As you may recall, my design features pre-cast concrete arches to support the heavy earth loads and let me have open spaces without requiring large spans. I had some old posts about how these will be built, and even my own experiment to build quarter scale models.
I did get quotes on having these ribs done by professional concrete pre-casting companies. One even sent me nice faux stone concrete samples, but when the cost estimates came back, they ranged from $40K+shipping to $80K (with shipping) for the 10 ribs… I thought that was ridiculous considering that each rib only used about 130$ worth of concrete and less than 200$ worth of rebar. I asked the companies how many forms they would make and what they would make the forms out of… All three said that 10 was a small order, so they would just make 1 form out of wood…
Obviously, they were charging way too much and I was going to have to take this into my own hands… I had designed the ribs to be cast easily in a 1ft deep form. I could do this.
But first, I wanted to make a computer model to figure it all out.
My model revealed that the cost of reusable parts, assuming I went with a rather expensive Melamine base and 2 layers of 1/4 inch smooth plywood for the side walls, would be about $575. I would probably make 2 in order to cut down on crane visits (the crane will have to come at least 5 times with 2 forms). Then each rib would require about $350 worth of rebar, concrete, etc. I also decided that I would need to buy a concrete polisher (wet) ($200) and a sawsall concrete vibrator attachment ($50).
All told, that would mean about $1150 for the 2 forms, plus $3600 for the rib materials, plus $250 for tools, which gives less than $5000. If I add 20% to cover misc, it comes to $6000. I plan to work out a deal with the concrete company to rent their crane for a reasonable cost. They currently use it to place pre-cast septic tanks which are about the same weight (35 cuft at 130 lbs each is 4550 lbs, plus the weight of the rebar).
Along the way, I thought about things like layout, materials, form removal, etc. For instance, I plan to build these on the front half of the garage slab. I will build the back half of the quonset for use as a shop, and then cover the front half with a large tarp to keep the rain out. I can then remove the tarp so the crane can pick up the ribs more easily. I plan to use some #4 rebar to create hooks on the top of the casting. In order to remove the form later, I will need a slot in the form that I will plug with pieces of scrap insulation during the pour. For a base, I plan to use melamine sheets that will provide a non-stick surface. I will then need to polish both sides of the form to get a similar finish on the trowel finished side of the concrete. I plan to build two forms, one left handed and one right handed… There are a few different configurations to lay these out next to each other to minimize the space needed, I think I will go with a 24×24 layout that will require 5 sheets in the top layer, 6 in the middle layer and 1 in the bottom.
Here are some pics with a few more details…
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Rib assembly. The brackets are screwed into the 2x# forms, which are bridged together with plywood scraps and all of that is screwed down to the melamine base… but the sidewalls are not actually screwed to the brackets…
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A detail of the hanger. The PVC pipes along the spine will make it easier to set the vertical rebar and feature ridged insulation wedges. The PVC is held to the form by a screw which is removed before the forms.
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Rebar skeleton, mostly #5 rebar tied together with #3 rebar loops.
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The loops are mostly spaced by 8 inches, but the engineer specified that the spacing be reduced to ~4″ near the high end of the lower spandrel.
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Closeup on the high end spandrel. You can see the PVC holes that will help tie the rib into the central tower.
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Low end of the form. The white PVC pipe will allow the rib to slide over a 1″ steel post in the foundation. The green “hangers” are 2×6 boards that will keep the form from bowing and help me suspend the rebar skeleton.
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Table to calculate costs of the forms and rib material
Well, August is here and still no hole in the ground. I didn’t post anything in July at all. Mostly, I blame work. There were a few weeks there where things got really crazy because I took on a big project that I should have declined. I spent my evening computer time preparing “packets” to make it easier for contractors to work out their bids and that didn’t leave much time for the website.
I submitted my construction drawings (emailed pdfs) to my neighborhood’s architectural committee on June 24th (just before my last post). I expected they would setup some sort of meeting so I could explain the drawings, so I offered to bring in the full size prints (one member of the committee told me he wanted prints instead of pdfs). Instead of inviting me to a meeting, they just sent me some questions by email.
I expected questions about the direction the garage is facing. The rules say the garage shouldn’t face the road, but because the road wraps around my property, it would have been difficult for me to face the garage away from the road, but I at least made sure it wasn’t facing the “circle” that my driveway comes off. Unfortunately, you could still see the garage doors from the circle. I talked about planting arborvitae to block the view and they were willing to accept that.
Rough landscape plan that we sent to the architectural committee
They did ask some questions about our landscaping plans. They didn’t give much detail about the green roof and I think they were concerned that we planned to leave everything “natural” on the roof ;^). Our answer of “park-like” seemed to satisfy. They also expressed some concern about the back of the garage, which I admit is not the most attractive side of the house. I promised to hide it as best as I could with trees and a bougainvillea vine.
