Before learning how toinsulate a cold pitched roof, what insulation method and material to use, you will need to know some basics about pitched roof types which will reversibly affect all the named questions. For starters, it is good to mention that there are many positive effects of having a properly insulated roof, not only to your roof space, that is your loft or attic but also for the rest of your home, which will become less subject to constant weather changes and thus more warm or cold, depending on the season. Well, you will probably find all the basic information right here.
Pitched roof definition and classification
First, a word or two on pitched roofs and their classification. You will recognize a pitched roof by having usually two sides joined in the middle, falling down at a specific angle, also known as the roofs pitch, supported by timber trusses or beams. The pitch will depend on many factors, including the climate and aesthetic value, since steep pitch is usually seen in colder climates where the pitch will allow the snow to slide down instead of accumulating on the roof. Steep pitch can also create some additional space under the roof, unlike shallow pitches which will create space, but unfortunately unusable.
Pitched roofs can either be cold or warm, which will determine the insulation process and insulation materials. While warm pitched roofs are insulated over, under or between the rafters, providing a protective, insulation layer for the space under the rafters (like a loft), cold pitched roof is insulated at the ceiling level, which implies that any space above the insulation is left uninsulated. This is why warm pitched roof insulation is probably a better option if you want to seal and heat your loft or attic space. If not, you can choose for either insulation method, keeping in mind that these techniques do not exclude each other, but can be successfully combined.
Insulation Methods and Materials
If you have opted for cold pitched roof insulation, know that it can be done in a few ways. The insulation method will depend on numerous factors, including your roof structure and accessibility, but it will also be affected by how much money and time you are willing to invest in the project.
Probably the easiest (and cheapest) solution in this type of roof insulation is insulating beneath the ceiling, by using some type of rigid insulation. Now, although much easier than the alternatives, keep in mind that this will have consequences to the proportions of the space and could damage your ceiling. Besides, this will often depend on some factors that are not under your control like ceiling heights or doors and windows positions. To avoid such issues, you could opt for removing the ceiling completely and installing a new, insulated one. Another option would be pushing the insulation down from the roof, which is not as demanding as the following one, but can block the ventilation and the installation process can be somewhat more difficult than in previously explained options.
If you are willing to spend more time and money to your cold pitched roof insulation you could remove the roof covering and place the insulation from above. This way, you will not only insulate your roof, but also get a chance to repair the ceiling if needed and install a vapor permeable layer. However, although a more effective solution, this is a much more complicated task, often dictated by weather conditions.
When it comes to choosing the right insulation material, the most important thing to consider is moisture resistance. As you are probably aware, your cold pitched roof insulation will be exposed to rain, condensation and moisture so it is crucial to use materials that will absorb and release moisture. The most commonly used insulation materials are mineral wool, semi-rigid or rigid insulation boards.
When installing cold roof insulation, always check for existing insulation, which need to be properly removed prior to insulation. Also, in order of avoiding thermal bridging that could affect thermal performance of insulation, make sure that the material is placed tightly, with no gaps or cracks. Your plumbing, wiring and water tanks also need to be properly protected in order of preventing potential freezing. Finally, take care of ventilation (secured by either gaps between the roof covering material or eaves ventilators) which will prevent timber joist rot and decay by allowing condensation to evaporate.