Full Hard Covering Of An Attic Floor

This job experience was imagined as content in Fine Homebuilding Magazine. Subject: the protection of insulation integrity and value, by complete air-barrier hard covering. The inspiration? Suggestion by writer Martin Holladay, that complete hard covering should apply to skylights. Great idea, I say, but it is simple logical extension then, all of an attic floor should be covered too. The example which follows is drawn from an associated Picasa Web Album. And, it turns out that another writer is not much wanted, for Fine Homebuilding.

I have many similar jobs with substantial floor decking, upon strong supports, found by picking blog Label: Strong Attic Floors , here, or at the right. The unique importance of this job is use of attic floor supports to keep attic weight from loading very-long 2x4 roof joists. Second floor walls do not directly support the roof, here, and fairly often. Add label: Roof Strength for this post. Try that to find more-complete discussion.

This photo is from a 1:120 scale drawing, structures in overlay upon a satellite photo, drawn in Adobe FrameMaker.












I think that bonding the composite beam top elements to the roof joists, reduces propensity for bowing of roof joists. Bowing may happen when the cross members can shrink in twist action.

With very-extensive support framing, it is easy to place flooring that comes closer than ever before, to a complete hard covering of insulation. The motives of strength and the protection of insulation integrity and value, are of equal importance.

Plywood is 1/2" CDX supported 16" on-center. With composite beam construction, it is readily set flat, with no panel edges to catch and trip upon. Plywood is screwed to upright 2x4 beam top elements called nailers. Nailers are carefully aligned and straightened using a good six-foot level. Bottom elements are often wildly twisted, and a surprisingly large range of revealed nailer is seen above the consistently-ripped plywood webs. Web rips here are 9" wide. Decking is also 1/2" CDX, pieces reassembled why-not, mid-ripped 24" x 96". I use lots of plywood, in creative ways.

Besides being a foundation for protective covering, the beams serve as thermal breaks, even where batts are not crossed. Conduction of energy is with high resistance transfer from 2x framing, to the thin plywood webs. Gaps behind the webs, between lower and upper 2x elements, are stuffed with insulation. Here insulation is in three layers of unfaced batts: upper and lower R19, and wider R11 batts  filling 2x spaces, in between.

The total of insulation everywhere is R49, in a depth 9.25" where compressed under decking. I think the air barrier and the added boundaries of conductive layers is good compensation for the small batt compression. This attic is improved from R4, to better than R38. Always add as much insulation as space allows.







Batts wider than spaces in deck framing are thinned by stored energy along edges. In-between there is billowing that will be leveled, pressurized and stilled of air circulation, by decking plywood. Wall insulation done right, is "bottled" this way. Why wouldn't you do the same in an attic floor?









None of this is for storage, though the space is now usable.

I would not go further in this home, to apply hard covering along the difficult edges. I would like to cover the periphery instead, with heavy cotton throws. Those throws would collect dust carried up into the attic through the heat engine of roof/ ceiling slopes. The throws could be laundered in periodic attic maintenance that includes vacuuming of roof vent screens, reducing need of a respirator in-attic. Where I will comment on thought of hard-covering skylight shaft insulation, I will point out that air-barrier fabric will be a preferred solution most of the time in existing-home retrofits. What will it be? It must not decay. It must be washable.

How Long Will The So-Cheap Natural Gas Last?

We all need to know natural gas made cheap by evil fracking is of very short duration. Here is one reference for that, published in respected Slate Magazine.

An optimistic "proved" total of 273 tcf would last eleven years at current pace, and the price would rise strongly, much sooner. Six years from now seems consistent with the chart.

Get to know Chris Nelder, who spoke the six-year fracked-gas number, in a radio interview that inspires this post. I listened to the interview again now for post diligence, and didn't hear the six number. It is there. Chris Nelder's analysis stands on its own, in this presentation:
http://www.smartplanet.com/blog/the-take/peak-oil-isnt-dead-it-just-smells-that-way/ 
There, read this prediction of grave happenings in only a couple of years.

"I expect world oil production to rise, weakly, for another two years or so, as America falls into a deeper slumber believing that fracking has cured everything. The media will reinforce that belief. And when it comes, the wake-up call is going to be harsh. In the meantime we’re just going to be waiting for the punchline.

So to those who can grasp the data, here’s my final thought: How will you prepare yourself for The Great Contraction? You've got perhaps two good years left of business as usual, and maybe another three or four after that before things really get difficult. I encourage you to use them well, and do what you can to make yourself resilient and self-sufficient. What will you do 10 years from now if the price of gasoline is $10 a gallon?"

Here is another reference in this, author Richard Heinberg. His book is a really easy read, in Kindle. No one can contradict the truth that fuel prices misleading planners, will turn in the next several years. Planners of weatherization must act now, to accelerate action by more than an order of magnitude. In Portland, Oregon, those who brag of weatherizing 3,200 homes under fat-laden $20,000 HPwES scams, in five years, will face humiliation. The need in this period was of progress by times-fifty, in work done honestly, perhaps in sacrifice for our common cause.

Looking For A Reading Light

A story here is first told in a web album:
Looking For A Reading Light 

Now tell the story again, here.

I have a genuine need for a bedside reading light. But for the living room with its fancy ceiling, each room is lit with one or more Glimpse LEDs, mounted in new RACO175 junction boxes of course. An overhead light is crummy for seeking sleep, badly aimed at a book, and not amenable to drowsy shutoff.

As a solution, I was offered this desk lamp with ready-to-go 100 watt incandescent bulb. I just can't bear to use it. I tried a clumsy directional LED bulb appearing in photos to follow. No go. I couldn't keep the lamp from toppling. 

I no longer expect to find innovation at Home Depot, but dutifully walked the aisles again this week. I found this, and went on to also buy new T47 and T67 disk lights. I hoped the bad dimmer buzz in those disk lights might be resolved. Wishful thinking, and all three trials will be returned. Darn the packaging. With this ecosmart, know to twist out the front-face bubble with little damage. Never get angry and use a knife or scissors.

I would try this much-lighter new version of the ecosmart technology, in my lamp!

Here is a labeled array of bulbs discussed here, out of packaging.

The year-old "75w" version of the ecosmart LED is at left. Next to it is the new "65w" ecosmart. At right is a Utilitech version of the L-Prize replacement of a 60-watt incandescent. 

Labels A through D are edited-in, for comments to follow. First, note weight of each. A = 429.2 g. B = 145.2 g. C = 27.5 g. D = 247.3 g.

In the desk lamp, the "65w" ecosmart is still toppling, and a bit ugly. I won't use it.

A 65 watt incandescent flood looks the same and is less toppling, but I won't use it even in cold-cold winter, where the heat feels good. I'm leaving that in place for night-time fumbling-for-a phone. It beats any stupid point source bulb. It's hard to believe people still use "bulbs."

Here is a collage of three individual photos of task illumination, with very limited discrimination of brightness. I use a Canon Digital Rebel SLR camera in No Flash mode for all comparisons. The setting allows automatic adjustment to found light, and individual photos are not comparable, except perhaps that brightness might be reveled in better camera focus achieved. It is not the way to do testing.

Again, I can rely on my Living Room test stand for unambiguous comparisons. Comparisons are most valid where side-by-side specimens have the same color temperature.

At left is a 4" Glimpse, 2700°K, 425 lumens.

At right is the "65w" ecosmart, 2700°K, 650 lumens.














Labels applied to comparison photos state unambiguous conclusions, where Brightness Numbers are noted. B4 is the standard, assigned to a 100 watt incandescent bulb. For all directional light beaming from a plate, compute Brightness Number as:
Tested Lumens/450 * B4.

The topply Ecosmart LED flood in a reading lamp is brighter than a 100 watt incandescent by *650/450 , brighter by  44%.

Here is one more demonstration of "B4", equivalence of a 100 watt incandescent and a 3000°K 4" Glimpse, 450 lumens.

