Basics of Insulation Options for an Old House

Living in a classic old house is a privilege. Older homes can evoke a sense of beauty, love, charisma.  They have a level of character and craftsmanship that are no longer seen in todays modern houses. However, during the cold winters, an older home can be quite uncomfortable.  If you are looking into insulation, you may find the information here to be helpful. 

Houses built in the midst of the 20th century were not well insulated. They had a natural ventilation system that allowed their walls to be hollow for it to “breathe” through it. Sitting in your living room on a cold winter night will tempt you to get the walls insulated the next morning.

One of the basics of learning about insulation is “R-Value”. The R-Value is the ability of the insulation material to resist heat and avoid its transfer from one place to another through that material. Usually, it is measured between 1.5 to 7 per inch, and the higher the value the better insulation it can provide to keep your home warm.  Before beginning any insulation project, you should also research your local codes as sometimes there are specific requirements for what minimum R-Value is required for attic, walls, etc.   

Here are a few options for insulating your old house, along with their R-value for comparison:

  • Fiberglass Insulation

Fiberglass insulation is the most common type of insulation used throughout the United States.  It typically has an R-value between 3.1 to 3.4 per inch. It is placed loosely into the stud bays of walls and rafters, allowing it to trap as much air as possible.   Additionally, an air barrier on the external wall helps to stabilize the efficiency of the insulation by preventing cold air from moving into the wall cavity in cold conditions.  

  • Spray Foam

The R-Value of open-cell spray foam insulation is about 3.6 to 3.8 per inch. It is easy to install as it can be blown inside and expands quickly, and you can shave off the excess as it covers the entire wall cavity. If you are spraying it in the cavity, it takes 6 to 8 seconds to set, but when you pour it into the wall cavity, it takes 5 to 8 minutes to fill it up. 

  • Closed Cell Foam Insulation 

This insulation is another form of spray-foam, but it is tough and rigid with a much higher R-Value of 6 to 7 per inch (about double that of the other regular insulation).  It also tends to be one of the more expensive options.  Closed cell insulation is best used on new construction projects as it has to be fitted into an open cavity of the wall and cannot be retrofitted. So, unless you are tearing out your interior walls of your home as part of your renovations, closed cell foam insulation is likely not a viable option.  

  • Cellulose

    Cellulose has an R-Value of 3.6 per inch. It is newspaper chopped up finely and mixed with boron or boric acid, which serves two more purposes. It acts as a fire retardant and also makes the insulation pest resistant. Moreover, it fends off mold, wood decay, and corrosion.  Thorough safety tests are conducted for open flammability to ensure the insulation is fire resistant.

    The cellulose is inserted with a blower, typically into the wall cavity with 2 holes, one in center and one at top. It is misted with a bit of hydration and then packed into the stud bay.
    A vapor barrier or retarder can be used depending on where you live in the country. This ‘loose-fill’ insulation will degrade and settle over time and it’s typical lifespan is in the range of 20-30 years.

Controlling the movement of Vapor in the insulations above:

Warm air contains a good deal of moisture and will always move towards colder air.  This warm, moist air needs to be prevented from entering into the wall cavity and coming in contact with the insulation.   A vapor barrier, like polyethylene is typically used for this purpose.  It can be stapled to the wall sides and should always be placed on the warmer wall, so if you live in a warm climate, it should be placed on the exterior wall, but in cold climates, it should be placed on the interior side. When the climate is different throughout the year, like here in NY, the vapor can collect on the backside of your drywall during summers, and the vapor barrier will not let it dry out. Hence we can use a vapor retarder that allows the stud bay to breathe and the vapor to escape. 

 If you are doing any major remodeling at your home, don’t forget to let your insurance company know.  Our experts at Bieritz Insurance will be happy to document your updates and assist you in finding your best options and rates if any changes are required.  Contact our team for an appointment or call our office at 607-547-2951.  We are happy to assist you with all your insurance needs.