Table of Contents
What is Thermal Bridging and How Does it Affect Your Home?
Written by: Briain Kelly
Published: January 13, 2026
Last updated: January 13, 2026
Reading time: 3 mins
The point of having insulation installed in your home is to create a seal that will prevent heat from escaping. For that to work, it is essential that there are no gaps in the coverage that insulation provides.
A thermal bridge, or a cold bridge, is an area in the fabric of a building where heat is able to pass through more easily. This ‘bridge’ between the inside and outside of the heat envelope can be caused by gaps in insulation coverage, material sticking through insulation, or where different planes of a building meet.
Why are thermal bridges important?
Heat trying to escape the envelope of a building will always follow the path of least resistance. That is why it is so important to have as complete a seal as possible.
If you have gaps in your insulation, it can negate a lot of the benefit that insulation can provide. This makes it more difficult and expensive to keep your home warm. A home with many thermal bridges can expect:
Higher Heating Bills: You will be spending more on heating to compensate for the fact that so much heating is escaping.
Reduced Home Comfort: Thermal bridges will create cold spots that will reduce the comfort of your home as it struggles to keep the temperature where they are more prominent.
Greater Carbon Emissions: Greater heating requirements will result in higher carbon emissions for your home.
Potential Health Issues: Serious and unaddressed thermal bridging can result in mould, which poses a health hazard in your home.
The temperature difference between different areas of the interior surface of a building, cold at the thermal bridge and warmer away from it, can also cause problems. Different temperatures can cause condensation. Over time, this can develop into a serious problem with damp, mould, or even structural damage in serious cases.
Where does thermal bridging occur?
There are multiple elements of a building which can create thermal bridges, either in the fabric of the building or in the envelope created by installed insulation.
Repeated Building Elements: Parts of a building, such as wall ties, rafters, joists, and studs.
Wall Junctions: Where the walls of the building meet the floor, the roof, or each other. The wall/floor junction is a serious bridge as it is more difficult to insulate.
Insulation Gaps: Parts of the building where there is a gap in the insulation, or it is thinner, such as around windows or doors.
Building Penetrations: Plumbing, wiring, flues or other elements that pierce the building envelope for whatever reason.
Thermal Bridges Created by Poorly Installed Insulation
On top of the issues listed above, thermal bridges can also be created when insulation is not installed properly, leaving gaps in the coverage.
Attics & Lofts
When installing attic insulation at the loft level, the main potential for thermal bridging is at the loft joists. The first part of insulating an attic loft is to put layers of insulation in between the joists. This leaves a cold gap at the timbers themselves.
The second step in loft insulation is put down another layer of insulation on top of the joists and the first layer in order to address this. The second layer should also be placed at right angles to the first layer of insulation. This leaves no continuous seam where the rolls of insulation meet.
When installing insulation on the roof of a building, it is essential that any solid insulation materials are secured properly. At the roof level, gravity is working against your insulation and could pull it out of place over time. The insulation must be cut snug to the gap between the rafters and secured in place with battens or netting if necessary.
Cavity Walls
With cavity wall insulation, the most commonly used material is polystyrene bonded beads. These are pumped into the cavity of the wall from outside, where they harden into a solid mass due to the glue coating them.
The installer needs to make sure that they have sufficient coverage and don’t end up leaving gaps where there is little to no insulation pumped in. Otherwise these empty spots will create thermal bridges.
Internal & External Walls
Internal and external wall insulation needs to be installed flush with the wall or stud wherever possible. It also needs to be firmly fixed in place. Badly installed insulation on your walls can sag over time, creating gaps. Having air gaps between the insulation and the wall can also lead to serious thermal issues and condensation.
What to do about thermal bridging?
There are multiple ways to address different types of thermal bridging to help make your home more energy efficient and comfortable.
Add Continuous Insulation: Add insulation that completely covers and goes past the junctions of building planes. In particular, try to insulate past the wall/floor junction.
Used Specialised Joins: Where lintels, windowsills, balconies and other joins exist, you can use materials which are specifically designed to act as thermal blockers.
Seal All Gaps: Ensure that where there is a break in the fabric of your property for pipes, wiring, or other elements, the gap around them is completely sealed to prevent airflow.
External Wrap: Adding a complete layer of external insulation may be one of the only ways to address all thermal bridges on a property.
Author:
Briain Kelly
EDITOR
Briain Kelly is a Leinster based journalist and content creator who has been writing about energy efficiency and renewable energy technologies for several years now. He researches the latest news in multiple areas related to solar power, electric vehicles, heat pumps, and home energy upgrades. His writing includes both technological developments and government policy.
