Roof Insulation Batts – Are Batts The Best Option For your Roof Insulation?
Everyone starting out with residential insulation wonders if roof insulation batts are a good option.
Fiberglass and cellulose are available as roof insulation batts. These are pre-cut to different sizes, widths and r-values. Measure your roof size and find out the local building codes about the minimum required insulation and buy the insulating materials that you need. This will allow applying for grants and concessions from the governments.
What Are Roof Insulation Batts?
These insulation materials are also available as blankets, which come as rolls of continuous material. For attics and roofs batts of r-value 30 to 38 are needed. For basements and walls different r-values are needed. Basic minimum values will be mentioned and these are not written in concrete. So, buy what is optimum for your needs while following all the rules.
These batts will lose their effectiveness if they are compressed. Another problem arises when it is cut to allow for appliances and electrical wiring as this allows air a free passage through the cavity. This again negates the whole purpose of having insulation, which is to prevent air transfer.
Having even small gaps will defeat this. Special care is needed in installing fiberglass batts. Installation experts will have the required experience and knowledge on fixing these problems and also get the maximum benefit out of the fiberglass batt insulation.
Installing Roof Insulation Batts
Fiberglass insulation is available in the form of batts and blankets. You can use a combination of both to insulate your roof. When opening the batts be careful to get the package lengthwise and it will quickly expand to the full volume once the package is fully opened.
The batts can be laid perpendicular to each other in two layers and the blankets can be used to go over the joists and other uneven surfaces, studs and other gaps where the batt can’t go.
Any gaps between the batts can become bypass for air movement. This can also become sites for moisture condensation. Fiberglass does not absorb moisture but moisture reduces the effectiveness of fiberglass insulation and reduces its r-value drastically.
A snug fit is important for the batts to give maximum benefit. If it is not possible use blow in loose-fill into the gaps left between the roof insulation batts. This will reduce air infilteration. Adding a layer of radiant barrier on the exterior will further reduce energy loss.
Pros and Cons of Roof Insulation Batts
Fiberglass batts are not the best option for insulation as other better options are available. An expert can guide you towards the best options in your areas for effective sealing of homes from air transfer and heat transfer. Some are also moisture resistant. They have several advantages over fiberglass as roof insulation batts.
Cellulose and cotton batts are also gaining popularity for roof insulation, which is considered environmentally safe. They have a higher r-value of 3.7. The materials used are recycled clothes, industrial scrap and other naturally available materials. No chemicals or petrochemicals are used in the manufacture of these batts.
So, as a green option this is highly recommended.
A few disadvantages are that they don’t have high efficiencies in terms of insulation like polyurethane foam. Also, moisture if it gets into the batts can play a major spoilsport, as it would be very difficult to dry a cotton batt.
Advantages for cellulose batts are the higher r-value compared to fiberglass batts, the use of recycled materials in manufacturing, the lack of toxic substances, no cancer risk from airborne fibers etc. Disadvantages are that the cotton batts are difficult to cut. Contractors will charge extra to cut these batts and it needs skillful handling to fit the batts into the cavities and spaces.
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