Addition Omnibus Progress Late Winter 2017 [Video]

Forgive me, for I have sinned: It has been almost a year since my last post.

We made good progress on our (seemingly interminable) addition project over last spring and summer. I took a lot of pictures with many blog posts in mind, but, well, «insert aphorism about the surface of a road to a bad place here», so I decided to do an omnibus video covering everything that we got done. Progress faltered, for various reasons (*cough* Trump *cough*), as summer faded into autumn. We did not meet our major goal of having the underfloor solar heat working — which would have let me continue with the trim-out over the winter — so I basically hibernated over the winter as far as the addition was concerned.

A 15-minute tour:

[Update 5 Mar 17] Fun Fact: the (will-eventually-be-) heated great room / under-loft floor has ~40 yd3 of concrete — that’s 160,000 pounds of thermal-mass goodness!

Addition Ready for Final Concrete Pour

Well, almost, still have to do the final cleanup. We are trying to arrange the final concrete pour, but with winter on the way the concrete tradesmen are very busy trying to get their outdoor pours done.

This pour is about 1068 square feet and will be 4½ – 5 inches thick. It is being poured on top of a suspended concrete slab subfloor. We want to add mica flakes at the end of the pour to add a bit of sparkle. From what we understand, this means trowel-finishing the entire floor.

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Here is the floor plan of the two slabs to be poured. Click to embiggen.

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Our lower driveway will let the concrete truck back right up to addition entryway.

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The concrete pump hoses will enter the addition via the exterior door at the top of the ramp. In this and subsequent pics you will see tools and supplies that will all be gone shortly.

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The vestibule, being closest to the door, will be the last space poured. The concrete will be poured to the top of the 4-1/2″ triple sole plate. The wallboard is already up and painted so we used blue tape and rosin paper to protect it. The space for the yet-to-be-installed 1×8 baseboard provides a space of bare studs to ease with the concrete finishing.

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Just inside the great room from the vestibule there is a staircase to the walk-out basement. The concrete finishers can use this for access as needed.

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The great room and under-loft rooms have 5/8″ pex heat tubing attached to the subfloor. At the upper right is the bow windows and at the upper left is the loft staircase the the concrete will need to flow under.

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A better view of the loft staircase corners where the concrete will go under it.

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Looking towards the loft. On the left you can see the stone chimney and the dumbwaiter enclosure.

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The galley kitchenette. Except for the bathroom toilet and shower drain, all drain pipes are in the wall.

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The view in the bedroom of one of the two closets. You can see more detail of the heat tubing — it is the zip-tied to poultry netting that is stapled to the sole plates. Tapcon screws and various brackets have also been used to help anchor everything down so the tubing does not float up. To the left you can see in the bathroom where the tubing goes through the subfloor to connect with the manifold in the basement.

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The curbless walk-in L-shaped shower. This will get troweled to a semi-rough surface to avoid slipping in the shower (sponge finish?). It will flow under and up against the granite walls and slope down to the drain at the end of the ell (not shown).

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The water closet.

Addition Update, Day 434 (Ouch!)

As I said in an earlier post, we got delayed in our construction over the summer. We got a six-month extension on our building permit, so mid-December is our new target for completion. Still lots to do, but now that the hot weather has broken I am able to get more done. My #1 priority is to get the heat tubing in place so we can schedule the final concrete pour(s). (#2 priority is to get the rooftop solar collection tubes up.)

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Here is the 1000′ roll of 5/8″ Uponor AquaPEX tublng I am putting down. The make-shift support of sawhorses, pipe clamp, and 4″ PVC pipe is working OK, though at first it took two people to unreel since the roll weighed in at 86 lbs.

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The first step was to put rosin paper up to protect the painted walls from concrete splash when the final pour is done. Next was stretching out poultry netting that I will attach the tubing to with zip ties — not really sure about this method but I read about on the Internet so it has to work well, right? Right?? I started with the trickiest of the three 300′ tubing loops, the one under the loft. Among other challenges was the fact that we had to thread the loop through the wall between the bedroom and galley kitchen.

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It took 4 days but the first heating loop is now complete. (FYI, I HIGHLY recommend that you not wait until you are in your late 50’s before undertaking something like this!) The only hitch was that I had miscalculated the layout and end up with some left-over footage that I had to get a little creative with around the bedroom closets. (Besides from the one time I kinked the tubing, but that is exactly why I chose PEX-a rather than -b or -c: you can fix a kink with a heat gun or hair dryer).

Addition Solar Heat Plan

The underfloor hydronic heat in the addition will consist of 3 zones with 4 loops total: basement 1-loop zone, great room 2-loop zone, and under-loft 1-loop zone. Each loop is 300′ 5/8″ PEXa tubing. The expectation is that the great room zone will the most active. The intention is to run each loop at 1.75 gpm, 90°F water in, 75°F out, which should produce 13K BTU/Hr/loop. So the system should produce 26K BTU/hr in “normal” great-room only mode, with an additional 13K each available in the under-loft area and in the basement.

