Older homes might seem like a work of art and take you down the memory lane, they require maintenance and upkeep. Otherwise, they might be uncomfortably drafty making cold weather unbearable. Unlike the modern airtight homes, most of the old houses have a natural ventilation system, and houses built before the 1960s were usually not well insulated.
One might be tempted to hire someone to get blown-in insulation done as this seems to be the answer to the question,’ how to insulate an old house cheaply?’ But before that, there are some things to be kept in mind. Some common insulation methods can actually cause long-term damage.


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 seemingly easy may allow condensation to form inside walls. Moisture can build up, eventually leading to mold, wood rot, and foggy windows.

Things to do before applying insulation-

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

Steps in insulating an old house from the outside-

  1. Remove the weather barrier and cladding before drilling holes.
  2. Replace single-pane windows with energy-efficient windows.
  3. Replace or add water-resistant flashing.
  4. Blow in loose foam insulation, and seal drill holes.
  5. Follow prior steps for exterior wall insulation.

Insulating an old house with plaster walls-

Houses built before the 1950s mostly have plaster walls. The most common problem with plaster walls is that they can crack and break away from the lath—thin, closely placed strips of wood—in chunks as they age. It tends to allow air into the house through the cracks in the walls.
Just adding some insulation to your plaster walls can help regulate your home’s temperature and decrease your heating and air conditioning bills. Insulation helps keep your home cooler in the summer and warmer in the winter by not allowing the air produced by your HVAC system to escape as easily through the walls. On average, homeowners save 15% or between $200 and $600 a year on utility bills once they insulate their homes.
Adding insulation to your plaster walls is definitely a task best left to the professionals. An experienced insulation professional can tell you where you need to repair large cracks in your plaster. They will also be able to retrofit your home properly without damaging the structural integrity.
To insulate your plaster walls, the contractor will blow loose-fill or foam insulation, and then install proper sealing and a water-resistant barrier. They may also add another layer of insulation that sits between the blown-in insulation and the outer walls. Ideally, they will then install a rainscreen layer to ensure that moisture doesn’t get into the walls. Once everything is in place, they will carefully seal any holes they cut to ensure that air doesn’t get into the walls. Finally, they will repaint the walls using a vapor-resistant primer.

How to choose material for insulating an older house?

Blown-in insulation is the easiest way to insulate walls since it only requires cutting a hole in the wall instead of taking the wall down and rebuilding it. However, the labor cost for spray foam is higher than other types of insulation because it requires more preparation and experience.

On average, spray foam insulation costs $0.45 to $1.50 per board foot. Blown-in cellulose is a little more expensive at $0.60 to $2.30 per square foot. Board feet are a measurement of volume, taking into account height, length, and width, while square feet only account for surface area.

Contact the best insulation installers in Iowa now and get a free estimate!!