Pre-Construction Work

The construction of steel or metal buildings doesn’t differ much from the construction of other buildings. Everything begins with a sturdy foundation.

Before pouring the foundation, your contractor will have to ensure the land on site has been surveyed by a professional to make sure its level. The steel building manufacturers must also be aware of the plot’s dimensions.

When the site is marked and surveyed, the physical leveling or grading process can be started. This part of the pre-construction work involves morphing the shape and height of the land to meet the needs of the building.

After the entire site has been leveled per the requirements of the surveyor, you can start excavating to pour the foundation. It’s best to speak with a foundation engineer to determine what excavation type will be required. Many metal structures with simple designs only need a minor amount of excavation, however, more complex models require something deeper. Your building supplier will provide you with the building reactions that the foundation engineer can use to design the appropriate foundation.

Steel rakes, shovels, pickaxes, and other simple tools can be used for shallow excavation. Bobcat shovels, backhoes, and other larger pieces of equipment will be needed for major excavation needs.

Don’t forget to hold onto some of the excavated dirt. It might come in handy in the near future for leveling the building or final grading. You might also need some of that earth for in-filling and back filling once the construction is complete.

Departments of Consumer Affairs on the state level, the Occupational Safety and Health Administration, and other governmental organizations lay out strict requirements when it comes to pouring concrete slabs.

Following these strict rules will make sure that your building is built soundly and that it is legal.

There are also beneficial safety guidelines laid out by these departments for any laborers that are involved in the process of laying down concrete foundations. Always make sure the workers are protected and safe during this process.

Slab

Slab foundations consist of poured and reinforced concrete. Both serve as the floor for the building and as the base to ensure a secure erection. Heavy bearing walls may have to be used around the entire perimeter of this slab and in other areas. If so, excavation must be a little deeper in order to provide the footings with stability. Slabs typically have a thickness of 3.5” – 5.5”.

Curb

Curb foundations only require reinforced concrete to be poured around the perimeter. Similar to street curbs, curb foundations stand a few inches above the grade and offer a secure base for the external walls of the structure.

Extra excavation can take place within the curb in order to offer a crawl space below the foundation if it’s within the owner’s preferences and if the land allows for it. Whenever extra curbs are created within the original curb to support weight-bearing walls, it’s called a “ribbon” foundation.

Floating Slab

Floating slabs are a combination of curb and slab foundations. They’re some of the most commonly used foundations in use today for a myriad of construction purposes. When the structure is being built on a relatively flat surface, a foundation curb with footings is going to be poured primarily. While that’s being set and cured, another slab is made within the perimeter of that curb. This functions as the ground floor for the structure overall. If done properly, floating slaps should help reduce cracking typically caused by settling.

Pier

Pier foundations give a building foundation through the use of individual piers (footings) which are set evenly throughout the perimeter of the structure. Typically, a pier such as this will be formed with reinforced concrete that’s been set deep below the ground to hit undisturbed dirt. Although they’re not recommended to be used for larger buildings, these pier foundations can be handy for smaller buildings like small shops or storage units. Speak with your engineer to hear about the individual pros and cons of using this type of foundation.

Ingredients

It’s important to choose the right ingredients when mixing concrete. This can determine the lifespan of your new structure. Concrete should always be durable and strong. Portland cement, gravel, sand, and water are the fundamental ingredients. Water retardant, fly ash, and other admixtures can be thrown in to help strengthen and cure the concrete.

Strength

There are two ways to describe the strength of concrete. Tensile strength refers to the concrete’s ability to resist expansion or stretching. Reinforcing bars made from steel can be used to boost a concrete foundation’s tensile strength. The other measurement of strength is called compression strength. This is a measurement of the total time a concrete foundation takes to cure entirely.

Mix

Concrete’s normal compression strength reaches 3,000 lbs. for every square inch within 28 days. In order to reach this ideal strength, the right mixture proportions have to be reached.

Forms have to be built before any concrete gets poured. Just like other forms used in construction, the concrete gets held together in desired shapes until drying completely. Forms are typically constructed from 2x4s although some people prefer using metal. It only matters that the forms are rigid and strong enough to not budge from the pressure that drying cement produces. Any deflecting, bending, or deforming is bad.

Concrete has to be spread evenly to ensure that any aggregates don’t settle at the bottom. The concrete mixture must always be kept spinning to keep it from hardening. Double-check to make sure all of the air bubbles and voids have been removed and that the rebar is covered completely. For larger projects, some people opt to use a pneumatic or electric vibrator to guarantee that all air is taken out of the cement before it’s poured.

