How much weight will overload a floor?

TommyTorpedo

I'm concerned that I might be stressing my little house.

I live in a small Victorian semi. Two rooms and a kitchen downstairs, two bedrooms and a bathrrom on the first floor, and a third bedroom on the second floor under the roof. I run a little business from that third bedroom, so it's an office space and a store for stock. About 1,500 books and a few other bits and bobs. No real idea of the weight, but I'd guess it could top 1,000 kg including furniture. It's fairly evenly distributed,  mostly around the walls and into the eaves where there's some boarded-out space for storage. It's been set up like that for almost four years with no obvious problems.

I've not long set up a new bookcase in the room in a space that was previously unoccupied. Shorlty after, I happened to notice some hairline cracks in the plaster on the floor below, directly below the new bookcase, and it's started me wondering if I'm overloading the top floor?

The cracks may have already been there. There's a busy railway line at one end of my street, and a section of ring road at the other. The plasterwork generally isn't great. There are several plaster cracks around the house that have been there since I moved in.

What do you think? Have a got lockdown fever and I've just spotted some insignificant cracks in an old house that happen to be near a new piece of furniture, or could all that weight on the top floor actually be doing some damage?

weeg

It depends (helpful, right?). Was the space under the roof properly converted in to a room, with a structural engineer's input, or was it just floored out? If the former, it should be ok, the second one, you may have a problem.

Domestic floor loading is 150kg/m2. Eaves storage, not being a room, won't be designed to take this. Usually 25kg/m2 is allowed for attic storage. (for comparison, a library is 240kg/m2). Now, obviously your victorian house was not designed to current building standards, but it's surprising how little has changed in the intervening century when it comes to uk housing.

All of which is a long way of saying, yes, the bookshelves have probably caused the cracks, but, no, it's probably not worth worrying about. The cracks are new stresses, which will redistribute and settle over time. It's just the house hunkering down.

TommyTorpedo

Thanks Weeg, that is helpful and reassuring information.

The room is not a conversion. All the houses of this type in the street were built with an attic room. It doesn't extend right into the eaves, so I had those sections boarded out for extra storage. Hopefully that means the top floor uses decent sized joists.