I have been quite busy since the last update, but lets talk about my biggest stress… The budget!
I will try to follow with an eye candy post later in the weekend.
Budget
If I had a million dollars, this whole thing would be a lot easier. But as it is, I will need to borrow to make this home a reality, and that means carefully counting the cost. I finally got in enough quotes that I could complete my budget and get a pretty good total estimate. It was pretty high, at least relative to my early hopes. I got a bit depressed about it, but we crunched the numbers with the 4.25% interest rate that my loan officer says is likely, and it is still affordable on my salary, so we press on… But I will be looking to save money any way that I can.
Some people are really against having a mortgage… I don’t mind it too much as long as it is my only long term debt (credit cards and other bills are paid off each month) and the mortgage payments are better than rent would have been. It probably helps that my job (and income) is relatively stable.
Possible Budget cuts?
Windows?
The fancy eyebrow windows came back as about half my window cost. I could reduce that dramatically if I was willing to replace them with hand cut poly-carbonate (Lexan). 1/4 inch thick poly-carbonate sheets have a decent R value (considering they are transparent) and I can buy a 4×8 sheet for less than 100$, cut and install it my self… I have had this idea for a while, but seeing how everything has added up has really convinced me that it may be a good idea.
Poly-carbonate is fairly flexible, so I could actually curve the windows to match the curve of the walls. My only concern at the moment is that they are more than 8′ wide, so I will either need to find someone selling larger sheets or break each window up into segments, which will mean more difficult installation.
Basement?
Could I get rid of the unfinished basement? I have been tossing this idea around in my head for a while.
While it is true that a basement is a relatively inexpensive way to gain square footage, mostly because it is square footage that doesn’t need an additional roof, it does still need its own walls, floor, and ceiling. Even an unfinished basement needs electrical and plumbing and that also adds up. The suspended floor over the basement costs considerably more than the slab-on-grade floor that would be needed without the basement.
A basement also complicates the construction process with a much more difficult excavation, deeper drainage pipes, a more dangerous construction site, etc.
My specific design only called for a partial basement. I thought that would contain the extra cost to just the area of the basement, but because I have a sandy site, the engineer specified a slope of 1/2. This means that my 10 ft deep basement will effect the construction for 20 ft around. I will need much more expensive “step footings”, taller stem walls, two levels of french drains, and probably other things that I have not thought of yet.
The egress window on the North side of the house is causing difficulty with earth sheltering because I need to be a lot more careful about retaining the earth. It looked good in 2D, but now that I am looking at it in 3D, I am a bit more concerned about the scale and cost of the retaining walls that will be required to keep earth from spilling into the basement.
My wife was mostly wanting the basement for storage, but I could more cheaply add a few feet to the length of my garage to make up for that. I wanted the basement for the placement of the mechanical room. If we got rid of the basement, we could use the location of the basement stairs as a main floor mechanical room, but the central location under the rotunda was important for my passive HVAC design. And after many years without a basement, Sherri and I both liked the idea of extra “unfinished” space down there to grow into…
You can’t come back and decide to add a basement later. You need to make that decision from the start of the building process. On the other hand, as Sherri pointed out, the storm room at the top of the tower is pretty superfluous and we could just decide to leave it off if we ran out of money. We could also come back and add it later if money became available, so maybe that is the best place to cut?
For now, I think we are going to wait to hear what the banker says about how much they will loan us and then decide what to do.
Sweat Equity
It seems like a number of the tasks are coming in with only ridiculous quotes… Some, like the precast ribs, the garage Quonset hut and the insulating “umbrella”, I always planned to do myself. But as I get quotes back, I am picking up more and more of the other tasks. I now expect to do much of the steel work myself (hopefully with a little help from my friends and family), along with a number of finishing tasks. Sherri is very concerned that I am taking on too much and that this could stretch out the build and wear me out… It could also be a great exercise program (I spend too long sitting and typing at my “computer job”). I also feel a bit like a kid who is getting a new giant sand box, I can’t wait to get out there and play… But it could get old after a few months, and I am not as young as I used to be… Something to keep in mind.
Smart little improvements to the plan
There are a number of smart little ways I could improve the plan to save money. For instance, The people who bend my steel arches charge by the bend, not by the length of the material. Instead of ordering a number of 90 degree bends for my apses, I plan to switch to ordering half as many 180 degree bends that I will cut in half.
