In the country, one of the chores we must do is to keep the garbage outside and safe from animals until either a garbage man picks it up or we take it to a landfill. For obvious reasons the bags although technically outside must still be kept in some type of enclosure. Bears and raccoons love people's garbage and will go to great lengths to get to their favorite foods.
We have had aluminum storm doors peeled back enough to let a raccoon inside for his picnic lunch. We have had wood shed doors ripped from their heavy duty hinges by a bear looking for an easy meal after waking in the spring. There are some very nice plastic or rubber sheds sold for this purpose but experience shows they do not stand up well to the teeth and 4 inch toe nails of a 400 pound black bear.
Pick a location for your shed that is easily accessible to you in the morning on your way out to work. If it is difficult for you to get to very quickly you will start to leave bags out until you get home. That is a big mistake. Bears can smell food miles away and can travel up to ten miles in one day's time.
Even with the garbage in the shed and the shed locked, a bear or raccoon may still attempt to gain access. Your job is to keep all but the most determined bears out of your shed. Bears are extremely strong and I've seen wooden roofs and shingles ripped off, heavy duty hinges bent into pretzels and plywood siding shredded. Bears will drag garbage with them if spooked and in turn spread the garbage over a wide area. If you don't clean it l up, it is an open invitation for every animal in the area. Nothing like going outside at six AM and seeing your garbage spread all over your yard.
Once the location is picked I recommend installing a concrete slab for the shed. A three foot deep, six foot wide and five foot tall shed is adequate to hold a good deal of bags. A four inch thick concrete slab is more than adequate for a base. Form the slab with two by fours or two by sixes. If you use two by fours excavate slightly below the forms inside to assure you get a full four inch thickness.
Concrete is figured as LxWxD so it would be 3'x6'x.3333=5.9994 divided by 27=.23 Cubic feet. If you are using bagged premix, it will tell you on the bag how many cubic feet of concrete each bag makes. Install some rebar or welded wire mesh n your slab to give it maximum strength.
Before the concrete sets, install six inch long anchor bolts around the perimeter of the slab No less than two on each side but four on the long back side would be better Make sure the threads of the bolts project above the finished concrete no less than 2 1/4 inches when all is said and done..Let the concrete dry for a couple of days, strip your forms and back fill the slab. Wire brush the bolt threads to remove any concrete residue form pouring the concrete slab.
The base plate two by four must be pressure treated lumber by building codes as it is in contact with concrete. Install this base plate two by four ad then using the anchor bolts, install a washer and nut on every bolt. After making sure your base plate is level and square firmly tighten all the nuts. Frame the shed wall using a minimum of three two by fours at each short wall end and twelve inch centers on the long back wall.
You will attach your hinges to these end posts later on so they must be as strong as possible. Now install a double two by four top plate all the way around the shed lapping each two by four onto the adjoining wall at each end. Most lumber yards sell metal strapping in ten foot lengths or in rolls. Install a diagonal piece of strapping on each wall from the top plate to opposite bottom corner plate on the outside of the framing. Nail the strapping to every stud it crosses and both the top and bottom plates.
You should now have a very strong framing cage for your garbage shed. A great material choice for the exterior is texture 111 plywood. It is extremely strong and is not terribly expensive. Using both a caulking gun adhesive such as trade name liquid nails or similar product, Run a full bead on each stud prior to applying the plywood siding. You can nail the siding but using trim screws is far better and will make the bear's job much tougher to rip the plywood from the studs. Do not cheat on the number of screws you use..Edges should be no more than four inches on center spacing and the fields six inches on center.
Complete all the plywood siding.
Since the roof has such a short span for rafters you may use two by fours for these as well. Twelve or fourteen inch centers is great but sixteen is OK as well. Stronger is better. Frame in all the rafters and add your front and back fascias also made of two by four materials. Do not use a light one by two material as a bear will splinter that in a second.
Hurricane anchors for rafters are available in all lumber yards and box stores today in all parts of the world today. Install a framing hurricane rafter anchor to at least every other rafter and securely nail or screw them to the top plates. Make sure every rafter is securely screwed to the top plates as well. Using adhesive glue and screws, install the roof plywood in one piece. Roof plywood should be at least 5/8 inch thick, 3/4 inch is better. Screw patterns are the same as the sides.
Now install your roofing. Whether you use fiberglass shingles, roll roofing or wood shingles a large bear can rip them off in a few seconds. These are replaceable items. What you do not want is for the bear to be able to get through the plywood roof or sides. The doors you build must be extremely strong as well.
The doors are only as strong as the hinges you use so pick as heavy duty a set as you can find along with a hasp set. I use one piece of 3/4 inch thick plywood for my doors as it is very difficult to splinter or tear. Reinforce the outside of the doors with a one by four trim and thereby giving your hinges more wood to fasten too.
Use carriage bolts to secure the hinges and hasp assembly as they are much stronger than screws and leave little on the outside for the bear to grip. As I left for work one morning, I was greeted by the sight of twenty or so garbage bags ripped open and strewn all over the yard and driveway. An hour or so later of cleanup I had to take the garbage that day as I was sure I would get another visit the next evening and I did. I simply left the doors open to the empty shed and he lost interest.
Put a couple of good coats of paint or stain on your shed and your good to go. Each time I remove the bags I sprinkle some bleach inside the shed to kill or prevent bugs, ants and other critters from making their homes inside the shed. It kills the garbage odor as well. An occasional washing out with soap and water will keep the shed floor clean and odor free.