If you are considering re-roofing your flat roof, consider insulating it. Both operations are usually done simultaneously to save time and money. A professional roofer should provide you with information on this subject.
There are two ways to insulate your roof, either from the outside or from the inside. It’s ideal and simpler to do it from the outside, but if you’re doing major renovations on the top floor, take the opportunity to ensure that the insulation is adequate.
Signs that you need to act
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A low R-value
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This value gives you an insulation rating. The higher the value, the better your insulation. A roofing specialist can help you determine the R-value of your roof. As a minimum, we aim a R28 factor for cathedral roof and R51 factor for a roof with an attic that allows for the installation of sufficient insulation.
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Your insulation is wet, soaked, or packed
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Either it is a question of infiltration, the source of which must be found
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Either an important condensation will have caused this phenomenon. In both cases, action must be taken, as damp insulation loses all its effectiveness.
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The vapor barrier is damaged or badly installed
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Suppose the function of the vapor barrier is to prevent water vapor from passing through the building structure. In that case, poor installation will likely have led to the formation of humidity and mold, affecting your insulation’s performance and the residents’ health.
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Traces of bugs
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Moisture in your attic will attract carpenter ants. Although they look harmless, they can wreak havoc on wood structures.
- Mouse droppings will also indicate abnormal humidity and will lead you to rectify the ventilation and insulation.
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It pays to insulate your roof correctly. Although it may be a significant investment, it will quickly pay for itself since a poorly insulated roof increases your heating bill considerably.
Two types of insulation to choose from for flat roofs
1- The advantages of urethane
- Ideal when space is limited, as in most flat roofs.
- No need to install a vapor barrier because urethane also acts as a vapor barrier.
- Urethane molds perfectly to all roof joist crevices.
- With a minimum of 5 inches of urethane, you will get an R30 factor.
- The insulation is good for the life of your building if the product is properly installed.
2- Advantages of blown cellulose
- It is a greener solution since it is a composition made from recycled paper.
- It is fireproof and rot-proof.
- No need for a vapor barrier if you properly seal (ideally with urethane) all the vulnerable elements listed below.
- It provides a good air barrier by preventing cold air infiltration and warm air leakage.
- If you blow in enough cellulose, normal sagging of the product will not affect your insulation, and the life expectancy is the same as for urethane.
Whether you choose urethane or cellulose, deal with a professional, as you must respect specific rules, including leaving a 1 to 2-inch clearance under the rafters for ventilation.
If you insulate your building better, snow will tend to accumulate, whereas a poorly insulated roof will allow heat loss and melt snow from below. You will therefore need to check the structure of the building, as the top is not always ready to receive a significant accumulation of snow.
Don’t forget to seal and insulate the most vulnerable elements
If you insulate your roof with the best materials, but the features added to the roof need to be better sealed and insulated, your investment will not be optimal.
Insulate the following with urethane
- Plumbing vents
- Roof hatch
- recessed light boxes
- Chimneys and roof ventilators
- Skylights
- The joint between the roof and the building structure
- Any other items added to the roof
Grants and loans to keep you warm in winter and cool in summer.
The government regularly offers grants to help with work that is part of an energy-efficient development plan. To qualify for these grants, you will need to have your job done by professionals.
You can also take advantage of a Réno-Prêt available to you from a Réno-Maître certified contractor.
The insulation and waterproofing of your roof are just as important as the materials that cover it. That’s why you must pay special attention to it. At Toiture Union, we have the expertise and certifications to help you with your project.
Do not hesitate to contact us about this.