The guardrail is drawn with straight lines, like wires, but I hope to use curved steel or aluminum tubes
The thing they were most concerned about was the safety rail. Admittedly, the architect did make it look like stretched wires (very nautical), but I explained that my intent was more for horizontal steel rails that could be bent to follow the contours of the land. They seemed to prefer horizontal rails to a vertical fence which may have appeared a bit like a palisade. In the end, “safety rails” made it past the neighborhood association’s fence restrictions, but meant the building inspector would be much more interested in them. They said that “before” they would approve, I would need to make sure those “guardrails” would pass inspection.
I contacted the inspector (who got back to me very quickly) and said that there was a rule for guard rails along a walking path next to a drop of more than 30 inches. It is basically a 4 inch ball test. Not sure how I missed it, but my wife found the exact wording of the rule on-line.
R 312 Guardrails are required on any exterior walking surface over 30in. from floor or grade. Openings in guards shall be designed such that a 4 in. ball will not pass through the guard at any point including open treads. Residential guards shall be 36 in. in height minimum from the finished floor or stairway nosing.
Horizontal rail, I would like this in black, but the relaxed openings would fail the 4 inch ball test for guard rails next to a walking surface.
If this rule is applied to my project, it means that I will actually need to go with a safety rail designed to meet that rule rather than the much cheaper and more open horizontal steel or aluminum fence that I liked.
On the other hand, the rule was intended for stair or balcony railings, so I am looking into if I could make a couple changes so the rule does not apply. For instance, perhaps it will not apply if I move the rail back a couple feet from the edge. I could plant bushes between the fence and the edge. Or perhaps putting a flower bed along the fence, instead of a walking path would change things.
Getting bids in summer (construction season) is no easy task. It gets a lot harder when the house is complicated. And the beautiful building weather we have had the past month has only made it harder. I keep hoping for some really hot days so that these guys will want to be inside, even if it means filling out a quote.
I am sure I will put in a page about what I have learned, but I am not done learning yet. Instead, I will give you my strategy and a few stories…
My strategy was to first put together a packet of information, and then phone each potential contractor for a conversation. Many contractors ruled themselves out right away because they are not interested in new construction.
One told me that new construction requires you to work fast, but he would rather do a good job. I have heard that line before and personally believe that a real pro can do both, but lets get back to the topic…
If they were interested, I could answer questions during the call with the information I had collected in the prepared packet (such as how many square feet of wall or how many fixtures). I could also write down their questions and add the info to the packet. For instance, the electrical packet included the electrical sheets from the construction drawings, as well as a spreadsheet where I had already gone thru and summed up the number of electrical outlets, light switches, 3 way switches, etc. so the contractor wouldn’t have to.
The strategy behind the packets was that contractors would get back to me more quickly if I made it easier for them. It would also make the bids easier to compare if I provided the counts and areas.
But once I had a contractor (such as an electrician) on the phone, they often asked questions I had not thought of; such as which rooms should have switches controlling the bottom half of the outlets, or who my electricity supplier was (because one of the suppliers requires a separate meter for the electric HVAC stuff). I then added this information to the packet so that all the bidders would have the same info. After talking to 3 available contractors, collecting questions and polishing up my packet, I emailed the information out to each.
Then I made a mistake, I gave the contractors a couple weeks of “space”. I think this may have sent a bad signal. After the couple weeks, I emailed. Again, too little too late. A couple weeks after that, I called them again… After a month of not responding to my emails, they mostly acted like the ball had been in my court the whole time. Sure, they got my packet, sure they were interested. Why did I wait a month to call and when did I want to get together to discuss it?
A couple of contractors have bothered to call me back and tell me that my project is too big for them. I appreciate that because I can just move on to another contractor. I know of at least one contractor who changed his mind and decided he was not up for it, but didn’t bother to tell me (I heard it thru the grape vine). I want contractors who find it interesting and actually want to be a part of the project.
In one case, I did get a quote and filed it away while I waited for others. After a few weeks, I took a closer look at it and compared it with the others. I realized that it was totally inadequate in terms of detail. It didn’t include the equipment rental costs and labor components that the other similar quotes had. I called them up and they said they could give a more detailed quote if I was actually interested. I said I was, which was why I had asked for the first quote, and they agreed to give it another try. So now I wait again because they didn’t take my first request for a quote seriously.
In another case, I drove an hour to meet with the contractor (who made himself available after hours) to discuss what I needed. I didn’t provide any information I had not already included in the email or phone calls. He showed me some brochures that I had already seen on line. After a while it became clear to me that it would be very easy for him to prepare the quote because he only had a few components to choose from and my needs made the final assembly pretty obvious. So, I said something like, “I guess this quote should be pretty easy for you to put together, you didn’t need me to come in after all”, and he let slip “Yea, but I like to have people come in before I bother. It shows me who is serious.”
