We should be able to figure this out

Some decisions have been pending for a while now:

• Floor
• Retro-Insulation
• Heat

What's the big deal?


Floor

Jeff Lane says he can refinish BR1 and BR2 and Geoff Hill says buyers like authentic hardwood, so let's do that. I kind of like carpet for BR3 and BR4 (the old living room).  It's a small house; we don't want lots of different materials. Baths need ceramic tile (for shower overspray for one thing). I'm thinking engineered hardwood in the entry, Trees Room, kitchen, dining, hall.

But wait--we need carpet in the Trees Room for sound attenuation. That could be a nice rug, but...decisions, decisions. Isn't it still lots of different materials? Why am I buying new hardwood and new rugs? (I say rugs, because the dining room wants a rug, too.)

If we're doing floor radiant heat (above or below), I'm not comfortable leaving the oak hardwood in BR1 and BR2, despite what Mark Janes says. So one choice depends on the other. Let's just say that if we go with radiant heat, we'll use radiators/baseboards in BR1 and BR2.

$4.50/SF for engineered hardwood (matl only) seems good. Bamboo is nice, but I like hickory, alder, maple, too--lighter is better for this house, I think. Jeff Lane estimated $4.75/SF to refinish the oak (and $11.25/SF for new oak).

BR1 and BR2 refinish 361 SF @ $4.75 = $1,715
BR3, BR4 carpet 507 SF @$4.00/SF ($36/SY) = $2,028
3 baths 140 SF tile $2,500 (per Homewyse)
Entry, Trees, Dining, Kitchen, Hall - engr hardwood ~1,000 SF @ $6.50 = $6,500
Ikea rugs Stockholm $300 (8' x 11') for dining room, Molby $150 (6' x 8') for Trees Room

So, $13,193 ($6.60/SF avg). I think we're done with the floor.

Retro-Insulation

How much insulation will we install in the existing house? The additions need full, but not clear about the existing house. SRC (Table R402.1.1) says: R-21 in the wall, R-49 in the ceiling, R-30 in the floor. Assuming R-1 for siding and gyp bd, in fiberglass, that's 6.25" wall, 15" ceiling, 9" floor.

Walls. The main house walls have 2" balsam wool now, which complicates blowing in cellulose. The east and south walls remain--that 70.12 x 6.67 = 468 SF. I'm guessing that BR3 has nothing, so we can blow in there--32.25 x 8.0 = 258 SF. The wall at the garage is 162 SF--we might want to use 2x6 studs there, too.

I have Arrow insulation coming next week, but assuming we need to pull off the drywall and possibly remove the balsam wool, we might want to consider putting in 2" EPS with spray foam all around--air infiltration is the bigger problem with older homes.

In new walls, we'll build with 2x6 studs and use 5.5" batts, but that doesn't quite achieve R-21--more like R-18.6. Not sure what they want from me.

Ceiling. The main house has 5.5" of blown cellulose in the 1230 SF attic, plus 138 in the breezeway. I'd guess that BR3 has some--maybe R-19--in the ceiling assembly, but it's closed up. So...should we plan on paying to remove the cellulose and installing a 15" thick batt blanket in the 1230 SF main house, or what? Or a 10" batt covering the dusty old cellulose?

We should make sure that the attic is ventilated--we need to add 4.1 SF of soffit vents in the main house. We'll need (7) 4x22 vents, each with a baffle to hold the insulation out of the way. Hey--if we put 2.27 SF in the ridge, we only need (3) in the soffit. Make it (4). Go nuts.

In new construction, we want an R-49 assembly. That's a 12" TJI with 10" of vented batts with 2" EPS on the roof--no, that adds up to 39.7. EPS is R-3.85 per inch at 75°, but it improves with cold (R-4.17 per inch at 40°). Not sure what the city wants from me--like the walls.

Assuming that we want R-49 at 25° (not at 72°), we can use the "improves with cold" property of EPS in a SIP: A 9.25" SIP is R-42. (7.25" SIP is R-33). Pile 2" EPS on top of a 9.25" SIP and you've got R-50.34, but a nearly 12" thick roof. They make 11.25" SIPs, by the way (R-51).

