Proper insulation is essential for saving energy and saving money. It also helps protect the roof from accruing water damage. Often the question arises as to whether you should insulate the roof or the ceiling. IS one better than the other? Before you can answer that, it is important to know the difference.

Is It Better To Insulate The Ceiling Or The Roof?

Roof or Ceiling Insulation

Roof insulation is the practice of installing insulation on the roof slope below the rafters. Ceiling insulation involves installing insulation within the floor nearest to the roof structure. Ceiling insulation is often easier to do so is more common. It involves spreading loose-fill or blanket insulation in the attack or airspace. The advantages of ceiling insulation include:

  • Simple installation
  • Affordable

Roof insulation is more common where the ceilings are part of the roof deck. The most common materials used to insulate the roof deck are rigid foam boards, radiant barriers, and spray foam. The advantages of roof insulation include:

  • Energy performance improvements
  • Prevention of moisture damage

In some cases, it may be more efficient to install insulation in the slopes of the roof assembly, such as with vaulted ceilings. A rigid foam board is the better insulation shove for these scenarios. The board is installed on top of the roof sheathing and below the plywood at the top of the roof. The advantages of rigid foam insulation include:

  • Reduced air leaking
  • Limited condensation
  • Reduced chance of ice dams
  • Interruption of thermal bridging in the rafters

Rigid foam insulation can be used in the ceiling as well. Placing rigid foam board and covering it with plywood is often preferred to loose-fill insulation as loose-fill renders the attic space unusable.

What Is A Radiant Barrier?

Radiant barriers are great for warmer climates. They can help you save energy by keeping interior temperatures more efficiently regulated. Radiant barriers are highly reflective materials that reflect heat rather than absorb it. This type of insulation reduces heat fain on the surface. With the sun being the main reason your roof gets hot in the summer, radiant barriers are best suited for warmer climates. Radiant barriers prevent the sun’s heat from reaching the interior of the building but are only effective if the radiant surface is exposed to the air. Radiant barriers can be placed:

  • On top of ceiling insulation, with foil facing upwards
  • Under roof sheathing
  • Up towards the rafters below the bottom of the chord truss

The most efficient placement is under the roof cheating or below the bottom chord truss. If placed on top of the ceiling insulation, it will collect dust over time which can interfere with its effectiveness.

What Is The Best Insulation?

As time goes by, more and more insulation is required for buildings. The reasons for this are that energy codes are getting more stringent as everyone is trying to make more energy-efficient buildings. The best insulation for you will depend on the climate you live in. Every locality has its own energy efficiency codes. You need to keep these in mind when looking at roof insulation. If you are looking to make your older roof more energy-efficient, you should sign up for an energy audit test. You can get a basic audit from your electric or gas company or a more comprehensive audit from a private contractor. The testing will help you determine the best ways to help improve your energy efficiency. If you are deciding between insulating the roof deck or the ceiling, Insulating your ceiling should be the priority. Not only is it easier but ceiling insulation is beneficial in a number of ways:

  • Keeps the temperature in the building regulated
  • Saves on energy costs
  • Helps prevent the accumulation of moisture
  • Helps avoid damage to the roof deck
  • Prevents heat due to conduction


Thermal conduction is likely the reason for your high energy bills because your air conditioning and heating units have to work harder to keep temperatures regulated. With ceiling insulation, conduction is reduced and so are your energy bills. The only times when insulating your roof is the better option is when the attic is part of your living space or when you have low-pitch or vaulted ceilings. Insulating the roof is also better for hot climates where the sun is beating down on roofing all day long. It is important to insulate your ceiling for a number of reasons. Insulating your roof may also be an option to consider. Speak with a professional roofing company to find out what is best for you so you can start saving money today.



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