Declaring Thin Insulation Batts - Defective

Unfaced R15 insulation recommended by my professional supplier as most cost-effective is:

Owens Corning R15 23x93 "Unfaced" Batts 103.98 sf per bag  See that despite forcing a Google search result of unfaced batts, only big-box store offerings show, mainly with kraft facing. A push of kraft facing upon consumers, is adverse. I can buy unfaced batts at Home Depot as a special order, minimum eight bags on a pallet, store arrival in 7 to 10 days, bag price $73.82.

At my professional supplier, I bought a 4-bag pod, at $77.97 per bag, ahead of a declared 9% price increase on 5/1/2018. Imminently then, the price to a professional installer of OC R15 UNF, is 1.09*$77.97/104 sf =  $817.34 per 1000 sq ft.

I brought the four bags of OC R15 UNF to my job site, a detached garage of a new home.
Determined to be trusting, I pushed all four bags up this very excellent Fakro LWP 22x54  newly-installed attic ladder. A 20.5" clearance is tight for the large bags, but there is nothing to snag a bag, with intelligent springs-on-door durable ladder hardware.

I have reinforced the 10' 2x4 roof truss bottom elements of a 20' wide two-car garage, by stitching on 6" rips of 5/8" or 1/2" CDX plywood, then capped by stitched-on new 2x4s. Apply American Wood Council Span Calculator to judge that 2x4 spans longer than 5' 9" can't otherwise bear storage loads. Truss bottom elements strengthened to 2x8 can carry prescribed 40 psf design live loads with span up to 11' 11".

I want to insulate the ceiling to R15, which one expects to be 3.5" thick. In fact, thickness must be 3.5" to have that value. I am beyond disappointment, although I am not surprised. I have known that unfaced R15 fiberglass batts from Johns Manville and Owens Corning, if not from all manufacturers, are dependably thinner than promised. The same is true of R21 batts not measuring up to 5.5" thickness (2x6), and R30 Cathedral batts not measuring up to 7.25" (2x8). High Density R15, R21 and R30c are premium materials, more expensive by more than ratio of density, than ordinary batts.

Building Science Corporation: Thermal Metric Summary Report (June 2015 Update) , reports at page iii:   When walls are constructed with the same installed R-value in the stud space, and are air sealed both inside and outside (i.e. there is effectively zero air leakage through the assembly), they  exhibit essentially the same thermal performance regardless of the type of insulation material used.
This, to me, is definitive proof from elaborate experiments, that no material has magic, to have declared R-value, even if it does not fill the space. Conversely this is credited by makers of loose-fill insulation, that uniform added and sustained fluff, makes added insulation from thin air. If makers of insulation, both as batts and as loose-fill, would defend the magic in thin batts, they can not have it both ways.

Rejecting magic then, I pulled up the placed batts, some hacked around lighting junction boxes, and returned them with bags not opened, to be credited back to me, and to be returned to the manufacturer, as defective, not to be passed on to a gullible other buyer. I am probably the first buyer to do this, and I hope I will not be the last. I imagine though that my distributor will not follow my instructions, except for the opened bag. I am compelled then, to be a constructive bother, in other ways. There will be first, this blog post that is within my control.

I have an associated action in progress at Insulation Institute Blog of NAIMA, North American Insulation Manufacturers Association . I perhaps abuse a post of April 5, 2018, in posted replies, accusing product design and quality as not-mentioned elements of achieving RESNET Grade 1 standing. Other readers in the few regions where training is offered, only care about the free instruction for their workers.
Free Grade I Training Coming to Four States 
I think I do not need to experience the training, to know its content. In service to RESNET, Insulation Institute has published a handout checklist guide: GRADE I INSULATION INSTALLATION . Nothing in the checklist tests product quality in the matter of reliably filling the space promised. RESNET Grade 1 is not defined in the Checklist. RESNET Grade 1 is not defined anywhere at the RESNET web site . RESNET is in the business of a Home Energy Rating System, HERS.

