How to Insulate an Old House Without Hurting It

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Old homes may radiate beauty and charm, but they often suffer from poor temperature regulation. This can make them uncomfortable to live in, especially during the cold winter months. Unlike today’s airtight homes, many old houses have a natural ventilation system. They “breathe” through air leaks, and houses built before the 1960s were usually not well insulated, especially when compared to newer houses.

If your old house has you shivering, you may be tempted to hire someone to add more insulation. But that might be a bad idea! Some common insulation methods can cause long-term damage.

Living room in an older house.

Before you take that step, learn how to insulate an old house effectively. In the following sections, we’ll explain how to safely insulate different parts of an old home:

Insulating the Attic and Roof

The average home loses roughly a quarter of its heat through the roof. Rather than insulating the whole home and risk causing problems like excess humidity, you can properly seal the attic of an old house. This is a safe first step to retaining heat and saving energy.

To do this, seal any gaps or cracks that allow warm air to travel through the ceiling into the attic with an appropriate sealant (caulk, weatherstripping, fireproof foam sealant, etc.).

Common areas where leaks occur in the attic include gaps around chimneys, ceiling fans, light fixtures, wiring, ductwork, exhaust fans, and pipes. Check around windows or vents, and examine the perimeter to look for tiny gaps or holes.

Once air leaks have been addressed, you can add insulation. Batt insulation can be added to the underside of the roof between rafters, and a layer of batt or loose insulation can be added over the attic flooring. Depending on your climate, an R-value between 38 and 60 is optimal. (Check here for Energy Star recommendations.)

Consider asking a local handyman team like Mr. Handyman to help you with attic insulation.

Additional tips for insulating the attic or roof of an old home

  • Check existing insulation for dampness and signs of mold or mildew, and discard accordingly. (Mold exposure can be a serious health risk. Professional mold removal is the safest bet.)
  • Be sure that your attic has proper, unblocked ventilation such as a soffit vent to draw air in and a ridge vent to expel air outside. (Check your state’s code for specific requirements.)
  • If you use a vapor barrier (or batt insulation that has it attached), the barrier should face the warm side: down (facing the floor) for cold climates, and up (facing the roof) for hot climates.
  • If you are layering new insulation over existing insulation, be sure that vapor barriers are not placed between the insulation layers. Remove barriers from new batting, if necessary.
  • Consider installing metal roofing. Metal roofs are lightweight, durable, and energy efficient.

Sealing Basements and Crawl Spaces

Another way to improve an old home’s indoor climate without hurting the home’s natural ventilation is by sealing basements and crawl spaces.

  • Seal cracks around basement windows and air vents, and gaps around ductwork, electrical wiring and pipes.
  • Add well covers to egress windows if not already present.
  • Install vapor or moisture barriers, and/or apply a waterproof sealing compound to walls and floors.
  • For extra protection, add batt insulation to floor joists. (If you are insulating a crawl space, be sure that entry points are appropriately covered to keep rodents out.)

How to Insulate Walls in an Old House

Knowing how to insulate walls in an old house may not be as important as knowing whether to insulate them. Many homeowners have made the mistake of drilling holes in walls, blowing in cellulose insulation and tightly sealing walls back up. This method may allow condensation to form inside walls. Moisture can build up, eventually leading to mold, wood rot, and foggy windows.

One way to insulate walls of an old house is to focus on the home’s exterior:

  1. Apply a house wrap/vapor barrier to exterior walls.
  2. Attach 1-inch foam board insulation.
  3. Install siding over the insulation.
  4. Replace old windows with energy-efficient units.
  5. Caulk window trim and use weatherstripping to reduce air leaks.

If you’ve tried everything else and are determined to insulate the walls of an old house, follow these tips to minimize risk:

  1. Remove weather barrier and cladding before drilling holes to avoid damaging these items.
  2. Replace or add water-resistant flashing to prevent water damage in the future.
  3. Blow in loose foam insulation, and seal drill holes to improve insulation.

More Ways to Help Keep Old Houses Warm and Toasty

Besides covering leaks and adding insulation, you should ensure that your heating and ventilation system functions properly. Old, inefficient furnaces may not be able to keep up with the heating demands of spacious, historic homes on cold winter nights. Consider enlisting an HVAC expert to upgrade to an energy-efficient model.

Another tip: Seal and insulate heating/cooling ducts, especially those that run through cooler spaces like attics, basements, and unheated garages. Use mastic sealant or foil tape to seal seams and joints, and wrap them in duct insulation.

Hire a Professional

Older houses have a lot to offer. Unique architecture, spacious rooms, and elegance are a few perks that come to mind, but remodeling projects can be complicated. There are many factors to consider before jumping into one. For example, houses built prior to 1978 may have lead-based paint that should be removed before you renovate. Many old homes have plaster walls that require special care when hanging pictures or other items.

Whether you’re undertaking a simple update or tackling a large-scale project like installing insulation, Neighborly has an entire family of home service experts ready to help! Check out the many services provided by our top-notch brands, and schedule an appointment today!

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