Maximum load - floor joists

In summary, the speaker is remodeling a recently purchased home and plans to add a pool table to an upstairs game room. They are considering reinforcing the floor joists by either gluing and nailing another joist or adding an additional joist in between. They are unsure which option would be better and are looking for a way to calculate the appropriate span for their sistered 4x6 joists at 8" OC spacing. The speaker also mentions concerns about the previous owner not reinforcing the ceiling joists properly. They are seeking advice on how to calculate the appropriate span and ensure their work meets current building codes.
  • #1
kyra
1
0
Hi everyone,

I am remodeling a recently bought home. One of the upstairs rooms is a game room and I plan on putting a pool table (1000 lbs) in it.

The original floor joists were 2x6 16" OC - I glued and nailed another joist on to existing joist - so now it is 4x6 16" OC. If I would add another joist in between, that would make the joist system 2x6 8" OC. The joist span is 13'.

I wonder which one would be better, that is, 4x6 16" OC vs. 2x6 8" OC.

How can I find out since there are no calculators I can find online that will allow me to get the appropriate spans as a function of sistered 4x6 joists or at a spacing of 8" OC?

The thing is the former owner added a second story, but did not reinforce the 2x6 ceiling (floor for the 2nd floor) joists. He simply laid 2x4's perpendicular to the "ceiling" joists 16" OC and used a single layer of tounge and grooved 3/4" floor boards. Upon inspection there are many places where the crossing 2x4 do not even tough the underlying joists.

The rest of information: Southern Pine grade #2; dead and live load of 10 and 40, respectively; L/360 deflection.

Maybe you could help me with an exact answer or tell me where should I look to calculate myself.

Thanks in advance!
 
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  • #2
If you are remodeling a purchased home, one thing I would watch out for is that, even though you did not do the work, since you are redoing things, you are responsible to bring it up to current code for your area. If you have any permits, you'll have to clear those and I would imagine that structural is part of that.

Honestly, I would see what code is in your area and do your best to get to that. Especially if it was done incorrectly the first time.

You'd be best off to get to a 2x8 with 16" centers, or even 12". But it sounds like you don't want to tear everything up. The beam's stiffness is more influenced by the height than the width which is why it should be a 2x8 preferably.
 
  • #3


Hi there,

First of all, it's great that you are taking the necessary precautions to ensure the safety and stability of your game room. It's important to properly calculate the maximum load for your floor joists to avoid any potential structural issues in the future.

In terms of the two options you mentioned - 4x6 16" OC vs. 2x6 8" OC - it really depends on the type of wood and grade of the joists, as well as the specific dimensions of your room. Without knowing these details, it would be difficult to provide an exact answer. However, there are a few things you can do to determine the appropriate span for your sistered 4x6 joists or 8" OC spacing.

One option is to consult with a structural engineer or building inspector. They will have the expertise and knowledge to accurately calculate the maximum load for your specific situation.

Another option is to use a joist span calculator, such as the one provided by the American Wood Council (https://www.awc.org/codes-standards/calculators-software/spancalc). This calculator allows you to input the type of wood, grade, span, and spacing to determine the maximum load for your joists. Keep in mind that this is just an estimate and it's always best to double check with a professional before making any structural changes.

In terms of the existing 2x6 ceiling joists, it sounds like they may not be strong enough to support the added weight of the game room and pool table. Adding the sistered 4x6 joists or 8" OC spacing may help, but it's important to also reinforce the ceiling joists if necessary. Again, it's best to consult with a professional for a thorough evaluation and recommendation.

I hope this helps and good luck with your remodeling project! Safety should always be the top priority when it comes to structural changes in a home.
 

1. What is the maximum load that can be supported by floor joists?

The maximum load that can be supported by floor joists depends on a variety of factors, including the type and size of the joists, the spacing between them, and the type of flooring material. Generally, a residential floor joist can support a live load (weight from people and furniture) of 40 pounds per square foot (psf) and a dead load (weight from the structure itself) of 10 psf, for a total maximum load of 50 psf.

2. How do I determine the maximum load for my specific floor joists?

To determine the maximum load for your floor joists, you will need to consult with a structural engineer or refer to building codes and standards specific to your location. These codes take into account various factors such as the span of the joists, the type of wood used, and the type of flooring material. Additionally, the size and spacing of the joists will also affect the maximum load they can support.

3. Can I increase the maximum load of my floor joists?

In most cases, it is not recommended to increase the maximum load of floor joists. Doing so can compromise the structural integrity of the joists and potentially lead to collapse or other safety hazards. If you need to increase the load-bearing capacity of your floor, it is best to consult with a structural engineer or contractor to determine the safest and most effective solution.

4. What happens if I exceed the maximum load for my floor joists?

Exceeding the maximum load for your floor joists can result in structural damage, sagging or bowing of the floor, and even collapse. It is important to follow building codes and guidelines to ensure the safety and stability of your home or building. If you are unsure about the load capacity of your floor joists, it is best to consult with a professional before making any modifications or adding heavy items to the floor.

5. How often should I have my floor joists inspected?

It is recommended to have your floor joists inspected by a professional every 5-10 years, or whenever you notice any signs of damage or wear. Regular inspections can help identify any issues with the joists and prevent potential problems that could compromise their load-bearing capacity. It is also important to have your joists inspected after any major renovations or changes to the structure of your home or building.

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