Should Decking Be Level?

Have you ever noticed water pooling on your deck? Or maybe you have noticed this on someone else’s deck and want to avoid it when you have your own built. Whatever the case may be, when water pools on a deck, it is generally due to the lack of a necessary slope.

That’s right. Decks should not be 100% level. However, don’t be concerned with being able to tell that the deck isn’t level, as the slope needed to keep your deck in good condition is very minimal and unnoticeable.

Let’s learn more about what pooling water can do to your deck, how much you should slope your deck and the benefits of a level deck with a slight slope.

What Happens When Water Pools on a Deck?

Rainwater needs somewhere to go so it doesn’t cause damage to your structures. However, if you have a completely flat surface, the water will simply pool because there isn’t a slope that will allow it to just run off.

Unfortunately, this can result in structural weakness in your deck. Over time, the deck is likely to warp, rot, crack, etc. due to the structural instability caused by the water build-up. This can ultimately lead to the lifespan of your deck being reduced greatly.

In addition, insects will be attracted to the pooling water. Depending on the type of insect looming around, they may bore into the wood of the decking. This will also impact the stability of the decking structure.

Benefits of a Sloped Deck

As previously mentioned, by sloping a deck, you will reduce the amount of moisture that accumulates on the deck. A small slope will provide rainwater and other moisture a way to run off the deck and avoid causing moisture-related damage to the boards.

A deck that slopes away from the home will ensure that water doesn’t enter the home or lead to foundation damage. You don’t have to be concerned with water draining towards the home, which can result in your foundation cracking or even sinking.

When water ponds, there is always the risk of mildew and mould growth. By sloping your deck, you are preventing the risk of mould or mildew from forming on the deck. This helps to prevent the wood from rotting as well—and rotted wood can be particularly dangerous if you have a deck relatively high.

In addition, a sloped deck will last longer. This is due to the fact that the build-up of moisture won’t cause the problems outlined above.

How Much Should You Slope Your Deck?

When it comes to just how level a deck should be, use some common sense. However, as a general rule, you are looking at a slope of about 1/8” per foot. This is true whether you have a freestanding deck or a deck attached to the home.

Always make sure the slope is headed away from the house. The main reason for sloping your deck is to avoid the accumulation of moisture and related damage, but if the slope is facing the home, the water will drain around the exterior of your home and potentially cause foundation issues.

In the event the deck boards run perpendicular to your home, then increasing the slope to 1/4” is a good idea. The same is true for solid deck surfaces. This slight increase simply helps water to be properly channelled away from the home.

Keep in mind that a slope isn’t necessarily needed if your deck has a small gap between each of the boards. These gaps serve the same purpose as a slope—to allow water to run off and avoid collecting on top of the deck’s surface. Of course, a slope can always be built.

Building Regulations for Sloped Decks

While there are no specific building regulations that state you must slope your deck away from the home. However, local building codes do tend to take moisture and water damage into consideration when creating these codes. For example, there may be rules that specify how your decking should be flashed.

Further, most codes require that attached decks be built beneath entrances to the home, ensuring excess water doesn’t flow inside your windows or doors. If you have purchased a home that has a deck already built and notice that the deck is level with the back door, then the deck wasn’t built to code. In this particular instance, you will want to invest in having the deck sloped away from the home.

Do Decks Built to Code Still Need to Be Sloped?

If your deck has been built to code, you may assume that sloping the deck isn’t necessary. This is especially true if the deck was built prior to you moving in. However, do you know 100% sure that the deck was indeed built to code? Without knowledge of the builder or communication with the previous homeowners, this is information that is left up in the air.

Further, going ahead and sloping an already built deck can help ensure water doesn’t build up on the boards. It simply helps to prolong the lifespan of the deck.


While sloping your deck is a good preventative measure and will help extend the life of your deck, there are certain instances when a deck can be level with no issues. This includes gaps between the deck boards.

If you are uncertain, go with a small slope of 1/8” per foot, as this will not be noticeable and will greatly reduce the risk of pooling water. If you decide to go with a completely level deck, make sure that local building codes are followed to prevent potential issues later down the road.

If you have any questions about your decking and whether it complies with regulations then don’t hesitate to get in touch with us.

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