This list of selections serves as a supplement to the Construction Documents (CD’s). Some of the selections below may be difficult to find or omitted on the CD’s. Check the CD’s for consistency with this list. Clarify with your contractor which document takes precedence for any inconsistencies.
There are many different ways to insulate the envelope of your house. Following is a brief description of common types of insulation used in new homes and additions. Keep in mind that a combination of different types of insulation may be used on one project.
The 3-1/2” thick fiberglass blanket (batt) insulation, used in 2 x 4 stud cavities in exterior walls for decades, does not meet the new energy code requirements in most cases. 5-1/2” thick batts, which require 2 x 6 studs, do meet the new code requirements in most cases. Batts are available in thicknesses greater than 5-1/2” for locations such as attics and rafter cavities. Roxul is a brand name for a different type of batt: instead of fiberglass it is made from stone and recycled materials. It is often used in interior walls for its resistance to fire and sound.
Spray Polyurethane Foam (SPF) Insulation
There are two types of SPF Insulation: closed cell and open cell. Closed cell SPF, while more expensive, has a higher R-value (resistance to heat flow) and qualifies as an air barrier. Both types of SPF are applied to the stud cavities and resist air flow better than traditional batts. The thickness of SPF may vary depending on the type of SPF, stud thickness, and your strategy.
Rigid Foam Board
Unlike SPF, this board insulation can be applied continuously to the exterior sheathing and be covered directly with most types of siding. They are available in different thicknesses, most commonly 1” -2” thick. There are two common types of rigid foam board insulation: extruded polystyrene (XPS) and expanded polystyrene (EPS). XPS has a higher R-value. The nailing fin on new construction windows should not be applied directly to the foam board; thus an extra step of applying wood strips around the perimeter of windows is required. Rigid foam board insulation is commonly used in combination with stud cavity insulation.
Blown-in (Loose fill)
There are three common types of loose fill insulation: fiberglass, cellulose and rock wool. One of these types is blown into the wall using a blowing machine. This method of insulation is ideal for existing walls and attics.
Once you have considered the pricing and R-values of the options above, you should select one strategy and verify the construction drawings clearly illustrate how the exterior walls and roof/attic are insulated.
Select above grade, exterior wall insulation from the common combinations below:
__ 2 x 4 studs, R13 or R15 batts at stud cavities, may not pass code for new houses
__ 2 x 4 studs, loose fill at stud cavities, may not pass code for new houses
__ 2 x 6 studs, R19 or R21 batts at stud cavities
__ 2 x 4 studs, R13 or R15 batts at cavities, 1” continuous XPS board insulation
__ 2 x 6 studs, R19 or R21 batts at cavities, 1” continuous XPS board insulation
__ 2 x 4 studs, 3-1/2” open cell SPF at stud cavities
__ 2 x 4 studs, 3-1/2” open cell SPF at stud cavities, 1” XPS continuous board insulation
__ 2 x 6 studs, 5-1/2” open cell SPF at stud cavities
__ 2 x 6 studs, 5-1/2” open cell SPF at stud cavities, 1” XPS continuous board insulation
__ 2 x 6 studs, 2” closed cell SPF and R-13 batts at stud cavities
__ 2 x 6 studs, 2” closed cell SPF and R-13 batts at stud cavities, 1” XPS board insulation
__ Other: ______________________________________________________________
Select below grade, basement wall insulation:
__ Batt insulation along interior face of concrete or CMU wall
__ Rigid foam board insulation along interior face of concrete or CMU wall
__ Insulated Concrete Forms (ICF)
__ Precast Concrete System (ie. Superior Walls)
__ Other: ______________________________
Select roof/attic insulation from the common combinations below:
__ 1 layer R19 batts between flat ceiling joists, 2nd layer R19 batts above
__ 3” closed cell SPF between flat ceiling joists, 1 layer R19 batts above
__ 1 layer R30 batts between sloped ceiling joists
__ 3” closed cell SPF between sloped ceiling joists
__ Other: ________________________________
Unvented attics may require more robust insulation requirements than vented attics. Review the type of insulation and R Value for unvented attics with your Architect and contractor.
Once the rough plumbing, heating, AC, ventilation, lighting and electrical work has been completed, check with your municipality to see if a rough inspection is required. Once this is approved, the insulation phase may begin. Confirm your selections are completed for all locations to be insulated.
Review Scope of Work with Insulation Contractor
- Conduct a thorough “walk-thru” with your insulation contractor and confirm the type of insulation you selected for all parts of the thermal envelope.
- Identify vulnerable conditions such as cantilevered floors, unvented rafter cavities, and eaves with minimal heel heights. Review the best strategy to insulate these areas.
- Confirm who is responsible for ordering, purchasing and delivering insulation materials and accessories such as baffles.
- Confirm who is responsible for installing air sealant around doors, windows & outlets.
- Review interior walls requiring sound insulation.
- Determine who is responsible for installing fire caulking, which is required at holes drilled through the floors and ceilings for plumbing, mechanical and electrical work. This services is commonly offered by the insulation contractor.
- Provide temporary protection from overspray at windows.
Inspect Completed Work
- Check for any conditions where ductwork or plumbing is located outside of the thermal envelope. Add minimum insulation required by code for these conditions prior to obtaining insulation inspection from municipality.
- Check all penetrations through the floor, especially for wiring, plumbing and ductwork, to make sure they are completely filled with fire caulking.
- Make sure spray foam is shaved so that it is not projecting beyond interior side of studs, ceiling joists and rafters.