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Floor Truss vs Floor Joist: What’s the Difference?

Floor truss vs Floor Joist

If you’re looking at replacing your floor supports or are building a new house or just want to know more about the designs inside your home, learning about floor trusses and floor joists is a great place to start.

Both refer to the supports underneath the floors in your home, and while they’re similar, they provide support in different ways. There are advantages and disadvantages to either option, so you should know about each one before you decide.

This guide breaks down everything that you need to know about floor trusses and floor joists. Whether you are simply looking to learn more or need to make a decision for your home, you’re in the right place.

flooring divider Overview of Floor Truss

open web floor trusses
Image By: mooreway, Pixabay

Floor trusses aren’t quite as popular as floor joists, but they could still be the best choice for your home. They have a triangular design to provide additional support, and this gives them a multitude of advantages over traditional joist floors.

Here, we go over the advantages of floor trusses and why they’re not the most common type of flooring support in homes today despite those advantages.

How Floor Trusses Work

You’ve likely seen how a truss system works, even if you never noticed or seen a floor truss. Trusses are the go-to design for roofs. Each side supports the other due to the triangular design pushing them together.

This design provides maximum support because it evenly distributes the weight of everything across each beam and to the exterior pieces.

Trusses are also common for bridges because they need extra load-bearing support.

When You Want a Floor Truss

If you have extra money to spend when installing supports for the floors in your home, there’s no doubt that floor trusses would be a good choice. They last significantly longer than floor joists and perform better.

They have a higher load-bearing capacity, bounce less, and warp less over time. This latter tendency makes them ideal if you plan on installing tile floors.

Floor Truss Costs

While floor trusses use fewer materials than floor joists, they cost more because you can’t get generic ones for a project. Every floor truss is custom made, and this significantly drives up the cost. It takes quite a bit of skill to build floor trusses. Labor is expensive and skilled labor even more so.

  • High load-bearing capacity
  • Long-lasting
  • Bounce resistant
  • Expensive
  • Low fire resistance


divider 1 Overview of Floor Joists:

house floor trusses and joists
Image Credit: ungvar, Shutterstock

Floor joists are the most common type of flooring support that you can find in homes. They consist of horizontal wood beams that support the rest of the flooring materials.

Here’s why floor joists are so popular and when they’re the best choice for your home.

How Floor Joists Work

Floor joists have a basic design compared to floor trusses. They are simply horizontal wood beams that run under the floor, and the floor sits on top of the joists.

Each end of the floor joist connects to the wall, and this is where they draw their support. Long floor joists require a support beam to provide the necessary load-bearing capacity that you need from a floor.

These additional support beams often form an “I-joist,” which gets its name from the fact it has the appearance of a capital “I” when it’s all together.

When You Want Floor Joists

The advantage of floor joists comes down to the price. Floor joists come premanufactured, which saves money on labor costs. This makes floor joists the most popular choice by far when it comes to flooring supports for homes.

Also, floor joists take longer to burn through than floor trusses, which is why fire departments prefer this type of flooring.

Still, it’s worth noting that even if they don’t last as long as floor joists, by the time flooring trusses would collapse, there would likely be many more concerns that could lead to fatalities.

damaged floor joists
Image Credit: AL Robinson, Shutterstock

Floor Joist Costs

Manufacturers can use premade floor joists on their projects, which enables them to save money on labor costs. This drives down the cost of the project overall, enough to completely offset the cost of the additional materials that floor joists require. In the end, floor joists cost significantly less than floor trusses.

  • High fire resistance
  • Cheap installation cost
  • Low load-bearing capacity
  • Don’t last as long
  • Not that resistant to bouncing

divider 1 Other Factors to Consider

While floor trusses are the most expensive option, this doesn’t take a few different factors into consideration. First, if the price of lumber continues to skyrocket, that will certainly help offset the cost, since trusses use less wood.

Second, floor joists don’t last as long as floor trusses. That said, floor joists still do last a long time. If you’re building a new home, it’s unlikely that you’ll need to replace either in your lifetime.

But if you’re looking at the long-term sustainability of these options, floor trusses are the way to go.

When Do You Need Floor Trusses?

The truth is that you don’t strictly need floor trusses, but there are times when you should strongly consider them, such as when you plan on installing a tile floor above the subflooring.

Floor trusses withstand warping better than floor joists. Tiles need a level surface; otherwise, they can crack. Floor trusses are better for this job than floor joists.

Still, it’s possible to install a tile floor over floor joists; just know that you might need to do more work during the tiling process.

floor joists repair
Image Credit: Marso, Shutterstock

I-Joist vs. Floor Truss

If you’re looking into floor joists, one term that might come up is the “I-joist.” This refers to a specific type of joist. An I-joist has a support beam going across a section of the joist, and this beam provides more support for the floor.

Most flooring joists today use an I-joist design because of the additional support. However, if you’re providing flooring supports for a much smaller building, you might not need I-joists.

Advantages of Floor Trusses
  • Last longer
  • Higher load-bearing capacity
  • Less likely to warp
  • Less likely to “bounce”
Advantages of Floor Joists
  • Lower cost
  • Higher fire resistance
  • Easier to install

flooring divider Conclusion

Whether you’re considering flooring joists or flooring trusses for your home, they’re both great choices that can provide plenty of support. Now that you know more about both, you can make an informed decision about which one is better for your home.

Before you decide, though, we highly recommend getting quotes for both options so you have all the appropriate information.

Featured Image Credit: (L) Piqsels, (R) Craig Russell, Shutterstock


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