I also noticed that there are a few spots where I can make a small layout adjustment and save a lot of structure. I will talk about that more next time I show pics from my virtual build.
Water isn’t very expensive
I had liked the idea of buying a 1000 gallon water cistern and installing it between the house and the garage. It could catch the roof run off and be used for watering the garden. The problem with many “green” ideas is that they don’t actually make financial sense. As I have mentioned before, I live in the Great Lakes basin where water is always plentiful (we have more than 20% of the worlds fresh water in our basin). At current electric rates, it only costs me about 25 cents to pump a thousand gallons from my well. See the calculation here. The thousand gallon tank costs nearly $800, but it would be double that by the time it was installed. There is also the risk that it would break down or become polluted… I would hate to look at my investment and know that, even full, it was only worth 25 cents, so lets skip it.
I also liked the idea of solar hot water. But I checked my current bills and I only pay about 20$ a month to heat my hot water. A decent vacuum tube solar array with the storage tank, pumping station and other odds and ends easily comes to $6000, plus installation. At 20$ a month, it would take 25 years to pay off that investment. Plus, it is not exactly attractive on my green roof.
I will set things up to install a solar hot water system some day, but not as part of the construction cost. Perhaps I will eventually be able to build my own for a lower cost.
As for the urinal in the boys bathroom… It may not have a rapid payback due to our cheap well water, but the total cost is not high, so I think I will keep that one ;^)
HVAC is expensive
My HVAC quotes came in. I knew that Geothermal was expensive, from the buried heat exchange tubes to the unit that goes in your house, they are expensive. But I had a nice back up plan to use the electric (in demand) mini boiler instead. With its much lower cost and much easier install (no loop field required), I thought it would save enough money to justify the higher operating costs. Due to the Federal Tax Rebate for Geothermal, it didn’t turn out that way. I put some info about my HVAC sourcing here.
However, the quotes are still very high, so I may take on the easy parts of the job myself. For instance, I may be able to save money if I install the radiant floor tubes myself. I am still thinking about it.
Light weight fill
My house structure consists of a number of vaults. It will be earth sheltered, so one possibility would be to fill those voids with 100 lb/cubic foot earth… That earth would hold water (or ice) and get a lot heavier or swell and cause me all sorts of problems. Instead, I wanted a relatively smooth top across the vaults, so I needed to fill them with something. I discovered “flowable fill”, this is a very light weight concrete (as low as 30 lb/cf) that can be poured into a void to fill it. The secrete ingredient is very tiny bubbles that are actually too small to pop. They are mixed with the concrete and fluff it up, reducing its density. Then the mixture is poured and finished much like regular cement. It can support more than enough pressure, but does not have a very hard surface (it can be punctured or dug with a shovel), so I will need to add a 2 inch topper layer of concrete, which is fine because that will form a very strong concrete triangle across each vault.
I did a lot of research and found the best aircrete product is from a company called “Cellular Concrete Technologies”. The problem is they don’t have any distributors in my area. I called them up and they were nice enough to tell me about one of their competitors in my area that I could work with. The competitors product was not as good, but I contacted a local crew and got bad service, followed eventually by a ridiculous price… A price high enough for me to buy my own equipment and do it my self and still have thousands of dollars left over. I called CCT back and they offered me a distributorship for Michigan. Part of me really liked that idea. I am an MBA student and I am pretty sure I could kick my competitions butts just by returning phone calls and a few other basic customer service or IT related things.
However… I am also in the middle of a complex build and I already have a good job, so I started to think about simpler alternatives that wouldn’t require me to purchase and ship equipment across the country and possibly even setup a distributorship. And also wouldn’t require me to commit to an elaborate, precise and yet, probably, messy process of pouring this fluffy concrete.
I worked out that if I pour 75 yards of this 30 lb/cf cellular concrete stuff, I can do it for about 90$ a yard… What other light weigh fillers could I get for that amount? Well, I can buy a rigid insulation, such as Formular 150, for $15.70 for a 1 inch thick board. Do the math and that is 158$ per cubic yard… Formular 250 is a bit pricier at 34.51 for a 2 inch board, which comes to 174.71$ per cubic yard. But how about ordinary (cheap) polystyene foam boards? I can get that stuff for 78.64$ per yard regular price at Home Depot… Maybe cheaper when I buy in bulk? Here is a table.
