How To Install Batt Insulation | Part 3

This is part three of a three part series on how to properly install batt insulation courtesy of NAIMA.Bottom of Form


In part 1 we covered the layout of the home and all the places that needed to be air sealed and insulated to meet resnet grade 1 criteria. In part 2 we discussed a few tips on how to make your insulation job go quickly, efficiently, but more important, accurately. Now we’ll discuss the pre drywall inspection process.


First and foremost, insulation should never have compression, voids, misalignment, gaps, or wind intrusion.


  • Compression: This impacts the R-value of the insulation, and depending on the case it can either improve or degrade the thermal performance of the envelope. Compressing insulation is fine when the compressed insulation completely fills the cavity or void you’re trying to insulate, but compressing that same insulation into a cavity so that it leaves an uninsulated void can result in greater energy loss.
  • Voids: These are defined as pockets or areas where insulation is missing.
  • Misalignment: This is when insulation is placed incorrectly and is not in touch with the air barrier, which can lead to a loss of energy through convection.
  • Gaps: These are spaces between insulation and framing, or between pieces of insulation that extend from the interior to the exterior surface of the wall cavity.
  • Wind intrusion: When exterior air enters the building envelope. It often occurs at roof eaves with soffit vents, and if the attic insulation at the soffit is left exposed the wind blowing through the soffit can flow through the exposed insulation, and in some cases blow it away from the edge. As a result wind intrusion can undermine the effectiveness of the insulation and create opportunities for moisture problems.


When conducting your walkthrough, make sure that there are batts in place and that they are properly installed. They should fill the cavity and be tight to fit around the framing. Look around windows to ensure they’re insulated around the frame. Check around obstructions like gas lines, wiring, and outlet boxes. Pull the insulation back to ensure the installation has been split around the obstructions to cover the exterior and interior filling and that it completely fills the cavity.


Check the caulking of the studs, the top plate, the bottom plate, and look up to ensure the band has been insulated. Also inspect the air sealing to ensure it is well sealed and that the insulation is cut tight to fit and tightly fits the framing on all four sides.


During the pre insulation walkthrough you will have checked for baffles to ensure that the end of the insulation was protected from air moving through the soffit vents into the attic space. Knowing that the insulations is well installed, that it’s tight to fit the framing, that it will contact the gypsum board once it’s installed, and that the ends are protected from wind washing, you are ready for drywall.


For homes with attics ensure the attic platform was insulated with fiberglass batts since you’ll be unable to access it after the gypsum boards installed. Also look for any gasketing material around the top plates, which helps ensure a tight seal between the drywall and the top plate so attic air can’t make it down into those framing assemblies.


In any bathroom, look for an air barrier that will continue from where the gypsum board will be in place down behind the cavity that this tub forms. For any walls with a plumbing stack, check to see that the insulation is cut to fit around the stack really well, and feel back behind the stack to ensure there’s insulation behind it and around it.


There are lots of other things that go into making a high-quality energy-efficient home but energy efficiency starts with good air sealing and properly installed insulation. Whether you’re a do-it-yourselfer or an insulation contractor we hope these insulating tips will help you achieve a comfortable and energy efficient home.