Add some more test-stand observations. These will further illustrate that task illumination, that properly distinguishes luminaires of differing construction, is not at all expressed in numbers of lumens or lumens per watt. The observations are useful in seeking a reading light, applying Year-2013 source material for a Year-2016 debate about "High-Efficacy Lamps." This addresses misconceptions about point-source LEDs. The point to be made is that a point-source lamp of any kind can never be "high-efficacy." An LED bulb that might screw into an old reading lamp must be directional with large beam angle, not with some concentrating lens. See the inefficiency of the US DOE "L-Prize" point-source LED bulb. vs. good directional LEDs:

A point-source LED A19 bulb, the Utilitech offering of the L-Prize bulb, gives really-awful illumination. Such expensive bulbs should never be used as desk-lamp reading light. Point-source bulbs are inferior for any task illumination.

It really hurts consumer decision-making when directional LED lighting is under-rated, by a large amount. It is time we fixed the packaging.

I'm still waiting for a good reading light. It might be in an art piece suspended from the ceiling. For a child, I have imagined illumination from "landing lights" on a remote-control model airplane, at quite modest cost. For me, it might be a soft-light broad panel with some provision for aiming, mounted to the wall. All best solutions will come where we at last have direct attachment to low-voltage DC.

More HVAC Circuitry, In A Crawl Space

This is a hydraulic design study considering before and after conditions of HVAC ducts in 

the crawl space overhaul reported here:

A Deep Energy Retrofit, Fall of 2013

The home is a well-built farm house, 1590 sf, completed in 1973.

It was necessary to remove and dispose all crawl space HVAC ducts, including some of the elbows approaching floor boots. This permitted cinching heavy R25 cotton batts into needed contact with the floor sheathing.  

Believe that the ducts demolition was needed for access to tie up the batts. 

Know that once again I have done a ducts rebuild by my own commonsense rules, without first characterizing the performance of the found ducts. And, what does performance  characterization mean? Characterization includes Diagnostic Static Pressure Measurements and a measurable sense of the equality of bulk air velocity at each floor register. I'm thinking the register equality is sensed by comparison of noise level at each register.

Removal of all found HVAC ducts was a needed first step. I found then that all supply distribution was with stupid leaky hacks of a single D-box directly under the furnace.

All flow paths out of this D-box are visible in this photo. On the RHS (front), two 9" ducts. On the side, two 6" ducts and on the back, one 6" duct. 

Find this Medusa distribution of conditioned air to be stupid and offensive, never to be taught to anyone. Air in motion must constantly be guided in least-resistance paths; else it must generate the net motion through gradients in wasteful and noisy, unstable turbulence.

The three 6" duct outlets each served one nearby 6" register. One 9" outlet served four 6" registers of southern rooms. One 9" outlet served an 8" register and three 6" registers in northern rooms. Assuning that the D-box outlets delivered equal bulk velocities, calculate register flows thus: 

Assume equal pressure drops at the five paths in the supply D-box. This happens with equal path bulk velocity in the paths if they have identical geometric loss, say k = 1.8  in each path, an imperfect assumption.  A direction having a majority of flow, to the East at 9" starters. will have higher drive pressure.

The sum of D-box exit areas a bit less than .7854 * ( ( 3 * 36 ) + (2 * 81) ) = 212 sq in

The three 6" registers each have total area 84.8 sq in.

The South-serving four 6" registers have area 113.1 sq in

The North-serving three 6" registers and one 8" register have total area 135.1 sq in.

The total area of pipes leading to registers is 333 sq in. Where pressure drops in various paths are in proportion to square of velocity, Q/A, the majority of fluid energy is dissipated at the D-box walls, mostly-regulating the flow distribution. The square of (212/333) is 0.4. The North-serving registers were favored by almost  135.1/113.1, 20%.

Accurate math here is impossible and futile.

Study further the sizing of the improved HVAC supply ducts:

The trunk area is 14 in x 19 in , 266 sq in.

