Had floors been constructed using frame beams and planks only, you would never have such strong and stable buildings.
That’s because the hollow space between the beams would make the floors unstable, causing premature damage and crack formation with time.
That’s why, to ensure structural integrity and optimal strength, constructors place joists between the parallel beams and planks.
These not only provide support to the overlaying construction materials like concrete or tiles but also enhance the structure’s stability by several notches.
In other words, they bring a lot of benefits to the table. But only if you get the floor joist spacing correct! No matter which joist design you choose, incorrect gaps between the planks will lead to instability and can further weaken the structure.
That’s why most constructors pay special attention to this attribute while designing and forming the joist structure. Having said that, we have compiled a detailed guide on how to get the floor joist spacing correct without any flaws.
Table of Contents
Why Does Floor Joist Spacing Need to Be Considered?
Load Distribution and Structural Strength
- Joists are added to improve the structural strength of the floors. They distribute the weight of furniture, appliances, occupants, and other things evenly, thereby creating a proper balance.
- However, if you design a structure with too much spacing, the load won’t get distributed evenly. It will lead to sagging with time and even sudden floor failures.
- Similarly, narrowing the floor joist space can lead to increased costs due to more usage of the materials.
Building Code Compliance
- It’s essential for every construction company to adhere to the building codes throughout the project’s timeline. If not, there could be issues with legal and compliance check departments.
- Now, as a standard rule, residential buildings should have a floor joist spacing of 16 inches right at the center.
- Failure to maintain this gap will cause issues in the inspection and might incur heavy fines.
Material Efficiency
- If you don’t get the floor joist spacing correct, material wastage and inefficient use will be inevitable.
- Solid hardwood lumber and engineered planks are mostly used to construct the structures. Sometimes, metal beams can also be used. Regardless of what material it is, incorrect spacing will lead to more use of the raw materials. It will further increase the overall project budget and lead to material wastage if present in excess after the joist construction is over.
- Also, if you don’t get the spacing correct, you will have to readjust the plank dimensions, which will introduce unnecessary delays.
Floor Stability and Vibration Handling
- The main purpose of a floor joist is to add stability to the entire structure by bridging the hollow space between the support beams. Now imagine the joist planks having more than adequate gaps between one another. There is no way they can deliver the expected stability to the floor’s structure.
- When the floor joist spacing is way above the recommended grade, it makes the floor bouncy and unstable. Any sudden movement from the above will cause squeaky sounds. Vibrations will also travel much longer instead of being dampened due to the hollow space between the planks.
- Correct spacing in the joist framework will prevent these unnecessary hassles and stabilize the entire structure. Whether you want thermal or acoustic insulation, it will live up to your expectations with ease.
What Tools You Need to Measure the Floor Joist Gaps?
First, gather all the necessary equipment you will require to measure the floor joist spacing. At least then, you won’t have to make round trips to your inventory and get the missing things while working.
Below is a list of basic tools you should have at your fingertips before starting to measure the joist spacing.
- Tape measure with at least a length of 25 feet
- Framing plans of the concerned architectural building
- Carpenter’s pencil or chalk line for marking
- Speed square as an optional tool for marking
How to Measure the Floor Joist Spacing Correctly?
Checking the Building Plans
- When construction drawings are prepared, architects and engineers specify the recommended floor joist spacing. Referring to the same will help you determine how much gap to keep between the adjacent planks. Plus, it would eliminate any risks of potential miscalculations just because you referred to assumptions rather than using correct data.
- For floors to have heavy loads like appliances and colossal furniture items, the recommended spacing between the joist planks is approximately 12 inches in the center.
- Standard residential floors should have 16 inches of space between the adjacent planks or beams in the joist structure.
- For floors where lighter loads will be kept, the spacing can be increased to 24 inches, but not more than this.
Locating the Starting Point
- Start with a particular end of the joist system, preferably the outermost or the rim joist. It will help you move accordingly and take measurements with higher accuracy.
- Your first job will be to ensure the rim joist has a perfect square shape. Additionally, check if it has been aligned accurately with the structural beam or not.
Measuring and Marking Joist Points
- Take the measuring tape and mark the positions where the other joist planks need to be placed. Ensure the markings are done along the rim joint and the ledger board only.
- For the standard 16-inch on-center spacing, follow the technique below.
- The first joist should be marked at 1.5 inches with respect to the outermost joist.
- The subsequent positions to be marked will be at 16, 32, 48 inches, and so on.
- Check the markings from the other end also to ensure they are accurate with no discrepancy. You can also stretch the chalk line for extra precision.
- Also, ensure the floor joist spacing is aligned with the load-bearing areas, electrical conduits, plumbing lines, and HVAC lines.
Wrap Up!
Ensuring correct floor joist spacing is more than a necessity; rather, than standard practice. Failure to do so will lead to structural instability, compliance issues, and so on.
That’s why you have to be more precise and careful while taking the measurements so that you can maintain the recommended spacing as per the building plan.
