How to Insulate a Sunroom Floor

Open the entrance under your sunroom. Clear away any debris and obstructions in the work area. Lay out your work light and tarp under the sunroom. Drag strips of insulation to the farthest point away from your entrance and work your way to the entrance, laying the strips out on the ground as you go.

Lift the first strip of insulation, paper side down, facing you, up between the joists under the sunroom floor. Staple along the paper tabs on both sides of the insulation. Staple through the paper and into the bottom of the joist above. Place a staple every 15 to 18 inches apart. Use your scissors to cut off ends for proper fit and to cut around obstructions. Cover any pipes and wires with insulation to protect them as well. Continue installing insulation until the entire sunroom floor has been covered.

Roll out your construction plastic outside of the work area. Roll out the plastic so that it is 3 feet longer than the floor of your sunroom. Cut the plastic with your razor knife. Drag the plastic into place under the sunroom. Lift the far corner of the plastic to the joists above and staple into place, leaving a 3-inch edge on the plastic. Place a staple into the plastic every 15 to 18 inches. Continue to attach the plastic to the joists while holding it tight. Trim the edges with your razor knife.