How to Slope an Existing Deck

Sloped decks are a popular choice for homeowners who want to add a stylish touch to their backyards.

With this kind of project, your aim will be to create a smooth transition from the yard into your back patio. There are several ways you can build sloping decks, but it all starts with building the foundation.

So, how do you slope an existing deck?

Let’s start now.

How to Slope an Existing Deck

Make use of a Laser Level

Make sure that your new boards are at an even height with each other and the deck floor before attaching them.

It will help you make sure you have the right amount of decking materials for your sloped decking project.

Mark where you want to add new boards, then cut the nails with a saw using a miter box or a circular saw.

Remove Boards One at a Time

Mark the location of the new boards on your existing structure with a laser level.

This is the best way to guarantee that your slopes are uniform and that the transitions appear natural from your yard to the home’s interior.

You can reattach the boards to the structure you already have by using the nail gun and the pneumatic nailer.

Mark the Locations of the New Boards

Use a laser level to mark the locations where additional decking boards are needed, then use a circular saw to cut the existing nails in the existing boards where the new ones will go.

Make huge Xs under the joists where your new boards will go, using a pencil and a tape measure.

Build a Temporary Deck

You may add more boards and create a stair step effect for visual interest on your sloped decking project.

Add this temporary deck at the proper angle, then use string lines to draw a line around the edge where the new timber will go.

Make Use of an Accurate Tape Measure

To achieve the most precise results, it is advisable to measure every piece of wood that will go into your deck.

A tool that can help you be more accurate is the tape measure. It can measure up to 100 feet and can help you measure each piece of wood or lumber with ease.

Using an incorrectly calibrated tape measure can result in a value that is wrong by as much as a foot.

One-Dimensional Slopes May Make Some Things Difficult

The simplest slope is one-dimensional, and when you build your deck that way, the slope will not be too dramatic, which will make life easier for you.

Before cutting the lumber, make two plumb lines at the ground and elevation points using a string line and marker levels.

Use an Average of 5 Boards

Find the average of the five closest boards to where you wish to attach the new boards and use this figure as your guide to check the actual length of the board.

Use a Miter Box

Begin by cutting the boards one at a time using a miter box or a circular saw.

Use Plumb Lines to Measure Lumber

Measure the distance in 16 inches between the raw edge and the end-mounted board’s ends.

Make Use of a Line Level

A line level may be used to determine the height of both old and new pieces to achieve a uniform look for your sloped decking project.

Place the line level beneath one end of a board and check its verticality by marking its vertical position with a pencil.

Use that number to figure out the slope so that the two pieces will fit together perfectly.

Angle a Ruler with a Pencil

Most people don’t have a water meter on their property, so if your slope is gradual, you can use an angle ruler and a sharpened pencil to trace the angle of the slopes.

However, you can determine the height difference between the bottom and top of the slope by lining a straight edge along both the inside and outside of the curve.

Simply fix it at an angle using masking tape, then use a spirit level to check for accuracy.

Divide this number by the number of panels you have to figure out what angle your sloped deck should be.

Make Use of a Wet Board

To slope an existing deck, place a plywood sheet at the bottom, then mark the area where it touches the ground by using a chalk line.

Mark the edge of the wet board in its new location, then remove the old boards and install the new ones.

This measurement may then be transferred to the rest of the pieces to achieve the uniform look you desire.

Make Use of a Water Level

To determine how far to slope your deck, measure the height difference at both ends of a panel using a water level.

To begin, measure the height of your railing posts as well as the distance from one post to the other on a flat surface.

Then, record the height difference between each post by measuring their distance using the water-level method.

Use this average height as a guide when you put in your new boards to make the whole structure look the same.

Also Read: Spray Paint Feels Like Sandpaper


It is not as difficult as you may think to change the shape of your existing deck, particularly if it is a modest size.

Most homeowners can do it themselves, but if you are worried about safety or structural integrity, you might want to hire a contractor.

The first step in sloping your deck is to use an accurate measuring tape or yard stick to measure the space you wish to fill with wood.

After that, dig out the dirt under the deck so that it slopes downward toward the ground.

If there are no natural channels beneath your structure, you may need to dig trenches and redirect the water away from your house and its foundation.

Leave a Comment