Insulation & Draft-proofing

The most important focus when attempting to make a building energy efficient is the insulation and draft-proofing. Irrespective of heating methods the better the insulation the lower-energy the building.

The need to achieve high levels of insulation and draft-proof all doors and windows is contrary to maintaining a healthy atmosphere in the home and controlling mould caused by damp stale air. This is particularly relevant in older buildings that do not have damp proof membranes. Usually if you seal-up an old house it will soon suffer from mould and damp.

Older buildings and the products used in their construction also need to breath in order to allow the natural transfer of moisture through the building by evaporation.

Our solution to insulation without damp

We did not want to use exotic and expensive building products to create this eco-home.

In order to make this project a realistic case study that is financially viable we have only used readily available mass-produced materials.

Most modern materials do have one main drawback in that they do not allow the building to breath. We have therefore tackled this through the introduction of mechanical ventilation and heat recovery (MVHR information shown on the 'Renewable Energy page'). This concept is pivotal to the successful insulation of the building.


Up to 15% of the heat loss from a house can be through the floors.

The floors were dug-out downstairs, a damp proof membrane was installed followed by 200mm of Celotex rigid insulation.

A self-levelling screed was applied...

...followed by another 50mm of Celotex insulation.

The second layer of insulation was used as an anchor to fasten underfloor heating pipes...

...then a final layer of self-leveling screed was applied.


Up to 35% of a home's heat loss can be through the walls.

The walls of this house consist of stone rubble of various thicknesses from 450mm - 800mm. In some instances this may be considered sufficient particularly bearing in mind the benefit of the added thermal mass.

However in order to better the U-Values to current building regulations we applied insulation-backed plaster board to the inside of all external walls. 

This gave the potential for thermal-bridging in all window and door reveals. This was tackled by applying 50mm of rigid insulation within the reveals and then over-paneling with either plain panel or detailed panels made to match existing shutters. Decorative architrave was also added to form the junction between the insulated reveal and wall.

Windows and doors

Windows and doors can account for up to 25% of a home's heat loss.

Rather than apply modern units where possible the period window frames have been preserved and a low-energy ultra thin stepped glazing has been applied. This is a small compromise on efficiency but aesthetically it is a much better solution.

New doors and windows were made where it was not possible to refurbish the existing.


The roof can account for approximately 25% of a home's total heat loss.

Due to the requirement for significant structural roof works the roof was completely removed and reapplied as a 'warm roof'. This means that insulation and draft proofing is applied just under the tiles rather than on the attic floor. This has meant that the attic rooms are now usable and better draft proofing can be achieved.

100mm of rigid insulation was installed between the rafters.

A further 200m of insulation was applied over the top.