Debris in attics is very common. Everything does have an R-value, including debris; however, the R-value of debris is significantly lower than insulation (less than 1 per inch, whereas, loose fill cellulose can be nearly 4 per inch) So, to answer your question, it's best if you can remove as much as possible. Also, you might seriously consider air sealing before you install more insulation. If you have lots of time and little resources, you can spend time moving insulation away from lights, chases and plumbing and then air seal electrical penetrations with foam, caulk or mastic. If you want someone to knock it out quickly and do a stellar job, have your attic vacuumed out before you air seal.

The last comment that I have is regarding batt insulation. The attic is probably the place where batt insulation performs the worst. Under floors and in walls, it does ok; however, it's tough to get a good continuous blanket in an attic, especially across the ceiling joists. It is even more difficult to get a continuous blanket if you have trusses. If you do proceed with batt insulation, make sure the blown in insulation is as flat as possible and level with the top of the ceiling joists. Also, make sure the batts are tucked nice and snug next to each other, like a well made bed. The best performing insulation (in my humble opinion) is loose fill cellulose.

Jacob Chavez, BPI, PTCS
Project Manager
FAISON Energy Solutions

If you are strictly wanting to use batting, laying it perpendicular to the floor will not be an issue if there are NO air gaps between the existing insulation and the new insulation. So, if the existing insulation fills the cavity between the floor joists, you should be fine. This would be the same for the areas where there is flooring. Any air gaps between existing flooring and insulation will negate the new insulation laid down. You could also consider blown in insulation. Holes can be drilled into the flooring to blow in the insulation.

It is difficult to say whether the debris needs to be removed without knowing what type of debris it is or how much there is. The crew does need to be able to move around.

If you are a qualified Oregon or Washington resident, and a customer of Portland General Electric, Pacific Power, NW Natural or Cascade Natural Gas and would like to obtain the cash incentive from the Energy Trust of Oregon (they pay for self-installations if you call prior to starting) then your insulation needs to be R38. Currently for Oregon residents the incentive is $0.25/sf. For example, if you have a 1,000 sf home, you will receive a check back for $250. This might make it worthwhile to bump the insulation up to R38.

Also, you may wish to call the Energy Trust of Oregon and request a free Energy Audit/Review. It takes about an hour and they will go through your home, look at existing insulation levels, bring out CFL & low flow faucet aerators, and identify energy leaks within your home.

Sharon Cannizzo, LEEDap, CSBA
General Contractor & Sustainable Consultant
Simply Sustainable, LLC