Blow insulation over catwalk?

tombobOctober 5, 2009

I am planning on blowing in cellulose insulation in an addition that has traditional fiberglass batts laid in between the joists, even with the top of the joists. The contractors built a catwalk on top of the joists, two 2X6s side by side down the center of the attic space. The attic has trusses.

When I blow in, do I cover the catwalk?

Thank you for reporting this comment. Undo
sierraeast

Cellulose packs down when walked on or even sitting things on it as light as a pipe wrench, for example. You didn't state what region you are in, but I would think 5-1/2" of blown in,( top of the catwalk), would be ample addition to the fiberglass. Be careful not to block any soffit or eave venting, and be careful around any lights/electrical,(such as recessed lighting), where the cans aren't rated for contact with insulation. Any other mechanicals that are safe to be covered, you might want to take note of where they are in case you need to access them.

    Bookmark   October 5, 2009 at 11:26AM
Thank you for reporting this comment. Undo
kudzu9

As long as the area underneath the catwalk is fully insulated, putting insulation on top of it is unnecessary, and would be annoying if you ever go up there. The first inch of insulation always makes the biggest bang, and tapers off in its effect as you add more. If you have got batts already to the top of your joists, your blown in insulation overall will make a very small difference in heat savings for the whole space, and not having it on top of the catwalk will be an immeasurable difference. I won't go into the mathematical reasons, but going from, say, 6" of insulation to 12" does not save twice as much energy. For example, if 6" of insulation reduces heat loss by about 95% (which it does), that's great; however, the combined effect of 12" will only improve that to about 97%. So you are gaining only 2% efficiency by doubling your insulation.

    Bookmark   October 5, 2009 at 1:00PM
Thank you for reporting this comment. Undo
sierraeast

The op's insulation is between the truss joists. Adding cellulose will help fill any voids, cracks, crevises that the batts do not take care of, but 5-1/2" is more than likely overkill. Agreed that you dont get double the r-value with twice as much insulation, in fact, with the air infiltration that fiberglass and cellulose allows, you're not going to achieve a true mfgr's claimed r-value anyhow. Best purpose in the op's case is to use it to fill voids and an even layer across the attic.Dependent on vent locations, i've seen attics where the wind coming in through the vents blew the cellulose out of the area and built up where the winds no longer reached it.

    Bookmark   October 5, 2009 at 1:57PM
Thank you for reporting this comment. Undo
manhattan42

Why is there a 'catwalk'?

Is it required to access mechanical HVAC equipment in the attic?

If so, you cannot cover it, and the catwalk must remain open and accessible.

    Bookmark   October 5, 2009 at 8:03PM
Sign Up to comment
More Discussions
How to stop leak in flat low slope roof
We have a low slope roof over our sunroom and car port....
thebigad
adjusting stop on lazy susan
Hi all, I have recently moved into an older home with...
blakekr
Sidewalk crack
Any way to fill/hide this crack? I could cut slot wider....
stoveguyy
Pouring a new driveway
Hello everyone, first time poster. I'm ready to sign...
cin_ram1972
Help - how do I fix this tippy fence - did a dumb thing
Am building a 6 foot wood privacy fence (L shape) from...
kashka_kat
Sponsored Products
Bronze Floral Over-the-Door Hanger
$9.99 | zulily
Contemporary Indoor/Outdoor Area Rug: Artistic Weavers Rugs John Beige 9 ft. x
Home Depot
BAZZ Recessed Lighting 300 Series 4 in. Recessed Brushed Chrome LED GU10 Light
Home Depot
Traditional Zebra Rug 8'6" x 11'6" - CHOCOLATE
$1,099.00 | Horchow
Newbury Antique Finish Medium 2-light Hanging Lantern
Overstock.com
Milagro Pendant by Eglo
$84.00 | Lumens
Reversible Fan and Light Remote Control
$37.00 | Bellacor
Lime Rickey Wexler Table Lamp
Lamps Plus
People viewed this after searching for:
© 2015 Houzz Inc. Houzz® The new way to design your home™