Comparing other properties, you can see that the aircrete can support much more load than these lighter fill materials, but the required load bearing capability is only a few PSI, so any of these options is sufficient. The advertised R value of the cellular concrete is pretty good, but it is tough to beat the light weight of the Polystyrene foam. And it would be even lighter if I left voids.
As far as final cost goes, I will have lots of garbage polystyrene left over from my quad-deck floor and can easily get much more, so I won’t actually need to purchase all the polystyrene that I will need. I can also install this pretty easily myself… Even my kids could help. Although I will still need a couple inches of concrete topper to seal it all in.
The tricky part will be figuring out how to place the rigid insulation so that I still get a good base for the concrete topper.
Anyway, I am still thinking about it. I have lots of other fun news. Meetings with contractors, progress on the virtual build, even a stock pile of eye candy, but I will save that for another time.
Virtual Build
Over the past couple weeks, I put in half an hour here and there in the evenings and moved the virtual build slowly along. Of course, I would be thrilled to get this virtual build speed in the real world ;^) Initially, the plan was just to illustrate the building process for various subs that would be helping. I planned to just show the construction of the basement, central tower and how the ribs would be setup. However, as you may have seen over the past couple posts, the virtual build has already helped find and solve so many problems that I have decided to press on with it. I added the garage and I am currently working on the bedroom wing. Next, I will work on the front of the house.
Virtual build as of Feb2nd, the garage, mezz and other areas are mostly complete, I am working on the bedroom wing and will work on the front of the house later. You can already see that this house design is very original.
I had been thinking a lot about how to lay out the ribs while I was casting them, I thought it might be a good idea to illustrate that with the virtual build. For a long time, our plan has been to pour the garage slab early in the build, but only setup the rear of the quonset hut. I could use the partial construction as a covered workshop in the back while I setup the rib forms on the front half of the slab. Without the roof in the way, I could use a crate to lift the 4500lb concrete ribs up and over to where they would be set.
I had planned to make a left and a right rib form because it would save me needing to flip and polish the “back” side of one that would be exposed against an end wall. I had already worked out (mathematically) that I could fit two of these on the slab in front of the partial quonset.
Now I was working on my gantt chart and considering how much time would be taken making these only two at a time. I also considered how much extra cost would be incurred with the multiple crane visits (to set them up 2 at a time). We had already planned to put a slab in-front of the garage (even if the rest of the driveway will be gravel), so the boys could play basketball. I started considering the option of placing the slab earlier in the process and building a few more forms. Even if the extra forms cost an additional 600$ each, I could make 2 more and save on 2 expensive crane visits and a couple weeks of time. I would probably at least break even on money, but save time.
There would be no additional cost to adding the concrete pad early since it was already planned for later in the process, but it may later be seen as “in the way” as construction equipment would need to be careful not to crack it…
So, I added the ribs to my garage model… You can see that it would be very difficult to fit a 3rd rib on the pad. Yes I tried other configurations, but I need room for the forms around the ribs and space too work, and I couldn’t let them go under the quonset or the crane wouldn’t be able to lift them up without dragging them. However, for the other ribs, I decided to make two left hand ribs and they can be put closer together…
Then it occurred to me that I needed to go back and reconsider my earlier decision about wanting to start with a left and a right rib to save time/money polishing (because one side would be placed against a wall.) I decided that I would save more money and hassle with the more compact arrangement of same-side ribs. In the software, it is pretty trivial to make the necessary changes and voila! Four ribs in a compact arrangement on the one slab.
I will update the Gantt to show building two forms first, then working on the second two forms while the first two ribs cure… Then I could position all 10 ribs in only 3 crane visits instead of 5. Of course, I still need to polish the back sides of the ribs, so I will need to flip them over before I set them, but I can place them in the (soft) dirt for that and I think I can get that done with only one extra crane visit for the full set. It seems like a plan for now.
Other revelations included that the steel stud layout for the bedroom was messed up by the architect (yup, I checked my original notes). It was a classic symptom of 2D design where the various views, created separately, were not actually compatible or build-able. I went back to check my original notes and sketches that I had sent in and they were correct, so I guess the architect just didn’t understand. I will document that another time. Lets just say my errata list is growing.
Sourcing
I have started hearing back from various contractors and the bids are looking much better. I got a very reasonable excavation bid to go with my good footings bid. I got bids on hooking up my electricity (a very reasonable $285 to setup the temp construction meter and then about $4.60/ft to run the permanent cable and setup for 400 amp service. I am waiting on an electrical and HVAC update that should be in early next week. It is clear that I still need to find a reasonable plumber bid (the 6 I got last year were all either too high or too un-reliable).
I also got prices on HDPE pipe for various diameters… Trying to understand the pricing structure better, I divided the price by area, weight, etc. and quite reasonably, it turns out to be priced by weight. $1.25/lb, delivered. For 8 inch pipe with a 1/4 inch wall (HDPE 8″ DR 32.5), that comes to about $3.83/ft. I need about 450ft for an earth tube loop, plus about 350ft for internal duct work in the house… So that goes into the estimates.
Shotcrete meet
A highlight of last week (for me anyway; I am not sure how your week went ;^) was a meet with my most-likely shotcrete guy. I have been talking to a couple other potential shotcrete contractors, but one is just not big enough scale and the other is not really sure about the whole earth sheltered concept. At this point, I trust Nate more than the others and I think his prices seem fair. The biggest problem is that he is hard to get ahold of. It has been more than a year since we managed a meeting. My project is just too unusual for him to quote confidently, so he had agreed to a time and materials quote, but I needed a better idea of how long he thought things would take and I still hadn’t got a quote on some aspects of the build, such as the specfinish on the inside.
I drove out to his place, which is about an hour from my current home and about 40 minutes from the building site (its a big triangle around Ann Arbor, MI). He had a couple big friendly dogs and a nice sized kitchen table to lay the plans out. I set up my computer and showed him my virtual build, my Gantt chart, etc. My main goals were to make sure that the plan for the build made sense to a professional and experienced shotcrete guy and to get good numbers for budgeting purposes. I showed him the virtual model and we talked about practical things like how to get the rebound (shotcrete that doesn’t stick to the wall and is, therefore landfill) out of the basement. We talked about the possibility that some of the non-load bearing walls could be built hollow (or filled with insulation) and still covered with a thin coat of shotcrete to match the more solid walls. We talked about hiring some of his guys to help tie the rebar (along with other tasks), and how quick they could work. He even shared some trade secrets about the fastest ways to tie rebar, plaster walls, etc.
Along the way thru the virtual model, we kept referring back to the Gantt chart, which included things like the dates for each of the 4 shotcrete phases and the amounts of shotcrete that needed to be applied in each phase. He factored in if it was high work or regular walls (which he kept referring to as “money walls”), etc. We discussed if the dates were good for him. He was a bit concerned about the first shotcrete date because it was in May, which is prime swimming pool season. The other dates are past swimming pool season, so he will be glad to keep his schedule busy.
We discussed equipment that I would need to rent and what his crew would bring (and the associated costs). No surprises there except that he mentioned he would bring lots of scaffolding at no additional cost, he just wanted me to make sure the floor was level enough to move them around.
We discussed how much notice I would need to give to schedule his crew.
The main rough patch came when I got to the part about using his gunite machine to spray the specfinish along the underside of the vaults. Nate did not want to do that. Apparently, it is messy horrible work. See this pic from monolithic.org where they create inflated fabric domes and then coat the insides with shotcrete to form the structure. Note the full body coverage including saran-wrap on the helmet. When the operators face gets covered, he can pull on the roll to get a clean section. My plan had most of the shotcrete structure applied from the outside and only a very thin (3/8″) layer applied on the inside, but still…
Nate said he would rather just have his guys apply the plaster by hand, but that sounds rough and slow to me. We talked about other alternatives including spaying on the ceiling with a drywall hopper gun or having an acoustic ceiling company come in and take care of it. I had already got a quote on acoustical ceilings, but my wife didn’t like the samples I brought back and didn’t want to consider it at the time.
Another option may be that I would use the same glue up styrofoam ceiling tiles that I planned to use to form (impress) the ribs. It may look good to have the same pattern in the vaults between the ribs, but I am a bit concerned about fitting the square pattern to the curved and radiating vault shapes and it wouldn’t work at all in the compound curved bedroom vaults.
I left the meeting with a few notes on minor changes that I needed to make to the Gantt and process and some homework to Google search a number of things that were discussed (such as a rebar tie belt with a reel). I also have the costs I will need to complete this portion of the budget.
The egress window on the North side of the house is causing difficulty with earth sheltering because I need to be a lot more careful about retaining the earth. It looked good in 2D, but now that I am looking at it in 3D, I am a bit more concerned about the scale and cost of the retaining walls that will be required to keep earth from spilling into the basement.
