What is the cheapest floor structure?

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With the soaring cost of building materials, developers, builders, and contractors want the best floor system to build faster/cheaper for their projects. Luckily, you have options! Read on!

Moxy Hotel – Omaha, NE. Picture courtesy of Hawkeye Hotels and New Generation Construction (NGC)

A floor framing system is a set of structural elements that supports a floor and can be a truss spanning between walls, concrete slab supported by columns, series of 2x10s wood beams with wood sheathing on top, or any of a dozen other systems.

Many factors go into choosing a floor system, but here are a few of the most important ones:

• Cost
• Level of Prefabrication
• Applicability
• Performance

Let’s dive in!

Costs

The square footage and labor rates in your area will influence prices. When it comes to cost, wood would be the cheapest, followed by metal, then concrete, but this can also differ by location!

*Highly volatile prices subject to geographic changes.

• Wood is frequently chosen if the construction type permits it. Typically for most markets, wood is the cheapest option. Either as a truss system or with I-Joists, wood floor systems are the best choice when your goal is to save on cost.

Level of Prefabrication

As you already know, prefabrication is the practice of assembling components of a structure in a factory or other manufacturing site and transporting complete assemblies or sub-assemblies to the construction site. Here are some of the most commonly used floor systems:

• Wood 2x: Wood dimensional lumber
• Wood Trusses: Trusses made from dimensional lumber
• Wood I-Joists: Wood I-Beams with engineered lumber flanges and OSB webs
• RC Slab: Reinforced concrete slab
• Hollowcore Plank: Precast concrete slabs with prestressing strands and voids to reduce weight
• Precast Double Tees: Precast concrete “T” sections
• PT Slab: Post-tensioned concrete slab
• Steel Joists: Trusses made from steel sections and rod
• Light Gauge C-Joists: Thin steel-shaped sections
• Long Span Steel Joists: Trusses made from steel sections
• Composite Deck: Steel deck topped with a layer of concrete
• Cold-Formed Steel Trusses: Trusses made from high-quality sheet steel

Most of these systems can be prefabricated. Here are the levels of prefabrications:

As shown above, Panelized Modular Floor Systems will help with how fast your development can be completed, as the more prefabricated the system, the shorter the overall built time.

• You can “panelize” some of these floor systems, which makes them have a higher level of prefabrication.
• The great thing about prefab is the higher the level of prefabrication, the smaller proportion of site labor is of the overall cost.

For example, wood trusses are prefab, but they aren’t really a floor system. They still need sheathing installed, which is all site-completed.

https://www.base-4.com/build-apartment-walls-in-a-factory/

Applicability & Performance

The limits of each material are also a factor that you need to consider.

• For instance, a hotel is typically limited to four stories, so the building can be wood constructed as Type V-A is very cost-effective.
• A 5-story building can be accomplished with Type III-B construction or a podium with type V-A above.
• Once over six stories (without podium), you are more limited and need to go with steel or concrete or both in construction types I & II.

Our team works with developers and general contractors to rethink traditional building methods by infusing innovative technology, forward-thinking design, and offsite manufacturing principles to build projects CHEAPER and FASTER!

We perform all services in-house, including architecture, structural engineering, MEP engineering, interior design, 3D BIM visualization, and construction administration. The BASE4 team has worked around the globe, providing a wide range of expertise in quality standards, specifications, and international best practices for design.

Thank you,

Blair Hildahl
BASE4 Principal
608.304.5228
BlairH@base-4.com

There are different types of floor structures – timber floor trusses, Ibeam floor joists, timber floor joists, reinforced concrete panels and other solutions. But which one should you use?

What is timber floor trusses?

Timber trusses used for floors is a structure that uses timber beams connected with metal plates. You can use timber trusses without load-bearing walls with up to 9m in length. Trusses are manufactured from spruce C24 timber. Those are manufactured using computerized saws and presses, which ensures very precise and fast production.

Advantages:

• Lower total cost.

• Short assembly time.

• Easy to install wiring, pipes, air ducts and other communication systems

• Easily customizable for each individual project

• Durable and ecological building material

The main advantage of using timber trusses for floor structure is that truss systems do not require additional structural support, which generally reduces construction costs.

The other key factor is the high quality and precision of the trusses, which are manufactured in a factory and custom-made for each project, thus minimizing the risk of error. Wood floor trussing provides easy installation and maintenance of plumbing, drainage, ducting and wiring since no holes for communication are required, which is why plumbing, heating, ventilation and electrical contractors love to work with timber floor trusses.

Timber floor trusses compared to timber joists and Ibeam joists

Timber joists have been by far the most common, traditional and also the cheapest type of floor structure, but one of the biggest downsides is limited span. Therefore, choosing this floor structure requires additional support or load-bearing walls. In addition, setting up the communication system will be a much more complicated process. In addition, it will take more time to install communications and most certainly will cost more.
A similar situation is with the Ibeam structure. It will require additional work to install wiring, pipes, air ducts and other communication systems.

The cost of floor structure from timber trusses is usually a bit more expensive, but the triangular interior structure of truss provides greater durability than the Ibeams, which means the floor overall structure will be more resistant to common problems such as structural offset or creaking flooring.

Beam and reinforced concrete structure for the floor

The cost of this structure is relatively higher than other types, but the installation of joists and reinforced concrete panelling is easy, significantly saving on labour costs.

Standard reinforced concrete beams usually reach up to 6 m, rarely 12 m, without additional support. Manufacturers often also offer customized beams. The joists and reinforced concrete slabs do not deform and the main advantage of this system is the high strength, which is very suitable for high-rise buildings.
It should be taken into account that this system is unsuitable if the floor is smaller than 50m2, because the installation requires special equipment, therefore this solution is most suitable for large projects and new buildings.

Factors to consider when choosing floor structure

Cost and installation.  Most often, the total cost and time spent on a project determine the major role in decision making. Despite the fact that the cost of a timber truss system is a bit more expensive than a timber joists and Ibeam joists, the truss has a significantly higher installation speed, taking into account communication installation and other related work, and thus the overall cost of the project is more cost-effective.

Communication installation. It is important to evaluate in a timely manner how and where all communications (cables, pipes, etc.) will be installed and which type of coverage will be most appropriate for the installation of communications.

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