How to insulate empty attic (no equipment)?

pbx2_gwFebruary 18, 2014

I have an empty vented attic (no HVAC equipment or duct work) with blown cellulose on its floor between joists (@ least to code if not exceeding)

This attic sits over our master bedroom, master bath & master closet.

Air in those room alway seems to be 2-5 degrees colder or hotter depending on season.

Have had HVAC equipment & airflow checked - all in line along with original blower door test which had us 50% tighter than the comps.

So I think somehow air is still leaking down over this part of my house & the only reason is that the attic roof area is open to the air infiltration & leaking below to the master space.

What is the most effective but cost conscious way to insulate the attic if HVAC equipment is not up there to get my temps back in line with the other spaces in my house?

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snoonyb

Do you know if you have Knob and Tube wiring in the attic space?

    Bookmark   February 18, 2014 at 8:51PM
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pbx2_gw

No knob or tube wiring that I am aware of.
House was just build this past April.

Supposedly the insulation installer foamed all the nooks around any canned lights, ceiling lights & any drill holes made before putting in the cellulose.

Like I said, the house is certified 50% tighter than comp but yet this section of the house just feels colder.

The attic over this area is a passively vented attic with combination of soffit, eave, ridge & cross (side) gable venting.

    Bookmark   February 18, 2014 at 9:36PM
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snoonyb

I the joist bays are not lull, I would fil or slightly overfill with unfaced batts and then add another layer of R-19 unfaced, perpendicular.

Be careful when adding in the joist bays, not to obstruct the vents.

    Bookmark   February 18, 2014 at 10:20PM
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rwiegand

use a smoke candle to look for drafts around any potential opening. You can also rent an IR camera to look for cold spots and leaks.

In an unused attic there's no reason not to pile up insulation to R60 or more. Rolling fiberglass batts perpendicular over the existing insulation is fast and easy, cheap and effective. Just don't block the soffit vents. Finding and stopping air flow should be your first priority though.

    Bookmark   February 19, 2014 at 8:43AM
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pbx2_gw

Thanks for the ideas rwiegand.

I will do that first before spending money on an official blown door test again.

    Bookmark   February 19, 2014 at 3:35PM
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pbx2_gw

Posted by snoonyb (My Page) on Tue, Feb 18, 14 at 22:20
I the joist bays are not lull, I would fil or slightly overfill with unfaced batts and then add another layer of R-19 unfaced, perpendicular.
Be careful when adding in the joist bays, not to obstruct the vents.

Can you ecplain what you mean snoonyb?
My enire floor of the attic is covered in blown cellulose that is supposed to be still fluffy & not compacted due to moisture.

So I am not sure if you are suggesting putting batt rolls right on top of that cellulose & thereby compacting them in between the joists?

    Bookmark   February 19, 2014 at 4:11PM
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snoonyb

If the joist bays are full, then just add the unfaced batts perpendicular to the joists.
There will be little or no compaction in this process, because the product will be supported by the joists.

    Bookmark   February 19, 2014 at 7:49PM
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pbx2_gw

Posted by rwiegand (My Page) on Wed, Feb 19, 14 at 8:43
...
In an unused attic there's no reason not to pile up insulation to R60 or more. Rolling fiberglass batts perpendicular over the existing insulation is fast and easy, cheap and effective. Just don't block the soffit vents. Finding and stopping air flow should be your first priority though.

So I found out from my builder that the attic over the colder master suite area is:
R38 & is passive ventilation via combination of eaves, ridges, & side gables.
Also that side has 4" walls vs. 6" for the rest of the house.

So that explains some of the causes.

Additional topping of blown cellulose would be no problem in an unused space but can it actually provide more comfort if I took it to R60?

I really don't care about savings as much as comfort when all is said & done esp. if it's just 5% for 675 sq ft.
Just don't want to have to pay for a Bentley (foam) when I could be happy with a Mercedes (more cellulose) if you know what I mean.

    Bookmark   February 20, 2014 at 6:39PM
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rwiegand

If the 4" walls are the issue you may just need to supply more heat to the room. Renting an IR camera (about $50/4 hr at the Borg) will tell you exactly where the cold spots are and therefore where you should focus your attention. You may find leaking windows, missed insulation, or unsealed openings. Going from r38 in the ceiling to R60 should save you money eventually, but is unlikely to change your perception of the room.

    Bookmark   February 21, 2014 at 11:58AM
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dhanson

An IR camera would be the fastest and easiest way to find areas lacking insulation or leaking air like rwiegand said but if you are not trained on how to properly use an IR camera or read the images then I would recommend calling out a company that performs this service for you. It usually is not that much more expensive than driving and renting the camera yourself. If you google "Home energy efficiency" you will find several companies that offer this service.

Here is a link that might be useful: Home Repair and maintenance

    Bookmark   February 26, 2014 at 2:54PM
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