Pier and Beam Foundations
Several people have asked me about David Weekley’s pier and beam construction process. So it took some time, but I went through all of my pics and pulled a collection that shows how they do it. Let me also preface this by saying I’m not a construction guy, but I play one on TV. I learned what I could from the real construction folks on the job, so take the terms and definitions I use lightly!
The first ingredient is an empty lot… 
After a series of surveys and soil tests, an engineering company (external to David Weekley) determines how deep the piers need to go into the ground. In the Houston area, especially land in the 100 and 500 year flood plains, there is a lot of moisture deep down in the soil. This can cause problems with the foundation settling etc, so it is very important to get the pier depth correct. In our case, for a 3600sq ft 2 story home, the crews dug 15 holes, each 16 to 18 feet deep. At the bottom of each hole, a special machine makes a “bell shape” so the concrete spreads out under ground. Fortunately for us, the holes did not fill up with water. Apparently ground water can cause issues when trying to pour the piers.
Here’s a pic of the machine that created the initial 18 foot holes. It has a massive drill bit and long shaft to dig deep and pull dirt out of the ground.
This is the machine that creates the “bell shape” at the bottom of each hole. It’s basically the same machine with a different drill bit. The bit has a couple of blades housed within a metal casing. When the bit gets to the bottom of the hole, the blades fan out to create the open space. Ultimately, the concrete poured into each hole will spread out at the bottom for steady footing.
Before they pour the concrete piers, they create columns of re-bar and insert them into each hole. Just like what you see in buildings and roadways, the re-bar helps reinforce the concrete.
After the piers have been poured, the foundation crew builds additional forms for more concrete. They put down a re-bar reinforced outer wall around the entire home footprint, and they also pour “pads” on top of each pier. Below you can see outer wall (and in our case the base of the front porch in foreground). Out in the middle, you can see the forms for each pad.
Here’s a close up of a pad form on top of the pier…
This is a pic of the entire foundation after they poured concrete… Not your “typical” post tension slab.
Close up of the pads with concrete. Here you can also see the PVC pipes for dirty water heading to the sewer. This is one of the benefits of pier and beam… if you have any plumbing issues, it’s easier for plumbers to access proplem areas.
At this point, all the ground work is complete and the crew will build a concrete block structure on top of the foundation. The exterior blocks will eventually have Acme brick attached to them, and 1/2 inch diameter bolts are also sunk in to the exterior blocks to secure the wood frame structure. Here you can see the pads now have blocks stacked on them. The blocks have concrete poured down the interior, so the complete pier is quite solid. On top of each pier you can see metal strips that are used to secure the beams.
Here’s a close up of the foundation. Notice the bolts around the outside, metal straps on each pier, and water proof ground cover to prevent ground humidity from damaging the underside of the house.
Let the sub-flooring begin! Pressure treated lumber is used to create the boundary between the blocks and subfloor. This wood is secured with industrial glue and the exterior bolts. A honeycomb structure of beams is created on top of the external wall and piers.
Here’s a close up of the sub-floor. The underside of the floor will be covered with insulation (hung by hooks), and the entire bottom will then be covered by a house wrap material.
And this is what it all comes down to… a pier and a beam! Here you can see how the metal straps wrap around the base of each beam.
The framing can now begin on the rest of your home…
On top of the subfloor, David Weekley uses 1 1/2 inch thick decking material for the floor. These pieces actually interlock with each other. The floor is initially nailed down, but ultimately screwed down after the roof is complete.
Since the subfloor is wood and not concrete (like traditional slab), when installing tile, David Weekley uses Hardie backer board to prevent tiles and grout from cracking.
Externally, you can now see the flood vents and brick walls…
And here’s the “almost” finished product. Still need a driveway, sidewalk and landscaping… in addition to finishing the front porch!
So this was a little longer than my normal posts, but hopefully you have an idea what goes in to building on pier and beam. David Weekley has done an excellent job on our project, and I highly recommend them to anyone reading this!
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