What Is the Best Insulation for Under Floors

The foundation of any home is its floor. Insulation is often overlooked by homeowners, even though aesthetics and durability may be desired features. Underfloor insulation in Wellington is a great way to improve energy efficiency as well as comfort.

This article will explore underfloor insulation, the best type of insulation for these spaces, and the impact that insulation has on electric radiant floor systems.

Understanding Underfloor Insulation

Why Underfloor Insulation is Important and What are the Benefits?

It’s important to know the importance of insulate these spaces before we get into the various types of underfloor areas.

Why Insulate Your Home?

Thermal Efficiency

Underfloor insulation is primarily used to stop heat loss. The primary reason homeowners invest in underfloor insulation is to prevent heat loss. Over time, this can lead to significant energy savings.

Moisture Control

Insulation can help to reduce the risk of dampness. Moisture is a major factor in mold growth, wood decay, and poor indoor air quality. Insulation reduces the risk.

Comfortable Increase

A floor that is insulated will provide a warmer walking surface, especially in the colder months. You can walk around your house barefoot without feeling cold.


Certain insulation types have also been designed to dampen sound and reduce noise transmission between floors.

There Are Many Types Of Underfloor Spaces

Insulation challenges are unique for each type of space under the floor.


A crawlspace is the area between the ground floor and first floor of the house. The crawlspace is usually just high enough to allow someone to crawl through.

Insulation Considerations

Crawlspaces are often damp due to their close proximity to the earth. Moisture resistance is therefore a priority. Ventilation is essential. In most cases, fiberglass or rigid foam insulation is installed along the perimeter wall, instead of insulating the flooring itself. To combat moisture, a vapor barrier may also be required.


Basements are completely excavated areas beneath a house. Basements can be finished as living spaces or unfinished to serve primarily as storage and utility areas.

Insulation Considerations

Basement insulation can be more complicated due to their size and the potential for moisture problems, especially when they are below the water table. It’s important to take into account both the walls and the floor when insulating. Spray foam, rigid panels of foam or fiberglass batts can be used. A moisture barrier should almost always be installed.

Suspended floor

Suspended floor elevated above the ground. Built on beams, pillars or joists to create a space between the floor and the ground.

Insulation Considerations

Air can enter the house through the sides of suspended floors. To prevent the insulation from sagging, it must be firmly fixed. To prevent heat loss and drafts, reflective foil insulation, mineral or fiberglass wool can be placed between the joists.

It’s important to take into account not only the type of insulation but also its R-value and thickness when insulating these areas. Although initial installation may be expensive, the benefits in terms of energy savings and comfort will make it worth the investment.

Insulation and Its Impact on Energy Efficiency and Comfort

Insulation can make or ruin the energy efficiency of your home. A good insulation will act as a barrier, preventing cold air from entering during the winter and keeping cool air inside during the summer. Reduced HVAC usage will result in lower energy bills. The comfort of residents is also enhanced by maintaining a constant temperature.

Underfloor Insulation Types

Fiberglass Insulation
Fiberglass is a popular and cost-effective choice. The glass fibers can be rolled into bats or blankets.

Spray Foam Insulation

Spray-on insulation fills in gaps and expands. This type of insulation has high R-values, and it creates an air barrier.

Mineral Wool Insulation

Mineral wool, made from slag or rock, is resistant to fire and has excellent soundproofing qualities.

Reflective Foil Insulation

It is ideal for hotter climates because it acts as a radiant heat reflector.

Rigid foam Insulation

This is a board of foam that can be used where space is limited, and has a high R value per inch thickness.

What to Consider When Choosing Insulation

Climate and geographic location

The U.S. Department of Energy recommends R-11 insulation (3 1/2″) under floors in warm climates. In cold climates they suggest R-25 insulation (6”-8”). These practical tips will help you achieve energy efficiency in your home and ensure maximum comfort.

Moisture Barrier and Vapor Barrier Considerations

It’s important to choose insulation that is resistant to mold and has a vapor-barrier in areas susceptible to moisture.

Accessible and inaccessible Underfloor Areas

It is important to consider accessibility when planning for underfloor insulation. Installation process and insulation types can differ significantly depending on whether or not the area is accessible.

Accessible areas

You can access these spaces without having to do any demolition or construction. You can choose from blanket batts, rolls, loose-fill or sprayed-foam insulation for these areas. Professional installers can ensure the best fit and installation.

Areas That are Not Accessible

It is difficult to reach spaces after construction. For example, enclosed cavities or gaps in a suspended floor. You can use blown-in foam insulation or injected insulation to fill these spaces without having to tear apart your home.

It’s important to fix any dampness or moisture issues, regardless of access, before you install insulation.

R-Value requirements

The R-value measures the resistance of an insulation to heat flow. The R-value is a measure of insulation’s resistance to heat flow.

Fire Safety and Building codes

Always make sure that the insulation chosen complies to local building codes and fire safety regulations.

Floor Insulation and Radiant Floor Heating

There are many different insulation materials, some of which are designed specifically for electric radiant heating systems. Ultralight insulation boards, and insulated underlayment for foil heaters are two of the most efficient.

Ultralight Insulation Boards

As the name implies, Ultralight(tm), insulation boards are light weight, making them easy to install and handle. They are lightweight, but have robust insulation properties.

These boards are designed to be used with Better Plasterers Ltd radiant heating systems. They provide a high level of compressive strength, which allows even heat distribution. The boards’ design reflects heat upwards for maximum energy efficiency.

These are perfect for tiles and stone floors, where thermal mass would otherwise slow the heating process.

Insulated Underlay for Foil Heater

The Better Plasterers Ltd Insulated Underlay Insulation is a special underlay designed to be placed beneath foil heating elements. It is made from layers of materials and combines insulation properties with an underlayment.

The insulated underlay is designed to work with the Better Plasterers Ltd. It ensures that heat is not lost and the heat is directed upwards. The design provides excellent acoustic and thermal insulation, and prevents the foil heating system from being in direct contact with the subfloor. This prolongs the life of the heater.

This product is best for carpeted, laminate, or engineered wood floors.

Better Plasterers Ltd Offers The Best In Radiant Floor Heating And Floor Insulation.

We at Better Plasterers Ltd understand the importance of radiant floor heating in conjunction with insulation. This is why it’s important to make sure that both components work seamlessly together for a warm, comfortable, and cost-effective home. Our tailored solutions will enhance the performance and longevity of your radiant heating system, whether you require ultralight insulation for tile floors, or an insulated underlay to cover foil heaters beneath wood and carpets.

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