Here is an as-found view of a new-home attic in Portland, Oregon. Standing atop the usual OSB rim about a hallway ceiling drywall-plunker-access, all is booby-trapped against usefulness. Pulled-up HVAC and fan ducts are in the way, obstructively kinked, everywhere. An adventure has begun, to make the huge attic useful. This post addresses repair of a ten-ft tall bathroom skylight with defective insulation, seen in this view. A full set of captioned photos of the process is consulted.
I imagine a City Of Portland building official inspected and approved the insulation in this home, relying upon 2009 International Energy Conservation Code in effect as the 2014 Oregon Energy Efficiency Specialty Code . See that such code is not accessible despite intentions; there is nothing at followed links. My 2015 IECC book at the Index, Skylights, calls out: R303.1.3 (U-values for glazing), R402.1.2 (skylight U-factor of 0.55, wood frame wall R20), R402.3 (words about fenestration, n/a walls),Table R405.5.2 (1)(standard reference design specifications, for skylights: None.). Defined: R202 (Glass or other transparent or translucent glazing material installed at a slope of less than 60 degrees from horizontal.)
An inspector might have looked for and found R20 at the skylight walls, but I will show that that is only wishful thinking. Find better requirements a Portland, Oregon insulation installer would have been required to follow, under better supervision of Specifications of Energy Trust of Oregon. These say:
skylight—Any window unit in an opening in the roof assembly, including one that is installed at a slope of 15 degrees from vertical or greater.
AT 1.13—Vertical Walls in Attic Spaces
Any vertical wall in an attic that separates conditioned space from unconditioned space shall be sealed for air leaks and shall be insulated to fill the cavity. Insulation shall be secured and covered with a vapor-permeable air barrier. Vertical walls may include side walls of vaults, skylights, transitions in ceiling height or other surfaces. See AT 2.6 for program requirements for knee wall insulation.
AT 2.6:
Knee walls shall be sealed for air leaks and shall be insulated and covered with a vapor-permeable air barrier.
Rebate Rules:
R-15 for 2x4 cavities; R21 for 2x6 cavities; cover attic side with vapor permeable air barrier.
Where this skylight has some 2x6 boards, R21 might be commanded. It isn't clear.
I persist in challenging that attic walls may be as thick as one wishes, unlike exterior walls. Better rules will deal with confusions including so much on-flat framing at a skylight. Where attic walls are extremely challenged by Summer heat, they should be insulated much better than exterior walls. I insulate attic walls to modest R25 (with R30 batts 7.5" thickness and with lessened framing thermal shorts). The vapor-permeable air barrier specified, can't be simpler than a thorough covering of good 3/8" plywood. I offer well-practiced means of attaching the plywood covering.
R21 was not achieved here.
Here is my math for the skylight with insulation merely draped over on-flat 2x4s of the trusses:
Say total inside area of skylight drywall is 100 sq ft. Skylight insulation is in contact with drywall only at end walls, 25 sq ft called R21. On side walls insulation has full effect only where draped over on-flat 2x4s, effectively R21 over 11 sq ft. Remaining area, 64 sq ft, has no insulation filling cavities, and at worst has no value.
100/(Reff + 3) = 25/24 + 11/24 + 64/3; Reff = 1.4 for the entire 100 sq ft area.
My insulation math at 95% furnace efficiency and natural gas cost of $2 per therm, says heat cost per year is: $2.4*100*.88/.95*(1/(Reff + 3)).
The penalty with loose draping, or any draping, is large. Draped insulation must not be allowed.
Accepting that draped batts do resist heat convection, allow Reff = 7, for payback math, vs. better insulation to be demanded and to be achieved. I believe that is a sufficiently large number to avoid over-estimate of weatherization savings. As in the title of this post, accuse that better than Reff = 1.4, can not be demonstrated. Energy savings at skylights is relatively easy, and comes with better safety too. An outside air barrier is required and is nicely provided in 3/8” plywood hard covering. 7/16" OSB saves some money, but scrap must be disposed as trash. In some homes the hard covering of a skylight prevents a deadly fall in an attic tumble against shaft drywall. Where one wants a useful attic and may not use a respirator, a nearly-complete covering of insulation is appreciated. Where my allocated cost of the skylight covered insulation is between $300 and $500, and savings are $15 or more, estimate an acceptable less-than-twenty years recovery of cost.
Mostly, be grateful for better summertime comfort, perhaps continuing to avoid the need and cost of air conditioning.
