, yet another role the mud sill plays in your pier and beam foundation is to allow the joists to be joined with the beam through easy means.

What Happens When a Mud Sill Fails?

mud sill need replacing

Mud sills are the first wooden “home part” that lies closest to the ground. Just like any other wood under a home, it is exposed to moisture and other degrading forces. Over time, mud sills can experience dry rot or wet rot and can also be prone to termite damage. The wood can become brittle and flaky, and then deteriorate into dust and crumbles.

Since the mud sill runs all along the perimeter of the home, anywhere that it becomes compromised can impact your exterior walls. If your mud sill falls apart, the joists resting on top of it will drop. This is what creates the telltale gap you might be seeing between your floors and walls. Some floor joists will also likely be damaged and need repair too.

Repairing Mud Sill to Fix the Gaps Between Floors and Walls

Repairing a deteriorated mud sill is probably the most complex and difficult type of sill beam to fix. I mean, you really don’t *repair* it, you have to replace it. Take what’s left of the old one out and put in a new one.

replacing mud sill

If you remember from many delicious layers of your pier and beam foundation, the sills are stuck in the middle and the mud sill is also bolted to the concrete beam. Careful attention must be paid to remove the bad mud sill and then get the new one sandwiched in there and attached properly.

The removal and replacement of mud sill would go something like this:

  1. Temporarily raise and support the home, lifting framing and floor joists off of the mud sill,
  2. Remove the damaged and deteriorated sections,
  3. Insert new mud sill boards,
  4. Re-anchor the mud sill in any needed locations,
  5. Repair any affected floor joists, and 
  6. Return the floor structure back into contact with the mud sill.

If your mud sill is damaged, you’re likely having a full-blown house leveling/foundation repair project completed on your home. Other issues are also being repaired simultaneously in addition to this mud sill fix.

How Does a New Mud Sill Benefit My Home

Mud sills are important and will certainly benefit your home when replaced. Any signs of foundation issues affecting the perimeter of your home will be helped by a new mud sill. More specifically, a new mud sill will:

mud sill replacement

Sounds pretty good, huh?

Do You Have Any Other Pier and Beam Foundation Problems?

Now you know all about how this gap is happening between your floors and walls and how it can be fixed. If you have mud sill issues, the chances are high that other parts of your foundation are having problems too. Sounds like some pier and beam foundation repair might be in your future . . .

mud sill to fix the gap in your floor and wall

Homeowners worry when they have foundation problems. You don’t know what to do or who to trust. Not only are you concerned about your home’s safety and stability, but you’re also worried about choosing the right house leveling contractor to take care of your largest investment. 

At Anchor Foundation Repair, we understand the stress and anxiety that comes with these issues and we’re here to set your mind at ease. We offer fair and impartial assessments, empowering education, and a fully transparent repair process.

Speaking of a transparent repair process, want to know what a pier and beam foundation repair project looks like? Check out House Leveling with Anchor: 4 Steps to Expect from a Typical Project.