What’s The Best Way to Add Drainage Around a Shed?


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Even the best spot for a shed will get water around it at times. You may have a sudden downpour, or rainfall for a couple of days. This is normal and is nothing to panic about unless you see that the water doesn’t soak into the surrounding soil or drain away promptly.

There are several methods to consider, the best way is to build the shed on high ground and slope the ground away from the shed. If this keeps happening, you’ll want to start thinking about putting in a drainage system around your shed to keep moisture from seeping into the shed and preventing soil erosion.

How Do You Install a French Drain Around a Shed?

See if there is a natural direction around your shed that water flows during heavy rain. You can usually see this by looking for places where leaves and other small debris have been swept. You’ll want to plan a trench going from your shed in this direction or slanting off a little bit.

Start a trench near the corner of the shed that is nearest your proposed drain route. Dig a trench eight inches wide by eight inches deep. You’ll need to slope the bottom of the trench at the rate of one foot per 100 feet of trench. To figure this, put a stake every 10 feet alongside the trench. Tie a string level between the first and second post.

Tie another one to the second post an inch below the first string, then tie that level to the third post and so on. Measure from the string to the trench bottom. This will help you get the correct slope.

Pour two inches of gravel into the trench. Smooth it out to follow the slope. Get enough perforated drain piping to stretch the length of your trench. The most popular choices for this pipe are PVC or flexible corrugated pipe. While the flexible pipe is easier to work with, the PVC piping is more durable.

Also, the pipe is smooth, allowing for any fine soil that may get into the pipe to just flow through. This soil can get caught in the corrugated piping if the water flow is insufficient to keep it moving through. If for some reason the flexible pipe becomes exposed in places over time, it can be damaged. The PVC pipe is not prone to this damage. Wrap it in landscaping fabric to keep out the dirt before placing it into the trench.

You can attach a PVC pipe with an elbow to the top end of the pipe to allow you to clean out any clogs in your drain pipe without digging. A cap on top of this pipe will keep debris out of it. Cover your pipe with gravel and fill it to about three inches below the top, then fill in with dirt. Periodically flush the pipe to ensure that nothing is building up inside.

How Do I Stop My Shed from Flooding?

Of course, the best way is to prevent flooding in the first place. Choosing the right location and using the foundation to keep your shed raised above ground will solve these problems before they start. Keeping vegetation away from the shed will help, as plants hold moisture in the soil with their root systems.

Root structures can also damage the foundation, eventually leading to cracks. Remove any plants that touch the sides, especially vines. Remove bushes and shrubs from around the shed. Grass growing is fine as long as it is kept short.

If you have water seeping under your shed door, you can install a sweep under the bottom edge. These have a metal or plastic base that attaches to the bottom edge of your door with a rubber edge that works like a windshield wiper. This will allow you to open the door and keep water out when it is shut.

If there is a gap at the base that actually lets water seep into your shed, and it’s a small gap, you could use some silicone sealant. Make sure you get a product meant to be used on the material around the gap. Another option is using neoprene foam tape to seal the gap. It’s relatively easy to install.

It has an adhesive side that is covered by a paper strip. Get a thickness that is a little thicker than the width of your gap. Peel off the protective strip as you work, squeeze the strip flat and push it into your gap. The neoprene will naturally expand to fill the gap. If you need some help if your shed is sinking  read my article How Do I Keep My Shed from Sinking?

Can I Put a Gutter on My Shed?

Sheds can certainly have gutters installed just like houses. The gutter system with downspouts will prevent water from pooling around the shed. Unless you have a good gravel space around your shed, once water starts flowing off a roof, after a while, the water flow will pound the soil it hits into a slight ditch, which will collect water.

The soil in this indentation gets pounded more firmly, making it even more likely to hold water. You can also add attachments or extensions to the downspouts to divert the water flow away from the shed.

How to Install Gutters on a Shed

Check for a slight slope near your shed. Natural water flow in the area will tell you where to situate your downspouts. You’ll want them on the corners that the water will flow toward. If there is no slope at all, you’ll need to get downspout extensions to steer the water away from the shed at least three feet. There are flexible extensions available to help you steer the water flow where you want it.

It’s easy to figure out how much guttering you’ll need. Measure the length of your long roofline and multiply by two. Measure the height of your roof to the ground where the gutters go to get the downspout height. If you’re not sure about how to buy these materials, your supplier will be able to help you as long as you have your measurements.

You may have a choice between types of guttering material. The most common is called the K-style gutter from the fact that it appears to resemble the letter K from the end. It is slanted at the front and has a flat back, enabling it to be nailed right to the fascia board.

If it is also slanted at the back you’ll need brackets. There is also a half-round gutter shaped like a trough. This type is easier to clean, but it needs to be installed with brackets. You’ll also need pop rivets or other connectors to install the downspouts and end caps.

