Attic Access 2009

A Complete Demonstration of 2009 Methods, Phillip Norman Attic Access

I spent a few weeks in this attic,

creating this:

I had to relocate a hallway fan/ light. 1 1/2" screws mount a RACO Cat. #175 deep box to a select length of 2x6. The 2x6 is shimmed for correct box reveal, and is attached to floor joists with 3" screws. The carefully-cut drywall fills the previous box location, with edge filling and texture match using flexible grout.

Sealing of this small plumbing and furnace duct chase includes GP Densarmor drywall, and tightly stuffed fiberglass. I had thought to use rock wool as stuffing, and found the fiberglass was advised.

A doorbell transformer is raised, never buried under insulation. Other junctions are raised as they are relocated, to not be covered by decking.

The fuller story as a pdf is titled "Completed Attic, Winter 2010, among my web site pdf offerings.

Retrofit Batt Insulation, Outside Walls

I am just now beginning to insulate the outside walls in my own home. I have known I would tear down interior drywall, to properly place batt insulation, as I did thirty years ago in my previous home, in Connecticut. This time I have access to much better materials.

The method includes removal of window trim, for concurrent window replacement, and saw cuts 1 1/2" away from ceiling and from baseboards.

The found walls are tight, with 1" thickness R2.4 Celotex sheathing. Further, they are complex, with diagonal bracing that would have made a loose-fill blow ugly, and destructive to the value of the home, with its irreplaceable, wide, old-growth cedar siding.

The new batts are Johns Manville U1319, R15 15" x 93". Total material applied is 106 sq ft.

Swedish Tenoarm vapor barrier, age-resistant and 8 mils thick, is sealed to full perimeters of walls and windows, with 3/4" width double-backed butyl tape. The Tenoarm, 9' 2" width roll, and tape, were purchased from Resource Conservation Technology.

Baffles with Batt Insulation: I thought that batt insulation is so mannerly, that I could always maintain pathways from soffit vents to upper spaces, without baffles. I must comply with new rules, that baffles are always required, and find it actually makes things easier, with fuller opportunity to stuff insulation out to floor edges. Here are some pictures that tell the story. I like styrofoam material, pieces cut approximately 23" x 12", from 48" lengths.

Sealing Attic Floor Pits: Dropped ceilings in closets are seen in an attic, as floor pits. Photos here, with corrective action, are of a home built in 1953. Attic air is freely admitted to walls the full height of rooms below, amplifying the ceiling-area heat loss or gain, by an order of magnitude. Let's try the math here, on that order of magnitude. Numbers in play are represented by L and W, the dimensions of the ceiling, and H, the below room height. I see that the influence of closet interior walls is debateable where the door is normally closed. Figure the amplified area as 2* (L + W) *H, where L = 46, W = 31 and H = 96. 2* (L + W) *H = 103 sq ft. LW = 9.9 sq ft. The amplification factor is 10.4. If insulating 9.9 sq ft saves $7/ yr, the larger saving is $73/ yr.

Closure of the pit employs half-inch drywall pulled up to floor joists, and edge-sealed with spray foam. I prefer GP Densarmor fiberglass-faced drywall, kept as scrap from my closet projects. Screw a length of 2x4 under the drywall for lifting and anchoring. Sandwich the drywall with another 2x4. I shape Densarmor edges with a Shurform plane. Ordinary drywall is too brittle, and paper facing resists trimming of edges.

