Image Source:
6 Mil Poly Vapour Barrier Home Depot
The “Ask a Builder” alternation is committed to answering some of the abounding questions Fairbanks association accept about building, activity and the abounding added genitalia of home life.
Image Source:
Q: Can I use aerosol foam as a breath barrier in a wall in Fairbanks?
A: The abbreviate acknowledgment is yes, as continued as you accept the appropriate blazon of polyurethane aerosol cream and any approval that may be all-important from architecture inspectors. However, while application aerosol cream as a breath barrier is technically possible, it can be difficult to accomplish this assignment in real-world applications.
First, let’s specify which blazon of aerosol cream can work. Closed-cell aerosol cream consists of gas bubbles that are trapped aural a polyurethane cast back the cream expands and cures. The trapped gas increases the insulation amount of the convalescent cream while the solid cast about the beef of gas functions as a breath barrier. It is additionally referred to as medium- or high-density cream because the cream anchor the air pockets charge be able and adamant abundant to allurement the gas bubbles.
Image Source:
Open-cell foam, on the added hand, does not allurement gas back it expands but instead consists of an abutting cream web with spaces abounding with atmospheric air (like a sponge). This blazon of cream is beneath close than closed-cell SPF. It cannot action as a breath barrier because baptize breath can biking into the foam’s accessible spaces.
SPF is installed application a gun that mixes two chemicals and sprays them assimilate a architecture assembly. Aerosol cream expands as it is installed to ample stud accolade and rim joists, alike extensive into cracks that are adamantine to ample with added types of insulation. But to accomplish as advertised, it charge be activated accurately by accomplished installers that accept the appropriate accessories and accomplish the accession in the appropriate ecology altitude (such as temperature).
Research conducted by the University of Waterloo has apparent that bankrupt corpuscle aerosol cream in a minimum array of 2 inches abundantly resists baptize breath circulation for algid climates such as Fairbanks. A thicker accession will accommodate added aegis adjoin breath diffusion.
Image Source:
However, the City of Fairbanks architecture cipher requires an alike greater akin of circulation control, agnate to 6-mil blubbery polyethylene bedding (commonly alleged poly or Visqueen), so approval by a architecture official will be all-important in the City to use bankrupt corpuscle aerosol cream as the breath barrier.
If you plan on applying to an activity abatement program, accomplish abiding to analysis with your ambassador or activity rater about application CC SPF as a breath barrier as aboriginal as accessible in the architecture appearance to abstain any abeyant complications.
It is accepted in Fairbanks to apprehend a breath barrier to additionally accomplish as an air barrier, which requires accurate absorption to air sealing at joints and about penetrations. This is a actual important additional function, as baptize breath can additionally move into walls through air leakage.
Image Source:
Properly activated bankrupt corpuscle aerosol cream makes for an able air barrier; however, it can be debilitated by framing access that aren’t covered by the insulation. One archetype is amid baron and trimmer studs framing a window opening.
Also, air leaks can arise in the bank afterwards architecture due to movement in the anatomy back it settles, back architecture abstracts dry or by added events. This complicates application bankrupt corpuscle aerosol cream as the air barrier arrangement for walls, as it requires transitions to added air sealing methods about areas not covered by the aerosol foam.
With able planning and an accomplished installer, bankrupt corpuscle aerosol cream has been acclimated auspiciously as a breath and air barrier. On the added hand, a band of 6-mil polyethylene is bargain and is generally acclimated as both a breath and air barrier, accouterment allowance adjoin damp problems in walls.
Image Source:
For added advice on this topic, Architecture Science Press appear a analysis address in 2009 on the charge for a breath barrier in above-grade walls with aerosol polyurethane foam, which is amid here: www.buildingscience.com/documents/reports/rr-0912-spray-polyurethane-foam-need-for-vapor-retarders-in-above-grade-walls
Ask a Builder accessories advance home acquaintance for the Algid Climate Housing Analysis Center (CCHRC). If you accept a question, acquaintance us at info@cchrc.org or 457-3454.
Image Source:
Image Source:
Image Source:
Image Source:
Image Source:
Image Source: