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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.
  • 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: 

    1. 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.
    2. Perc Test (soil consulting) $600
    3. Board of Health Permit $190
    4. Building Permit $82.07
    5. Contractor going up to the factory to be trained on SIP: $194.39
    6. 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
    7. well / rainwater collection: We bought a rainwater collection & filtration system for around $5,000 
    8. solar / solar heat / batteries, etc. / radiant heat (I will go into this in depth later):
      PEX tubing for radiant heat:
      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.

Now, when you're adding up these figures, remember some items are systems for an off grid house- so if you're connected to utilities, this will be less for you. Again, realize these don't pertain to your local costs of your material and labor.

Well, we will see what more of the actual costs are...
Keep yer eyes peeled!

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At 1/23/08, 1:58 AM , Blogger Myleen and Jan said...

Wow!! I love your blog. After reading your post with costs and your liking for SIPS, I feel we are kindred spirits! You should check out my blog, as I did the same. My budget is on there and I'm also going to build a modern, green SIP home! I am also interested in selling Green Home Kits (preferably modern) to Scandinavia (where my husband is from) because there is a demand for summer cottages and Europeans are wanting to buy American because of our poor dollar value right now! Do you want to exchange some business ideas? Please feel free to contact me. I saw you through Building Green TV.

At 10/9/08, 6:49 PM , Anonymous Anonymous said...

Great Blog, Copeland. It will be a great house. You may have said somewhere, but what about a septic system? And did you have no site work costs?

At 10/9/08, 8:12 PM , Blogger Passive Solar Prefab Homes said...

I desperately need to revise this post- will hopefully get better figures next week.

We have a composting toilet, but that still does not really address septic because I agree kitchen water is blackwater, not gray.

We are also stalling on the well/rainwater *filtration* system (not rainwater collection, which can irrigate the field).

Because we are doing this in stages, we can better make some of these decisions as state laws catch up to us/waiting on some systems purchases as technology is changing right now so our investment will last longer & be more efficient.

So what you will see in the next few months is a darned cool house, but I am purposely leaving some systems leeway to most efficiently invest in the *right* way to do things vs. what code & current market allows.

But yes, I will sit down and revise this post in more detail next week.

(Am I talking too much? Do I ever talk too much? ; ) )

At 11/5/08, 1:45 PM , Anonymous Anonymous said...

Where and what kind of supa-cool siding and roof package did you get?

Love your blog by the way - very helpful.

At 3/4/09, 10:58 AM , Blogger Kara Johnson said...

First, let me say I love your blog. Second, Prefab is what landed me on your site, which them opened up a new world as I know nothing of SIP's, but now I'm totally enthralled. I live in the Seattle area and everything out here is expensive but like you I don't understand why cool design has to escape me, so I'm trying to see if it's possible to build our first home without driving ourselves into the poor house to do it. Any recommendations on where I should begin? And, how did you decide on a budget?

At 3/4/09, 11:38 AM , Blogger Passive Solar Prefab Homes said...

Thank you, Kara!

Our budget is determined by what we could pay in cash combined with a loan. Last year I paid over $30,000 in cash towards paying off the house kit & labor, just from saving, saving, saving and then throwing that money towards windows or the house kit that we then didn't have to put on an interest-based loan.

So the more I pay in cash, gives us leeway for systems, etc.

HOWEVER, as we are building our farm piece by piece, I am waiting for more affordable new technology to come out before splurging big on permanent systems. So our initial systems are the hot water solar, and a basic solar package for under 5k. That will get us through the next few years as we build the farm, so that when we move there full time we'll have better technology to consider for our full-system purchase for the rest of our life.

I will try to update this post again next week with more numbers- for what it's worth, the contractor has quoted me about $1,200 to finish the interior walls, so that will happen soon this spring... saving it up now so I don't have to put it on a loan!

At 11/5/09, 9:07 PM , Anonymous steve wilson said...

i appreciate the blog posting of costs. i intend to build a casa ti green house as a spec.
reviewing your costs it appears the roof package is high for galvalum standing seam snape lock roofing
the cost should be about $450.00 per 10x10 square. the cost for the roofing material is $200.00 a square.
the siding cost for corrugated galvalum is the same or slightly less.
both material thicknesses are 26 mil. the labor for siding should be similar.
with proper planning you should be able to purchase all lengths to the desired size to save on labor
also there is a government program for going green that will provide a tax credit of $1500.00 i think for both the roof and the siding
additionally the geothermal provides a tax credit of 30% of the cost of the system install

At 12/5/09, 3:34 PM , Blogger Unknown said...

Do you have an updated costs list that can be posted now? Or am I just missing the link to that when I search?

Hoping to build our own sip house in about 1.5 years if all works out.

At 12/5/09, 4:49 PM , Blogger Passive Solar Prefab Homes said...

Thank you for your information on the galvalum. I am telling consumers upfront that they may request a quote from that company but that I never felt quite comfortable with the deal I got- but in my area (Richmond, Virginia) they were local and the only option I could find that could also service other house kit purchasers. (Sorry I didn't see your comment until now!)

We will be updating this again very soon. We are still getting quotes on installation / electric / plumbing and finalizing systems. We haven't been in a huge hurry to do so as:

1. the house kit itself is complete so everyone is going to do their own things with it from there, some might be on grid, some off, etc.

2. we are being fiscally responsible and as our children have to be here through 5th grade before we can move, we are not in a huge hurry to finish, as inconvenient (yet a good memory later) as it is.

3. only once we get quotes (and this *is* being finalized now, THEN we get a loan to finish the prefab.

In the meantime thank you all so much for your interest and enthusiasm and if you have any more questions, ask away!

At 4/30/10, 7:25 PM , Blogger Unknown said...

What was the final cost?

At 4/30/10, 8:00 PM , Blogger Passive Solar Prefab Homes said...

We are installing systems this summer so can tally them son! Don't forget we have chosen to be zero energy / off grid / rainwater so our systems costs are very different than "the usual way" - i.e. on grid.

At 3/25/11, 3:04 AM , Anonymous Anonymous said...

Hello there,

Thanks for sharing this link - but unfortunately it seems to be down? Does anybody here at have a mirror or another source?


At 3/25/11, 9:41 AM , Blogger Passive Solar Prefab Homes said...

Exactly which link do you mean?
This is also a note to myself to update this post!

At 1/15/12, 11:38 PM , Anonymous West Terrace said...

They only shows that in every construction it has a different cost base in its design. I wonder if how much is the total cost of the building since the material cost is always increasing. :D

At 1/16/12, 8:04 AM , Blogger Passive Solar Prefab Homes said...

That's what I always try to explain to people- for example, you could build the exact same prefab house (our casa ti, for example) with the exact same cladding and systems, and in one place the end cost would be totally different from another place- picture: rural Virginia vs. the same house in Las Vegas or the Hamptons, for example. It is all determined in the end by local costs of materials and labor, which is why only your contractor can provide the most accurate "finished costs" estimate!

At 1/23/12, 4:30 PM , Anonymous Plumbers said...

Well that was a very informative post. It all states the estimate cost and budgets for the construction.

At 3/7/12, 4:14 PM , Anonymous Brian said...

Giving consumers a rough estimate of what their budget will look like is very important. I think that people often don't consider the high amount of costs that are incurred.

At 6/5/12, 2:27 PM , Anonymous Anonymous said...

$124k for everything?

At 6/10/12, 5:32 PM , Blogger Passive Solar Prefab Homes said...

I haven't updated this lately but... that kind of was the costs documented for The Big Stuff as material + labor are in our area...


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