12″ Wider All Around
Your gravel shed foundation should be 12″ wider all the way around the building. That means if your shed measures 8’x12′, your foundation should measure 10’x14′. There are good reasons for this which we’ll explain below.
In cases where your shed has an extra large overhang, you may want to make your foundation big enough so that the water that runs off the roof runs onto the stone pad. Another option in this case would be to add a gutter and downspout to control the runoff.
Gravel or Concrete: Which Makes a Better Shed Pad
Should you build your shed base using gravel or concrete? We already addressed this question in the blog post, “Gravel vs. Concrete: Which Shed Base is Best for You?“. So we won’t go into detail here.
The basic idea is that if your shed comes with a floor, you should choose a gravel foundation. If your shed doesn’t have a floor, you should choose concrete.
The benefits of making your shed base 12″ wider than your shed apply mostly to a gravel shed base. If you purchase a shed without a floor and you decide to pour a concrete foundation, it should measure the exact size of the building.
4 Reasons to Make Your Gravel Foundation Wider than Your Shed
Protects the Wood Siding
Making your gravel shed foundation wider than your shed helps to reduce the amount of water that splashes up against your shed. Repeated contact with a significant amount of moisture over the course of several years is what causes the siding to rot around the bottom (see photo).
You’ll notice that if you pour water into a bucket of gravel, it splashes less than if you pour it into an empty bucket. The same thing happens when water runs from the roof onto a gravel pad. It splashes less than if the building was surrounded with concrete or another hard surface. This keeps your shed dryer.
Keeps Your Shed Cleaner
Another benefit of making your gravel foundation wider than your shed is that it keeps your your shed cleaner. If rain water splashes into the dirt and up against your shed it will make your shed look like it took a mud bath.
If you allow grass to grow around your shed you may keep the mud from splashing up but then you’ll have another problem which we’ll address below.
Blocks Grass and Weeds
Grass and weeds growing up against the sides of your shed is a problem because it traps moisture after a rain fall. Your shed won’t dry out as quickly which can cause problems in the long run.
Another problem is that you may need to weed whack around your shed which can scuff the paint or scratch the vinyl siding. Eliminate this with a wider stone pad.
Reduces Water Runoff
A gravel shed foundation acts like a basin that collects rain water under your shed. This allows the water to soak into the ground instead of running off and causing other possible issues.
If you live in an urban area, your township may require you to put in a deeper stone base so that it can hold more water. This is one way to control water runoff issues that can be created by installing a shed.
A Gravel Shed Foundation: Better All Around
A gravel foundation is your best all-around option when installing a shed or garage that comes with a floor. It will help your investment last longer and you’ll have fewer issues down the road that might come from your building settling. Making your foundation 12″ wider all around the building is another way to maximize the benefits you’ll get from installing your shed on a gravel shed base.
You may also be interested in our “how-to” guide on leveling the ground for your shed.