Insulating and Air Sealing an Attic with Spray Foam (Short Version)


On this episode of Dr. Energy Saver’s “On the Job” series, Larry Janesky, founder of Dr. Energy Saver discusses the importance of an energy efficient attic, and shows us why it should be the number one priority in terms of energy-efficient upgrades with this spray foam attic insulation project.

The typical attic is vented and not considered part of the conditioned space of the building. Attics are typically very hostile environments, as temperatures change drastically, year round, according to the seasons. In the winter time, the attic can get very cold, with freezing air getting into the space through open soffit and ridge vents. In the summer, the sun radiates heat through the roof, raising temperatures in the attic to scorching hot levels, much higher than the outside temperatures.

If the attic lacks adequate insulation and proper air sealing — and according to the U.S. Department of Energy, a significant number of homes in America have this problem — these dramatic temperature variations will be transferred to the living areas, either conductively through the ceiling, or through air leakages.

In homes that have HVAC ducts running through the attic, energy losses can be even greater. During the winter, heated air will lose temperature as it passes through ducts that are housed in a freezing cold attic. During the summer, the cool air running through a scorching attic will get warm before reaching the rooms that need to be cooled.

Consider that an average of 40% of your home’s total energy consumption going toward heating and cooling! With such large percentages of energy consumption going toward heating and cooling you will easily understand how important it is to conserve as much energy as possible in these areas.

The typical attic insulation job involves isolating the attic from the house (conditioned space). To do so, we utilize spray foam, to air seal any gaps that may cause air from the conditioned space to leak into the attic. Spray foam is applied around gaps around light fixtures, plumbing, wires, wall partitions, and chimneys in the attic floor. After air sealing is complete, blown insulation — fiberglass or cellulose — is commonly used to bring attic insulation R-Values up to the U.S. D.O.E. recommended values for attic insulation for each specific region of the country.

In this particular home, however, the attic wasn’t a typical attic. The multi-level ceilings stood over walls that protruded from the attic floor, making it very hard to seal and insulate. This attic also included over 100 can light fixtures, posing some difficult challenges when it came to insulation and air sealing. To make matters even worse, the HVAC ducts ran through the attic!

For special cases like this, the best approach is to include the attic into the conditioned area of the home, and establish the roof, not the ceiling, as the thermal boundary. While there are a number of different materials that can be used to transform a vented attic into a conditioned space — including Dr. Energy Saver’s Super Attic System, this particular job, spray foam became the insulation material of choice.

Spray foam expands when applied and fills gaps and voids, so the space is air sealed and insulated at the same time. With our job complete, this homeowner now has a more comfortable home and already reports big energy savings from the newly insulated attic.

Would you like to have a more comfortable home and save money on energy bills? Let Dr. Energy Saver help! Call us or visit our website to locate a Dr. Energy Saver energy specialist in your area, and for a free consultation!

24 Comments

  1. nprudhomme111
    May 7, 2013

    2:32 why install vapor barrier paint on open cell and not closed cell spray
    foam directly? another question is air flow from soffit to ridge vent block
    or did you install channel behind spray foam

  2. johnatdrenergysaver
    Jun 18, 2013

    Roofing shingles are designed to withstand intense and often rapidly
    changing temperatures caused by the intense heating energy from the sun and
    then equally rapid cooling effects from weather. The 8 to 10 extra degrees
    of added heat caused by encapsulating an attic are a proverbial ‘drop in
    the bucket’ compared to the brutality of daily outside conditions. We have
    not seen any indication that the shingles can’t handle this generally
    slight temperature increase.

  3. johnatdrenergysaver
    Jun 18, 2013

    As explained above, if water vapor cools below the dew point and condenses
    it then and only then presents problems for the roof assembly. Closed cell
    foam is far more capable of resisting the natural vapor drive so it
    adequately keeps the water vapor from reaching the colder/condensing
    temperature. Open cell foam has very little resistance to the vapor drive
    so a vapor barrier paint is used to prevent this problem.

  4. videodistro
    Sep 29, 2013

    Um, that’s most of the point of the video. Did you have the volume turned
    down?

  5. videodistro
    Sep 29, 2013

    What paint did you use as the vapor barrier? I tried finding someone in my
    area to spray closed cell on the under side of our kitchen roof but could
    find only open cell contractors. I now have ~6 inches of open cell on the
    underside of the decking but it is open cell foam. Can you recommend a
    vapor barrier paint that is friendly to the open cell foam? Thanks!

  6. Number1Digit
    Oct 20, 2013

    Like he said often times ducts and vents circulating conditioned air is
    affected by the temperature in the attic (IF these ducts run through the
    attic of course), also attics are normally built ventilated so the outside
    air is right above your ceiling. In cases where circulated conditioned air
    is not affected by attic temperature the attic floor will be sprayed
    instead of the roof deck; preventing air leak and/or heat eascape. (40% of
    heat lost through roof of homes)

  7. Spray Foam
    Nov 2, 2013

    SPF manufactures generally require specific “end product configurations”
    for their products. Find out which manufacture and then call them for
    proper building application information. Visit sprayfoaminspections(DOT)com
    for the chart for SPF insulation R-value Depths.