NAIMA then, steps in to do the quality description in words and illustration focused entirely on RESNET, despite a confusion of rival quality rating-by-number schemes. I think this is the most-complete expression of NAIMA teaching:

INSULATION: A GUIDE TO PROPER INSTALLATION , by Advanced Energy , 24 page PDF

Advanced Energy is a non-profit energy consulting group in North Carolina. Advanced Energy separately publishes its' advice as:
prepplusinsulation.pdf, SUCCESS WITH HOME ENERGY UPGRADES What every contractor needs to know. 

NAIMA publications including those by Advanced Energy, take care to not conflict with a thin-batts problem  in manufacturing, that defies achieving claimed insulation value. Nothing may compel an installer to fully fill insulation space, to achieve best rating. Here is deliberately-foggy instruction, in words:

Summary of RESNET Grading Criteria:
Grade I – Minor Defects


Occasional very small gaps are allowed. Voids can’t extend from the interior to the exterior (i.e. the full width of a wall cavity). The product is installed according to manufacturer’s specification and cut to fit around electrical junction boxes and is split around wires and pipes. Compression or incomplete fill amounting to 2% or less, if the empty spaces are less than 30% of the intended fill thickness, are acceptable for Grade I.

If a batt fills the insulation space from side to side and is on-the-bag called the correct R-value, this is good enough for Grade I.

(from homedepot.com)

Know that the installer has carefully avoided pushing batts to contact with the exterior sheathing, to then unavoidably, very difficult of retraction, lack Ithe appearance of a full fill.

I think the NAIMA/RESNET Grade I definition in words, allows under-fill on thickness by up to 30%. Maybe Grade I, not Grade 1, is abbreviation of Grade Incomplete. Grade II is really-incomplete.







The full-appearance-only is quite difficult with R13 batts in 2x4 framing, where batts are never more than 3" thick. Watch the technique, in this NAIMA training video .

Consequences of thin batts are especially awful, where batts are fully out of contact with exterior sheathing, then not stilling the convection of air where temperature gradients are most steep. Find proof of this consequence in  training videos produced by Owens Corning, one showing installation techniques good and bad, and another reviewing installation details alongside infrared scans upon covering drywall.

Part 1, Installations
https://www.youtube.com/watch?v=NpkXxHRp8U0 

Part 2, Include Infrared Scans
https://www.youtube.com/watch?v=WXr5E3gb0P0 

These are R13 kraft-faced batts about 3" thick yet bag-labeled as code-compliant in 2x4 framing.The center joist cavity in the photo above purports to have a thin batt. It is "thinner" than other batts only because it is "compressed," gently pushed into good contact with exterior sheathing, then with kraft facing nominally 1/2" out from the drywall.

Here are the filled cavities including that on the right where there are voids outboard, challenged by parting and sloppy fit around a badly-foamed outlet from some long-ago other demonstration and around romex wires.

The "thin" batt has warmest drywall surface temperature. Carelessly placed batts left and right, especially that at left under a window, have lots of cold green and blue infrared indication. The outlet badly bleeds heat despite the foam, where evidently the foam has no penetration behind the outlet wall box. Acceptable insulation has generally-pink or red infrared indication on interior drywall, governed much by indoor and outdoor air temperatures. None of these three cavities is filled to Grade 1. Actual insulation value can only be known with full fill.

https://slideplayer.com/1689063/7/images/3/Infrared+Radiation+Spectrum.jpg
(An ice cube in a glass of hot water, I imagine.)

Know that the consensus quality labeling attributed to RESNET is in Arabic , not Roman numerals.

Should I be concerned that I am threatening to fiberglass insulation manufacturers and their lobbyists, NAIMA? If so, this is not the first instance published. At this thought, I have added Label: Thin Insulation Batts in this blog. Find associated writing at that Label, and at Label: Building Codes . I have been engaged in this for at least ten years, and addressed incomplete insulation fill of walls in a proposal for the 2018 revision of the International Energy Conservation Code.

