Thursday, August 27, 2009

Using Baffles With Attic Batt Insulation

This use of a one-foot length of Durovent baffle material seemed to work. The flimsy foam shape is held against roof sheathing by batt insulation stuffed beneath. Placing the top-course crossing batts goes faster, and I get more insulation at the periphery, when I don't have to worry about blocking vents, of whatever baffle material is deemed acceptable.

Here is a photo album detailing this job, rationalizing use of flimsy Durovent baffles. I have never used cardboard baffles.

In 2016, advise against use of Durovent, too. I have seen expanded polystyrene board  insulation under siding, disintegrated under heat of less than ten years service. I will not guarantee service of EPS. 
I now use only strong plywood baffles, reaching all the way to the attic floor and blocked by good 2x4 remnants. Please see a presentation at my web site. Here is another blog post, where plywood baffles were foollishly installed. For the photo at the left, note  concern that plywood roof sheathing should have edge clips over 24" spans. Brittle shingle underlayment may be cut by a plywood edge, causing roofing failure (a hard-to-fix leak). How, now, would one align the plywood edges? This is stated in a September, 2012 update of this post, I have become opposed to deployment of continuous roof vents, especially as soffit-area air inlets, which slot the sheathing and underlayment. I want to rely on underlayment as a second stop against water driven under shingles. What will happen in a reroof, where slots are "lost", and a product like SmartVent no longer covers a tear? Make good use of your soffits, if you can.

Add more on 7/26/2016, from this album :
R30 crossing batts align with tops of baffles 18" tall. Make the baffles from taller scraps if you wish. With this steep roof, place outer R30 batts as 12” lengths. Split a 12” R30 batt to stuff under a baffle. Take care to fit most batts of  consistent 24" x 48" dimension, so that lifted batts someday do not become a jigsaw puzzle. Expect to briefly lift and reset a few regular-sized top-layer batts for safe footing on joist tops for maintenance as in inspecting and cleaning soffit vent screens.

In a national plague of stink bugs, expect frequent need to reach down the tolerant baffles occasionally to vacuum. You could never do that through a cardboard silly-thing 36" tall.

Wednesday, August 5, 2009

Kneewall Closet Access and Insulation

The light at the floor aims at a difficult insulation opportunity, behind finished knee walls.

Let's see what is behind this crude door.

A conscientious installer of cellulose insulation made a best effort to weatherize the ceiling of the home Living Room. Coverage is a spotty twenty percent, with none in the lee of obstructions.

I will fix this, from a new, better access. Attic Access is what I do, and that involves willingness to cut and crawl through plaster walls.

With a hole in the knee wall, the problem is manageable.

I have improved ceiling insulation to R40, over 80 sq ft, and the accessible areas of the cut knee wall to R15. After rebates, despite access cost, the job cost will be repaid by energy savings, in less than ten years. For the homeowner, it is one more thing to feel good about.

The real-plaster patch need not demand support by a professional plasterer. Block opening edges and reset lath. Repair pre-existing cracks with flexible grout as a nice plus of the weatherization. Prime edges, brushing on Plaster-Weld. Screw-attach expanded-metal lath. The patch area is easily filled in one application of Structolite plaster, struck level with a 4-foot feather-edge if it fits. Here, there was compromise, using other tools to level the patch.

Final finish is with broad application of mud. This will need texture and primer.