How to build a storage shed: Frequently asked questions (© Popular Mechanics)

Over the years, Popular Mechanics has published several articles about designing and building backyard storage sheds, many of which I'm proud to have written. These articles have always generated a lot of mail from readers looking for specific answers to their shed-building questions. It's not possible to answer every question, but here are answers to the five most frequently asked ones.

1. I'm about to build a 6-by-8-foot storage shed for my lawn and garden tools. Do I need a building permit for such a small building?

Great question. There's a common misconception that building permits are required only for sheds larger than 100 square feet (or some other arbitrary size). That is simply not true. You must apply for a building permit regardless of the size of the shed, and there are three very good reasons why.

  • First, the town building inspector will want to make sure the shed is built to code so that it won't sink into the ground, suffer a catastrophic roof collapse or be blown over by a strong wind. (Go ahead and laugh, but all three incidents occur all the time.)
  • Second, town officials will need to approve the proposed building site to ensure it isn't encroaching into wetlands, sitting over a septic system or straddling a property line.
  • Lastly, if you build a shed on your property without first obtaining a building permit, the town can make you either move the shed, or even take it down completely.
  • For specific shed-building code requirements in your town, visit the municipal building department.
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2. We're fortunate to have a relatively large backyard. Do you have any tips for where we should build the shed?

One of the most important aspects of building a shed — regardless of the size of your backyard — is selecting the most appropriate building site. Here are some general rules to consider when siting your shed:

  • Never build a shed at the bottom of a hill or in a low-lying area that collects water. The constant moisture will rot wood, blister paint and cause mold and mildew to grow on items stored inside.
  • Maintain the setback distances suggested by the building department. You typically can't build a shed within 10 feet of the rear property line, and 15 feet from a side-lot line.
  • Don't make the mistake of building a storage shed into the deepest back corner of the yard. Such an out-of-the-way site might look nice, but it's not very convenient when you must traipse back and forth across the yard every time you need to retrieve a tool. Build the shed closer to the house or garage, and everyone will be more likely to return items.
  • If your backyard is slightly sloping, position the front of the shed (the side with the door) on the high side, so land slopes down toward the rear. In that position, it'll be much easier to step into the shed since the door's threshold will be closer to the ground.
  • If possible, keep the shed away from extremely shady areas. Exposure to direct sunlight and breezes will keep a shed dry and free of rot and mold.

3. What type of foundation would you recommend to support a 10-by-16-foot storage barn?

There are two basic types of shed foundations: on-grade and permanent. The building inspector will ultimately decide which type of foundation you'll need to build; the decision is typically based on the size and height of the building. The following are the basic differences between the two types.

  • On-grade foundations are the easiest to build since they don't require digging postholes or pouring concrete. Instead, they're built right on top of the ground. On-grade foundations — sometimes called floating foundations — are usually constructed with solid-concrete blocks laid out in evenly spaced rows, or with parallel rows of large, pressure-treated timbers (aka skids). In each case, the blocks or timbers are leveled and then used to support the wooden floor frame.
  • On-grade foundations are suitable for small- to medium-size sheds up to about 200 square feet. For your 10-by-16-foot shed, I'd recommend using twelve 4-by-8-by-16-inch solid-concrete blocks arranged in three rows of four blocks each. But again, be sure to get approval from the building department before beginning work.
  • Larger sheds require a permanent or "frost-proof" foundation, which extends down to the frost line. This is necessary to provide the proper support and to protect the building from ground movement caused by seasonal freeze/thaw cycles.
  • Permanent shed foundations are most often built by digging down to the frost line and pouring concrete footings, piers or slabs. Another option is a centuries-old building technique known as pole-barn construction: Holes are dug down to the frost line, then tall round poles or square posts are set into the holes and used support the floor frame, walls and roof.
  • Contact the building inspector for frost-line depth in your region.

4. We had an old metal shed with a low-angle roof that eventually caved in after a 12-inch snowfall. I'm going to remove the metal building and construct a 12-by-16-foot wooden shed. What angle should I build the gable roof to properly support snow?

I never build sheds with shallow-pitched roofs because they have very little interior headroom, they don't shed snow and debris very well — as you discovered — and frankly, I think they're ugly.

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For any gable-roof shed, I recommend a roof slope ranging between 10-in-12 (40 degrees) and 12-in-12 (45 degrees). Roof slope is calculated by the number of inches it rises vertically for every foot of horizontal run. For example, a 10-in-12 roof slope rises 10 inches for every 12 inches of run. That's plenty steep enough to shed snow, especially if you install metal roofing. Of course, this is assuming you frame the roof to satisfy the local building code. Using undersized rafters and spacing them too far apart won't support a heavy snowfall, regardless of the roof slope.

5. Where can I purchase plans to build my own shed?

There are a few good online sources for shed-building plans. My favorite by far is Better Barns, which also sells high-quality shed hardware, but also check out: Summerwood Products, Barns, Barns, Barns and Today's Plans.

Note that if you don't have the time or inclination to build a shed from scratch, you can buy a precut kit and assemble it yourself. For more information and to see what sizes and styles of sheds are available, visit: Better Barns, Handy Home Products, The Cedar Store, and Lancaster County Barns.

By Joseph Truini, Popular Mechanics