My so-far-best summary of the 2018 building codes quest is in this post:
Math Assessment Of Poorly-Placed Insulation . Copied from that post is this statement of the proposal to deal with thin batts:

My proposal 11881 offered:
R402.2.1 Over-fill of insulation. Wherever possible, insulation shall be confined on all six sides. Insulation fill shall be complete and without voids that could allow air bypass of the insulation. Overfill of insulation shall be required to achieve complete insulation fill. In addition to installation methods that prevent voids within the insulation, the methods shall prevent the presence of air spaces between a barrier film such as the kraft facing of a batt or the containment mesh for blown cellulose, and hard wall coverings such as drywall.

I was an inexperienced individual, investing about $5,000 in preparation and attendance at hearings in the Louisville, KY Convention Center. I stood up for ten proposals and in each, in less than five minutes, accepted unanimous disapproval. Things move so fast, that each Judge surely has somehow noted his vote in advance, I accuse, with small regard for technical merit. If there is weight in standing up to defend or oppose, it is with those honored for repeat engagement, the lobbyists. My sure opponent each time was the National Association Of Home Builders, NAHB . NAHB guards the short-term interests of major home builders, to pocket as much as possible in each home sale, not much caring about interests of home buyers. For the Overfill of insulation proposal, the overwhelming single opponent, was NAIMA.

I have remained engaged with NAIMA, to no effect. I have been willing to try again in Louisville, but know it will be futile if NAIMA has not seen that the proposal is in fact good for its represented manufacturers. How could it be harmful to manufacturers if better code allows them to sell more insulation, I figured. Where in this conversation I state my observation that placement technique for photos and instructional videos, thin batts are delicately placed proud of joist front faces, for appearance of fullness, I am threatened: I must not question the honor and good intentions of NAIMA. Else, I will be shut out of conversation. I have been in defiance of this threat for more than a year, still thinking I might have NAIMA as an ally in Louisville. This post is perhaps the ending of that hope.

Get on then to what I have done on a job, after returning Owens Corning batts R15 unfaced, as defective.

Here is Rockwool R15 in nominal 22 1/2" space. No fussing needed to have uniform 3 1/2" thickness.

There is no buckling in accommodating 5/8" reduction of available space where I have used plywood webbing in growing the truss bottom elements to load-bearing 7" thickness. In a five-star review at the Rockwool web site, I credit edge compression without buckling,  to material friability . Crushing without buckling is virtue, but in trade, the batts are subject to falling apart when carried. The densely-packed insulation bags could not be pushed through 24" oc framing reduced to 20.5" clearance in the attic ladder frame. I carried insulation up one batt at a time, with occasional fragmenting in my grasp.

I am quite happy with 3 1/2" fill of R15 Rockwool batts (always unfaced). The honest-value Rockwool batts cost less too. Unit cost is $39/60.1*1000 = $649 per 1000 sf. Compare to an unsupportable, price-fixed $817 per 1000 sf cost of Owens Corning R15 unfaced fiberglass batts (see above).

Addition to this post will detail layup of batt insulation in layers, rather than thinking batts are readily parted to sandwich wall plumbing and wiring. Knowing that underfill shall not be allowed, unfaced batts about R11 shall be readily available, for sandwiching, and for fill-in at any low spot at an internal or outer layer. Layering/ fill-in batts must be visibly on offer for novice installers at big box stores too. Where fill-in might slow a pro, batts thinner than promised might remain unacceptable.

I will have may examples of layering with Rockwool batts. Here 2x10@16" framing is extended to 2x14. All wiring is laid atop the 2x10s, and is revealed by lifting plywood and top-layer R15. A trampled 12" depth of loose-fill fiberglass, with many voids and bare spots, was effectively not better than R10. Loose-fill has been redistributed to 4" depth now under R23 Rockwool. The serviceable new total of insulation is nearly R49.

Unhappily, I have buried can lights, with much effort in the placement of Rockwool batts. I have several thicknesses of Rockwool AFB batts useful in this, especially 1 1/2" thickness.At my professional insulation supplier, IDI, I may choose between Rockwool, and Owens Corning Thermafiber. I stick with Rockwool because there are fewer thickness choices with Thermafiber.

