Installing STYROFOAM CLADMATE/CLADMATE XL – Existing Frame Walls (Residing/Retrofit)

Before you put up your new siding, install a layer of STYROFOAM™ CLADMATE™ or STYROFOAM CLADMATE XL extruded polystyrene insulation and it will go a long way to help you save energy for years. And it makes your home more comfortable. It covers cracks in the walls and gaps around doors and windows. This helps prevent cold air from penetrating your home in the winter and hot, humid air in the summer. What's important too is that the rigid panels give you a smooth, level surface for mounting your new siding.

Tools and Materials Checklist
  • Safety Goggles
  • Measuring Tape
  • Carpenter's Folding Ruler
  • Level
  • Utility Knife
  • Chalk Line
  • Hammer or Power Nailer
  • Portable Power Saw
  • Hand Saw
  • Nails (foam, siding, jam)
  • Carpenter's Metal Square
  • Vinyl Siding
  • J-Channel and Trim
  • Jam and Sill Extenders

Before you get started, you'll need to select the correct insulation for your needs. Remember that the thicker the rigid foam board, the more insulation value it offers. We suggest a minimum 3/4" (R-3.75) up to 1.5" (R-7.5) of STYROFOAM CLADMATE or STYROFOAM CLADMATE XL insulating sheathing for most re-siding applications. Before covering an old wall with insulation and new siding, be sure the wall is sound. Do not install new siding over walls that have deteriorated from moisture, insects, etc.

1. If the old siding installation is flat enough completely cover it with STYROFOAM CLADMATE/CLADMATE XL extruded polystyrene insulation. Alternatively, remove the old siding to expose the original non-insulating sheathing for attachment of the layer of STYROFOAM insulation. Butt the edges of the boards tightly together. The shiplapped edges of STYROFOAM CLADMATE and STYROFOAM CLADMATE XL ensure an energy-efficient, air tight joint. After measuring, score panels with a utility knife, then snap off the excess piece over the edge of your work surface.

2. Measure the combined thickness of the insulation and the new siding. Use this measurement to determine the thickness of the door and window jamb extensions. You may also need to extend sills. Be sure to extend flashings.

IMPORTANT: Have a qualified electrician extend exterior outlets, light fixtures, doorbell buttons, etc.

Figure 1
Figure 1

3. Nail insulation panels directly over old siding or the existing non-insulating sheathing if the old siding was first removed. Use plastic-capped nails with minimum 1/2" diameter washers. Nails should be spaced 6" along the perimeter of the insulation boards and 12" x 16" in the field of the board.

Figure 2
Figure 2

NOTE: Do not overdrive nails. This can crush the insulation and can also cause a "wavy" siding installation.

4. Apply the new siding and trim. Use nails recommended for vinyl siding. Be sure nails go through the insulation and into the underlying structure, not just the old siding. Follow siding manufacturer's instructions for installation.