Floating shelves.... How deep to go?

[ToughButterCup]

I have about 100 meters of m12 threaded bar leftover from earlier traumas. I could use some of it as the support for floating shelves. 

 

SWMBO wants shelves. In her panty.

 

I'm thinking using 25 mm MDF (MRMDF) with the 12mm bar inserted into the MDF about I00mm. I say inserted - I mean epoxied.

 

The shelves are planned at 200 mm wide. The bar will be held by the concrete (ICF)

 

How deep should I drill the holes to hold the bar? 200mm? 100mm?

 

Edited October 19, 2020 by ToughButterCup

[markc]

M12 threaded rod needs 75mm embedment to be at full pull out strength.

Floating shelves will mainly impose bending and shear loads  so even 50mm into concrete is sufflicient

[ProDave]

My concern is in a pantry, the shelves are likely to be heavily loaded, to the point of bending M12 studding.  Floating shelves in that situation would not be my choice.

[markc]

1 minute ago, ProDave said:

My concern is in a pantry, the shelves are likely to be heavily loaded, to the point of bending M12 studding.  Floating shelves in that situation would not be my choice.

Just re read the original post and have to agree, plus the ICF would not support the bar close to the wall increasing the likelihood of bending.

[ToughButterCup]

8 minutes ago, ProDave said:

.....  Floating shelves in that situation would not be my choice.

 

Agreed. But. Lets see what 150mm does. They just look so neat.

Thanks both.

Ian

Edited October 19, 2020 by ToughButterCup

[PeterW]

1 hour ago, ToughButterCup said:

SWMBO wants shelves. In her panty.

Funny lot you Lancastrians .... 

[ToughButterCup]

Phhhhhhhhhhh. Haste and spell-checkers dont go together.....

[Ferdinand]

Never take risks with shelves if they may have different loads on them later, just cos it looks cool. Eg books or tins. especially if dealing with interior designers or other non-engineering types.

 

And only count that bit of the screw that is in the structural bit, not the plaster or whatever ?.

 

 

[ToughButterCup]

Ok folks. I ppreciate the caution. I know it's my responsibility. To calm your nerves, heres what I propose, demonstrated on an empty block. This is a plan view.

The concrete is I00mm thick, (the empty space).Theres 40mm of block - I propose a 150mm shelf supported by the M12 threaded bar embedded in at least 90 to  100 mm of concrete and 40mm of block.  

To me, the highest risk is of  drilling the holes in the block wall where two blocks join. So I'll do some pilot holes to make sure I hit concrete. Then embed the M12 in the shelf last.

[PeterW]

What shape are the shelves ..?? U or L shape shelves will pick up the torsional loads and if you can “catch” the edges as they touch walls with L shape brackets then it makes it much stronger. 

[ToughButterCup]

Straight: sides unsupported. Godda have a challenge every now and then..

[Mr Punter]

2 hours ago, ToughButterCup said:

Ok folks. I ppreciate the caution. I know it's my responsibility. To calm your nerves, heres what I propose, demonstrated on an empty block. This is a plan view.

The concrete is I00mm thick, (the empty space).Theres 40mm of block - I propose a 150mm shelf supported by the M12 threaded bar embedded in at least 90 to  100 mm of concrete and 40mm of block.  

To me, the highest risk is of  drilling the holes in the block wall where two blocks join. So I'll do some pilot holes to make sure I hit concrete. Then embed the M12 in the shelf last.

 

There is a wasp in this picture.  Exercise caution!