2x4 Framing Build-Out To 2x6

This is the most-read blog post  of individual Phillip Norman, of Portland, Oregon, USA.

(a grand-daughter draws a best smile)

Surely this post is of value to more than the few who have offered comments. I hope that an introduction will improve participation. I will share your credited story related to this, or to any of my posts. I welcome and will share criticism, where I might mislead.

Please consider virtue in the accurate and strong build-out of 2x4 to 2x6 thickness in this exterior wall section of my 1955 home in Portland, Oregon. Here is that build-out immediately upon demolition of the wall formerly separating the kitchen from an on-foundation concrete back porch. Found 2x4 framing in this exterior wall is strongly thickened to 2x6 with added 2x2s upon plywood box-beam webs. The extended kitchen has 2x6 outside wall framing.

See that add-on sheathing  is 3/4" tongue and groove flooring plywood deck-screwed to the new 2x6@24 framing. Prefer maximum rotational strength at this house corner, to a bit of added insulation value in original Celotex sheathing if such could be obtained.

This photo shows an initial setup with on-flat 2x6 segments at the floor. 

See strong steel banding under the 3/4" plywood sheathing, at the new house corner.

See that I could do much better in the 2x4 build-out, with a continuous upright 2x4 at the floor, shimmed out 1/2".  Want ability to nail floor moulding anywhere. Want least obstruction through the 2x6 sill plate, for angle-drilled plumbing. 

Here is my kitchen in a nearly-complete condition, September, 2018. Added depth of exterior walls was important too, to better framing of windows and a door, and simplified  plumbing and wiring.

Google the title of this post: 2x4 Framing Build-Out to 2x6 .

Find no one else offering what I do, employing only available dimensional lumber as-produced, and plywood rips. 2x2 is usable for plane perfection regardless of curl. Achieve a rigid and flat interior wall regardless of defects and progressive twisting of ever-more offered imperfect 2x4 framing.

Summary graphics that follow, and the math of insulation values and heating costs are presented in this document:

• My 2x4 Framing Build-Out to 2x6 

Please find virtue in my simple Insulation Math. Find important conclusions in the applied math of the above-linked document, including:

• I have achieved average R22 for a net of all kitchen exterior wall area, the same for new 2x6 walls and the 2x4 built out to 2x6. This is R-value as the inverse of carefully computed U-values. R value of employed insulation is nearly the same.

Here is the fix:

With clarity in what I do, I may digress to the bigger picture.

Detailed records of my construction process are in job photo albums:

• Develop a cleanly accessible conditioned crawlspace  
• Expansion onto the on-foundation back porch 
• Kitchen completion 

There was a master plan down to finest details of walkability and function. The little house would continue to have no little-used dining room. Instead, maximize kitchen activities, including breakfast views of an urban sunrise if at a cozy table inspired by a friend grown-up in Europe.

Have a natural ventilation path through large tilt-in screened windows at front and back walls.

Have no plumbing except over the crawl space.

Have a good in-line fan drawing directly through a window over the kitchen stove.

8/7/2026, 8:30 AM

House interior 75°F.

Outdoors 65°F.

Tilt windows and other windows cracked open.

Kitchen fan and bath fan exhausting the house.

Four hours of this had cooled the house from 77°F.

This remains my form of air conditioning, for now.

See that little energy is involved in fresh air indulgence.

I had despised drop-ceiling headers over kitchen cabinets. Such headers are awful heat bleeds in most homes, where at exterior walls they are not accessible for insulation. Too often, none of the headers are filled with insulation. I have the opportunity to expand my kitchen 40% with modest effort where the little kitchen exited to the back yard via a concrete porch fully on-foundation. 

It was a crummy little kitchen, and held down the usefulness of the house, beyond being the last room in my house where I had not demolished interior drywall to accomplish data and power wiring improvements, plumbing replacements and tight R15 insulation.

In this one room I would accomplish R22 wall insulation in 2x6 framing.

See my build-out to 2x6 thickness of an existing 2x4 wall. At top place an on-flat 2x4 and 1/2” plywood rip. Stitch on lengths of 5” rips of 1/2” plywood as composite beam webs. Place 2x2s true vertical and flat, leaving 1/2” thermal breaks of both the 2x framing and the webs. The 1/2” gaps behind 2x2s enable simple running of wires, without steel plates to mess up drywall flatness.

My kitchen overhaul occurred in stages, working by myself while improving my home in other areas and while working alone as a general contractor, never advertising:

Condition my crawl space, 9/2012 to 11/2012

Attic refinement, 1/2014 to 12/2018

Expansion onto porch, 8/2014 to 4/2015

Planning, 4/2015 to 7/2017

Completion, 7/2017 to 10/2018

Serious about this in late Summer 2017, I have reset the wall build-out to employ an upright 2x4 at the floor, for better baseboard attachment opportunity, and insulation a bit better.

I will have a much better kitchen, in a home that inspires possibilities with solidly-built homes of the 1950s.  I have done all work except cabinetry fabrication and the shaping and setting of quartz countertops.

My circuit breaker panel is just beyond the garage wall that rounds this corner to the right. Most of the new kitchen wiring passes through the thickened South wall, with no need of nail-stop plates. See plumbing drains and vents well-reimagined in the crawl space below. All plumbing resides over the crawl space; none over the inaccessible former back-porch slab. Walls of the new half-bath will be elements of kitchen cabinetry, bolted to uninterrupted tile floor.

All appliance wiring passes along the South wall, including that to the electric range at the East wall. 

See four water service shut-offs under the kitchen sink. Spare Hot and Cold service without water to the refrigerator and disabling the dishwasher would enable valved temporary plumbing to a temporary handicap shower unit possibly to be needed someday.

See invention of a module of wiring and plumbing devices that will plug into a careful rectangular cut through the back of the cabinet base for the kitchen sink. At right see some of the safe wiring opportunity, behind 2x2s of an outside wall bump-out to 2x6. Want that hidden wiring is fully revealed by removing outer/ top insulation batts.

Angle-drilling of kitchen sink water and drain lines is aided by the thickened 2x6 wall above.

The high end of house drain and vent piping, for a time, was at the laundry in the garage and at  the added half-bath.

See a more-elevated high point of the drain plumbing where a 1 1/2" ABS drain P-trap was added to collect consensate of the high-efficiency gas furnace and of a heat pump water heater. The kitchen overhaul with attendant new plumbing, enabled other important home improvements.

While exposed, the built-out framing was a laboratory of insulation methods, sharing photos in conversation with Insulation Institute .  I started out with remnants of an exceptional exterior wall judged to be R_total = 5, U = 0.2 not counting added value of wall joists and to-be-added insulation batts. To a generally-applicable R3 value of airtight sheating inside and outside, add  R2 value of Celotex sheathing . Exterior air tightness is achieved both at well-set old-growth cedar siding, and at overlap of Celotex edges. Start with less than half the conductivity and heating cost of common, cheap, non air-tight construction, Rtotal = 2.5, U = 0.4.

Walls built this way are to be treasured and preserved. I'm not sure what should be done with more-ancient walls, hopelessly leaky, hollow, cobweb strewn, with structural defects and dangerous wiring, ruined of insulation value. I suspect though that salvageable homes are determinant not by age, but by investment at time of construction.

Where is the pride of any employee or contractor of the US Department Of Energy paid to support residential energy efficiency, when USDOE Home Energy Scores treat all exterior walls without some insulation stuffing, as of paper, R_total = 0.4, U = 2.5 ? This perhaps-deliberately fuels older-home demolition regardless of solid construction. This is applied for all insulation opportunities, exterior walls, ceilings and floors. It encourages false claim that very-huge energy savings can be achieved by a blow-and-go scammer foolishly just adding some partial insulation atop wiring, plumbing and structural messes, if the home is not demolished.

