[Greenbuilding] Question about attic insulation

[Norbert Senf]

It depends on how tight you actually are. If you are tight, foam won't add
tightness. If you are not, it depends on the height of your building
envelope and how much positive pressure there is at the ceiling to drive
exfiltration on a cold night. Loose pack cellulose won't provide any
reduction for pressure driven exfiltration.  ... Norbert

On Fri, Jul 6, 2018 at 12:26 PM, Lynelle Hamilton <lynelle at lahamilton.com>
wrote:

> Thanks, Jeff. I've never used open cell foam or indeed any foam in an
> attic space, so had no idea it was advantageous at all.
>
> On July 6, 2018 11:45:10 AM EDT, Jeff Martin <jeff at open2learn.ca> wrote:
>>
>> Lynelle,
>>
>> From your description, the area is already well air sealed and 16 inches
>> or so of cellulose should provide fairly good resistance to air
>> infiltration where there are small leaks. I don't see any advantage to
>> using foam, especially at twice the price.
>>
>> Jeff
>>
>> Sent from BlueMail <http://www.bluemail.me/r?b=13187>
>> On Jul 6, 2018, at 9:03 AM, "Lynelle A. Hamilton" <lynelle at lahamilton.com>
>> wrote:
>>>
>>> Hi All,
>>>
>>> Again, I ask this group for advice!  Am insulating an attic space. It's
>>> 720 sq feet. The roof is a north facing slope and gets a lot of wind all
>>> year, including winter. There is a 48 ft ridge vent and hand-built vents.
>>> Location is Greater Toronto area, so definitely a heating climate.
>>>
>>> We've installed vapour barrier, in anticipation of using blown in
>>> cellulose to attain R60. We've been careful to seal all openings, including
>>> the area around the access hatch and there are no pot lights. The one duct
>>> that runs in the attic (bathroom vent fan) is insulated.
>>>
>>> I've had two contractors (both in the field for some time) suggest using
>>> open cell (1/2 pound) foam, as it will fully seal the attic area and allow
>>> less heat, condensation, etc. At R60, it's about twice the price of
>>> cellulose, though.
>>>
>>> I've no concern about the ability of either contractor to appropriately
>>> install.
>>>
>>> I've pored through all of John Salmen's videos and articles that I can
>>> access about best approach in this setting but confess that I'm no less
>>> perplexed.
>>>
>>> Any thoughts, folks?
>>>
>>> Thanks in advance!
>>>
>>> Lynelle
>>>
>>>
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> --
> Sent from my Android device with K-9 Mail. Please excuse my brevity.
>
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-- 
Norbert Senf
Masonry Stove Builders
25 Brouse Road, RR 5
Shawville Québec J0X 2Y0
819.647.5092
www.heatkit.com
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