Too much weight on 2nd floor

I have a 2 garage unit above which there are 2 rooms. There is no wall separating the garages.
My tenant wants to put some very heavy structures in these rooms, im getting worried about the flooring giving away and collapsing.
The unit is around 20 years old.
She wants to put roughly about 600 lbs of weight upstairs.

A rough sketch of what I mean.

     RM1   |  RM2
|                             |
|    G1            G2    |
|                             |

G1+G2 = ~ 20 ft

Is there any web site where I can get more details on the construction or strength testing process?Or is there a
procedure I can invoke to prevent her from putting too much weight on these rooms, some clause in law or something?

What you’re really wanting to find out is how much distributed weight your floor will hold. I distinctly remember my high school science teacher discussing this. Back in the 80s when waterbeds were popular, some people were worried their floors wouldn’t hold them. We calculated it out. Basically if the floor was strong enough to support someone standing on it, it was strong enough to support the waterbed. So the real matter is how much of an area the 600 lbs will be distributed over.

There is also a big difference in “dead” load and “live” load. Another huge factor is where the weight will be, as stated above. If you are putting a 600lb weight set right in the middle, you should have someone help you with the calculations as this would be a dead load at the weakest point in the floor.

A 600lb weight set in the corner should be no problem.

600 lbs of regular furniture scattered throughout the room is no big deal either.

Also, 600lbs, albeit too heavy to lift, is not much weight when talking about properly built structures.

In any event, make a nice pencil drawing of your veiw from inside the garage, measure the distance of all the “spans” and measure the size of the floor joists that are over your head. Also, measure what the garage walls are made of where the floor joists rest. (2x4 or 2x6 probably)

Take all of this to your local lumber yard and tell them exactly what you are placing above and ask them if you’ll need additional support.

They have a book that tells them the load capacity of all the puzzle pieces in your structure and can give you a more reliable answer than we can from your comments above.

Good luck! Do the above and you’ll sleep better at night!

Don’t forget your insurance requirements. If something happens because they put too much weight they may not like the answer that you checked with your local lumber yard and they said it was ok.

If you can’t check with someone licensed and bonded I would suggest you deny their request. Another option would be ask them to pay for the assessment.

And the other thing to consider is that they can claim they asked you and you approved it. This may leave you without any recourse if something happens.

Having said that, I agree with JasGot - 600 lbs is not that heavy - 4 people will weight that much. Can you have them scatter the weight throughout the rooms?

Hope this helps. Good luck!

If you are worried about it, just tell her she can’t do it.

Installing a beam across the the center to support the floor would be inexspensive and easy. Lumber, Galv Hangers, and Screw Jacks. From the diagram it looks like the walls are in the center and should assisit in keeping the load distributed. Also 600 lbs. doesn’t seem like alot of weight three people on a couch would equal that.

I just Google’d (Architecure Forum) and found a bunc of forums maybe someone there could help you.

600 pounds is nothing, if you have a house that is only 20 years old it is built to hold a lot more weight than that. I had a house that was 80 years old and spanned around 17 feet that held about 40 people in my living room. Minimum about 6000 pounds, no problems and it didn’t have modern joists.

If you are worried about it don’t let her do it. Or you can always put 2, 2x4s on edge screwed together with a couple 2x4s under it. Makeshift wall like this could support a lot of weight.