The subjects with preeminent insulation industry promoter NAIMA: Insulation Institute  have been layering of batts to kill framing thermal shorts, full batt containment to avoid air circulation, and lack of value where insulation does not fully fill available space.The official instructions of NAIMA are set in a year-2012 series of instructional videos:

 

Answer the question “How do I install batt insulation?”

• Video 1/3 – Pre-insulation Walk-Through
• Video 2/3 – Insulating Tips From the Pros 
• Video 3/3 – Insulation Inspection

I wait, and wait, for recall of misinformation in Video 2/3 above. I bought and here tested a bag of the yellow Certainteed R13 insulation placed by the championed installer. Please watch the video, and see that the installer takes great care to not press edges beyond joist faces. I just don't know how to do that, making a fluffy batt a maximum of 3" thick look like it fills the cavity space, as it must. It seems that alone among insulation manufacturers, Rockwool (formerly Roxul) , makes batts specified for a framing depth, that reliably fill the space. Look closely at the beginning of the video to glimpse Rockwool as exemplary insulation.

Here in my 2x4 garage wall, is a length of Certainteed unfaced insulation wrongly rated as R13 in a 2x4 wall. It has been placed here for more than a year, in incomplete communication with NAIMA, North American Insulation Manufacturers Association. At 2016 hearings for revisions to 2015 International Energy Conservation Code, NAIMA defended code-allowed underfill of framing, defeating my proposed requirement of full filling always, by overfill that accommodates small-batt tolerances











In fact, R13 batts NEVER fill 2x4 framing. Where gaps will exist all around a batt, then with low flow resistance for air. Air circulation, driven by energy convection and outside wind pressures, may reduce insulation value to zero. There is no reason this should be allowed.

Search for posted examples of under-fill paired with infrared images as proof that full filling matters .

As the principal result of this Google AI search, find this paper by Building Science Corporation: Info-501: Installation of Cavity Insulation . There must be no convective looping within and around the insulation!

My Google AI search did not find new instructive infrared imaging graphics.  I hope that these images already known to me will suffice. They are from a YouTube video posted by IDI Distributors:  https://www.youtube.com/watch?v=WXr5E3gb0P0 

Two adjacent wall cavities differ where that at LHS is a thicker Owens Corning FastBatt not tethered to joist faces by stapled tabs. The full-filling performance is impressive except that some compression by excess width would have payback. Side-edge contact might be complicated by persistence in having silly paper kraft facing. Kraft facing does much more harm than good when rippled in a narrow cavity.  Crumpled kraft facing as dispensed from a roll, creates wild air bypass opportunity. Kraft facing is not useful as an air barrier; it is not useful and not wanted, as a vapor barrier.

At last rounding this corner with drywall, I apply last-minute grouting of a vent annulus, with my always-available flexible grout. See that Rockwool R15 insulation  thoroughly fills the space, accurately cutting to width from 23"x 93" batts. Do the math on cost of this Rockwool vs. the experimental Certainteed R13 with no value, for one 16" oc frame bay, batt area 14.5*92/144 = 9.3 sq ft. The Rockwool cost $649 per 1000 sf. The R13 cost $397 per 1000 sf. The one batt cost, 9.3 sq ft, is $6, vs. $3.70. Proper code must keep a silly person from pocketing the negligible difference in installed cost. A DIY home owner must never be tempted to do wrong in a cheaper choice, by believing a "For 2x4 Framing" label on a crummy R13 bag.

Rounding the corner from built-out 2x6, to an ordinary 2x4 garage wall, report upon a layering trial to the right of that plumbing vent bay now filled with shaped R15. Where I have added a bath fan and overhead light junction box, 14/2 romex leads between a new 2G switch box and the attic, sandwich the wires between Rockwool AFB batts. See that R15 Rockwool is uniformly a bit thicker than 3 1/2". Two layers of AFB batts are 4" thick except as pressed in at edges, but better too thick for the space, than too thin.