Put a nail on each end of your shed roof’s fascia board about one to two inches below the roof lip at an equal distance. These don’t have to be pounded into the board all the way, as they are just being used for markers. Connect the two nails with a string pulled tight. This will enable you to see how level the roofline of the shed is and to adjust it for gutter slope.

Adjust the string until it is level, moving one of the nails as needed. The gutter will need to slope downward by 1/4 inch for every ten feet. Figure out the correct slope for your distance and move either nail accordingly. A good rule of thumb is that the slope should be 3/8 inch if the shed length is less than 15 feet or 1 inch for 20 feet.

Remember that it’s better to have a tiny bit too much slope than too little. Mark this slope as a guideline along the string with a pencil or chalk line. If your fascia board is installed at an angle, you’ll need to install shims where your fasteners will go.

A hacksaw and heavy-duty tin snips are needed to cut your guttering to size. You can buy guttering with the downspout connection already installed or you’ll need to install it before putting up the gutters. Cut out a hole to fit the downspout connection using tin snips. Fit in the downspout connection and use silicone glue to attach it and seal the connection. Then attach rivets or screws at the corners and seal them. Connect the end caps the same way.

If you are using brackets, they get attached along the chalk line. They should be evenly spaced about 16 inches apart. You may need to adjust this distance to fit your roof length. Attach the brackets using two-inch stainless steel lag screws. Drilling pilot holes and applying soap to the screws will help them penetrate.

Lay the gutter into the brackets and rotate the back edge up until it fastens into the hook on the bracket. Attach the gutter to the bracket using one-inch stainless steel screws with a flanged nut. Then attach the gutters to the fascia board using stainless steel hex head sheet metal screws about every two feet.

Attach the downspout to its connector, making sure that the end is facing the correct way. Use a heavy bead of silicone sealant to the connection and to any extension you may connect to the end of the downspout. This sealant should dry overnight.

Do I Need Drain Tile Around My Shed?

Drain tile is great around a shed, but a four- or five-inch deep trench filled with gravel will help a lot. It should extend about a foot all around the shed. Putting landscape fabric in the trench before adding the gravel will keep weeds from sprouting up in the gravel.

How to Choose a Dry Location for a Shed?

Pick two or three possible locations for your shed well ahead of time. Watch what happens to these locations when you have a lot of rain or a heavy downpour. Does water tend to collect there? Is the location in the middle of a spot where rain naturally runs through when rainfall is heavy? See what kind of soil is around the prospective shed locations. Is it full of clay that will hold water or does it have some sand in it that will allow water to drain normally?

Notice the kinds of plants that are currently growing there. Certain plants often grow in places where water tends to stand. These include moss, knotweed, chickweed, crabgrass, violets and sedge. Of course, these plants aren’t limited to wet places, but if these are the only plants you see growing in a lower spot, you’d probably have some water problems there.

Another consideration is the amount of sunlight the spots normally get. Plenty of sun means plenty of drying potential. While having some shade over your shed is great in warmer climates, building a shed under a lot of shade is not a good idea. Trees can prevent airflow over and around the shed, especially if there is dense growth.

This encourages moisture to build up and allows mold and mildew growth. It will also encourage moss and algae to grow on your roof where you may not notice it right away. For more information on picking the best spot for a shed read my article What’s the Best Location For an Outdoor Storage Shed?

How to Avoid Water From Getting Under Shed?

You can get a plastic-type barrier material that comes in rolls and different thicknesses. It is fairly easy to cut. The best way to install it is to dig a trench next to the shed all the way around. Drop in the plastic, fill the dirt back in, then attach the top part to your shed foundation with sealant.

If you have rocks in your yard, this would be a great time to use them. You can build a rock barrier in front of the side of the shed that faces the water flow to divert it around the sides a few inches away from the shed. If you have a French drain installed, you can use the rocks to steer the water toward the drain location.

This doesn’t have to be a big project. Depending on the size of the rocks, you can just pile them up into a barrier. It doesn’t have to be very tall, and unless you use really small rocks, you won’t even have to use cement. Just place larger rocks next to each other and fit in smaller ones like a puzzle. You can also build a short brick or stone wall for a barrier to steer water away at the edge of your gravel trench. Slant both sides to steer the water around. I have an article How Do I keep Moisture Out of My Storage Shed? where you can get more information.

Best Material to Use Around Shed to Drain Water Away

Gravel is the best material to use around your shed. Not only does it help to drain the water away but it also enables the water to evaporate more quickly.

Conclusion

While anticipating possible drainage problems before building or installing a shed is the best way to prevent problems, there are always things that crop up that weren’t foreseen. Fortunately, you have several options to fix the problems yourself without calling in professionals.

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