December 8: New Construction Begins

During October, I interviewed 4 contractors.  In November, I selected one and hammered out some additional details, signed contract, and paid $500 deposit.  After he had been selected, the contractor said he would begin work around December 8.  On December 7 I got an email saying he would meet me at 9am on December 8.

And today, December 8, the contractor, supervisor, framing supervisor, and 2 workers showed up. We went over construction details, selected and marked positions for door, window, and A/C.  Window is now to be 8 feet from front inside wall, with AC unit closer in, separated by 18 inches.  I paid $2500 additional deposit.

They plan to start work today, but it is quiet now because they have gone back to lumber yard because contractor got 2x4 studs instead of the 2x6 specified.  They plan to work on Saturday.  Supervisor suggested I make appointment with electrician for Monday or Tuesday to do electrical rough in.  I've made appointment with electrician for Tuesday.

Temperature is 45 degrees.

Heater Controller

Here is a very nice thermostatic heater controller.  It features a thermostatic relay made by Johnson Controls (their factory just a few miles from where I live!).  It is intended to control heaters to keep cold blooded reptiles alive.  (A reptile can die if it gets too cold.) My application is keeping all my antiques in the workshop from getting damaged by cold.  I will turn on a small radiator heater set to 600W and a small fan to help circulate the air.  A controller will prevent the heater from running at all on warm days.  (The thermostats on portable heaters are bad about that, they often run just a little even on warm days.)

Solar Metal Roofing

I'm not planning to do this anymore, but solar metal roofing is discussed here.

The Best Climate Control Option

I need 5000 cooling BTU or less to maintain temperatures below 82 degrees in my supremely well insulated 165 sq ft room.  Generally through-wall A/C start around 6700 BTU or more, and don't include heat until you get to 7500 (lowest I've found, but old fashioned mechanical control model) or 11900 (top of the Friedrich line Kuhl with auto changeover) BTU.

So I'll have to forgo built-in heat, and supply heat separately.  The lowest BTU through-wall unit I've found is actually very nice, a 5500 BTU commercial grade Friedrich XStar XQ05M10 with digital controls, MoneySaver auto-fan (fan is off unless compressor is running), and other nice features.  The XStar is the 2nd in quality and features only to Friedrich's Kuhl line, but nearly as nice and sophisticated.  Instead of 7 day setback system, it features 24 hour timer, actually I like that better anyway, much easier to set.  It has auto adjusting SmartFan and Comfortwatch temperature monitor and remote control.

For heat, I'll use my Delonghi radiator, set to low (600 W).  It's very safe, only getting touchably warm, and I believe 600W is high enough to get the job done (assuming it's online all the time, and not simply turned on for a blast of heat, which it doesn't do well anyway) and low enough power draw that even if, due to malfunction, it ran simultaneously with the above AC, it wouldn't come close to overloading even a 15 amp circuit (my intention is to get 120V 20A circuit).

The problem in this application is that the Delonghi, like most portable electric heaters, has a horrible thermostat.  No matter how hot or cold it is, it cycles on and off.  So it cycles on during the hottest days, wasting energy, and cycles off on the coldest days, especially if you've set it low enough to minimize on cycling.  The solution is to get some sort of remote thermostatically controlled AC switch.  I'll look for that.  In the worst case, in principle, I could build one with conventional thermostat and relay.  Then an additional fan could plugged into the same thermostatically controlled switch to help circulate the air.

Then, with AC and heat through separate units, I've achieved both low cooling BTU for max efficiency and auto-changeover.  That's what I want.  Set it up and forget it.  I hate being turned into a slave to operate my climate control systems semi-manually.

*****

At Amazon, the XQ05M10 air conditioner gets a lousy review from some guy who complains about the noises it makes.  The XQ06M10A gets great reviews.  The "A" suggests it is a slightly revised model.  The difference is only 300 BTU (from 5500 to 5800) and it uses only a few hundred milliamps more of electricity.  So I think I will get the XQ06M10A.  Seems like Friedrich would have intended to make 5000 and 6000 BTU units, but somehow it didn't work that way.

Roofing lifetimes

Turns out steel roofing does not last forever, though it almost sounds like steel roofing manufacturers make that claim.

The longest life roofing may be some kind of tile.  According to Eagle Roofing, modern metal roofs have a projected lifetime of 45 years.  Of course, that is a projection, galvealume and modern PVDF coatings haven't been around that long.  Top quality roofing manufacturer Berridge only guarantees the finish and the roofing panels for 20 years.  Meanwhile, Eagle claim tile roofs have a 75 year lifetime, and their tiles are guaranteed for a "lifetime" (lifetime of what or whom?). Tile roofs have on historic buildings have been around for centuries (however not without maintenance).