I think insulation installers wrongly do not expect to find a family of batts that in layers, add up to fill the space, giving promised R-value.  AFB batts about R8 are not sold as suited for layering with object sandwiching.  2x6 walls may be filled with R23 Rockwool batts, or when necessary, with layered AFB:  R8 and R15.  2x4 walls may be filled just-barely, with R15 Rockwool batts, or when necessary, and perhaps better always, with two layers of AFB. Layering of manufactured consistent batts to deal with odd cavities, is not just good practice. Rockwool batts do not part, and hacked cuts make a big mess of a job, with puzzle pieces that challenge patience and result in deficient R-value. 

In new 2x6 walls, begin with AFB batts. there is certain ability to stuff an inch of effective insulation behind a crossbar that allows outlet placement distant from a 2x6 joist.

This is the complex southeast corner of the new 2x6 framing.

Draw many details to think-through the planning. Here is the kitchen southeast corner, built around found 2" steel pipe porch roof supports, fully stuffed with Rockwool insulation:

Here again see my trusty cerrated commercial bread-cutting knife, used for all cutting of batts. Cutting in and around friable Rockwool batts is easier and more precise than in stranded fiberglass batts. Where we admire honest, uniform thickness and easy shaping of Rockwool batts, also celebrate discarding of ill-conceived kraft facing as a leaky, crummy "vapor barrier." 

We need combinations of mineral wool batts that may sandwich wiring, as parting is just too awful.  One R15 batt and one AFB batt, or one R23 batt. nicely fill a 2x6 space. Doubled AFB batts as sandwiching in a 2x4 wall have excessive overfill. One needs many screws to pull in the drywall with compression.

Overfill is not the goal. Overfill is demanded only where batts have unreliable thickness, to get complete fill always.

With full demolition of drywall at the garage 2x4 wall, see dripped flexible grout from wall header sealing in the attic long ago. Plaster the gap now.

Seal the wall header fully.

For good reason and as demonstration of good example, buy a new coil of Resource Conservation Technology BG32 EPDM gasket.

The BG32 gasket consumed here will cost me less than $6. With flexible grout sealing of existing drywall, it will block a leakage path to the attic that is poorly accessible, and was not sealed before.

At the somewhat conditioned garage wall, insulate with R15 and layered-R8 Rockwool.

Finish GP Densarmor drywall pieced-in, using flexible grout and Structolite plaster, over joints well stitched with screws and backing lumber. Set joint paper tape in 24" lengths, at ceiling and wall corners only.












Date: 2/23/2018. Ideal condition for wall observation with an infrared camera. And, I don't own one. A camera investment of about $10,000 can have no economic return to me. I leave no voids, always maximizing insulation value. I believe there was nothing more to do, to  improve comfort and reduce operating costs at these exterior walls. I have at least the R23 before-framing-allowance achievable in 2x6 framing, with tight mineral wool batts. The modified 2x4 wall is yet-better insulated. And ask now, by how much, and how much some defensible difference, matters. Least-rigorous math has 1/Reff = 0.25/5.2 + 0.75/23, Reff = 12.4 for simple 2x6 walls with 25% framing factor, R23 batts. Use Insulation Math for this home, Annual cost of heat = $2.4*Area*U. U = 1/(R + 3),   Wall area 250 sq ft, Annual cost of heat = $39. If I could somehow have R23 framing, the annual cost of heat would be $23. I'm being glib about window and door much larger heat losses accepted as imperative. Have I done something wrong to accept $16 per year unavoidable heat loss for walls in this room?

I will not be shamed by extremes in this current blog post of Insulation Institute: 
3/21/2019, Mineral Wool: A Solution to Thermal Bridging 
See what they might have me do as exemplary use of mineral wool batts:

 I see wasteful failure to fill 2x6 framing space. I see exterior insulation that can't be part of sensible and strong construction. I see failure to be realistic about thicknesses and labeling of on-offer batts, 2" R8, 3.5" R15, 5.5" R22, 7" R30. There are no 3" batts. There is no acknowledgement that mineral wool batts can't be parted to go around wires or pipes. Then offer layering, for example:. 2" + 3.5" = 5.5", ~R22.