Plywood thickness for backing board used to drill french cleats into

[dasinc]

Howdy all,

I am looking to put some plywood up on my brick shed walls and was wondering what thickness of plywood I would need to be able to hang french cleats on it. The heaviest would probably be a circular saw or something like that.

Any ideas? Thanks in advance

[Fuzzie]

Online tutorials seem to mostly suggest 3/4" with cleat strips screwed on at distances equivalent to wall stud spacing. The main forces of stuff hanging on the cleats is vertically down and might not need a lot of screws holding the cleat strips on. A large circular saw on a cantilevered platform cleat might add a horizontal pull out force that, if a problem, could be countered by adding a few more strip fixing screws.

[Mobyturns]

Firstly, your location is shown as Perth - so a very important consideration - is the brick wall a single skin??

It would be very prudent to check the construction method of the wall, the reinforcement of engaged piers etc BEFORE attaching any loading to the wall!

If a single skin it will have negligible reinforcement so I would not attach any weight bearing sheeting, or shelving to it! Cumulative loading can be surprisingly significant. Any load bearing shelving, racking, or structure should be self supporting, i.e. pallet style racking etc. There have been instances of wall collapse from events such as attaching basket ball hoops etc to single skin brick walls. IIRC a child was killed not so long back in such an event plus there is this one …

https://www.watoday.com.au/national/western-australia/police-investigate-after-man-dies-in-subiaco-20181209-p50l65.html

https://www.commerce.wa.gov.au/announcements/safety-warning-hidden-dangers-attaching-items-around-your-home-0

[dasinc]

Thanks guys. Something to think about
Yeah the main wall I wanted to put stuff on is single brick, the others are double.
The plywood will be pretty heavy I imagine....mmmm

[malb]

Assuming that the ply is placed vertically from floor upwards, and is strong enough to not crumble, the weight of the ply itself should be largely taken by the floor, and mounting into the brick wall should only be stabilizing it. However, once you have anything canterlevered off the wall, like shelves, cabinets etc, they introduce a turning moment into the ply, which the fasteners then couple to the brickwork. This, rather than the actual weight of the ply, is what will cause issues with the wall structure.

On the other hand, if you fix the ply above floor level, the wall is left carrying the weight of the ply, resulting in the wall being asymetrically loaded, and inducing a moment into the wall before anything is hung onto the ply.

The issue you are dealing with is the fact that unsupported single brick walls are not designed to be loaded asymetrically, because they are made up of layers of material joined by a softer easily crushed and brittle mortar. Uneven side loadings can easily move individual bricks or cause mortar cracks which allow the wall to move toward the load, and ultimately to be dragged down by it.

Medium to long term, the weight of the ply sheeting can become insignificant compared to the weight of the materials hung from it, particularly if you move from the property and the later occupants start to hang more off the sheeting without being aware of the potential issues they are creating.

[dasinc]

Thanks for the info

What if I was to forgo the plywood, and just make some french cleats directly anchored to the wall? I guess I could reduce what I am hanging....but I did want my tools spread out up there.....jigsaw, dremel, a couple of drills, maybe a cabinet with screws.....

[Cgcc]

I've got French cleats - great system. Individual holders for power tools etc won't be a problem. They're going to be a small fraction of the weight of a full sheet of ply.

[BoneInspector]

You will still end up with the loading issue discussed before.

you might need to make an interior frame to support your plywood instead.