Pull the nice but useless Certainteed R21 kraft-faced batts from the skylight side walls. Build simple wall extensions of 3/8" plywood cuts 7 1/4" wide that efficiently consume 96" panel length, and stitch them to the 1 1/2" truss depth wherever they fit and align with 2x2 nailer positions, that will support hard siding of 3/8" plywood. In the truss rows, add 2x4's to increase depth for added end wall insulation. Ensure that the plywood cuts forming top and side constraints of the side wall insulation, are very nearly air tight.
Use new Certainteed R13 unfaced batts 15"x96", accurately cut, to cover skylight drywall. Stuff through the floor gaps, completing R60 insulation about the skylight below the floor that is up 21.6" from the attic drywall floor. Where the skylight peak is nearly 10 ft tall, be grateful for the elevation boost of the higher attic floor of 5/8" plywood. A stool for added reach is safely used upon a flat and complete attic floor.
The found R21 batts are stripped of their ripped and crumpled kraft facing, and nearly complete the R30 insulation fill, now easily cut to fit.
Use insulation scraps to fill in low spots of the R30 insulation.
The 3/8" plywood side panels were cut to fit, before the insulation was placed. See that R30 insulation is complete and pillows to greater than the 7.5" thickness defined by 2x2 nailers. See thorough already-completed R30 end wall insulation.
See progress cutting the next skylight face plywood. This end of the now-floored attic is a quite nice, brightly-lit wood shop, for now. I love my Milwaukee saw with laser light well suited to my right-handedness. All sawdust and wood scrap will be recycled as bark mulch. Then don't use less-expensive OSB that must be disposed as trash.
Pre-fit the second skylight face, set with screws.
See 2x6 uprights tied into the truss planes at this end of the skylight. With 2x4 nailers now secured to the side walls, I may release end wall plywood facing to trim the 2x6.
Skylight finished now. The brightly-lighted attic is the best place to do brush-on paint coats of the R15 access cover.
Where Energy Trust Of Oregon chooses to do nothing upon notice of this post, I have edited post Labels to include "Voids Under Attic Insulation." Emphasize then that voids behind some insulation are more sure of being energy hogs, than voids under insulation. The energy dissipation is in convection, air flow past an energetic surface, at temperature different from ambient. Smooth skylight drywall is a superior energy convector of air in motion through gaps. Gaps are made worse where out-of-contact insulation has smooth or deformed facing. The situation is surely better than worst case R2 average, but may not be better than R7. There is no basis for treating insulation as fully effective. There clearly is not compliance with Energy Trust Specifications, in loosely-written new-home building code. Energy Trust calls for treatment of a skylght shaft, R15 insulation, same as for 2x4 exterior walls. New-home building code does not mention skylights. Look in the 2015 IECC code table below to see that a new home skylight in Zone 4 should have insulation of 2x6 construction. In fact, non-specific instructions, are ignored.
Doing right or not is the question, in contrasting this bid , with the superior work I do. The customer is my sister, who I will love and protect. The bidder is the most successful weatherization contractor in Portland, Oregon, and is allowed, thus encouraged, to do minimum work at maximum cost, by weatherization sponsor, Energy Trust Of Oregon. It is a national problem of counterfeit weatherization under the veneer of grand Home Performance with Energy Star, HPwES. Do a required blower door show, maybe. Deliver blow and go, for little result, at top dollar. Want a useful attic? Forget it. Problems and safe access will be obscured with least-cost blown loose fill.
I hope the reader will care to study poor work offered, but that will make more sense after I describe the work actually done. For now, just know the sponsored bid is perfectly typical of those issued under sponsorship by nonprofit Clean Energy Works Oregon, CEWO, now renamed Enhabit . Now-Enhabit bids with extremely high overhead cost must come to a bid total of about $20,000. If you are an uncooperative home owner, like my sister, the Enhabit bidder will drop you in an instant.
Prep for weatherization, or anything, is not simply doing what is possible. The means must be found, to do thorough, best possible work. Here, access is not initially an issue. It is an unusual 1952 home, Cape-Cod style, where a bedroom is built over a low-ceiling garage. The CEWO bidder called it 1 1/2 stories. I call the opportunity, construction with a loft ceiling, as contrasted with cathedral ceiling. A loft ceiling is not a transition from conditioned space to outdoor conditions with the large energy transition that rots cathedral ceilings; a really good idea.
Anyone might work in this well-used, lighted attic, so some of the prep is easy. Drop ceilings over the kitchen might be filled, not concealed; yet the CEWO bid missed this opportunity.
Attic walls about the loft bedroom are uninsulated despite concealing mineral wool batts. Many are falling-down. This prep opportunity, to take down batts and provide intimately-fit insulation is also beyond the offering of the CEWO contractor.
