How To Install Foam Board Insulation Under Siding

How To Install Foam Board Insulation

Installing foam board insulation under the siding of your house brings with it a host of benefits. One of the most important benefits is that it raises the “R-value” of your home. The “R-value” is used in the building industry to refer to a building’s thermal resistance for every unit area. It indicates how well the insulation material can resist heat flow and is typically established for the materials used.

Foam, for example, has a higher R-value than some popular insulation materials such as plywood or fiberglass batts. You can see why learning how to install foam board insulation under siding is a great idea.

The process for how to install foam board insulation under siding is quite simple and straightforward. All you have to do is accurately measure the walls in your home, set the panels, secure them with nails, and seal any seams that can be found between the panels.

Read on to learn more about each step of the process.

Steps To Install Foam Board Insulation Under Siding

It should be noted that such large-scale projects are best undertaken by professional contractors who know exactly what they are doing and will be careful not to tamper with all the wiring and piping hidden within your walls. However, that isn’t to say you can’t take it on yourself. Here are some tips on doing that if you are determined to make this a DIY project.

Step 1: Gather The Necessary Materials

Much like every other building project, you need to make sure that you have all the necessary materials ready before you get started. Not only will that give you an inkling of the scope of work involved, but it will also help streamline the entire process making it more efficient. Here is what you will need when installing foam board in siding:

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  • Tape measure
  • Hammer
  • Foam board insulation (XPS or other)
  • Reciprocal saw
  • Utility knife
  • Sealing Tape

Step 2: Measure Your Walls

You need to take accurate measurements of your walls from top to bottom. You will find that foam boards, be it XPS or any other type, come in two main measurements: 4×8 or 4×9. Whichever measurement you go for, make sure that it covers the entire wall from the roofline to the base of the wall.

  • Note: Homeowners tend to use XPS or polystyrene foam boards that are 3/4 to 1-inch thick. However, it’s best to check with your local building codes for the exact recommendations in your area. You could also check with your trusted local hardware store for regional recommendations.

Step 3:  Set The Panels On Your Walls

To set the panels on your walls, you should use galvanized nails that have 3/8 inch heads. The idea is to get nails that are not only long enough to go through the foam board but at least 3/4 inches into the wall itself. When setting the panels on the walls, go systematically by beginning at the end of the house. Ensure that the panels’ edges are aligned with the corners and base of the wall before nailing them into place.

Step 4: Use Panels To Cover The Entire Wall

You should make sure that the panels cover the entire wall. This means strategically making cuts into the panels to allow for spaces such as windows and any protrusion on your walls. You can use a reciprocal saw or a utility knife so that the spaces are precise and snug.

Step 5: Seal The Seams

Your rigid foam board insulation is going to have seams between the panels. These are often found at wall corners and window openings. If the seams on your insulation board are not sealed properly, the foam panels of the rigid foam insulation might not perform as well as expected.

To do this, use only the specific sealing tape recommended by your rigid insulation manufacturer. Then, go over the entire wall, thoroughly sealing any spaces between the panels and ensuring that there aren’t any gaps at the bottom or edges that could render your work unsatisfactory.

Step 6: Use An Extra Layer Of Moisture Barrier

It’s always advisable to use an extra layer of moisture or vapor barrier once you install your foam board insulation panels and seal all the seams of the insulated siding. One of the best layers of moisture protection is polystyrene wrap.

Step 7: Re-Mount Your Siding

Once all this is done, it’s time to reinstall your new siding. This is as simple as nailing the new siding through the foam insulation board and into the exterior wall framing of your house. Be sure to use long nails to go through the siding, the foam board, and into the framing.

As simple as it sounds, installing foam board insulation under the siding is not only tedious but also quite delicate work. The biggest issue is that some walls have a lot going on under them, including electrical wiring, AC, and even plumbing.

If you aren’t entirely confident in your DIY capabilities or don’t think that you will have the time to complete the project in good time, it’s best to hire a professional contractor to do it for you. That being said, the steps highlighted above teach you how to install foam board insulation under siding.

Frequently Asked Questions

Does using foam board insulation under siding help to save energy?

Using foam board insulation under siding does help when you are trying to make your building more energy-efficient. It also helps prevent any moisture infiltration problems you may experience. In addition, you can place foam board insulation under the siding during a new reconstruction and when you are remodeling your current home.

What kind of insulation do you recommend putting on your exterior sheetrock wall?

The recommended R-Value for an exterior wall is R-13 to R-23. However, you can also benefit from improving the insulation for your interior walls as well. When it comes to attic spaces and ceilings, you want R-30, R-38, and R-49.

Should a vapor barrier be installed over exterior grade plywood?

A vapor barrier is not always required in warmer climates. And if the vapor barrier is installed in the wrong kind of climate or the wrong side of the building materials, it can cause more harm than good. For example, latex painted gypsum board with one coat of latex paint is considered a Class III vapor retarder.

What is insulating foam sheathing?

Insulating foam sheathing provides an additional layer of insulation to a house that is run continuously past the exterior face of the wood studs. Insulating sheathing plays a vital role during the construction of a home since it offers continuous insulation and is an air barrier that can prevent the transfer of air between the interior and exterior of the home.

How To Install Foam Board Insulation
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