We are trying to add bookshelves onto our apartment wall; specifically, elfa system shelves (site is in Swedish, but I'm sure you can get the gist based on the photos). However, we are somewhat concerned as to whether or not the wall can support the shelves.
Our concern, however, is that the wall itself may not be ideal to mount into. It is built over the brick exterior of the building with approximately 5cm of empty space between the plaster wall and the brick. The drywall itself, unfortunately, does not run all the way to the ground: due to a water pipe that runs along the floor to a radiator, the plaster doesn't sit directly on the ground, nor on anything, really.
We have used a stud finder, but what it has found is… inconclusive. We could not really consistently find any indication of what the plaster is mounted on that we could use to also mount our shelves into, and so our only hope would be to mount the shelves directly into the drywall.
We are aiming to mount the rails with these kind of drywall anchors, but the concern of course is that I assume any description of how much weight they can support is predicated under the assumption that the drywall itself is well-supported. Unfortunately, we can't really tell if that is the case or not.
Our questions are the following:
- Is possible and safe to mount bookshelves directly into the drywall?
- If not directly, is there something we can do the help support the shelves?
- More generally, how can we get a sense of how much weight can be safely supported?
We should not that this shelf would be above our living room couch, so since we don't relish the idea of always wearing safety gear while relaxing, we want to ensure that our shelves will be stable enough.
Best Answer
Not possible by just going into drywall. The achors are not designed to bear that kind of load. The reason this won't work is because of torque. Drywall anchors are designed to support loads that are very near the wall (i.e. pulling, more or less, straight down along the wall). Your shelf will probably have the load offset from the wall by a few inches, which will eventually pull the anchors out of the wall. This is because of torque. The farther you go from the wall the more torque you have. While the shelf may hold for a while I would not trust it.
The torque on the anchors can be mitigated by putting in angle brackets. These effectively redirect the load from the edge of the shelf back to the wall. This is better, but I still wouldn't trust this shelf unless it is secured into something more than drywall.