How to Insulate a Loft Conversion? What to Consider?


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A loft conversion is a great way to add extra living space to your home. But prior to appreciating your new space, you’ll need to insulate it properly. This will preserve your home cool in the summer and warm in the winter and also help reduce your energy bills.

In this detailed guide, I’ll teach you how to insulate a loft conversion yourself. We’ll wrap everything from picking suitable insulation to inaugurating it properly. So, whether you’re a DIYer or you’re looking to hire a professional, this blog post has you covered.

What is Loft Insulation? Why Insulate Your Loft?

Loft insulation is a material that is used to trap heat in your home. It is generally installed in the attic or loft space and can be constructed from various materials, including cellulose, fibreglass, and mineral wool. There are several reasons to insulate your loft.

  1. It can assist in keeping your home cool in the summer and warm in the winter. This can result in substantial savings on your power bills.
  2. Loft insulation can help enhance your home’s air quality. By trapping heat, insulation can help to prevent cold zones from developing in your home. This can help reduce the dust and mould that can be developed in your home.
  3. It can help to enhance the soundproofing in your home. By stopping noise from outside, insulation can develop a relaxing and more peaceful home environment.


Loft Conversion
Loft Conversions

What Are the Regulations for Loft Conversion Insulation?

According to current regulations, the u-value of the roof must be 0.18W/m2 or lower. If you’re unfamiliar with u-values, this translates to a recommended insulation thickness of 270mm using fibre or wool or 175mm using rigid boards. Another option is a spray foam filling with a thickness of approximately 125mm.

How Do I Insulate My Loft Myself?

Note: I always suggest going for hiring experts to insulate your loft area. However, you can follow these steps to insulate your loft yourself.

  • Measure and Calculate

To begin, measure the area of your loft to determine the required amount of insulation material. Take into account the recommended insulation thickness and calculate the quantity needed based on your loft’s dimensions.

  • Prepare the Space

Clear out any belongings or debris from the loft region to create an accessible and clean workspace. Ensure no leaks or gaps in the roof need to be addressed before insulation.

  • Choose the Insulation Material

Select the insulation material that best suits your needs and budget (I have added the recommended materials below). When choosing, consider factors such as thermal performance, fire resistance, and environmental impact.

  • Insulate the Loft Floor

If your loft has a floor, the easiest and most common method is to lay the insulation material between and over the joists. Roll out or lay the insulation evenly, ensuring there are no compression or gaps. Use insulation supports or netting to keep the material in place if necessary.

  • Insulate the Roof Slopes

If you have a pitched roof, it is recommended to insulate the slopes to prevent heat loss. Install insulation material between the rafters, ensuring a snug fit without leaving any gaps. Use insulation boards or rigid insulation for this purpose, cutting them to size as needed.

  • Seal Gaps and Cracks

Inspect the loft for gaps, cracks, or areas where air leaks. Seal these openings using caulk or expanding foam insulation to prevent drafts and maintain the integrity of the insulation layer.

  • Install Insulation Around Pipes and Objects

Pay attention to any pipes, cables, or objects that pass through the loft space. Use insulation sleeves or wraps to insulate them, maintaining the overall insulation integrity and preventing heat loss around these areas.

  • Consider Ventilation

Adequate ventilation is crucial to prevent condensation and maintain a healthy loft environment. Ensure there is proper airflow by installing vents or maintaining existing ventilation systems.

  • Inspect and Maintain

Regularly check your loft insulation for any indications of damage or wear. Replace or repair any damaged insulation promptly to maintain its effectiveness.


What Are Loft Insulation Materials to Use?

Several materials are there that can be used as loft insulation material. But for optimal insulation, we recommend using materials with a minimum K value of 0.16 W/m²K. The following are a few choices worth viewing.

  • Wood-Wool

This hybrid material is primarily composed of waste wood products. Its notable stiffness makes it a suitable choice for projects requiring added durability. It boasts a K value of approximately 0.038 W/mK.

  • Hemp Quilts

These insulation quilts typically combine hemp and recycled cotton, although variations exist. Hemp is an excellent eco-friendly option, thanks to its rapid growth, and it also aids in reducing carbon dioxide levels in your home. The K value for hemp quilts is approximately 0.039 W/mK.

  • Recycled Newspaper (e.g., Warmcel)

Despite not being actual paper bits, this insulation consists of recycled paper fibres. It is cost-effective, making it popular for large loft spaces. However, it may have a shorter lifespan compared to other options. Its K value is around 0.035 W/mK.

  • Sheeps Wool

True to its name, this insulation material is sourced from unwanted fleeces in the wool industry. Sheep wool insulation has a K value of around 0.038 W/mK.

Which One to Choose: Cold Loft or Warm Loft Insulation?

When it comes to loft insulation, there are two primary types of it: warm and cold loft insulation. To decide between cold loft and warm loft insulation, consider the intended use of the space, along with checking the following comparison table.


Cold Loft

Warm Loft


Storage purposes only

Livable space (office, bedroom, playroom, etc.)

Insulation Location

Insulate between the roof and loft floor

Insulate between the roof and the new loft ceiling

Thermal Performance

Minimises heat loss from downstairs rooms

Provides insulation for temperature regulation


Relatively cost-effective

Cost-effective and efficient insulation method


Relatively simple

Straightforward installation process

Safety Considerations

Laying a flat surface for safe access

Ensuring proper ventilation to prevent condensation

Ventilation Requirements

Adequate ventilation may not be necessary

Gaps between insulation and roof slats for ventilation

Usage Suitability

Not suitable for living spaces or guests

Suitable for creating comfortable living spaces

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