The flow constriction through electric resistance heaters is to area area about 120 sq in, with extreme high velocity and unfortunate high pressure drop equally reducing all path flows.We should wish some day to have a ground-source heat pump, eliminating the supplemental heaters.

The above diagram of this crawl space warm air duct system is a 1:120 scale drawing, with overlay of structure details upon a Google satellite photo. Please note similarity to planning graphics and involved ducting elements for similar achievement in an attic.

The really curious may examine too, a full photo album A Deep Energy Retrofit, Fall of 2013

 including found conditions of the failed UltraTouch batt installation by "twining" method, and of impassable and leaking conditions in the found system of steel warm air ducts. A separate blog post will address the cotton batt insulation repair. The involved home in Hillsboro, Oregon is also the site of a publicly-shared full photo album documenting attic floor weatherization with UltraTouch cotton batts: Real Sealing Fixes HPwES Sealing In An Oregon Attic. Full pdf photo albums always tell a story best, but please know they are poorly rendered when viewed in GoogleDocs. If you want to examine such albums, please bother to download them.



Elements of a new warm air duct system are in two nearly-equal branches, called North and South. The branches include a well-considered set of plenum components below the furnace. A 14x19 turning plenum replaces a crude D-box.

The furnace plena have a 1" insulation liner and end in a triangular head with two 12" starter collars serving a system of flexible ducts.

Two 6" registers near the furnace are served by the first of four lateral take-offs, circuit label T12x6. These and all steel couplings of flexible ducts, are hung from the overhead via eye bolts. These two, hanging low, are pulled up by wire loops. Never support steel couplings by strapping upon the flexible ducts. Don't rely on screws and tape for suspension via metal couplings.

Here note the 1" insulation lining, and turning vanes. Getting prepared with such well-conceived and well-built elements is a small step of installer professionalism. Expect you may need a couple of weeks lead time for fabrication by a superior sheet metal fabricator. My fabricator in Portland, Oregon is Vinje & Son.

Don't accept dissing of flexible ducts, that they have extraordinary friction. Where each duct section is fully supported by straps and by steel couplings, draw small tension in the liner, taking up coils as needed, to align the duct and coupling. High-resistance problems are always the result of careless alignment, with tripping over steel edges. Plan excess of insulation jackets, to draw them fully-overlapping, over couplings.

This is coupling component R8x6, used two places at branch ends, where 6" ducts to registers are of length not more than six feet. I wish for simpler one-piece reducers, but want ample starter lengths for liner take-up and secure taping. Here and in the previous photo, see that the eye bolt hanger of a steel fitting passes through a hole in plywood overhead. A wood dowel cut from nimble tree branch passes through the bolt eye to releasably hold everything up. The release can allow better fit of insulation jacket overlap.

Here is the completed end of the North branch at a 6" register. The hanger of the R8x6 is out if sight above the jacketed water pipe. See only tough black liner, strapping and some Nashua 557 tape. Leave no opening for mice. Wherever possible, draw ducting tight against plywood guides, as barrier to mice.

This is the new heart of the duct system under the furnace, with a turning plenum.

This is the well-strapped head of the North branch 12" duct, tightly in contact with overhead 1/2"  plywood strips. One can readily crawl anywhere in this crawl space, sliding under the smooth plastic covering if necessary.










The following is an exercise in defense against anticipated criticism there are no balancing dampers and ACCA Manual D consideration, in new invention of furnace warm air ducts.

Please see that residential HVAC should be naturally balanced with good flow dynamics in orientation and more, of plena, take-offs and reducer or wye fittings. Air flow in thoughtless ducting can be extremely chaotic, and not amenable to tweaking with manometer measurements not-at-all understood. With smart ducting, simply rely on the already-present register grills.

Do accounting math as in this example, to avoid excessive velocity in any path segment.

