How to Construct a Kerfed Rim Joist for Patio Decks

What You'll Need
2 x 10 lumber
Tape measure
Straight edge
Table saw
Circular saw

Curved patio decks add a distinct look to your home. A deck with curved ends can seem more tranquil and add a softer look to the outside appearance of your home and landscaping. Building curved patio decks requires certain construction techniques that can be easily learned by a do it yourself homeowner. A cantilever design is needed for the joists to overhang the footing piers. As well, a kerf rim joist is needed to produce the curve in the outside edge. Here are the steps needed to cut the kerf rim joist for your curved patio or deck.

Step 1 - Mark Kerfs in Joist

The kerfs are made by cutting slots along the length of the back of the rim joist. In order to cut these slots you will need to measure and mark each channel. While this is time consuming it is worth the effort to keep everything aligned correctly. Start at one corner of the 2 x 10 and measure in 1/4 inch. Make a mark. Then measure another 1/8 inch and make another mark. These are the edges of the kerf cut. Draw a line from the mark to the other edge with a straight edge. Repeat with other mark. Continue with this measuring process until you have completed the entire length of the joist.

Step 2 - Cut With Jig Saw

One of the ways that you can cut out the kerfs in the rim joist for your deck is to use a jig saw. You will need to make sure the blade does not extend more than 1/2 inch into the wood itself. Cutting the board with a jig saw does require a great deal of patience and not forcing the cut. If you move too quickly with the cut, you can break the blade inside the wood.

Step 3 - Cut With Circular Saw

One of the easiest ways to cut the kerfs in the lumber is to use a circular saw. Set the blade at a depth of 1/2 inch for a consistent cut. Set the lumber on a sturdy surface and begin cutting the channels. Run the saw across the wood in several passes to remove the wood between the marks.

Step 4 - Cut With Table Saw

Another way to create the channels in the rim joist is to use a table saw. Set the depth of the blade of the table saw to 1/2 inches and remove the fence. You will need the entire length of the table. Line up the marks and run the lumber through the blade. You may need to make another pass to remove the wood.

Step 5 - Use Router Bit

Another option is to use a router for cutting the kerfs in the rim joist. Install a 1/8 inch straight bit into the router and run it along the length of the lumber.

Step 6 - Attach Laminate Joist

When using a 2 x 10 joist you will have sufficient strength of the rim joist. However, if you are using a 1 x 10 you will need to make a smaller kerf cut, but also add strength by using a laminate joist on the outside. Attach this with glue and wood screws.