How to Space Between Concrete Patio & Home

The perfect patio needs room to move.

Concrete expands and contracts based upon moisture and temperature. This can lead to your concrete patio cracking if you have not placed expansion joints to cushion this movement. When pouring a new concrete patio against an existing structure, it becomes even more important to create an expansion space, or the cracking can become severe. Easily create space between a concrete patio and your home using expansion joint material, which is available at building supply stores.

Things You'll Need

• Brush
• Waterproofing compound
• Cork fiber expansion joint material
• Box knife

Instructions

1. Brush the concrete of the house foundation clean of any dirt or debris in the area where the concrete patio will be poured against the house (the house foundation, which comprises one side of the patio form).

2. Paint the concrete of the house foundation with waterproofing compound where the expansion joint material will be placed. You don't have to paint the whole thing--just enough to cover the depth of your new concrete patio. Waterproofing compound is used for two reasons. First, it is sticky enough to hold the expansion joint material in place; and second, because the expansion joint material will retain moisture, it is helpful to have an additional layer of waterproofing on your foundation in this area.

3. Press the expansion joint material into place against the house foundation. Cork fiber expansion joint material comes in strips 6 inches wide by 6 to 8 feet long. Place strips of the material against the house so the bottom of the joint material is pressed into the bottom of the pour area, and each piece butts the next, so there are no gaps.

4. Pour and finish your concrete patio. When the concrete is fully cured, trim the expansion joint material with a box knife so it is flush to the top of the patio. This will make it less noticeable.

Tips & Warnings

• Install your expansion joint material before you place any rebar or wire mesh in your concrete patio form. This way, you can get the proper clearance from the expansion joint material, and not have to go back and cut the rebar or mesh to make room for it.

• Never use an expansion joint material that is less than a 1/4 inch wide, or it will be incapable of cushioning the movement of the concrete, and cracking will occur.

References

• JohnBridge.com: Control Joints

Resources

• MostlyBuildingArts.com: Concrete Foundation Expands and Contracts