Concrete tile roofing is available in highly reflective colors, all the way up to a white with SRI of 96, exceeding the reflectivity of PVDF white coated steel.  (Eagle makes that color, Hanson tiles only do a light colors with SRI up to 45.)

Two shortcomings of tile: (1) it rarely has the highest impact resistance.  Hanson tile is only rated to class III.  Most Eagle tile is rated to class III also, the exceptions are the flat tile which is rated to Class IV.  (2) Freeze/thaw cycles, though concrete tile manufacturers claim their product is fully resistant.

But the different lifecycles themselves of different roofs need to be considered.  Tile, especially of the non-flat variety, randomly breaks from hail and other weather events.  Thus it needs to be inspected periodically, perhaps annually.  The cost is not in replacing the tile, which is either cheap or lifetime warrantied.  The cost is in the work of replacing tiles.  Metal roofing does not require annual breakage inspection.  What happens first is that the coating deteriorates.  Thus, repainting is required in about 20 years.  Since externally applied paint probably won't be as good as factory coating, future repainting could be 5-10 years.  If you're not fussy about appearance, it could go longer.  But failure to recoat could lead to premature failure (though that seems doubtful for galvalume, one would think it would be OK without coating).

Thus the maintenance story goes like this: tile roofs require frequent, but relatively inexpensive maintenance, to maintain water shedding performance.  Metal roofs require infrequent, but comparatively expensive maintenance, largely to maintain appearance and long term lifespan.  Then, the metal roof will need to be replaced entirely sooner.

A third type of material shows up as well as metal in Eagle's roofing lifetime charts.  Polymer shingles.  I need to check those out.

Foam Insulation; Metal Roof

So far, I've interviewed two new contractors.  They had very different styles.  The first, a licensed general contractor, arrived exactly on time, asked questions, said little, left in 30 minutes, and delivered a written estimate the next day.  The first estimate included metal roof and foam insulation.  I suggested those, and the contractor didn't debate them at all.  Actually, a little more discussion would have been nice.

The second contractor I interviewed last week was very reluctant to do foam insulation, so I said I would also accept fiberglass batts, as on my written specs (because that was what Ronnie wanted to do, and he convinced me it was OK).  However since then, I've decided I must do closed cell 2 lb foam insulation as mentioned by the first contractor (though strangely not included in his estimate, apparently I agreed to 0.5 lb foam because of better acoustical properties).  Foam insulation is by far the best, and 2 pound foam is the best of the best (see below) for thermal insulation, though 0.5 is somewhat better for acoustical insulation.

Here's a great link recommending 2 lb spray foam insulation.

Here's an even better link with all the technical data:

Open cell (0.5 pound) vs Close cell (2 pound):

R Value per inch:
Open   3.9
Closed 6.9

STC (Sound Transmission Class)
Open   51
Closed 43

Noise Reduction Coefficient
Open   0.7
Close   0.2

The really relevant number is the STC, that's a complicated measure of how sound is attenuated as it passes through a structure, very roughly speaking, the dB's of loss in transmission.   The NRC is a measure of how well a material prevents sound from reflecting, therefore it is more applicable to surface treatments (studio foam panels, traps, acoustical ceilings, drapes, etc.) than wall structures.  Normally STC needs to be evaluated as a complete structure, because leakage through any part (such as, the studs) can compromise the whole, so it's not entirely clear what the above specifications mean (were they evaluating a pseudo-wall of nothing but foam, and if so, how thick was it, or were they evaluating a real wall, and if so, what were the other materials and how thick?).

But it seems both types of foam have excellent STC.  The STC of a standard uninsulated interior wall is 33, the STC of a typical insulated exterior wall should be above 40. 44 is the STC of a cinderblock wall 4 inches thick.

Although no doubt 0.5 pound foam is better for acoustical insulation, 2 pound foam is not shabby, and it's hard to know how much difference it would make inside a wall structure.

All spray foams have one thing in common, unlike old fiberglass insulation (which gets worse over time in this regard) they much better seal against airflow.  But in that regard, closed cell foam is the best.

Contractor #2 also didn't like the metal roof idea, and tried to convince me to use composition shingles instead.   It's cheap now and cheap to replace in 20 years.  No, that's not what I want to have to do, I don't want a roof of rotting shingles.  So I gave him some links.  Here's a great list of metal roofing manufacturers in Texas, several in or near San Antonio.

