[Greenbuilding] Weight of spray cellulose

[Bill Chaleff]

Dense -pack cellulose is installed at a minimum of 3.5 pounds per cubic foot.   That's the industry standard minimum to be "dense-pack."
 
Bill Chaleff A.I.A., Leed AP
 
 
-----Original Message-----
From: Sacie Lambertson <sacie.lambertson at gmail.com>
To: Greenbuilding <Greenbuilding at lists.bioenergylists.org>
Sent: Mon, Feb 13, 2017 9:36 pm
Subject: [Greenbuilding] Weight of spray cellulose



I have a situation where cellulose will be sprayed under an existing attic roof.  Thanks to a suggestion on this forum we are making ply gussets to extend the existing roof rafter to allow for at a minimum of 11 " of dense pack cellulose to be blown through netting against the spray foamed under roof.


My question is how heavy is 11" of sprayed dense cellulose?  At the perimeter of the space, where the extended rafters meet the floor joists over the rooms below, will the cellulose sag so much it will create a potential bulge problem on the drywall that will be covering the ceiling below?



The floor joists of the attic are old full 2x4s 16" apart.  Where the potential sag might occur therefore is a space that is about 14"x11".  The suggestion has been to take attach thin 2" wide plywood across the space, thus bridging it so the dense pack cellulose won't weigh too heavily and protrude into the ceiling space below.


However if we do this, we will obviously have to cover the entire ceiling this way before we put up drywall.


(The unseen dilemmas of rebuilding a very old house)


Thanks for all good opinions.


Sacie

_______________________________________________
Greenbuilding mailing list
to Send a Message to the list, use the email address
Greenbuilding at bioenergylists.org

to UNSUBSCRIBE or Change your List Settings use the web page
http://lists.bioenergylists.org/mailman/listinfo/greenbuilding_lists.bioenergylists.org
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.bioenergylists.org/pipermail/greenbuilding_lists.bioenergylists.org/attachments/20170214/ecf54ec4/attachment.html>