What type of foundation should I use?
There are a lot of things to consider when building a shed, but one of the most important issues, even though it’s not something most people want to consider, is the the foundation. The foundation is usually one of the more physically demanding parts of building a shed. There are several different kinds of shed foundations
1. cement block
2. cement piers
3. helical piles
4. cement footings, with or without a concrete floor
Cement blocks under a wooden floor are the most common type of foundation, and they can serve for many many years with little to no problem if certain precautions are taken.
First off, it is important to place the blocks exactly where you will be putting the shed. A typical shed will be far too heavy to move around after it is built.
Typically it is not a good idea to set a block foundation directly the ground without placing drainage gravel down, and tamping it (compressing it so that it is not loose). You will probably need to dig down the earth to a certain extent in order to make sure all of the blocks are placed in the correct location, and that they are level and square with the other blocks. Remember, this foundation will dictate how level your shop will be in the end.
Piers are another type of foundation you can put under your shed. For sheds in Fredericton, and anywhere in New Brunswick, you’ll need to make sure that the piers go below the frost line (about 4 feet). At the bottom of the hole that you dig, you should put a few inches of drainage gravel, and tamp it slightly. Use a form for the pile, and if at all possible, use a type of form that is wider at the bottom than it is at the top, this will minimize frost heaving on the pier. Remember to call before you dig to avoid utilities and any other possible dangers.
Helical piles are a type of (steel or aluminum usually) metal pole with a helix on the end of it. The purpose of this item is to screw into the ground, and go deep below the ground, without all of the hassle of pouring concrete into forms, and all of the associated digging.
Piles can be purchased at the hardware store that will be suitable. They should be placed in the exact location needed. They do not do well in rocky ground, or hard ground of any sort, so if that is what you have, then you may be better off with blocks, or some other method like piles. Follow the manufacturer’s recommendations for installation. There are companies that also install them professionally, but they are more costly.
For either the DIY method or professional installation, you will need to call before you dig to make sure you don’t hit utilities of any sort.
Another option is using footings as the base for your shed. This is probably the most involved method.
In this set up, you will need to dig footings down below the frost line and then build forms on top of those footings in order to pour a knee wall. The knee wall will be the foundation for the wood floor for your shed.
The other options is to pour a concrete floor inside of the perimeter of the knee wall, then build the shed on the knee wall. You will have a concrete floor, with the walls sitting on the slightly raised knee wall. As always, call before you dig to check for utilities.
No matter what option you decide to pursue, owning a shed can be a rewarding experience to help organize and clean up.