Weight capacity of residential flooring?

Title really says it all, I’ve often wondered this when I decide to drag something new into my house.

What about commercial floors?

Depends on the building code and the type of building. I think residential wood frame is something like 40# psf for the live load. That doesn’t mean it will only hold 40 pounds in one spot in the room at a given moment. It means it will safely hold 40 pounds over every square foot in the room all at once.

Residential floors are mostly wood framed and it’s not real simple since a certain amount of flexing is allowed and they’ll be much stronger near the walls and over supporting walls and beams. I think it’s around 20-30 pounds per sq. ft. typically. A slab floor will depend on the thickness of the slab but it’s going to be much higher than 20-30 lbs/sq. ft.

Commerical floors will be stronger than that since otherwise they’d limit the value of the building. I think residential garage floors have to support 40-50 lbs/sq.ft., and commercial building floors may be at least that. I remember looking for commercial space and being told ratings up to 1000 lbs/sq.ft. at industrial sites.

American Wood Council

Living room floors - 40 lbs/sq.ft.
Bedroom floors - 30 lbs/sq.ft.
Attic floors - 10 lbs/sq. ft.

It’s more detailed than that and local codes will vary.

When water beds were the craze, a lot of pre-existing apartments prohibited them because they exceeded the weight capacity of floors that were not designed with such a load in mind.

You should also consider the hardness/density of whatever floor covering is installed.

Solid 3/4" white oak is a bit better than sheet vinyl, for instance.

I was pondering this, having just put laminate flooring in our lounge. We have storage heaters which weigh about 300lb each and rest on two feet maybe 6in by 2in each. After heaving the heaters back into place the floor seems OK but you can see it dips a small amount if you look along the bottom of the skirting board. I wonder if it will cause the joints to fail in time.

That’s the point I was going to make. I can’t think of many things* you’re going to put in your house that are going to fall through the floor. The bigger risk is leaving marks as you drag it across certain types of floors. For example, I have some marks on my linoleum from where I’ve moved my fridge once or twice.
On Ask This Old House, when they deal with sagging floors, Tommy will sometimes mention that the worst area is by the fridge. Not only do you have the weight of the fridge and it’s contents, but also 150-200# of person standing in front of it. It’s not a big deal in a newer house, but in a hundred year old house when some of the joists start to crack, you can end up with part of the floor an inch or two lower.

As long as everything is structurally sound, I wouldn’t be too worried. Remember, even though things look big, most of them are empty shells. Washing machine, dryer, oven etc, not that heavy. A bed is spread out over a big area. The heaviest thing you probably have is a couch, especially since you might have 3 or 4 people on it at a time. Also, all these things are usually near walls where the joists are going to sag the least.

*The big thing I can think of, off the top of my head that might cause a problem is an aquarium. My 40g tank, with water, rocks, the tank and stand is probably a bit over 400 pounds and isn’t a problem. I have a 100g tank that I may use some day and that one would be closer to 1000 pounds fully loaded. If I use that one I plan to put some lally posts in the basement to keep the joists from being able to move. On one of my fish advice forums someone was looking into getting a 600g tank and the advice from other members was to have an engineer come out and look at the house. As someone said, that’s like parking a Dodge Ram in your living room.

Like parking a Dodge Ram in your living room… on end.

You should be fine with the 100 gallon tank against wall.

Yes, it would be concentrated on a smaller spot.
As for my 100g tank, it would (probably) end up with the short end against a wall and running parallel to the joists.
Either way, lally columns are pretty cheap. My plan, if I did it, is to cut a few pieces of plywood, the same size as the tank, screw them into the ceiling under the tank and use (I’m thinking) two lally posts to push up on the plywood, with them under a joist. I’d put them there before the tank is filled and with just a bit of tension. For a hundred or so dollars, IMO, it’s worth the money. This would insure that the floor can’t flex at all, or at least not much. 1000 pounds is a lot of weight and a lot of water to gamble with.