Does Foam Board Insulation Under Siding Help Save Energy?

Updated on April 9, 2019
Energy Guild profile image

I am currently a licensed contractor performing remodeling services for residential and commercial customers in Wisconsin.

Many people install vinyl siding or concrete board sding to improve the look and value of their home. With budgets tighter than ever now, contractors and do-it-youselfers are tearing off the original siding, and installing a thin foam board underneath claiming it will improve the energy efficiency of the property. Is this true? Depends.

1/2" Polystyrine Foam Board Insulation

This is typically used to go over the existing siding in order to create an even surface to keep the siding plum during installation. This is most common with vinyl siding. The foam board is nailed in place with washer head nails should be taped at the seams to prevent air movement. The typical R-value of this product is R-2.5 to R-3.5 depending on the density of the foam board. This amount of R-value will make no difference in efficiency. What may help though, is the taping of the seams and the caulking of all penetrations through the siding once completely installed. This type of installation typically sees a 0-5% savings in energy, 5% being a rare scenario.

Foil Faced Foam Board Insulation

Foil faced foam board insulation is a great idea but is not a good choice for hot climates or cold climates as an exterior insulation product. We will start with hot climates.

Hot climates already have a lot of heat and vinyl siding tends to expand and contract with temperature changes up to 1" if the siding is made of recycled vinyl material. When the foil faced material "reflects" that heat, the area between the siding and the reflective covering turn into an oven-like environment and can permanently damage the siding.

In cold weather climates, you actually want your building to absorb as much heat that the sun gives off, not reflect it. So it doesn't make a lot of sense to install a product like this for an exterior application unless you live in a perfect world of 70 and sunny in which case, you wouldn't need insulation.

Standard Polyicynine Foam Board Insulation

Basically, in order to get a good insulation value out of foam board, it has to installed directly on the sheathing of the house. If the house is brick or stone, the foam board may be applied directly to the brick or stone. The best installation of foam board insulation is at least an R-10 nailed to the sheathing surface with all seams taped. The reason the foam board should be at least an R-10 in because the thermal transference will be much less between the outside and the inside making condensation issues from thermal conductivity much less likely. In fact, a perfect insulation system would be installed on the outside of a building only. We'll get to that a different time.

Basically, if you want extra R-value for your walls but do not want to tear off your siding, don't bother with the foam board. You are economically better off spending your money on dense pack cellulose insulation for the stud wall cavities and the company performing the work will charge you less because they can just drill through the existing siding without taking it off.

If you are tearing the siding off anyway, it would be beneficial if you are adding at least an R-10 to the exterior. You can still do the dense pack cellulose.

If you are not sure about the kind of energy efficiency project to perform, you should hire an energy consultant. They will go through your home with you and give you a report with the energy efficiency upgrades that will help you save money.

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.


    0 of 8192 characters used
    Post Comment
    • profile image


      9 years ago

      Our house is built like this. They didn't even use the pink board, they used the white stuff. I feel like its a cheap ripoff of a house. I have read many different sites and the ONLY cons are that it supposedly has a better R value in certain climates (not all of them). Even then, you can make up that R value with better insulation. But the main con is that it is cheap cheap cheap. And i bet you, that your house is just as expensive as the guys down the street who has plywood. The only person who saved that money was the contractor who charged you as if he had used plywood. GOOD contractors use the plywood, then the Rboard--flashing it between the joints (cheap contractors don't do this for extra moisture protection), use spray foam between the gap left at the bottom of the Rboard, then the exterior wall. This setup gives you the best of both worlds.

      Rboard is bad when used for anything other than exterior insulation (where it can breathe). They need to make it illegal for houses to be shealthed in it just for the security reasons alone. You might as well have your possesions in a tent.

    • profile image


      9 years ago

      Yes, indeed! It really helps us save energy but it still depends on the people living on the house with foam insulations in it. Well, I hope everyone does save energy these days.


    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at:

    Show Details
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the or domains, for performance and efficiency reasons. (Privacy Policy)
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)
    ClickscoThis is a data management platform studying reader behavior (Privacy Policy)