  8. Larry Janesky
    Dec 5, 2013

    Vapor barrier paint? Benjamin Moore makes a vapor barrier primer paint.
    But it at at Benjamin Moore paint store. Simple!
    Larry

  9. applejacks971
    Dec 10, 2013

    Wish they’d kill the music…WAY distracting. It’d be nice to watch an
    instruction/information video, not a music video

  10. John smith
    Dec 28, 2013

    Does all this need to be redone if the roof sheathing needs to be replaced?

  11. Robert Wewer
    Dec 29, 2013

    I just hope that the roof above is not fiberglass reinforced asphalt
    shingles. If so, that roof is toast. These products must be allowed to
    transfer heat through and into the attic. That does not make sense either
    but it is the nature of the beast. Five years – tops and the roof is toast
    if it is fiberglass/asphalt.

  12. dia480
    Feb 12, 2014

    I am about to build a new home and I am building it on a slab on grade with
    Hydronic floor heat, nothing but truss system in attic area, would just
    spraying foam directly to attic side of ceiling be a good idea?

  13. Vera Maier
    Feb 20, 2014

    How about long-term experiences ? 20- 50 years?
    Could it be sprayed on tiles (which may have some holes to the out-side of
    the roof) ?
    What cover material? What insulation thickness is required?
    This technology is quite old, but still has not found mass usage in such
    applications – why ?
    Too much moisture because it is air tight ? Cost per m³ – spraying firm
    included? Which companies do provide this in Germany ?
    Does it burn ? Dangerous chemicals ?
    etc etc. 

  14. The Dow Chemical Company
    Feb 24, 2014

    Roof icicles can happen due to air leaks, causing energy loss every day.
    Dow technology is helping home owners to save energy and money! Learn more:
    http://ow.ly/tMxG2

  15. Maarten Robaeys
    Feb 24, 2014
  16. Marc T
    Feb 25, 2014

    Conditioning attics with spray foam is an accepted practice in the home
    energy retrofit industry. If homes are sealed “too tight” we can add
    mechanical ventilation (ERV’s, HRV’s or bath fans) as needed to meet any
    standard for air exchanges that needs to be met. We also will air seal
    attics at the floor to reduce air leakage into the attic and add Tru-Soft
    cellulose insulation to R-60 here in the northeast. Our decision to either
    condition attics or build an aligned, intact and sufficient thermal and
    pressure barrier at the attic floor depends on many factors, including
    homeowner preference

  17. Cory Boehs
    Mar 27, 2014

    One of the best videos I’ve seen. Attic is an important part of the house.
    It must be properly taken care of.

  18. Vanrocco66
    Mar 30, 2014

    Do you apply vapor barrier paint to a closed cell foam as well or is it not
    necessary because of the closed cells? … Is this material fire retardant?

  19. Ted Kidd
    Apr 5, 2014

    “Redefine” your attic?

    More and more are doing it – Great Attic Spray Foam video – Thanks Larry
    Janesky!

  20. Bob Hanker
    Apr 21, 2014

    Kudo’s to you sir for rocking a mullet with confidence! Great video and
    thanks for the info..

  21. Robert Wewer
    May 7, 2014

    I keep getting responses relating to the elimination of the condensation
    issue. I am in complete agreement with that aspect of the discussion,
    however there is a problem and that is with roof degradation. I know that
    there are studies out there, seemingly self serving but still measuring
    nominal heat increase on the topside of the roof. I am not sure as to the
    actual cause but it seems heat related. This effect is found on Asphalt
    shingle but I have found a surprising correlation to slate roof premature
    failure in the field where spray foam is used. 

  22. Laquisha Moore
    May 28, 2014

    LOVE IT!

  23. Mykle Bust
    Aug 22, 2014

    r ventilation-spacers NOT necessary before u foam the roof???

  24. Photolight PhotoLight
    Oct 15, 2014

    what was the temperature of the roof outside? I bet it was near the 65
    degrees you mentioned the underside is now.
    Insulation on buys you time but does not keep the cold on the outside in
    this case.
    If, that was so then we could avoid heat all together with your 3″ of
    insulation.
    Getting 68 degrees into attic is not a good thing at the roof structure
    (the dramatic temperature difference will create moisture) perhaps putting
    it on ceiling would have given you the entire “compartment” of the attic as
    a buffer for moisture and not potential damage the rafters and roof decking
    with moisture.
    Currently, you have a 40 degree difference – you want to be a gradual
    transition not dramatic.
    They are still losing heat via the roof through your spray foam.
    Sorry, for the bad news. Radiation, conduction and convection.
    All these insulating material just buys you time but they will all come to
    the ambient temperature within a few hours; in these conditions. But, in
    this attic situation, you have made it a heated area via transfer of heat
    through the ceiling form the heated space below. Can you tell me which of
    the three ( I mentioned above) is the form of transfer?