Plywood Decking: I batt-insulate decked attic floors to R38, with a total joist depth of just 9." If floor joists are 2x4, I build crossing deck frames of 2x6 on-edge. If floor joists are 2x6, I build crossing deck frames of 2x4 on-edge. I over-fill insulation, with R19 plus R25, or R19 plus R25, taking the compressed array, where crossed batts break joist thermal shorts, as R38 net. Thus, there is sufficient headroom in many attics, to allow traffic and storage above R38 insulation. 2x4 floor joists may quickly be overloaded with stored items, or stored items upon the added weight of decking. There are limited 2x4 floor storage possibilities, where loads can be applied directly to load-bearing walls. Old-growth 2x6 floor joists receive distributed loads through covering deck structures; despite some added weight, these structures can be beneficial. This photo is of the attic with the covered pit, above. The next set of deck assemblies will cover that pit area. Note tactics of staging, immediately employing completed flooring to simplify further construction.I use 11/32" CDX plywood, ripped to 2'x8' dimensions, with supports 24" oc. Each deck section is separately removable to regain access to floor joists.

Teaming up with a loose-fill installer: Commitment to provide access in a job, does not always go along with providing batts as added insulation. Here a plywood crawlway has been assembled the full sixy-foot length of a large, low attic. Many flexible ducts from a gas furnace challenged the use of batts, to top an R18 bed of cellulose. The crawlway of 1/2" plywood, and some heavier flooring found at the furnace, is raised onto on-edge 2x4 framing. A wandering rail bed past obstacles is 16" oc, staked down by long screws. The bed is filled with R15 or R19 batts.

The new insulation material is Owens Corning ThermaGlas, described at "Page 6" (type 7 to get there), here. I found the material dusy and more collapsible than I had hoped. Hereafter, I will prefer more-expensive, less-fluffed and less-dusty white loose-fill from Johns Manville or Knauf. I will try to discredit any manufacturer who advocates low density to get more coverage. There will be a density or a particle shape, that avoids settling, and limits damage from passage by a workman. I complain of Owens Corning in this job because my installer did not choose the best material, due to poor guidance. An Owens Corning representative advises that, contrary to cited literature, ThermaGlas is intended for packing into walls, not for use in an open attic, where it is not packed, and where the dust is less safe to health, than alternatives.

A string of lights, switched at the attic entrance, is part of the job.

A loose-fill installer may need other access support. In this job there was a space of nearly-inhabitable size, about the chimney, below the attic entrance, exposed to attic temperatures. Flimsy fiberglass, now barely filling a small floor below, was doing no good at two outside walls. All is now well insulated, sealed in with new drywall, and is protected and further insulated, by newly-framed decking. The job involved loose-fill transfer with 55-gallon drum liners. What will ensure that loose-fill installers do not forego such repairs? The home owner will benefit from hiring a responsible and capable job manager.

Decks Constructed With Kiln-Dried 2x6 Lumber:

I have been slow to embrace plywood as best attic flooring. Kiln-dried 2x6 lumber is so pretty, and conceptually easy.

This is a truss garage attic with 2x6 boards:

Bridge truss elements with 2x4's. Lay on the 2x6's, and you're done. It is a relatively heavy floor.

Plywood Decks:

To place plywood, I use 4'x8' modules. This, with supports 16" oc, is used with 1/2" plywood. The 2x4 frame is held within 2x6 rails. The 2x6 rails are screwed to on-flat 2x4's that are screwed to each joist, to ensure deck load is not concentrated on high spots. The beginning insulation is R11 rock wool. This will be covered with crossing layers of R11 and R19, even within the deck.

The trial-fit 2x4 frame is slid away to place R11. Here reassembly is guided over a 2x4, to not snag the R11.

The R19 is proud over framing, and will lose a couple of points of r-value when capped with plywood. For the same money, you get better insulation than with R15.

Here is the completed deck, with a very nice, safe, Fakro attic ladder.

And, this is a "before" picture of that attic.

A Truss Attic:

Here bottom elements of a 2x4 truss attic are loaded with care. 9.25" tall pieces of 1/2" MDF are screw-attached to bottom elements and to floor-support 2x4's, becoming in-effect 2x10 floor beams.

The found loose-fill is transferred out, giving needed addition beyond the deck.

Insulation under decking is two layers of R19.

With supports 24" oc, use 5/8" plywood.