Forums | Home Repair | Home Improvement | Painting | Interior Decorating | Remodeling | Landscaping


Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Building & Construction

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Search this Thread Display Modes
Old 07-25-2010, 08:08 PM   #1
Newbie
 
Join Date: Jul 2010
Location: Pittsburgh, PA
Posts: 6
Share |
Default

Remove old attic insulation and critter mess?


Do I need to remove old attic insulation before putting in new stuff?

Live in a 1969 house with two layers (approx 6 in) of insulation in the attic. I live in the vicinity of Pittsburgh, PA. The second layer was paper-backed and simply laid on top of the first layer with the 2nd layer's paper facing the living area. 1st layer is also paper backed and facing the living area.

While in the attic to extend storage flooring and fix some electrical work, I also noticed LOTS of OLD evidence of animal infestation (nesting materials, droppings, rat poison bags, etc).

Should I remove all the old insulation as well as the animal infestation stuff before blowing in new insulation? I plan on blowing in 13 inches for approx R38 of blown cellulose (assuming R value of 3 per in) in the next year or so.

R/
Mike
merlanvp is offline   Reply With Quote
Old 07-26-2010, 06:11 AM   #2
Member
 
Join Date: Dec 2008
Location: Wilmington, DE
Posts: 3,114
Default

Remove old attic insulation and critter mess?


Remove the second layer with vaopr barrier, or resue the insulation after pulling off the vaopr barrier. You mention critter mess, but don't elaborate, how much, what kind??? If a lot of poo and such , I would remove it. Whatever, use a good quality dust mask!!!!
Just Bill is online now   Reply With Quote
Old 07-26-2010, 08:18 AM   #3
Newbie
 
Join Date: Jul 2010
Location: Pittsburgh, PA
Posts: 6
Default

Remove old attic insulation and critter mess?


Not sure what kinds of critters. All the old straw and nesting material (including bunched up insulation along the edges of the house (no soffits, just where the roof meets the facia holding the gutters) is a pile-of-crud. I have found 4 areas that were probably nests at one-point or another...but nothing current. Lifting insulation to do an electric-wiring trace, I found small black pellets that remind me of hamster-poo...so am inclined to thing squirrels.

I did not wear a mask when moving the insulation that time...a mistake I will not repeat---that stuff stayed with me for hours in my coughs (ugh...)

Mike
merlanvp is offline   Reply With Quote
Old 07-26-2010, 01:43 PM   #4
Registered User
 
Join Date: Mar 2009
Posts: 9,886
Default

Remove old attic insulation and critter mess?


Remove both because only removing one adding 1.7# per sq.ft. of cellulose will compress the fiberglass batt negating it's value: http://www.bc.com/dms/wood/ewp/3_Gui...0Materials.pdf

That's like putting a 12ounce water bottle on every square foot of batt insulation. Then you will be able to air seal the attic/living space: http://www.rd.com/how-to-seal-attic-...icle18158.html

Make sure you have either 16"o.c. ceiling joists with 1/2" drywall or 5/8" drywall on 24"o.c. 1/2" drywall on 24"o.c. will not work, cellulose is too heavy and could cause ceiling sag. Blow the cellulose 20% more to achieve projected R-value due to settling: http://www.energyguide.com/library/E...SubjectID=8375
It should state on the bag installed weight per sq.ft.--- per inch.

Good time to check your balanced attic ventilation, now: http://www.airvent.com/homeowner/pro...it-specs.shtml

Add some roof venting above the fascia, if needed--- to protect against ice dams: http://www.cor-a-vent.com/PDF/S4002P.pdf http://www.cor-a-vent.com/in-vent.cfm

Be safe, Gary
__________________
Clothes taking longer to dry?
Clean the dryer screen in HOT water if using fabric softener sheets.
They leave a residue that impedes air-flow, costing you money.
Clean the ducting in the last six months? 17,000 dryer fires annually!

Last edited by Gary in WA; 07-26-2010 at 01:47 PM.
Gary in WA is offline   Reply With Quote
Old 07-27-2010, 09:32 AM   #5
Newbie
 
Join Date: Jul 2010
Location: Pittsburgh, PA
Posts: 6
Default

Remove old attic insulation and critter mess?


Good point about venting...redoing roof next week and removing power attic fan, replacing with ridge vent for outflow, adding smartvents for inflow at a mid-roof installation (no soffets, and insulation needs to run to the edge of the roof joist/facia connection), and retaining the gable vents.

Had not really thought about the weight of the cellulose. Should have. The joists are 16 OC and not sure about the dry wall. In the bathrooms, where I just replaced ceiling fans, it appears to be 1/2" sheet rock, 1/2" rock board. Is blown fiber glass a better option if the sheet rock is 1/2"?
merlanvp is offline   Reply With Quote
Old 07-27-2010, 09:51 AM   #6
Electrician
 
Proby's Avatar
 
Join Date: Jul 2010
Location: NJ
Posts: 818
Default

Remove old attic insulation and critter mess?


I would definitely get rid of all that crap. That would give you an nice open area to find out where the critters could have come in and seal it and also seal all penetrations into the house. Around caulk around wires, caulk or spray foam around pipes, spray foam over electrical boxes.

Quote:
While in the attic to extend storage flooring
3/4" plywood has an R value of less than (1) so try to limit your flooring. If your joists are 2x8's than you have about 7" of space to put insulation which will only be about R-20.

However, the law of diminishing returns applies here, I've found that after about R-20 or so the energy savings drop off significantly.
Proby is offline   Reply With Quote
Old 07-27-2010, 04:36 PM   #7
Registered User
 
Join Date: Mar 2009
Posts: 9,886
Default

Remove old attic insulation and critter mess?


Block off the gable vents as they will short-circuit the ridge vents, page #606: http://books.google.com/books?id=Z8a...0vents&f=false

Rip the plywood into 12" pieces to allow the moist air from below to by-pass it and not deposit the water on the ply bottom facing the insulation, causing mold. It has a low permeability and will stop the water there. Space the pieces 1-2" apart.

Proby made a good point on value vs. cost: http://www.enersavesystems.com/pdf/E...Insulation.pdf

Be safe, Gary
__________________
Clothes taking longer to dry?
Clean the dryer screen in HOT water if using fabric softener sheets.
They leave a residue that impedes air-flow, costing you money.
Clean the ducting in the last six months? 17,000 dryer fires annually!
Gary in WA is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





Top of Page | View New Posts

Copyright © 2003-2014 Escalate Media. All Rights Reserved.