Of Piers & Beams; From "Ask Us Anything"

If you haven't had a chance to check out the "Ask Us Anything" page on our website, then you're missing out. Here's the most recent question and our answer.

Question

1) How many beams would you expect to find under a home that is 63 feet wide and 26 feet deep, plus has a garage 18 by 18 added to the back of one side?

2) Should interior piers be placed under the beams if the foundation is getting raised at least 3 inches?

3) Would one expect to find a beam under a load supporting wall that runs 63 feet from the west to the east side down the center of the home (centered at 13 feet deep)?

Answer

Dear Ellen,

Great Questions! While we are not builders or construction engineers, we have developed some construction-related perspectives due to the multitude of houses we have sought to repair. I am going to attempt to answer your questions based on the presumption that the home of which you speak is built on a slab on grade concrete foundation.

The number of beams one would expect to find and the number of beams present, if any, can be quite different. I would LIKE to find three beams from side to side; one being directly under the primary load bearing wall and another seven (7) feet offset on either side of it. If the foundation is going to be lifted three (3) or more inches then, YES, I would want the piers placed to directly support the beams.

It is not a matter of whether the foundation COULD BE LIFTED if the piers are not under the beams, but IT IS a matter of whether anything less will assure you of a LONG TERM HOLD without breaking the foundation at the point of contact at each pier.

As far as a beam being UNDER the load bearing wall, that is where one would hope to find one. But rarely have we found that to be the case; the most common situation we find is where the load bearing wall sits off from the beam two to three feet.

Some other concerns for you to consider are the pier type and depth, the stress the lift will place on all plumbing and the preparation of gas and electrical connections so they will lift with the house without being broken. Also,if you have not hired an independent engineer to design the scope of work to be attempted then I would highly recommend that.

If you have any more questions we can address please let me know.

Sincerely,
Alan Ardoin.

Get more information by visiting www.AceFoundation.com.

Pier & Beam versus Slab Foundation, Part 2

This is the second part in our multi-part series of posts, "Pier and Beam versus Slab Foundation." Be sure to read the first post in this series, if you haven't already.

In our last post, we discussed pier and beam foundations (sometimes called post and beam foundations), including what they were, and their pros and cons. In this post, we'll covered the basics of slab foundations.

The Basics

Slab foundations are usually the easiest (and thus the least expensive) foundations to build. The slab is a flat concrete pad poured directly on the ground. This takes minimal site preparation, very little formwork for the concrete, and less labor to build than a pier and beam foundation. Slab foundations work well on level sites in warmer climates (like what we have here in north Texas and southern Oklahama). Slab foundations can be problematic farther north because when the ground freezes during winter, this freezing may shift the slab. This may damage the structure sitting on the foundation, plumbing running through and under the foundation, and the foundation itself.

How Slab Foundations are Constructed

In most cases, the perimeter of the slab is about 2 feet deep. The interior of the slab can be as little as 4 or 6 inches thick. Below the slab sit a 4 to 6 inch layer of gravel. To keep moisture from the ground rising through the gravel to the slab, a 4-millimeter sheet of plastic is placed. Reinforcing bar (rebar) is laid out in a grid framework (supported a few inches above the plastic sheet) and the concrete is then poured over everything.

This type of foundation is commonly called a floating slab since it "floats" on the soil. What holds the foundation in place is the deeper layer of concrete around the perimeter of the foundation.

In places with common and severe winter freeze, the concrete along the perimeter extends below the frost line.

The Advantages and Disadvantages of a Slab Foundation

Slab foundations offer the following advantages:

• Slab foundations usually take less time to construct.
• Slab foundations require less prep work of the site.
• Typically, slab foundations cost less, due to the two points above.
• Since there is no crawlspace under the home, there's no risk of animals getting underneath the structure.
• Since the slab sits on the ground, entries and exits to and from the structure are close the ground -- perhaps only a step or two. This is good news for those with disabilities or other restrictions that makes steps difficult to navigate.

On the other hand, there are a few drawbacks to slab foundations:

• Since the plumbing and gas lines (if applicable) run directly through the concrete slab, it's more expensive to fix these problems below the home. Also, shifts in the foundation can break pipes (fresh water, sewer lines, and gas).
• Once a foundation has failed, it can be more expensive to fix the foundation since piers have to be sunk below the home. (In contrast, a pier and beam already has piers, which may only need adjustment.)
• Slab foundations cannot be used in homes where a basement will be built.
• Slab foundations cannot be used in areas with significant or prolonged freezes. The seasonal upheaval and other shifts can destroy a slab foundation.
• Concrete slabs can crack. These cracks can range from minor annoyances to major problems.

Concrete slabs can be a good choice for your home or business, but it has to be done right from the get-go, and only for the right type of conditions. If you have quesitons, feel free to contact us or shoot us a question.

Pier & Beam versus Slab Foundation, Part 1

The two most common types of building foundations in north Texas and southern Oklahoma are pier & beam foundations and slab foundations (also known as "slab on grade" foundations). As a rule of thumb, most foundations for homes built during the 60's and before are pier and beam while those built later are slab foundations. So, why the change in foundation types, how exactly is each type of foundation constructed, and what are the pros and cons of each? We'll cover each question over the next several blog posts and, as always, you can ask us your questions about foundation construction, repair, and maintenance and we'll give you the answers.

Pier and Beam Foundations

Pier and beam foundations (sometimes called post and beam foundations) have a crawl space (typically at least 18 inches) between the home and the ground. The base of the building is uses a series of beams supported above the ground via piers. This type of foundation takes longer to construct than a slab foundation, but allows easier access to heating and plumbing utilities. (With a slab foundation, it may be necessary to break through the concrete slab foundation to service or repair plumbing and such.)

Since the piers separate the structure from the ground, the foundation is less susceptible (as compared to slab foundations) to damage from the ground shifting. When ground shifting occurs and the foundation needs adjusting, the piers are more easily adjusted than is a slab foundation.

The advantages of a pier and beam foundation are:

• Provides easy access to service plumbing, electrical and other issues under the house.
• In many cases, pier and beam foundation problems can be less expensive to fix than problems with slab foundations.
• Some remodeling projects and home additions are more easily accomplished with pier and beam homes than with slab foundations.
• Since the structure isn't resting directly on the ground and air is a natural insulator, the temperature within the structure may take less energy to maintain. That is, your home isn't sitting directly on the cold hard ground during the winter and, thus, your heating bills can be less.
• Many people feel that floors supported by a pier and beam foundation have a bit more give and are therefore more comfortable. This is not to say the floor rebounds like a trampoline as you walk across it, but there is a difference according to many homeowners.

The disadvantages of a pier and beam foundation include the following:

• Pier and beam foundations take longer to construct than slab foundations. This increases the cost of the home or other structure.
• Floors supported by pier and beam foundations may creak and move.
• Broken vent screens and insufficient other barriers may allow bugs and rodents to get under the structure.
• Pier and beam foundations have to be vented properly to reduce moisture. Sufficiently high moisture levels can lead to mold, rotting wood, musty smells.

In our next post, we'll discuss slab foundations.

Get more information by visiting www.AceFoundation.com.

Pier and Beam Video

Here's a video we found that we think does a pretty good job of describing a pier and beam foundation.

Note the reference to the clay soil, which is common in north Texas and southern Oklahoma.

Get more information by visiting www.AceFoundation.com.

Great Video on Pier and Beam Foundation Construction

We found this great video over at 5min.com about the construction of a pier and beam foundation. Watch it and tell us what you think. Don't forget, you can always ask us anything when it comes to foundations.

Pier Beam Foundation

Get more information by visiting www.AceFoundation.com.