Floor. It's pretty bad that the floor has no insulation, but heat rises and the ground stays 55°, so the temperature differential is only 17° (not the 48° we have for the rest of the house). We've got 2x8 joists, and the city seems to want 9" of batts. They'll take 7.25" and like it--that should give us R-24.2 in the floor assembly (not the R-30 the city wants). That's 1230 SF of labor--Homewyse says about $1/SF for labor and materials.

BR3 is on an (almost certainly) uninsulated slab, but I doubt we have to do anything about that. We probably want to over-heat BA3 to cope with the additional heat loss.

In new construction (the kitchen, dining, entry and especially the Trees Room), we need to approach R-30. I had planned on 5.5" SIPs for the Trees Room floor. They have R-26 at 25°. If the city insists on R-30, we'd have to bump up to 7.25" SIPs (R-33).

Heat

We have a small house here. The Trees Room and Dining room ceilings are high, but that doesn't mean we have an extreme challenge.

We should run gas for cooking, so we will have gas available for heating. We should remove the oil tank and line. But, even though we know that gas will replace oil, Seattle has some of the cheapest electricity in the country. We don't have to use gas for heating.

We have several options for creating heat:

• Air-to-air heat pump, like a mini-split. 
• Air-to-water heat pump, like the Daikin unit I saw on the Green Home Tour. 
• Ground-to-air or ground-to-water heat pump (geothermal) - generally most expensive, I'm told
• Boiler (or water heater) that heats water directly. Boilers are more compact, but they're expensive. Some say that water heaters are undersized for heating.
• Gas-fired furnace (replace oil-fired furnace)
• Electric resistance (cheap electricity, remember?) COP of 1.0 won't win any green awards

Once we have created heat, we need to distribute it. That means hydronic, forced air, or ductless.

1. Ductless. Mitsubishi Heat Pump + 4 or more units inside. Two or three mini-splits would probably work, but it would be nice to have BR3 and BR4 on their own thermostats. So, four mini-splits? Hmm.

2. Hydronic Distribution - floor, radiator, baseboard, fan coil
Daikin Altherma heat pump
Noritz water heater as suggested by Janes
Navien or Viessmann boiler
Geothermal heat pump

3. Forced Air. Only problem here is getting hot air over to the garage, but we have new raised floors at the entry and the Trees Room. Also, the height of the Trees Room ceiling presents a problem that a radiant floor helps with--heated air will rise faster, leaving the floor cold.

What would I tell a client? Forced air is a reasonable solution--the cheapest, but still fairly efficient. Tall ceilings mean the heater works a little harder, and ducts require bigger chases. People online say radiant heat feels so much better--no blowing cold air and allergens around, in-floor works from your feet up. Silent.

Zones. I think I need 3 or 4: BR3 Suite, BR4 Suite, BR1 and BR2, and Trees Room/dining/kitchen. I could combine the main house, but the suites should have their own thermostats.

Here's a system: Polaris gas water heater (50 gal, 130K BTU, $3700). Zone 1 (Trees Room, dining, kitchen 880 SF) underfloor tubing and baseboard radiators over SIPs. Zone 2 (Bedrooms 480 SF) underfloor tubing. Zone 3 (BR 4 400SF) underfloor tubing. Zone 4 (BR 3 240 SF) baseboard radiators over slab. What Radiantec calls an Indirect System: one pump for DHW to a heat exchanger, another on the heating side (or one per zone, not clear). Radiantec's "ballpark" calculator prices this out at $8,500 with 1/2" pex tubing and 4 zones. (But they don't sell baseboard units.)

Domestic Hot Water. If we're heating water for hydronic heat, it is a fairly simple thing to provide domestic hot water (DHW) as well. But DHW has two goals that such a system doesn't address any better than a conventional water heater: instant hot water and sustained hot water for a long shower or simultaneous showers. A conventional water heater and a point-of-use water booster or an instant heater would likely meet the needs better than a tankless. I like a 200° water dispenser in the kitchen for soup and other things, but that's not what I want.