How to prevent heat loss in your loft conversion

UK Home Improvement

How to Prevent Heat Loss in Your Loft Conversion

According to the Energy Saving Trust, approximately a quarter of the heat generated in the home is lost through the roof if left uninsulated. In order to prevent this from happening, and in a bid to retain all the warmth we can throughout the course of winter, insulating your loft conversion is the most simple and effective way to reduce both the amount of heat you’re losing and your heating bills.

loft converted into office

Things to consider when insulating your loft

A loft conversion is relatively easy to access and should therefore be simple to insulate if it isn’t already. But there are still a few things that need to be thought about before insulation is added to your loft, both before and after the commencement of your loft conversion, including:

Storage space

If your loft will remain as storage space, even after your loft conversion, then you may wish to think about the items you’ll be keeping up there. If they’re very heavy or considerably bulky, then boards will need to be laid over the joists to reinforce your loft and protect the insulation.

For maximum insulation, raise the level of your floor so that an adequate amount of mineral wool (take care not to squash this when fitting the boards over the top as it will hinder its ability to insulate your loft) will fit underneath the new floor level.

If this sounds like a viable option, then consider adding timber battens across the joists or buy specially designed plastic legs that will fit comfortably on the joists in order to support the new floor. You must leave a ventilated air gap between the boards and the insulation – this will reduce the risk of condensation forming on the underside of the boards.

Insulate the rafters

This is an ideal alternative to conventional loft insulation techniques. Fitting insulation over and between the rafters can be just as effective as more traditional methods. The sloping timbers act as a guideline for adding insulation material with care and precision, meaning no gaps are present for heat to escape through.
A rigid board can be used, which has also been cut to the correct size, can be gently applied, or an insulation foam can be sprayed between the rafters instead.

Walls and ceilings between a heated and unheated space are insulated

Sloping ceilings and vertical walls can be insulated with an adequate layer of plasterboard inside the insulation. If you have a flat ceiling, then this can be insulated in the same way as an average, conventional loft.
If you have dormer windows installed, then ensure the walls and ceiling around them have been insulated properly. A high-performance glazing for the windows can also be used. The same also goes for skylights.

Damp lofts

Insulation is designed to stop heat from escaping from our homes, however, this could cause existing damp to develop or worsen. With this in mind, it’s important to ensure your insulation is well-ventilated. If you aren’t sure, then ask a professional for some advice, and rectify any damp problems before installing insulation.

Materials needed for a well-insulated loft

The different types of insulation available include:

  • Glass fibre insulation
  • Mineral fibre insulation
  • Rock fibre insulation
  • Plastic fibre insulation
  • Polyester fibre insulation
  • Rolled batt insulation
  • Blanket insulation
  • Sheep’s wool
  • Foil-backed felt

Loose fill materials

As well as the aforementioned types of insulation, there are also loose fill materials available that will also adequately insulate your home, including:

Spread loose fill – a loose insulating material that is spread throughout the loft space as opposed to being rolled out along it. Typically, it’ll be glass or mineral wool, although there are more sustainable options available, such as recycled newspaper and cork granules.

Brown insulation – this is mechanically blown throughout the loft as opposed to being spread or rolled. This method can only be carried out by a team of professionals and should not be done yourself

Insulated boards

Also known as sheet loft insulation, this type of insulation can come in the form of either boards or sheets. This is often acts as an ideal alternative to loose or rolled insulation when insulating sloping or vertical surfaces, as the latter may not work as well in comparison.

Insulated loft boards are also an option, as they’ve been specifically designed to be laid over the joists, which can allow you to place things over the top of it, or use your loft as storage space should you not have any immediate plans to have your loft converted.

The difference between internal and external insulation

External solid wall insulation

This is usually insulated with expanded polystyrene insulation board at around 100mm thick. This can be applied to the outside of the property, usually with plastic bolts and adhesive for a double-strength bond, which also means minimal cold bridging. This will then be rendered to ensure it looks aesthetically pleasing – there are also a variety of colours for you to choose from, should you select this method.

Internal solid wall insulation

As the name would suggest, this type of insulation is applied to the inside of the property. Seeing as it won’t be exposed to the elements in the same way as external solid wall insulation, the final finish will have fewer protective properties, however it will still save you a considerable amount of money on heating bills.
Internal solid wall insulation typically takes the form of PIR board, such as celotex which is applied to either internal walls or over the top of stud walls that are made of plasterboard – this sandwiches the insulation between the plasterboard and the brick wall.

The benefits of a well-insulated loft conversion

There are many benefits to having your loft insulated, including:

  • Prevent a quarter of heat generated within the home from escaping
  • Save money on gas and electricity bills
  • You’ll be helping to save the environment as your home will be producing less carbon
  • Your home will be cooler in the summer and warmer in the winter
  • Condensation will be less common throughout your home
  • There’ll be a reduction in outside noise
  • Your home’s Energy Performance Certificate rating will improve, thus raising the value of your home and making it more attractive to home buyers should you wish to sell.

Money saving statistics, according to the Energy Saving Trust

Energy bill savings (£/year) throughout England, Scotland and Wales

0mm-270mm loft insulation

House typeSavings (approx)
Detached £225
Detached bungalow£195

120mm-270mm loft insulation

House typeSavings (approx)
Detached £21
Detached bungalow£17

Energy bill savings (£/year) throughout Northern Ireland

0mm-270mm loft insulation

House typeSavings (approx)
Detached £280
Detached bungalow£240

120mm-270mm loft insulation

House typeSavings (approx)
Detached £25
Detached bungalow£22

Kingsmead Conversions will always be on hand to assist you with the planning, construction and development of your loft conversion. Through this process, we’ll help to ensure that your loft is fully insulated, meaning you’ll be able to enjoy a warm, cosy room in the winter and a cool, airy room in the summer. For more information about any of our services, including loft conversions, garage conversions, Velux roof conversions or our design and planning services, consider getting in touch with a friendly, knowledgeable member of our team today – we operate throughout Aylesbury, Bedford, Bicester, Oxford and the surrounding areas.


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