floorgarage
I need an educated opinion about how to fix the garage floor shown below. I need the surface to be level and even. As you can see I have two items, a table saw and and work bench that have adjustable casters or legs. Every time when I move them into position to work (usually they sit on the sides of the room) I have to adjust the legs to bring the table top level with the table saw top.
Since you are contemplating shelving, I am going to assume that
I've got a shelving unit in a storage area that can fit at absolute maximum volume capacity about 24 of these 10 gallon storage bins:
With all 24 on the shelves, I physically cannot add any more weight to the shelves because all of the volume is already consumed.
I estimate the maximum weight that I put in each of those bins is about 50 pounds of stuff. From moving them around and comparing them to the dumbbells at the gym, it's way more that 20 pounds and definitely less than 100 pounds. As a reference, filling the tub with water would weigh 81 lbs, filling with lead is about 946 pounds.
So, based on my estimate, I will be storing up to about 1200 pounds (24 tubs x 50 pounds each) of stuff on that shelving unit. More than 1200 pounds is unlikely because the shelf will reach its volume capacity first.
In this case I dare not use a shelving unit that will collapse under less weight than 1200 pounds because there will be nothing preventing an unsuspecting family member from exceeding that weight by adding another item to the shelf.
The shelving unit in the example above is 4'x2'x8' (WxDxH) or 64 cubic feet. Given the 1200 pound capacity, the density of stuff I am storing works out to 18.75 pounds per cubic foot. When I design shelving for my home, I use the round number of 40 pounds per cubic foot for a 2x safety factor.
For your example of 1.5'x8' shelves, assuming they extend to an 8' ceiling, you should design for an astounding 3840 pounds of load (1.5'x8'x8'x40 pounds per cubic foot) to be safe. This is not an exaggeration. Good shelving allows you to store a remarkable amount of weight in an extremely small volume, that is its whole purpose after all.
The stuff you are storing on wall mounted shelving is an overhung load. The wall mount shelving supports this overhung load by applying a torque to the wall to which it is mounted. Walls in residential construction are not designed to support a significant amount of overhung load.
To make matters worse, the torque on the wall increases with the square of the depth of the shelving because you are increasing both the weight and the lever arm of the overhung load. So, the torque from an 18" deep shelf is nine times the torque from a 6" deep shelf. Because of the squared relationship with torque, I never use wall-mount shelves deeper than 10".
On top of all this, even if your wall is able to withstand the torques involved, there are two additional worrisome aspects to consider:
A real risk is this scenario: A child climbs a wall mount shelf loaded with hundreds of pounds of stuff. The weight and motion of a child causes the multiplied forces in the bracket to exceed the failure strength of the bracket. This causes a catastrophic failure of the shelf's ability to support the load, and the child and load falls to the floor, crushing the child.
All of the problems that results from multiplying forces, the squared relationship of torque with shelf depth, and a wall that can't support weight are alleviated by using free-standing shelving.
I recommend using a properly engineered system like EZ Rect Type 1. It looks like this:
As I understand it, the EZ Rect system's patent has long expired, and there are now many manufacturers of that system. I've been using a generic version of that system for all my high-density household storage for almost 10 years.
Here are the benefits of EZ Rect Type 1 shelving solution as I see it:
Whatever system you end up with, you should expect the above benefits to be standard -- if it's not, keep looking.
Here is a picture from my last moving day. Shown is 7 "bays" of dismantled shelving capable of safely storing about 24 tons (42,000 lbs) in about 600 cubic feet of space.
I've encountered an amount of skepticism about whether catastrophic failure of shelving is, in fact, something to be concerned about. Here are two examples of catastrophic failure.
A worker died in this workplace accident in 2012 when an overloaded shelving system collapsed.
This is an extreme case of what can happen. I think it is instructive of the dangers nonetheless.
The great Jon Skeet tweeted this photo of what seems to be catastrophic failure of a wall-mount Cookbook Shelf:
I'll try to take your questions one-by-one.
You have two easy options for leveling the chalk line. The first would be to use a carpenter's level; you'd measure 34" from the floor at one end of the bench-to-be, then hold a long 2x4 to the studs with one end right at the mark. Lay your level on the top of the 2x4 and tip the 2x4's other (not at a mark) end slightly up or down until your level reads an accurate level. Now you can have a helper mark across all of your studs with a pencil instead of a chalk line. The second easy option doesn't concern itself with level at all, only with being parallel to the floor. Measure 34" from the floor at each end of your bench-to-be and mark that spot.
Since you're in Washington, I think you'll probably have 2x4s available in spruce or "pressure treated", and probably no other options. Spruce should be just fine.
The plywood braces (you can make them from either 3/4" CDX or ACX plywood) may be mounted only on one side of each stud or for greater strength & rigidity may be mounted on both sides. I've built a "strongarm" wood-storage rack very similarly to what is described here; I used smaller braces, but mounted both sides. For most in-garage DIY purposes, a brace on only one side would be just fine. If you plan to do heavier work, you may certainly install one on the other side of each stud, too.
Elmer's Wood Glue, which is a yellow PVA (Polyvinyl Acetate) glue, is perfectly satisfactory. Franklin or Gorilla or TiteBond would also work just fine. You'll want a yellow glue or a polyurethane glue here; white glue gives you more work time before it sets up, but it's not as strong.
You could use nails instead of screws, but they'll be much harder to drive without damaging anything. Your siding is attached to the outsides of those studs, so every time you beat on the side of a stud the nails holding the siding in place will become looser. I'd much rather that you used screws. You can use 1-5/8" drywall screws. It helps if you have a drill to drive them (much easier on your wrists).
If you're not going all the way to the end, just stop wherever you want to stop. Until you install your benchtop, your new supports will feel very flimsy, but it will suddenly stiffen up when you install the top. There's no need for any additional brackets or supports.
Nope, the 2x4 braces don't have any direct attachment to the studs - they're held only by the plywood braces.
If you like, you could certainly stain and/or varnish your benchtop. If you do, though, and if you do any heavy work on its top, the stain/varnish will soon look terrible. You can use the same plywood for the top as you used for the braces. If you use ACX plywood , you'll have a much nicer benchtop than if you use CDX plywood, but a lot of very hard-working benchtops are made from CDX - they just have shallow knotholes in some spots (CDX may have "voids" and knotholes that won't be present in ACX).
I'd like to urge you not to make a 36"-deep bench. They seem handy in theory, but your back cannot be comfortable reaching that far - you get backaches very quickly. Really. I'm 6'2", and I'm not comfortable with any bench deeper than 24". Also be aware that a 36"-deep bench is going to work as a much larger lever against the wall, and so can't be expected to carry as much loading as a 24" bench can carry. If you're really sure you really want 36", though... make the triangular braces at least 24" square. That'll take quite a lot more plywood - you can get only (16) 24" braces from a full sheet, and your 36" top will consume a full sheet leaving you with a 12"-wide strip of "waste" that can't be used for braces.
Best Answer
Ahh, the ancient quest for flatness.
You could put down a mortar bed, but it will degrade over time if it is unsurfaced.
In general, putting good concrete over bad concrete doesn't work. Trying to flatten just one area of a garage will not be easy. One possible procedure would be to get a jack hammer and remove about 1 to 2 inches of concrete everywhere you want to be flat. Then get down on your hand and knees with a level and chisel it all out so it is pretty smooth and level. Then pour new concrete into the draft, or better yet get an experienced paver to do it. Making really smooth flat concrete surfaces takes a lot of skill.
Also, you could do all that, and whatever caused the crack in the first place will crack your new concrete.