Attic contents now fill the loft bedroom over the garage, the nearest move from the attic. And, yet, there are obstacles. Demo the stored plywood. Pull up the shiplap flooring, preserving most of it as treasure to be shared with neighbors. Keep the best, long pieces.
Head bangers are taken-down, to be replaced with roof-peak steel strap ties.
Forty-year old yellow batts look nice, and the CEWO competitor would have left them as-is.
Lift the edge of any of the yellow batts, and see an intolerable mess. The batts are wimpy R13, ancient technology subject to wind washing where not covered, and a health hazard. A foil facing was slashed everywhere although a partial air barrier would have been beneficial. There are voids under the batts where base mineral wool is uneven and spotty. Any insulation simply poured over the yellow batts, as bid by the CEWO contractor, would have no insulating effect, where energy transfer possibilities (natural convection) must drive air flow. There will be much work (prep), in stripping the ratty facing to reuse batts, and for many actions down to the drywall; none in CEWO bid.
This is the untouched condition of mineral wool under the slashed fiberglass batts of the attic floor. Absolutely uneven, much bare drywall, no chance of intimacy with topping fiberglass.
All found wiring will be replaced, with new boxes, devices and LED luminaires.
Wall headers are sealed 100% with flexible grout, as they are revealed.
The central attic floor, within knee wall braces, is raised to 9 1/4" framing depth (2x10), by composite beam method , and this space is used to consume most found mineral wool and all wimpy fiberglass batts, stripped of facing. Needful raising of floor supports for preservation of insulation, strengthening the floor, and restoring useful space, is large work of prep never imagined by the CEWO contractor.
Complete house rewiring is happening concurrent with insulation work. Most work is outboard of knee walls, conveniently emptied of insulation.
I claim R38 insulation value for cumulative five or six layers of found insulation. Batts are filled proud of the 2x10 framing, to become slightly compressed. The air barrier plywood flooring adds to insulation value, compensating for batt compression. A covered-all-around no-voids condition shall be required of all insulation.
As flooring is created, move stored items to begin insulation of the floor at the attic entrance.
As further wiring is allowed, modernize power outlets. Always install junction boxes against wood backing. It is OK with my unique opportunity, to offer better methods to electricians.
Long 1x8 shiplap is treasured. Protect it out-of-the-way, until storage space is found.
Work will get easier where there is an excess of floored space.
Some of the composite beam webs are challenged where 2x4 framing is staggered. I readily cope, placing web pieces wherever convenient, about a straight 2x4 nailer path.
2x4 nailers zigging between plywood web elements yet come out level. The plywood floor will be level and smooth.
I keep moving the needed chop saw station.
Bring in drum liners now, to dispose a dirty layer of cellulose in-the-way, over the bedroom. Disposal is not because of a contained sprinkling of gardening vermiculite. This is a morning activity in high Summer.
I cut away most bracing at the crawl-in over the bedroom, very needful to make the access bearable.
An 8'x16' space outboard of a knee wall is needed for lumber to be stowed, and more. Build decking elevated over R38 insulation. Know that this framework is built in place, not fitting through knee wall braces.
An uninsulated space about the chimney has been troubling. A person can't fit. The CEWO contractor overlooked it or saw it was too difficult, so don't mention it. I will just do it, fully filling the space with batt insulation using reach poles. It is in the nature of prep, fitting in at a final stage in the insulation of the loft ceiling.
Neat, complete. Tight.
Despite low headroom over the bedroom, raise framing as 2x10.
Before setting insulation and flooring over the bedroom, fill 36" ceiling slopes. Run new wiring.
At last get ready to move out of a 4'x8' space, moving in plywood flooring.
A crawl-upon surface is a lot more valuable than evident headroom. This should be decked, for many reasons.
The attic walls must be largely completed where insulation laces with that atop the bedroom.
Build out 7 1/2" framing for R30 attic wall insulation.
Someday, this attic wall process will be commonplace.
With forethought, there is maximum plywood piece size, and minimum waste.
Composite beam webs raising the supports of attic flooring, are inderrupted or slotted everywhere wires cross the found floor framing. Where a single batt thickness fills the added height of the composite beam, wires are revealed by lifting only those top-layer batts. This is very important innovation in safe, serviceable household electrical wiring. This practice should be taught to electricians. Use slightly longer wires to run them at the periphery of raised flooring.
The attic is poorly ventilated absent a powered fan. Rebuild the found, dead fan, in a "aperture box." The screen against bugs is of much larger area than the gable louver now not obstructed. I recycled a corroded and crumbling copper screen that had been blocking the louver.
