I am building an addition that consumes part of an attic and need to insulate
these new rooms and better insulate the remaining attic.

Presently the attic appears to have blown very short glass fiber fluff (grey and is not cellulose). It has compacted a good bit and appears to be breaking down. Its 20 years old, is very friable and generates airborne dust/fibers when touched. I need a good filter mask whenever doing anything in the attic.

I am thinking about DIY insulating the new partion walls with fiberglass batts and the roof joists (where they form a room ceiling) with fiberglass batts with preformed convection channel inserts to separate the batts and the roofing nails. My soffit venting was already increased and I installed ridge venting with the new roof.

In the remaining attic area, I am considering DIY or contracting for blown in cellulose to blanket the existing grey glass fiber fluff and increase the thickness. My hope is to seal off the glass fluff so that it no longer gets airborne while improving the R value.

Are these two strategies likely to be the most economical and successful or are there other approaches that might be better.

Thanks in advance,

John S.

 

I would compare doing part of it yourself and the cost of buying the insulation, plus having a contractor blow in the section you want, to having the contractor do the old and new section for you. The hardest part of blowing in insulation is setting up.

 

My professional choice would be to simply install unfaced fiberglass batts over the existing blown in fiberglass and install fiberglass batts in the new walls as well.

Although blown cellulose can be a bit cheaper to install and afford a slightly greater R-value initially, this advantage is quickly lost over time as blow cellulose compacts and loses its ability to insulate, gets blown about the attic by winds thru ventilation inlets, or gets damp or wet from humidty changes and loses its ability to protect you.