Warm Pitched Roof Insulation - Pitched Roof Insulation Part 3

by Mark Row

Insulation methods and techniques: Warm pitched roof insulation

Warm pitched roof insulation is another way of insulating pitched roofs, besides cold pitched roof insulation. Warm pitched roof insulation is based on insulating in the rafter line, using different insulation techniques which will be presented here, alongside some things to consider before and when installing insulation.

Insulation Tips

Warm pitched roof insulation, as explained, involves the insulation over, under or between rafters, or a certain combination of these. Although it is usually much easier to insulate your pitched roof at the ceiling levels, as it is done in cold roof insulation, it is not always possible, if the top floor is being used and needs to be heated as well, where insulation above, below or between the rafters come into place.

Installing insulation along the rafters line can be a complex  and risky task, so the assistance of a professional is usually needed. It could also compromise levels or the overall character of the building, or include the change if the roof covering material, so certain permits may also be required by the applicable construction regulations. Since this process includes the removal of roof covering, it should be done with great care, making sure that the installation process is not affected by rain, wind or other potential external influences and that the roof space is thoroughly and carefully cleared of dust and dirt.

Since you are already removing the roof covering, use the opportunity to remove any existing ceiling or between the rafters insulation, taking all needed precautions, such as using protective masks, gloves and suits. Make sure to seal all gaps and cracks, since these can reduce thermal performance and cause thermal bridges. Finally, always try to minimize the condensation risks, especially around ducts and pipes.

Insulation methods

Now, let’s talk about placing the insulation. One way is to position the insulation above the rafters. Known as the “sarking” insulation, it includes placing the insulation above the rafters and below the roof covering. This way of warm pitched roof insulation allows the placement of an unbroken layer, which minimizes the risk of the appearance of thermal bridges, condensation within the timbers and reduces solar gain, but it is quite an expensive process that requires high technical and constructional knowledge and is best done by a professional and may require the raising of the roof.

Alternatively, insulation can be added between the rafters, which is a less costly process and does not include the roof height change, but could be affected by water vapor, timber rot and potential thermal bridges.

Another way is to insulate below the rafters which is a good solution whenever the inner space between the rafters allows easy access. This approach does not include the change in roof height, depending on the roof felt could be done without removing the roof covering and allows all gaps to be properly sealed. On the other hand, it could affect the size and appearance and functionality of the inner space, and usually requires the consent from local authorities.

Finally, some of these techniques in warm pitched roof insulation may as well be combined, like combining insulation above and between the rafters or below and between the rafters, as the most common ones which involve additional cost but it could as well be the most effective insulation solution, since it only accentuates the advantages of every insulation method combined and negated the potential deficiencies.

Insulation materials

Things to consider when choosing the warm pitched roof insulation material are the condensation risk that needs to be minimized by using proper insulation product, the expected vapor movement, since your insulation material must be resistant to it and the materials durability.

When installing above the rafters or between the rafters you can opt for rigid insulation boards, which can reduce heat loss, the appearance of cold spots and gaps and air filtration. For insulation between the rafters,  you can choose some natural fiber insulation, like thermafleece or mineral wool insulation or some flexible mineral and glass wool batts. All these products are available right here at Insulation London, so you can simply choose any product from a wide range of insulation materials and be sure that you have provided your home a high quality, long lasting product that will really keep your home protected.

Knauf Universal Insulation Slab                   Rockwool Flexi Insulation Slab

Feel free to share your thoughts on Warm Pitched Roof Insulation in the comments section below. I will be happy to answer all your questions.