How Do You Install Insulated Siding?

Insulated SidingInstallation of insulated siding not only improves the appearance of a home, but also improve its energy efficiency and value. Installing insulated siding is a project worth tackling.

Prior to Installation of the Insulated Siding

Perform a pre-installation check to make sure the exterior walls are level, sealed and that there are no moisture issues, according to the Vinyl Siding Institute. Next, establish a taut level chalk line running from corner to corner of the house. Once it is level, snap the chalk line against the house and level around every exterior wall.

Installing Insulated Siding

Underlayment Starter Strip Installation

Solid core siding panels will expand and contract so always leave 1/4-inch space in channels to allow for this and don’t nail it down tight. Place the nail in the center of the slots, and allow a 1/4-inch gap between the starter-strip ends. Then nail the starter strip at 8- to 12-inch intervals, flush with the top of the chalk line. Make sure to keep a distance of 1/16-inch between the nail head and the house.

Corner Post/Inside Post Installation

Measure the corners of the house and add 3/4-inch to the bottom measurement for the inside or outside corner posts. The bottom edge of the corner post must extend 3/4-inch below the starter strip. Next, set the corner posts in position. There should be a 1/4-inch gap between the post top and the eaves/soffits. Insert a nail at the top in the upper nail slot on both sides of the corner post. Do not hammer the nail flush with the slot or house; but leave a 1/16-inch gap between the nail head and house to allow for expansion. Make sure to hammer the nail in straight, and not at an angle. Next, confirm the corner post is straight before nailing by placing the level alongside its edge on either side. Then, you should add nails every 8 to 12 inches in the nail slots provided down the corner post on either side. If you need more than one length of corner post, overlap the top over the bottom 3/4-inch to prevent water from seeping underneath the siding. The corner post hangs from these nails.

Seaming Panel Installation

Solid core siding panels will easily slide into the newly installed corner posts. The correct way to seam two solid core siding panels is to slip the vinyl edge of the rear portion of the seam between the unfused foam and the vinyl on the adjoining panel. Then slide the panels together until proper foam-to-foam contact is achieved. Foam-to-foam contact is critical to ensure proper long-term weathering and optimal insulation value.

Installing Around Obstacles

If an obstacle (such as a spigot) has been J-blocked, simply measure the dimensions and cut the proper clearance out of the siding panel. If the obstacle is not J-blocked, cut panels to seam around it by cutting the first panel 1-inch beyond the obstacle. Slightly trim the second panel to the contour of the obstacle. Then simply slide the panels together and nail them up. Another technique is to take the panel, turn it over, position it and press it into the object, to cause an impression in the foam, then cut around the impression for a perfect fit. When installing in the rake or gable areas, mark the proper angle on the panel, then cut. The cut edge on the panel should be secured by crimping with the snap lock tool.

Working Around Windows

It’s important to properly flash around windows before installing siding. Measure the window opening, use 1 1/8-inch J-channel and trim around the entire window. Nail the slots every 8-10 inches. Create water diversion tables on the J-channel at the top of the window. Measure and cut the panel to fit under the window. Use a snap lock tool to crimp the cut panel. Depending on where the cut falls on the panel, you may need to install a piece of universal J-channel right inside the 1 1/8- inch J-channel below the window.

Top Course Finish Out

The recommended finish for a side wall is to use backplate and finish board. First install backplate at the top of the wall. Install the last course of siding and snap the trim board into the backplate.


Installing insulated siding is a big investment and keep in mind, specific products may differ in detail so it’s always a good idea to consult the manufacturer’s recommendations as a guide to proper installation and care. When compared to other exterior treatments, siding is inexpensive to maintain, increases energy efficiency and ranks among the highest returns on investment for remodeling projects.

Related Resource: Vinyl Siding Maintenance