What is Thermal Bridging and How Does it Affect Your Home?
Published: January 13, 2026
Last updated: January 13, 2026
Written by: Briain Kelly
Reading time: 3mins
The point of having insulation installed in your home is to create a seal that will prevent heat from escaping. For that to work, it is essential that there are no gaps in the coverage that insulation provides.
A thermal bridge, or a cold bridge, is an area in the fabric of a building where heat is able to pass through more easily. This ‘bridge’ between the inside and outside of the heat envelope can be caused by gaps in insulation coverage, material sticking through insulation, or where different planes of a building meet.
Why are thermal bridges important?
Heat trying to escape the envelope of a building will always follow the path of least resistance. That is why it is so important to have as complete a seal as possible.
If you have gaps in your insulation, it can negate a lot of the benefit that insulation can provide. This makes it more difficult and expensive to keep your home warm. A home with many thermal bridges can expect:
Higher Heating Bills: You will be spending more on heating to compensate for the fact that so much heating is escaping.
Reduced Home Comfort: Thermal bridges will create cold spots that will reduce the comfort of your home as it struggles to keep the temperature where they are more prominent.
Greater Carbon Emissions: Greater heating requirements will result in higher carbon emissions for your home.
Potential Health Issues: Serious and unaddressed thermal bridging can result in mould, which poses a health hazard in your home.
The temperature difference between different areas of the interior surface of a building, cold at the thermal bridge and warmer away from it, can also cause problems. Different temperatures can cause condensation. Over time, this can develop into a serious problem with damp, mould, or even structural damage in serious cases.
Where does thermal bridging occur?
There are multiple elements of a building which can create thermal bridges, either in the fabric of the building or in the envelope created by installed insulation.
Repeated Building Elements: Parts of a building, such as wall ties, rafters, joists, and studs.
Wall Junctions: Where the walls of the building meet the floor, the roof, or each other. The wall/floor junction is a serious bridge as it is more difficult to insulate.
Insulation Gaps: Parts of the building where there is a gap in the insulation, or it is thinner, such as around windows or doors.
Building Penetrations: Plumbing, wiring, flues or other elements that pierce the building envelope for whatever reason.
Thermal Bridges Created by Poorly Installed Insulation
On top of the issues listed above, thermal bridges can also be created when insulation is not installed properly, leaving gaps in the coverage.
Attics & Lofts
When installing attic insulation at the loft level, the main potential for thermal bridging is at the loft joists. The first part of insulating an attic loft is to put layers of insulation in between the joists. This leaves a cold gap at the timbers themselves.
The second step in loft insulation is put down another layer of insulation on top of the joists and the first layer in order to address this. The second layer should also be placed at right angles to the first layer of insulation. This leaves no continuous seam where the rolls of insulation meet.
When installing insulation on the roof of a building, it is essential that any solid insulation materials are secured properly. At the roof level, gravity is working against your insulation and could pull it out of place over time. The insulation must be cut snug to the gap between the rafters and secured in place with battens or netting if necessary.
Cavity Walls
With cavity wall insulation, the most commonly used material is polystyrene bonded beads. These are pumped into the cavity of the wall from outside, where they harden into a solid mass due to the glue coating them.
The installer needs to make sure that they have sufficient coverage and don’t end up leaving gaps where there is little to no insulation pumped in. Otherwise these empty spots will create thermal bridges.
Internal & External Walls
Internal and external wall insulation needs to be installed flush with the wall or stud wherever possible. It also needs to be firmly fixed in place. Badly installed insulation on your walls can sag over time, creating gaps. Having air gaps between the insulation and the wall can also lead to serious thermal issues and condensation.
What to do about thermal bridging?
There are multiple ways to address different types of thermal bridging to help make your home more energy efficient and comfortable.
Add Continuous Insulation: Add insulation that completely covers and goes past the junctions of building planes. In particular, try to insulate past the wall/floor junction.
Used Specialised Joins: Where lintels, windowsills, balconies and other joins exist, you can use materials which are specifically designed to act as thermal blockers.
Seal All Gaps: Ensure that where there is a break in the fabric of your property for pipes, wiring, or other elements, the gap around them is completely sealed to prevent airflow.
External Wrap: Adding a complete layer of external insulation may be one of the only ways to address all thermal bridges on a property.
Author:
Briain Kelly
EDITOR
Briain Kelly is a Leinster based journalist and content creator who has been writing about energy efficiency and renewable energy technologies for several years now. He researches the latest news in multiple areas related to solar power, electric vehicles, heat pumps, and home energy upgrades. His writing includes both technological developments and government policy.
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