After much research, I have decided to go with this 800 Liter Solar Water Heater System from Duda Diesel. We will be adding the Turn-Key option and upgrading to Freeze Protection tubes so the collectors can handle routine temps below 14°F (which, based on this past winter, I would have to say that we get). The choice between evacuated tube and traditional flat-plate solar collectors was difficult. The reasons why I chose tubes include: lower weight and individual components for easier rooftop installation (we do not have enough non-floodplain sunny areas for ground-based collectors); space between the tubes provides a lower wind resistance; purportedly better performance on cold and/or cloudy days. My concerns are mainly related to the fact that because the outside of the tubes stay cool any frost or snow can take longer to melt than with flat plates. Oh well, a grand experiment awaits!

The heating is a open direct system, with a 211 gallon solar storage tank supplying the underfloor hydronic heat, as well as preheating the water for a standard domestic hot water heater. The 211-gallon solar tank has a built-in heat exchange coil for rooftop solar collectors and an electric heating element for backup. It is not at all certain whether the electric backup, combined with the large thermal mass of our insulated suspended concrete slab floor will be sufficient to keep us warm during extended bad winter weather (but I am quite confident that we will remain at most chilly, not frozen!). Our backup plans include the fact that we still have wood stoves in the old house (our only heat for 17 winters.)

The solar collection side is a closed-loop system with a glycol mixture to prevent freezing. The collectors will mounted on the addition’s east-facing 5/12 pitched (22.62°) metal roof. They will face 11° east of south (the orientation of the house itself) and be tilted up at a 45° angle.

Click on any of the images below to see a larger version:

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Schematic of the hot water and heating system [Updated 2015-07-22].

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Location of the rooftop solar collectors. I hope that placing them close to the addition gable end will minimize blocking snow build-up.

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Solar heating schematic from the east. Total heat tube (supply plus return) is about 150′.

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Solar heating schematic from the north.

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The two-zone, three-loop main floor underfloor heat tubes. I need to re-do the loops to put a couple in the bow window floor area. (Our original plans called for a window seat in that area.)

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The underfloor heat tubes in the basement. Placing all the equipment in the mechanical room on the right will be tricky. There are two water tanks, two expansion tanks, and two sets of controllers. Plus I want to plan for a battery bank for future PV solar electric, and the bank will go into a vented box (I have a 3″ PVC conduit in place for that.)

Underfloor Heat Components [already purchased unless noted otherwise]

Polystyrene, Rebar, and Concrete

The main floor of our new addition is a suspended concrete slab (i.e., a slab that is not in direct contact with the ground.) We are using the LiteDeck ICF system for this slab.

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The LiteDeck system starts with a base layer of 6″ thick expanded polystyrene (EPS) with imbedded steel C channels (both for strength and to provide a way to screw on the basement drywall ceiling). It is shaped with a beam pocket 6″ W x 4″ H every 2′.

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Then foam “top hats” (4″thick in our case) are added to deepen the integrated concrete beams to 8″ H x 6″ W.

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Next is the rebar. Lots and lots of rebar: Two ¾” pieces along the bottom of each beam, two ½” pieces along the top, ½” U-shaped cross pieces to help hold the length-wise bars in place, topped with a 2′ x 2′ grid of 1/2″ to stiffen the slab.

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Ready for concrete. The rebar is all wired together as a unit. The foam pedestals are for running plumbing and electric through the slab. You can also see the sole plate at the edges – the outside band is temporary bracing. The wooden box-like protrusion on the left is the where the basement stairway will go, the one on the right is for our dumbwaiter.

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The result (as poured yesterday.) The slab is around 4½” thick. At the top is the vestibule, a 3-season unheated room that also serves as an airlock for the addition entryway. To the right is the cantilevered floor of the bow window.

As I type this the plumbers are here to run a new well pipe through the previously-installed conduit that runs through the foundation. Once inside, it is going to temporarily run through the dumbwaiter window and reattach to the existing house plumbing. Later, we are going to relocate all the plumbing mechanical (pressure tank, de-acidifier, water heater) into the addition’s basement mechanical room. But for now, this will keep the pipe from freezing this winter and allow us to finish back-filling around the north end of the new foundation where the well is.

Next week, the exterior wall framing should begin. The bottom of the wall will be triple-plated so that when the exterior shell, including roof, is in place we can pour the final 4″ of concrete for the final floor. Before that happens, though, I will be running the heat tubing that will end up embedded just above the middle of the 9½” thick floor slab.