Prefab Green Home Construction Costs: Money money money... money!
Sigh... when I started this post I had no idea I'd be running into Liza Minnelli.
And when I started this project I had no idea I would be where I am with SIPs, the solar choices I made... and the budget I have to get there and achieve my goal of gorgeous, affordable, off grid modern design.
This dream began with the realization that dragging a shipping container out to our land was not practical. Though recyclable, we would have spent 7k at the end of the day for a... metal box. Not an investment. Not insulated. Not passive solar. Not... ok you get it.
So then we explored metal buildings... and couldn't resolve the insulation issue.
Then we discovered SIPs, kidnapped some award-winning architects (in my real life I'm a bandit), and committed to investing in a home to enjoy for generations. (That's sideways speak for: Pony up, Copeland, at the end of the day it's a lot of money.)
So, without further ado, I dispatch my estimated and actual costs (which will be oft revised as estimated costs turn into actual figures):
(I'll put estimated figures in blue, real figures in green so you can see what is what. I also remind all readers that prices vary in everything, this is just what it costs to build a casa ti in central Virginia in 2009!)
- casa ti kit house: $22,537.91 for a 1,200 s.f. kickin' modern house kit.
- shipping: $1450 per truck to get from northern to central Virginia
- engineered drawings (gears kit documents for local zoning): $1,910.00
- poured concrete foundation: $4,886.70
- concrete finisher (prevents cracking, contractor swears by it) $910.00
- foam that goes under and around the foundation: $1034.68 (This is important! Why get an energy efficient house kit with insulated roof and walls if you don't also insulate below/around the foundation? You can order this foam from the factory if you like.)
- Mike's plumbing and Heating: (they laid the radiant tubes, plumbing in foundation) $3,450.00
- Interior Wall Finishing: sheet rock: $4,000 --> We eliminated drywall.
Wellz, folks... this will be a combination of the contractor building interior walls with plywood, *while* lining the interior of the SIPs with... VMI's BASKETBALL COURT! 'Cause you know I'm all about reuse, and history. *That* cost (oh, by the way, did I mention I acquired that historic solid maple flooring for about $1 per sq. ft?) will also be offset by the fact that I'm going to auction off the VMI logo on ebay... which might just end up paying for it all.
Outside of basic scope: We paid $1,015 for labor so far to have Bobbie, our carpenter, cover the bedroom / hall walls with VMI's basketball court reused over the SIP yet leaving one side open so that we can come in with the electrician and plumber for systems when we're ready later this year. So more work does need to be done. Note the materials used were the VMI basketball court, and purchased interior doors (about $100 apiece). We also paid Ron our contractor to frame the interior walls, which is in his costs.
- You could also do a SIPs stew to save money on the interior to smooth out the OSB: http://www.greenmodernkits.com/2008/03/sips-tips-i-think-ill-call-this-one.html
- You can also paint the interior with a thicker "paint" to smooth the roughness of the OSB on the SIP - I found a great solution that also increases your energy efficiency- Super Therm (http://www.spicoatings.com/products/supertherm/). It also has exterior applications!
- Another option to consider is PlasterMax: http://gigacrete.com/products/plastermax-2/
- EXTERIOR lumber and framing lumber for the load bearing INTERIOR wall $4,294.40
- Interior walls: $2,200 --> This was the original estimate, it was later accounted for in both Ron, our contractor's costs + in our case the contractor chose to do the framing himself and therefore we don't count this towards the total.
- Phase 1 LABOR for putting house kit together / exterior framing / interior load wall framing (i.e. Phase 1 of getting the house kit weatherproof. Phase 2 is labor for putting on cladding, Phase 3 is finishing the interior) $4,484
- Phase 2 LABOR for installing cladding: $9,610
- wiring: $5,700 Our current quote from the electrician is $3,600 for the solar installation and $6,300 for wiring. Note this wiring is for SOLAR, and takes DC wiring into account. If you are going to be ON the grid it will be a different scenario.
- windows: $8,071
Original quote: $9,051.39: I waited until they had a 20% off sale to place my order, made some adjustments to the door, and hence my costs were: $7,689 + $59 delivery charge + $368ish tax: see the post "Get Yer Windows" for details on how to save money and bring the price down!
- plumbing: $4,500 (Actually I think this was Mike's Plumbing costs, above, for which we were already invoiced $3,500 to install in the foundation AND radiant loops / tubing- part of the plumbing has already happened and we now need to just finish it / hook up systems.)
- Roofing: Roofing labor to install membrane, etc. : $2,118
- Lowe's (I have no idea, but it's on the contractor's cost sheet so there ya go!) $196.35
- Equipment rental for a light trailer $87.12
- contractor: $6,021.66 for phase 1-2, plus 10% on SIPs, siding, windows/doors = 3,880 --> $9,901.66 (as of February 14th, 2009, now we have to finish interior. Estimate to do interior walls is $1,200 but that does not include systems installation.).
- roof / membrane / one green roof / cladding decisions: We're using Galvalume, we are not adding the green roof (although you certainly can on the north side of the casa ti, that was in David Day's original idea) because we are using that for rainwater collection.
Supa-Cool Siding/Roof Mod Package! $8,776.11
Shipping for super cool siding package: $268
- Heat / Energy Recovery Ventilators: Don't you dare let me hear you don't have 'em installed. We recommend two manufacturers, depending on your needs, in the $700-$1,800 range.
- Zero Energy Off Grid Systems: Depending on YOUR power needs and climate and which vendor you choose, this will vary widely. We are happy to share with you what we chose, but this is something outside of the "house kit" scope.
Now here are some costs that are not really directly related to the house kit / building a house but I wanted to include:
- Excavation and seeding: Anonymous below asked about site costs: Good point, totally did not include that. Fortunately, when we bought our land it was... exactly as it is, except for excavation of the site- so we did not have to cut down a single tree, yet have a super south view! We situated our house at the end of the pre-existing field. Costs for excavation *and* seeding: $1,200.
- Perc Test (soil consulting) $600
- Board of Health Permit $190
- Building Permit $82.07
- Contractor going up to the factory to be trained on SIP: $194.39
- Driver tip for SIP delivery because we're nice and in a rural area and they went above and beyond their call of duty $80
- well / rainwater collection: We bought a rainwater collection & filtration system for around $5,000
- solar / solar heat / batteries, etc. / radiant heat (I will go into this in depth later):
PEX tubing for radiant heat: $670.50
Solar systems: $11,594.00Note: this is a gentle, minimal solar system to get us through the coming years as we expect off grid technology to advance for the prefab, as well as that we embrace changing our energy expectations of usage to be less, challenging ourselves to do more, thinking strategically about power usage vs. having mass systems.
Well, we will see what more of the actual costs are...
Keep yer eyes peeled!