If you have to pour a deep foundation, keep in mind that water will sometimes rise to the top because of the pressure caused by gravel and sand. Latinate is the name used for this bleed-water and it has to be taken away once it arrives at the surface.

The process of removing excess concrete from the slab once it’s poured is known as screeding. Typically, you’ll end up pouring a little more concrete than the project requires. Once you’ve ensured that all of the necessary areas are filled, you’ll have to remove the excess concrete so you’re left with an even and flat surface. Large metal or wooden boards called screeds are taken across the top of every form. Two people are usually needed to perform this job. Excess cement just gets thrown down at the end of each form. It can be left to dry and simply removed during the cleanup process.

There are usually two steps involved in the finishing process. Step number 1 is to use large metal or wooden tools known as floats to force bigger aggregates down deeper into the mixture. These float tools are pulled and pushed around until the surface is smooth and even. The concrete is still going to be pretty wet.

After the rising water has been evaporated and the mixture allowed to rest, the second portion of the finishing process can begin. This is accomplished with steel trowels. These tools are used to create an even smoother surface on top of the mixture. Metal rakes will be taken to the concrete slab if it will be used outside in order to prevent slipping when it gets wet.

The Portland cement and water produce a chemical reaction that helps to cure and dry the cement. Moisture and temperature also directly impact the durability and strength of the concrete. The ideal weather conditions for creating a perfect slab of concrete is around 50 or 90 degrees Fahrenheit. Once 72 hours pass, the concrete should be sturdy enough for further construction.

You’ll have to take extra precautions and prepare something unique if you’re pouring the concrete in an area that experiences cold weather regularly. The same is true for areas that experience very hot weather. Concrete foundations that don’t settle properly could lose up to half of their strength and cohesiveness over time.

Footing and walls are the two primary components of which concrete foundations are comprised.

Footing

The footing of a foundation refers to the structural units that require extra reinforcement and excavation. The purpose of footings is to help distribute the structure’s overall weight to materials designed for bearing large loads.

Wall

Foundation walls are just concrete walls that have been poured to extend below and above the ground level. These walls are load-bearing to help serve as extra support for the columns and walls of the structure.

While steel constructions don’t produce much vertical load, there are a lot of horizontal loads that need to be accounted for. This tends to force pressure and weight outwards. If the loads can’t be distributed properly during construction, structural failure can result in the framing or the foundation. Fortunately, there are a few common methods for distributing and resisting horizontal loads:

Tie Bars

The first strategy recommends connecting steel tie bars to anchor bolts. This helps connect the columns of the building together for an evenly distributed load. For instances when the building’s horizontal load isn’t so high, hairpin or spread ties could be used to put the load onto the rebar that was used when making the floor.

Enhance Footing Size

Through this method, the horizontal load is counteracted and any chance of the foundation shifting is prevented. While this solution is effective, it is also more expensive than the other choice.

Slab

The majority of building installations have a floor that’s created through the pouring of a concrete slab. This happens within the walls of the foundation. The slab can either be poured when the foundation walls are built or once they are finalized. To avoid cracking and add strength, reinforcing bars made of steel are sometimes used in the floor as well. Concrete that’s resistant to cracks and rebar should also be used for buildings where heavy vehicles or machinery will be used.

Vapor Barrier

Visqueen, or a polyethylene plastic sheet, should be laid down on top of the surface where the slab of concrete will be poured before any pouring actually beings. This helps to prevent any water vapors from getting into the floor and allows for a better curing process.

Thickness

Each floor’s thickness will be dependent upon the loads it will have to bear over time. Normally, the thickness of a slab is equal to that of a 2×6 or 2×4. However, there are some buildings that require even thicker dimensions. Some jurisdictions even have requirements when it comes to a floor’s load-bearing capabilities and thickness. It’s always important to check your area’s building codes before starting the process.

Joints

Many concrete joints have to be placed between concrete pours or between other construction components. Expansion joints are often placed in areas where normal contraction and expansion takes place. This helps the floor withstand some normal movement in the concrete. When the concrete is being cured, it might shrink a little bit. During this time, the expansion joints will help to keep the concrete floor from falling apart and cracking. In the future, the joints will do the same when temperatures fluctuate and the floor contracts and expands.

Waterproofing

When the curing process is underway, it’s advisable to use some waterproofing substance in order to prevent any further intrusion of moisture. The best type of application technique and substance to use will depend on what the building is used for.