# Art/Object Issues > Space Preparation >  Weights in movable walls

## Matt I

Can anyone point to a resource or have a calculation for how much bottom ballast or weighting we need to do to our 12' tall and either 8' or 12' wide walls.  They are 3/4" ply under 5/8" gyp.  They are stout.  UNFORTUNATELY, someone told the structural engineer that it needed to hold up to 900lbs on one side of the wall.  Super-crazy and will NEVER happen, but now we are stuck with having to take all these weights in and out of the walls every time we move them.  BUT until I can point to something else I have to go with the prescribed weights for liability issues. HeLp!

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## Paul Brewin

How thick are the walls and how much weight are you putting into your walls? Of course 900 lbs on a wall can be interpreted lots of ways also: position on the wall, size and projection of object, etc. We have 6-1/2" thick walls 10' high but almost always have them in stable configurations if freestanding or attached to a perimeter wall, or other ways to keep things from being able to tip.

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## T. Ashley McGrew

Here is a response that came from one of the most insightful folks I have had the priviledge to know. Unfortunately at the time I forgot to request a formula for calculating optimal ballast in these situations (which I should mention he has passed on to me on more than one occaision and yet I find I cannot at present lay my digital hands upon). I will try and remedy that one way or the other. 


_Hi Ashley,
The first question there is the start, "How thick are the walls and how much weight are you putting into your walls?" Then, how is the weight/ballast distributed within the walls - how low and how high does it go up? Then, how much weight are they hanging/adding to the walls and where is the weight located on the walls? These effect center of gravity. Then, what force [g force] are they using to evaluate the stability? In Sacramento it should be pretty hefty.
As you know, while I'm a big fan of using weight/ballast in individual pedestals/cases, I've never been a fan of weight/ballast in freestanding walls - in my opinion they need to be anchored or arranged in stable configurations._ 


_Bruce_

Also it occurs to me that if you can get your hands on a copy it seems to me that there is something along that line in the Getty publication on seismic mitigation. Unfortunately I can't get my real hands on that either right now as I am far away from home. I understand that my the family dog (who is not allowed on the furniture) has taken over my seat in the living room and proclaimed himself the "alpha dog" in my absence. Unfortunately he isn't sleeping well though because apparently he takes the job way too seriously.

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