The practical concerns in duct design are to allow overall free flow, limiting air handler power draw, and getting the heat where a deficiency is noted. The complaint to be resolved will be of too little heat in a favored room. Don't respond by dampering flow to other rooms. Just tackle the duct path to that room. Find an obstruction, perhaps a crushed or pinched duct, or misalignment in a coupling. Failing that, increase the size of ducting for that room, perhaps just in a more-intelligent register. Look for missing insulation as the cause of discomfort.

At Pinterest , please find a growing collection of affordable and suitable HVAC registers, that include easy damper adjustment.

Insulate Exterior Wall of a Bathtub or Shower

Outside walls should be insulated and hard-covered before a bathtub or shower unit is placed. Here is a reverse-chronology abbreviated photo album of my trial of methods, where I demand hard backing for wall tile. 

Here are all photos split into three groups:

First Sixty

Second Sixty

Third Sixty

I really, really want feedback for my effort in the job and in this post.

I use two layers of 1/4" backer board, for reasons including secure tile overlap of a copper seal edge. 

I will not rely on tile or caulk in sealing the tub edge. Here two-part epoxy seals a copper edge to the tub lip and exposed areas of the backer board.

After several trials, I chose a Kohler porcelain tub of ordinary height, with sharpest inside corners. I believe least maintenance and best suitability if handicapped, is with a tub this height, with good shower curtains, not glass doors.



See the pencil tracings on backer board above? Yes, my plumbing supplier took in exchange, an undamaged too-tall fiberglass Maax Skyline tub. I thought the Maax tub flanges would be conducive to edge sealing, but they are not. I find no tub built to not rely on caulk. The copper idea was volunteered by friend Copper By Design. I inquired about stainless steel.

Tiling was done atop ultra-flat 1/4" ACX plywood framed below as a strong and flat table. Bottom tiles will rest on the plywood, and that tile rest edge will remain exposed out of sight, sanitary with full gap filling of flexible grout. Flexible grout has added mildicide. I offer free samples and seek to inspire manufacture of the versatile flexible grout, at blog plasterrepairhowto. With some reluctance, I report that anyone may apply a commercially-available equivalent, Custom Pro Tile Grout.

My material, in other applications, has advantage in being sandable-like-drywall-mud. I appeal to Custom, to offer that product.

Finished bathroom outside wall. I will towel dry the tiles daily, as is experienced where we find shiny shower walls in a hotel.

The tile is backed with plywood set in the walls, and two layers of 1/4" backer board. Many screws ensure tiles and grout should never be distressed by any action in the wall. Thermal stability with the insulation will help too. 

The plywood is 3/4" thickness and should have extended to the ceiling, for secure mounting of the outer layer of 1/4" backer board even where there are no tiles. This plywood is moderately-well fastened. It may not adequately support grab bar attachment points. I might have toed many more screws into the joists. Wish for more space, such that plywood is atop the framing, for mounting of whatever, anywhere. More-ideally, plan grab bar attachment points of solidly-mounted 2x lumber.





Choose batts always wider than bays filled, commonly 15" in a 14 1/2" space. In a 2x4 wall, I will accept R19, but must struggle to bring edges out to the wall surface. These are a layer and a half of R15, R21. I didn't want the minimal fill of R19 in this wall, and enjoyed the better body of R15 strands stuffed into non-California corners. R19 is so wispy.

I hope others will find this example instructive, and will comment. Do you have a better way? If you have ample bathroom space, perhaps you would clad plywood over over walls to be tiled, plywood inboard of joists. Who has had bad experiences with tile placed over drywall, not over very solidly-set backer board? If putting a one-piece shower unit directly against framing, what is desired as insulation covering? Is a good plastic barrier like Tenoarm, sufficient then? Please know I believe that in my marine environment with low relative humidity, I should have a full interior vapor barrier at all exterior walls.


I do this for for very-rare customers where I have new-drywall opportunity. I have failed to inspire other contractors, to my knowledge.

This is a bedroom in my home, with all Tenoarm edges sealed with double-backed butyl tape.

Did I do right in my bathroom, to despair of Tenoarm with difficult blend of backer board/ tile, and drywall facings? 

I must report that Swedish Tenoarm is no longer offered in USA.