Insulating your roof: the way to go about it

A well-insulated roof is essential for an energy-efficient and comfortable home. Did you know that around 30% of the heat in your home is lost through the roof? By insulating your roof or attic, you’ll save on your energy bills and enjoy a pleasant indoor climate all year round. What’s more, renovation grants are being phased out, so now is the best time to tackle your roof or attic.

Reducing heat loss through the roof means you consume less energy, shrinking your energy bill. It also improves both your home’s EPC score and its indoor climate. What’s more, you increase the value of your home.

You should start by checking whether you need to insulate a pitched roof, flat roof or attic floor. Each requires its own approach and choice of materials.

• Pitched roof: 
  This is typically insulated along the inside surface using glass wool, rock wool or insulation boards between the rafters. This method is affordable and quick to install. If you don't want to lose space, you can also insulate the roof from the outside. This is technically more complex, but provides an additional heat buffer and makes your roof airtight. For good results, 16 to 22 cm of glass wool or rock wool is recommended.
• Flat roof: 
  In this case, adding insulation to the outside is the best option. PIR or PUR boards are glued or fastened to the roof, preventing cold bridges and moisture problems. While it is also possible to add insulation to the inside surface or existing roofing material, this requires more expertise to avoid problems with condensation or mould. For flat roofs especially, installing insulation incorrectly carries a significant risk of moisture problems and can even cause damage. For flat roofs, 12 to 14 cm of PIR or PUR is ideal.
• Attic floor:
  If you have an unheated, open attic, it’s more efficient to insulate the attic floor than the roof itself. This limits the volume of space you need to heat and you save energy.

The effectiveness of roof insulation depends on proper installation. By ensuring an airtight finish with special tapes and sealants, you prevent unwanted air flows. In addition, a damp-inhibiting interior layer is crucial to prevent moisture problems from affecting the insulation. A vapour control membrane is required if your roof is vapour-tight, or a standard moisture barrier if you have an open roof. This will keep your insulation performing at its best and prevent condensation and mould.

The cost of roofing work varies depending on the type of roof and the method chosen. For a pitched roof insulated from the inside, you can expect to pay an average of 40 to 60 euros per square metre, and 70 to 120 euros per square metre for a flat roof insulated from the outside. This investment usually pays for itself quickly, as a well-insulated roof will save you up to 30% on your energy bills. Grants are still available but these are being phased out. Make sure you’re properly informed, and if you’re not sure or your roof has a complex construction, be sure to consult a professional.

Our partner ‘Impact us today’ can provide reliable experts for the insulation of external walls, pitched roofs and flat roofs. Using KBC Mobile, you can quickly and easily find a reliable contractor to carry out your roof insulation professionally.