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wtchywmn9
Wall mounted book shelves vs bookcases - structural question

Last year I moved into a house that was built in 1920...2 story colonial. Plaster walls. Hardwood floors. 9 ft ceilings. It's a beautiful house.

I literally have a few tons of books. Most of them are currently shelved in floor-to-ceiling bookcases in one of the upstairs bedrooms. The bookcases are along 3 of the walls. The 4th wall spans the downstairs ceiling, and I didn't want to run the risk of cracking the ceiling plaster downstairs, so that wall doesn't have bookcases.

I've recently noticed thin but long cracks in the plaster running perpendicular to the ceiling on the walls that have the bookcases. Most of the cracks are a few inches from the ceiling. One of the walls backs onto the stairway that goes to the attic. There's also a new crack in the plaster on the stairway wall...this one is lower down, and running perpendicular to the floor.

I think it's safe to assume that the cracks are from the weight of the books. Luckily, there aren't any cracks showing on the downstairs ceiling.

What I was wondering was would it be better to use wall-mounted shelves instead? They would be anchored on the studs that run under the plaster. Would the studs bear the weight better than the floor? That would take the weight off the floors, but would it still cause cracks in the wall?

Thanks.

WW

dj1
Re: Wall mounted book shelves vs bookcases - structural question

If you are talking massive weight, you will need to beef up your wall framing. When I once built a library in a custom house, I remember doing all 2x6 studs with 1/2" 5-ply plywood.

Mastercarpentry
Re: Wall mounted book shelves vs bookcases - structural question

That's a LOT of weight and my guess is that the 'library' floor is beginning to sag from it. Based on the design of the bookcases and the layout of the wall studs you might be able to transfer some or more of the load to the wall behind which would help considerably. You'd want to do that upgrade with the bookcase you're working with empty.

This is more load that the floor is designed for. Perpendicular to the joists you might be OK with it. On the parallel sides you may have one or no joists under the load and that could become a big problem. The walls should be OK with the bookcase load as long as they have a direct load bearing path to an adequate foundation- that would need to be confirmed by inspection. Hairline cracks on plaster are usually only an aesthetic issue but they need to be watched for widening. Patching the plaster is the fix. Cracks you can slip a folded business card into indicate a more immediate need to address them- especially if they get wider. This might require more than just patching the plaster since it indicates more movement. Anything wider than this is trouble and a major issue.

Most houses with libraries of this size had the walls and floors designed to carry them when they were built. You may end up with needing to do that level of reinforcing to keep the library as-is. I love books too and I can only imagine having that many. May you get to enjoy them all!

Phil

JLMCDANIEL
Re: Wall mounted book shelves vs bookcases - structural question

My advice would be to bite the bullet and hire a structural engineer.

Jack

A. Spruce
Re: Wall mounted book shelves vs bookcases - structural question
wtchywmn9 wrote:

What I was wondering was would it be better to use wall-mounted shelves instead? They would be anchored on the studs that run under the plaster. Would the studs bear the weight better than the floor? That would take the weight off the floors, but would it still cause cracks in the wall?

From experience I can tell you that books are EXTREMELY heavy, shelves attached to the wall will not suffice unless they are super-size beefy, even then I wouldn't do it! What you can do is combine the best of both worlds, that is to say, have some bookcases made with multiple strongbacks (cross bars that will attach to the wall ) that will help distribute the weight between the floor and the wall.

If you look inside your upper kitchen cabinets you'll see a 1x4 at the top and bottom in the back of the cabinet, this is the strongback that I'm referring to. I would recommend one strongback for every 1 to 2 feet in height. Each strongback would be screwed into every stud with at least one screw. In addition to the strongbacks, the bookcases should have a solid back of at least 1/4" plywood, this will stabilize the cabinet and help to distribute the overall weight throughout the cabinet, as well as the attachment and support points.

wtchywmn9
Re: Wall mounted book shelves vs bookcases - structural question

Thanks for all of your feedback. It was very helpful.

Last weekend I re-did the first of the bookcases. As with any project, it takes a while to get around to it. ;)

I put up a sheet of 1/2" plywood, firmly attached to the studs, and painted it to match the rest of the walls. Added bracket standards, using anchors though both the wall and plywood. About 2/3 of the books are supported by shelves attached to the wall, and 1/3 are on the fixed shelves of the bookcase. The floor isn't creaking like it was before, so I think it's working.

One down, 2 bookcases to go...

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