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Do you need a soils report for your steel building foundation?

You can have a foundation for your steel building by calling the Salsa Steel Corporation.

Give them a call - they can also help you with your foundation questions.

559.665.0879 fax
P.O. Box 396
Chowchilla, CA 93610


Do I need to have a soils report?

How thick should I pour my slab foundation?

Some basic tips for a solid slab foundation

Concrete cracks, is it normal?

Three primary purposes for reinforcing slabs


How Thick Should My Slab Be?
Your slab must be at least 4" thick. It can be thicker and should be thicker depending on the use of your building and slab. For instance if you are working on large heavy equipment a thicker slab and high concrete strength would be more suitable. And likewise, a storage building or studio would only need a 4" thick 2,500 psi foundation.

Slab thickness must be determined by a foundation engineer or your local officials. For ballpark estimating purposes, slabs in the southern half of the U.S.A. tend to be 4 inches while the thickness can exceed 8 inches in northern climates.

Tips for a Successful Foundation

WWR when installed properly provides adequate reinforcement, it is imperative that supports are used. Do not let your concrete contractor “pull?the wires up. For beginner/novice concrete crews we recommend using rebar as your choice of reinforcement.

Cut your foundation control joints in within the first 12 hours. Properly placed and cut control joints will hide and control the cracking of the slab due to shrinkage.

Avoid using a concrete sill notch. This adds unnecessary concrete to your foundation. Ask your Metal Building Supplier to provide you with a formed base angle.


Common Foundation Problems

Welded Wire Reinforcement

Below is a picture of a 4 1/2" concrete slab with welded wire reinforcing (WWR). As you can see the WWR is on the bottom of the slab penetrating only about a 1/4". The WWR should be located between the center of the slab and the top 2 inches. This is a very typical scenario. This slab failed under normal loading conditions and had to be replaced.

Not all Foundations Are Created Equal!

A good alternative would be to use a heavier gauge wire reinforcement with supports. A better solution for beginner/novice crew would be to use a rebar reinforcement, for example a #3 bar @ 18?o.c. It should be noted that WWR when installed correctly is a great reinforcement material. However, it takes a very skilled crew to place it properly.

Concrete Cracks

Perfect concrete without cracks is nearly impossible to find much less achieve. The very nature of concrete is to crack somewhere, it is a mixture of concrete, aggregate, and water. Cracks are generally caused by the rapid evaporation of the water. Most cracks (hairline to pencil lead) are aesthetic at best and present no load failure. However improperly placed reinforcing and control joints are the leading factors to major cracking (3/8" and greater) in which case need to be treated.


There are three primary purposes for reinforcing slabs-on-grade and they are:

Shrinkage Control
Shrinkage control is the greatest design concern with slabs-on-grade. Steel reinforcing along with joint spacing offer two primary elements that can be effective in controlling shrinkage cracks. The most common mistake among designers and engineers is not providing enough of steel reinforcing for a slab-on-grade.

Temperature Control
Concrete is brittle ?it is very susceptible to additional cracking and fracturing by dramatic changes in weather. The change in temperature is commonly referred to as Temperature Gradient. Steel reinforcing offers the best assistance because it essentially has the same coefficient of thermal expansion, thereby expanding and contracting at the same rate as the concrete.

Moment Capacity
Slabs-on-grade design procedures usually provide a designer with the slab thickness. The thickness of the slab is a function of loading, subgrade, modulus of rupture for concrete, and slab stiffness.
As you can there are three primary design considerations for a every foundation:

Steel Reinforcing
Joint Spacing (Crack Control lines)
Slab Thicknes

Having a firm understanding of each and their relationship is key to any successful project.

Types of Reinforcement

There are 3 types of reinforcement that we utilize in our foundation designs:

Rebar is a steel deformed bar ranging in size from #3 (3/8") to #18 (2 1/4") diameter. These bars come in two grades. Grade 40 and Grade 60 Typically all bars over #5 are specified as grade 60 and like wise #4 and #3's are grade 40. Grade refers to the yield strength of the bar. Your only concern here is, that when placing your order your specify the correct grades.

WWR (Welded Wire Reinforcement) is a smooth or deformed welded wire reinforcement that is available in mats or rolls. With its cost efficiency, WWR is frequently the reinforcing steel of choice for slabs-on-grade. However, WWR’s full benefits of controlling cracking and reducing maintenance can only be realized when it is positioned accurately and properly placed on supports. One of the primary causes of under-performing slabs-on-grade is the inadequate positioning or complete absence of supports(1).
Supports are imperative to the accurate use and design of WWR in any slab. This firm will not specify/design nor sponsor the use of rolled wire reinforcement in any of our foundation designs. It is the opinion of our principals in charge that rolled wire reinforcement is the most difficult reinforcement to place properly. It is also our opinion that properly placed (Rolled) WWR happens less than 5 out of every 100 slabs poured. See Foundation Problems for more information.

Mesh Fiber is a synthetic or steel (hair like) fiber reinforcement that is mixed into the concrete at the mixing plant. It offers great reinforcement against (shrinkage) cracking in the concrete. However, a common mistake many make is to eliminate steel reinforcing all together. While this may be acceptable in some scenarios (slab portion), steel is still a must in the footings. The mesh typically cannot handle the heavy service loads alone. A better solution is to use mesh along with WWR and Rebar. Mesh fiber adds about $7-$15 per cu yard of concrete. Mesh is typically used in high performance specs.

(1)Tech Fact 702-R-03, Wire Reinforcement Institute

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