When it comes to metal building construction in Houston, Texas, it is crucial to include a strong foundation. Because of the different types of soil in the area, several steps should be followed to ensure that the foundation can handle the weight of the steel building, and the proper materials and tools must be used. Using a design build contractor is the best way to make sure you get the correct type of foundation for your project.
Surveying, Plotting and Grading the Site
The first phase of building a foundation during warehouse construction is to survey the location of the building and to plot and mark its boundaries. The ground must then be graded, or physically leveled, to ensure that it conforms to the surveyor’s stakes.
To ensure the structural integrity of your steel building, make sure to use the appropriate excavation method. Minor excavation is appropriate for simple structures and can be accomplished using hand tools. A two-to-three-inch base will generally suffice. For larger, more complex structures, major excavation is generally best, and construction equipment like a backhoe is required.
Your foundation may have a floating slab, or it may have a pier, footing or grade beam that carries most of the vertical load. Regardless of which type you use, make sure the concrete is sufficiently strong and durable. For best results, use a mixture of water, aggregates, Portland cement and fly ash or another admixture. Ideally, the concrete should have a compression strength of 3,000 pounds per square inch after 28 days. Its tensile strength should be strong enough to resist the stretching and expansion of the concrete.
Pouring the Concrete
The next phase in the industrial construction process is pouring the concrete. Metal or wood forms must be placed to hold the concrete while it dries and to help it retain its shape. Drainage troughs should be used to keep water from below from affecting the integrity of the concrete.
While pouring, make sure aggregates have not settled at the bottom. Keep the mixture churning to prevent this issue. Along the way, remove water that seeps up from below.
Screeding and Finishing
Screeding is the process of leveling a floor by pushing away excess concrete. Use a template to move concrete to under-filled areas. Next, use a float made of wood or metal to compact the concrete, and then use a steel trowel to smooth and compact it even more. A steel rake can also be used to add texture if the concrete will be wet or otherwise subjected to slippery conditions.
Concrete cures, or hardens, due to a chemical reaction between water and Portland cement. Ideally, the conditions should be dry, and the temperature should be between 50 and 90 degrees Fahrenheit. This is especially crucial during the first 72 hours of curing time.
Walls and Footings
Foundations consist of walls and footings. The wall, which is a load-bearing structure, is partly below ground, and the footing distributes the weight of the building to the load-bearing components. Make sure to account for the horizontal load weights, which can be accommodated with steel tie bars. You can also increase the size of the footings, but this is a costlier option.
Laying the Floor
The floor of a foundation typically consists of floating slabs or slabs on a grade. Use steel rebar to add strength and to ward off cracks. Prior to pouring the floor, lay down a sheet of polyethylene. This will keep soil water vapor from negatively impacting your foundation. Also, check the local building codes to find out how thick the floor needs to be. Use floor joints between separate pours and components.
Near the end of the curing process, or right after it is complete, use chemicals to waterproof your foundation. This will help to maintain its structural integrity and allow it to withstand the elements a lot more easily.