Completion photos, at last. Despite giving up 6" of headroom, the attic is much more useful.
See long lumber stowed over the bedroom. That is a further benefit of the covering of attic floor insulation. See also importance of the covering over the stairwell ceiling. As with skylights, one might else have a very dangerous step-through fall.
Look back before completion, to note some details of the insulation outboard of knee wall braces. In one of the few offers of prep by the CEWO contractor, four soffit vent baffles were offered, surely cheap cardboard. I have my own ways, broadly shared, employing good 1/2" plywood, 2x4 scraps and a few deck screws.
Plan each baffle to accommodate variable meeting of roof and floor joists.
Know that the Enhabit contractor would have put up cardboard baffles falling-down with small staples, to rot in less than ten years, following Energy Trust Specifications .
Top-layer batts reach all the way to eaves. See little revealed of edge batts 16"x23". At a baffle, place a batt 12"x23", well-stuffed-down. A common edge is achieved for R19 batts 24"x48" in a regular pattern easily rebuilt someday.
The usable volume of a closet off the garage is doubled after demolitions needed for house wiring. The completed better garage closet has 1" combined drywall thickness and a floor of fire rated plywood.
With the complete house rewiring, prep was more than 90% of the job. The wiring was mandatory, starting with a decrepit fuse box and corresponding decrepitude of wires and devices. My way, there was a unique and one-time opportunity to get wiring up to code for the next sixty years. There must be much more mandatory work for electricians, publicly supervised and funded, prerequisite to weatherization. Much post-war wiring is far more dangerous than the knobs and tubes sometimes set in the way of weatherization. Let decrepit roofs and plumbing also be in the way of weatherization, with public solutions. There shall be no deceitful blower-door barons of public action. Damn the actors of Building Performance Institute, still in the way of true weatherization and crucial maintenance of our homes.
In specific weatherization work, prep and the energy savings due to my unique methods, prep is always at least two thirds of the job. The CEWO contractor would have completed criminal fraud in the "prep", the can of foam trick , in an hour. Please read his bid and see that there is no offer of the gaining of access, to do real prep.
Discounting the exterior wall ruin of blown insulation, furnace replacement and some pretense in the crawl space, all of the CEWO contractor's work would have been done in a day. There would have been no real prep, no honest work done, and my sister's house and finances would have been in ruin. We live on the edge, and fraud can ruin lives.
I will be adding to this in context of challenging weatherization at a national level, soon to participate in debate of proposed changes to the International Energy Conservation Code. My contribution is first in better rules for attic access drop-down ladders, doors and other portals . There will be debate of lots of rule changes on required house tightness as measured with a blower door. In this, as with hype about attic ladders, there is a lot of misunderstanding, and no comprehension of the math and the meaning of numbers. Some of my thinking in preparation for the code conference is presented in recent update of my post My Home Performance Test . For most houses, tightening against infiltration, at best is effectively the closing of one or two holes 5" diameter, each amounting to reduced infiltration by one ACH50. ACH50 is the number of changes of the air volume in a home in an hour under artificial conditions that of a 20 MPH wind blowing against all outside surfaces. For my home and again suggesting this might be a national average, the ACH50 air flow under natural draft is 7 cfm, perhaps one tenth the flow of a bath fan. Make-up heat to bring that air to 65°F ambient, costs about $10 per year.
The poor understanding of physics and math by blower door practitioners, the CEWO/ Enhabit/ HPwES bidders of my sister's home, is evident in their bid:
Absent a test, they proposed that a blower door would have read 1068 cfm at minus-fifty Pascal test conditions in the home. A number 10.7 air changes, is air changes per hour, at the test conditions. It has nothing to do with the word occupancy. It is an affordable, healthy amount of fresh air, 0.5 ACHnat, changes of house air volume per hour under natural pressure differential. Nothing offered in the bid would have caused reduction of the blower door number in test-out. Any sealing opportunities would be found by sight, long after a test-in, and never guided by the observations in the home under test conditions.
$2628 would have been stolen. Theft. Fraud. Whatever, it is a commonplace HPwES crime. For all who go along with blower door madness , it is at least a great misunderstanding. I hope I can address this at the code conference, productively.
Absolutely, air sealing is prep, and it is the best investment one can make in weatherization, with quickest repayment, where done at fair cost without the testing scam. Mainly, the sealing in an attic will be of floor pits, with little or no impact on a blower door test. Test-out or none, an existing-home owner will most probably have wished fresh air of about 0.35 ACHnat. Should he have less, he won't be offered expensive mechanical ventilation schemes that might be affordable only in a home under construction.
