Insulated Vinyl Siding Installation (Laminated)
Many of insulated siding’s attributes and installation techniques are the same as those of vinyl siding. The information contained in this section should be used as a supplement to information available in installation instructions included with insulated siding manufacturers’ materials and in the VSI Vinyl Siding Installation Manual,17 which was developed using the ASTM D4756 Standard Practice for Installation of Rigid Poly(Vinyl Chloride) (PVC) Siding and Soffit.
General Installation Instructions
Installing insulated siding requires many of the same techniques as vinyl siding. Before getting started, it is important to review several rules of thumb for insulated siding installation. For more specific details and illustrations of proper vinyl siding installation, including vertical panels, please consult the VSI Vinyl Siding Installation Manual at www.vinylsiding.org/installation/manual. While the insulated siding manufacturer’s installation instructions should always be consulted, the following rules are critical for proper installation:
- The installation of specific products may differ in detail from the instructions provided in this guide. Always follow the manufacturer’s instructions, using accessories specified by the manufacturer, to ensure proper installation.
- When cutting insulated siding, use a circular saw with a fine-tooth (plywood) blade inserted backwards and cut slowly. Do not attempt to cut materials other than vinyl or insulated siding with a reversed direction saw blade.
- Do not drive the head of the fastener tightly against the siding nail hem; allow approximately 1/32” clearance (the thickness of a dime) between the fastener head and the vinyl siding.
- When installing a panel, it is critical that the lock is fully engaged with the piece below it. Without stretching the panel, reach up and fasten it into place by either pulling it down for stack lock pieces or pushing the panel up for traditional siding.
Figure 5.1 Insulated Siding Panel Overlap
- No gap is needed between the foam at the ends of siding panels; be sure to butt each piece of foam together when installing panels,unless installing in cold weather (see Figure 5.1 and consult the product manufacturer’s instructions).
- Fasten nails or other fasteners in the center of the nailing slot; make sure the fastener penetrates a minimum of 3/4” into a nailable surface. Use the same type of fasteners as used for vinyl siding installation, but longer lengths may be needed. Consult manufacturer’s instructions for fastener specifications.
Insulated siding installers should always consult the manufacturer’s instructions, but the following general panel installation instructions apply:
- Because of the insulation material integral to the panel, insulated siding is thicker than vinyl siding alone. Be sure to purchase accessories that will accommodate the full thickness of the insulated siding. Consult the manufacturer’s instructions for specific accessories (e.g., J-channel, corner posts) or techniques that work best with a given product.
- Use the starter strip specified by the insulated siding manufacturer to ensure proper performance.
- A water-resistive barrier should be installed under all insulated siding. Insulated siding is not a watertight covering; therefore, it allows the material underneath it to breathe. It functions as an initial barrier to rain and significantly reduces the amount of water that reaches the underlying water-resistive barrier.
- On the factory-cut ends of insulated siding panels, the insulation is set back from both ends of the panel. This set-back is required to ensure correct overlapping of adjacent panels. To correctly overlap the panels, insert the vinyl tab at the end of one panel in between the insulation and the vinyl of the adjacent panel. Slide the panels together until the ends of insulation touch. It is recommended to have a gap of 1/8” during installation under cold weather conditions (i.e., 40° Fahrenheit or 4.4° Celsius). For best appearance, lap factory ends only. If you must lap a non-factory end, create the required insulation set-back and siding panel notches following the siding manufacturer’s instructions.
- When determining the length of the final panel of a course, measure from the edge of the foam on the installed panel to the corner, allowing 1/4” for expansion. Apply this measurement to the final panel, measuring the foam instead of the panel. This will ensure foam-to-foam contact, with the necessary amount of room for expansion of the siding.
- Using a circular saw with the fine-toothed plywood blade turned backwards, cut slowly with the vinyl face up. Be sure to cut all the way through the foam.
- Avoid using panels shorter than 24”.
Around Windows and Doors
Because insulated siding is thicker than vinyl siding, windows, doors and openings may have to be built out. Installers should use wood shims and either aluminum trim coil or vinyl lineals to build out openings.
To complete the final course of insulated siding at the top of a wall, installers should complete the following:
- Take the height measurement of the remaining open section in several locations and subtract 1/4” from each location to allow for movement.
- Cut the panel to the required measurement and cut back the foam 2”.
- Using a snap lock punch, punch the vinyl siding along the cut edge every 6”, so the raised lug is on the outside face.
- Install utility trim along the top of the wall to receive the top edge of the siding. Use shims under the utility trim to match the angle or distance from the wall of the siding edge.
- Push the siding into the utility trim. The raised lugs will catch and hold the siding firmly in place.
Before installing insulated siding, inspect walls for evidence of moisture damage. If the condition of the existing siding, sheathing or interior wall finish indicates an existing moisture problem, no insulation should be installed until the moisture problem has been identified and corrected. Seal gaps in external window trim and other areas that may admit rain water into the wall. Level the exterior wall by removing existing siding or sheathing or add surface leveling foam such as fan-fold over a water-resistive barrier.
Insulated siding can be installed over furring strips, but in order for insulated siding to qualify as home insulation, it must be installed directly over a water-resistive barrier and sheathing. Insulated siding installed directly over furring strips would not be considered home insulation.