Tuesday, December 10, 2013

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.

Friday, December 6, 2013

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: 
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.