Here's one in San Antonio, Berridge, which seems to make top quality 24 gauge Class IV galvalum roofing.  Here's the Berridge color chart, showing that both natural white and almond meet Energy Star and LEED 2.2 requirements for low slope roof (2:12 or less).  Natural white has higher reflectivity but almond has higher emissivity.  Combining the two in SRI, White is naturally the best overall at 93 but almond close at 82.  Above 2:12 slope, actually most colors qualify for Energy Star and LEED, despite typical SRI's in the 30's.

Another roofing manufacturer with branch in San Antonio, MCBI, also has white and almond colors.  However, they only offer almond in their higher end Signature 300 series which uses Kynar and/or Hylar.  In the Signature 200 series, which uses a proprietary siliconized polyester, the SRI's are generally lower so that the white (a non-pigmented polyester) actually has lower SRI than the Almond in the 300 series.  And it has no almond, only a similar Light Stone which brings the SRI significantly down to 58.

Updated Workshop Design Plan

Synopsis: Shed workshop built to exceed quality standards for residential housing, especially wrt energy efficiency, durability, and low maintenance.  Exterior size: 14'10" by 12'6" with 9 foot walls.   Best available materials and construction techniques.

0.  Already done: Concrete Slab: engineered and inspected with #6 and #3 rebar grid and wire mesh and 27 inch beams, 4000psi concrete, wet cured 1 month.

    a) Needs removal of forms, cleanup of scrap concrete, removal of unused rebar.

1.  Exterior dimensions 14'10" length, 12'6" width and 9' height or higher exterior walls.

2.  4x8 Hardiepanel vertical line siding (not plank!) painted to match house.  30 pound felt or Typar on 5/8 plywood backing.

3.  Hardietrim, Azek, Miratec, or real cedar wood trim on corners, around window, door, and A/C.

4.  2x6 framing on 16" centers.  Optional: 2x4 framing on north and east walls (for better acoustic internal dimensions).

5.  6 foot wide coated steel double french doors with internal blinds, Energy Star, facing east (toward house).  Lowes  ReliaBilt #289766 ($698).  Flexible pull screen system in front of door.

6.  One 29x47 Fleetwood Westwood 250 casement window (already obtained).  Facing north at 5 feet (min) from front, 36 inch minimum height.

7.  5/12 slope 2x8 framing for roof support.

8.  Eaves at 18" depth with (suggested) HardieFascia boards with drip edge.

9.  24 gauge galvealume steel roofing with hidden fasteners and white Kynar (PVDA) factory coating.  Class 4 hail resistant.  Strongest and most permanent seam design: Berridge Z-lock 180 degree mechanical double lock or equivalent suggested.

10.  Roofing rests on 5/8" plywood with radiant barrier facing down.  30 pound felt or Grace.

11.  Lowe's Valspar Premium exterior paint (top rated consumer reports), tinted to match house.

12.  6x2 foot concrete ramp poured on compacted soil with 3" gravel base.  Not attached to foundation for minimal effect on foundation integrity.  Some settling and drift is expected and tolerable.

13.  Two pound closed cell foam on all walls and under roof deck to fill maximum depth available with shaving to fit sheetrock.

14.  All 5/8 sheetrock:

    a) 5/8" Fireguard (tm, available at Lowe's) sheetrock on side and back walls.  This relatively expensive sheetrock also has reasonably good acoustical properties.  (optional: double sheetrock.)

    b) 5/8" QuietRock EZ (SeriousMaterials) on ceiling at 9 foot (flat) height and front wall.  I figured 8 pieces leaves plenty of margin for both, available through Building Specialties in San Antonio, quoted $58.38 per piece.

15  Electrical connection and wiring to be done by John Jones Electric if possible.

a.  Center ceiling fan with switch near door, remote control and screw in lights.

b.  Side outlets and light/fan switch by door.  10G copper wire in exposed conduit for all circuits.  Industrial grade switch and GFCI outlets, unbreakable nylon Decora plates.  All wiring in interior exposed insulated conduit to avoid wall and ceiling penetrations and enable future modification.

c. 220V AC connection with building panel and shutoff.

16.  24" deep shelf at back of building, minimum clearance of 6 feet.

17.  Two rows 16" deep shelving on sides past back shelf at 6.5 foot and 7.75 foot height.

18.  Porcelain non-slip freeze resistant tile, (suggested) Marazzi "Brazilian Slate" available at Home Depot.

19. 5800 slide-out BTU Commercial Grade Air Conditioner with digital controls (already obtained) mounted through wall on north side.

20.  Best quality interior white paint.

21.  optional: Marking to show location of studs and electrical wiring.