Replies

1. 
   _mj_ | Jul 25, 2021 10:42am | #1

   1) weigh a meter of your books.
   2) tough to say without knowing about your chosen hardware, what do you mean by "strength/integrity of the fixing"?

   Anything you hang on a wall imposes a load on that wall. A free-standing bookcase would not, because the load would be on the floor.

   The load rating from the manufacturer for a specific bracket will be for a specific install, according to their instructions. Based on your sketch I suggest building it as a single unit and then working out how to hang it. Getting all those lines straight on a rough stone wall will be a nightmare with loose parts.

1. 
   Deleted | Jul 25, 2021 11:31am | #4

   “[Deleted]”

2. 
   john_c2 | Jul 25, 2021 10:48am | #2

   It's natural stone, but is the stone full depth, or a veneer?

1. 
   conran | Jul 25, 2021 11:19am | #3

   it's an exterior wall - and thick

3. 
   gulfstar | Jul 25, 2021 11:31am | #5

   The kg/m2 applies to the shelves loading, not the anchor bolts, that would be in kg or pounds. So you need to weight one meter of books and divide the weight by the product of the length(1 meter) and width of the shelve. For example if the books weight 25 kg and the shelve is 25cm wide (0,25 m) the loading is 100 kg/m2.

1. 
   conran | Jul 25, 2021 01:45pm | #6

   many thanks for your reply - but could you help me understand this?

   1 metre of books weighs 13kg, and the shelves would be 13 cms wide.

   so based on your formula, the loading would be 100kg/m2.

   but how does that kg/m2 figure help me know that each pin can easily support 13kg of books per metre?

   (see spec sheet extract below)

   
4. 
   gjoakes | Jul 26, 2021 11:05am | #7

   You may want to consider "back plate" style floating shelf brackets such as shown here .... https://www.sheppardbrackets.com/

   This would give more flexibility in the number and location of fasteners going into the stone. Also would make alignment of the shelf brackets easier (as pointed out by others). This particular mfg supplies a drilling fixture with purchases and drilling the "pin holes" into the shelf is not a big deal. You do, however, have to relieve the shelf to allow for hiding the back plate.

   Myself, I would probably choose to use epoxy techniques for securing fasteners to the solid stone.

1. 
   conran | Jul 26, 2021 01:25pm | #10

   thanks a lot for the sheppard link - but I'm in the UK, and they're not available here unfortunately. However, I think your suggestion about epoxy fixing is well worth exploring - many thanks indeed.

5. 
   gulfstar | Jul 26, 2021 12:05pm | #8

   Seing the graph the loading per square meter makes no sense. It has to be loading per meter of shelve length. You then can use it two ways, if your weight per meter, including the shelve, is 20 kg you can go 30 cm on shelve width. If your shelve is only 13 cm wide, you can go to to the corresponding weight on the scale.

   The fact that you have vertical dividers however makes using the chart unnecessary since it is for a stand alone shelve. You will be basically hanging a box to the wall so there will be no bending forces on the anchor bolts as long as the vertical dividers are part of the structure.

1. 
   conran | Jul 26, 2021 01:22pm | #9

   i agree that expressing load ratings in kgs/m2 seems to make no sense - esp for specialist shelf supports. (The supplier's technical people can't provide any ratings per metre run, however, so obviously don't see it that way.) The vertical dividers are there partly for aesthetic reasons (a long run of shelving wouldn't look like a book case) but also because I hope - as you suggest - to be able to add more supports, spreading + minimising the load throughout. I've since found some pins that are rated at 40kg max load per metre run - more than enough for bookshelves. Hope it all works well - many thanks for your feedback.

6. 
   rob_ss | Jun 06, 2022 04:45am | #11

   I suspect that you are massively overthinking this.
   Floating shelves commonly use really robust hardware that will support plenty of weight.
   Your main issue is going to be the unevenness of the wall - that will compromise the effectiveness of some kinds of shelf mount.
   The problem is that the length of the bracket is very short which places it at significant mechanical disadvantage. A traditional bracket is almost as deep as the shelf is wide, sharing the load very evenly. Leverage is very much increased when a wide shelf acts on a narrow bracket - if the bracket itself does not bend then it may pull the screw out of the wall.
   This is further exacerbated on uneven surfaces as these might reduce the effective width of the bracket, but will not increase it.
   You can increase strength by:
   1. Using a wider mount (thicker shelf)
   2. Using really strong wall anchors.
   3. Using very thick steel in the mount.
   4. Choosing flatter parts of the wall to attach mounts.

   I am NOT an engineer so bear that in mind for what follows:

   Were it my project, I would sink 10mm holes at least 50mm into the wall. I would stick 10mm rebar in the holes, secured with epoxy if needs be. My shelf would hold off those. I would use one 200mm from each end of the shelf and one per 600mm in between. A 150mm wide shelf should be able to hold plenty.
   If you go for a wider shelf then go for wider rebar and slightly deeper holes.

7. 
   _mj_ | Jun 06, 2022 07:38am | #12

   Old thread revived by spam