So, how do you insulate a flat roof or ensure you have adequate insulation already installed?
That is a question asked by a lot of homeowners when it comes to their flat roofs. Inadequate insulation costs money. Not to mention the increase in discomfort both in the winter and the summer. So having a properly insulated flat roof not only saves you money, it increases your comfort levels by maintaining the temperature in the house to a respectable level.
Most residential flat roofs are constructed of I-Joists or open web 2 x 4 construction topped with OSB underneath the weatherproof layer of roofing material. This leaves very little space for insulation. The contractor can and usually will insulate the space between the joists as best they can but it still is not an effective method, so the basic option is to insulate from the top by adding a layer of rigid foam overtop of the OSB board.
This method works but the R-Value or efficiency of the insulation is limited due to the restrictions on thickness of the foam.
Another method commonly used when insulating a flat roof is to layer the roof with tapered deck which gives some space for insulation and adds a slight slope to the roof giving it a more effective way of shedding water.
So, what is the best method you ask?
The simple answer is converting your low-sloped roof to a sloped roof by either tearing off the old roof and building a new, sloped one in its place or constructing a slope on top of the flat surface. This is a rather expensive and not always feasible option. Many homes with low-sloped roofs here in Burlington and Oakville are architecturally designed around the low-sloped roof so any changes made will affect the visual appeal of the house.
The next option is firstly, to get rid of the can lights that are commonly installed in low-sloped ceilings. They look nice from the inside, give off nice accent light and illuminate the room well but cannot be insulated, thus, effectively create a massive hole in the ceiling for heat to escape. This can be a problem for some homeowners as they like the visual appeal of the lights. You have to decide if the energy loss is worth the energy costs or not.
Next thing is to properly insulate the roof from below. New, modern insulations are on the market today that are great for low-sloped ceilings. Spray foam insulation will work its way into the openings of your ceiling and seal it more effectively than blown insulation will but it is expensive. The second option is blown in insulation, which can be done from the inside by cutting small openings in your ceiling which can then be repaired.
When it comes right down to it however, the best option for your particular house won’t always be clear, so it is best for you to seek the help of either a flat roofing specialist, who can inspect your roof and make suggestions both for design and insulation or to speak with an insulation specialist. If you were to ask me, I would seek the free advice of both technicians to gain a broader understanding of what your particular house requires.