In another case, during the initial phone call, I found the contractor did not have email. Instead, he wanted me to drive out to the property (1 hour each way) to meet with him and “walk the site” with me before he could quote it. His references were good, so I drove out and I spent over an hour with him. I also gave him some print outs. A couple weeks later when I called, he said he had sent the quote. I checked and said he hadn’t. I called again the next week and he said he was working 100 hrs a week, and hadn’t had time to quote it. I said I would have to find someone else who had time for my project. He said he did have time for working, just not for quoting. I told him I needed the quote before I could hire him, so he said he would get it done that weekend… Then a couple weeks after that I called him again (now six weeks since we had met) and he admitted that he had forgotten most of the details, could I come out and meet him again to “refresh his memory” and bring more print outs… I called a few other contractors to start the bidding process with them instead.
In another case, after wasting a month, I started calling a particular ICF distributor every day for a while. I left 7 messages over two weeks and got no replies. I realized that I had not got a reply to anything (email or phone) in 2 months. I did get a reply from him months earlier after meeting him at a trade show, so I know I had the right email and phone number. I decided to contact the main company and told them I couldn’t get a hold of their exclusive distributor in my region. They confirmed the contact info was correct and said they would follow up. Two weeks later, they called to say they tried and tried, but couldn’t get a hold of him either and put me in contact with the next closest distributor. Actually, this other distributor was much closer to my building site even though I was technically out of their region, and with corporate watching, they got me a good quote in a day or so.
In another case, the office person responsible for quotes kept acting like she was just about to send me a quote. I kept missing her because she had gone to lunch or was in the shop. She never called me back. Eventually she sent me a scan of a hand written quote. I couldn’t read it (it was too faint to make out her handwriting), but I could see that it was only a few lines long and couldn’t possibly be complete, so I called again and this time I got her. After 5 weeks, she told me that the drawings in the packet I sent were not sufficient and I would need to get shop drawings made before she could quote accurately. I thought the drawings were good enough, so I asked her what she would like to see. We opened the excel doc that I sent here at the same time so were were looking at the same thing. She started saying how it didn’t give enough info to bid… I asked her if we could go thru a row together. We started on the first row, and it was clear that she had not got past the 5th column. Once she saw that, it started to click for her. Then I got her to pan over even further to the right where I had inserted the drawings in the sheet (I had also sent them separately as PDFs which she had not noticed). The lights went on (I heard a little gasp) and she said she would get me a proper quote right away. That was 10 days ago, I guess I should call her again.
In another case, I had met a contractor who had impressed me by already printing out the drawings I had sent him so I didn’t need to give him my set. We were going thru the plans and he said that he guessed most contractors would take one look at these plans and decide that it would be easier to bid on a more standard job. But he thought it was cool and he give me the name of a contractor for another part of the project who he though would also think my project was cool enough to want to be involved…
My main shotcrete contractor has not yet been able to meet with me or talk to me since I started the bidding process. He is just too busy and I am starting to get concerned. I will call him again this week and try to set something up.
A number of the contractors I have spoken to have said they would need to bid “time and materials” for such an uncertain job. For a contractor to make a bid, he is betting that he can get a job done to your satisfaction for less cost than the bid. He needs to estimate carefully so that he makes his bet correctly. If he bids too high, you will choose someone else, if he bids too low, he may end up losing money (worse than you choosing someone else). All the contractors make sure to guess a bit high to protect themselves. You are paying a bit more than they really think it will cost because you are paying them for the risk of the fixed price bid. On the other hand, if they can send in a “time and materials” bid, they are passing the risk over to you. You should expect to pay less if all goes well, but pay more if it doesn’t. The problem with “time and materials” is a lack of motivation for the contractor to get things done efficiently. If you want things to go as slowly as possible, pay by the hour. However, if you trust the contractor to work at a reasonable speed, “time and materials” gives a lot of flexibility. You can ask them to add something without needing to renegotiate. It will just add to the time and materials cost.
After a number of weeks, one of my steel stud contractors got back to me with a quote that was about 10 times what I was expecting (well over $100k for just the vertical steel stud work). So that was shocking… I thought maybe he had mistyped, so I wrote him back and asked him to separate it into Labor and Materials. I thought he would catch his mistake, but he just confirmed that it was more than $30k for materials and more than $80k for labor, for just the steel studs… Ouch.
But then I got talking to another steel stud contractor who told me that I would probably need specific drawings of how all the steel studs went together. He said it would be helpful for his quote, but probably required by the county building inspector. I asked the inspector about it and he gave some cryptic answer about how I should want the drawings so I would have a better record of what was hidden behind the walls. I wrote back and asked if he could be more clear about if I need those drawings or not. My architectural drawings just have one wall detail cross section with a note that says something something basic and generic like “STEEL STUDS, 24″ ON CENTER”. My steel stud work is very basic, with no load bearing walls or connections with floors or roofing assemblies… I can always take a photo before the walls are closed if I wanted good records. I am still waiting to here if I need these, but if I do, it will be more expense.
And on and on it goes. I should be making a bunch of calls this next week. But I also need to keep my job ;^). My plan is to make an hour of calls in the morning and another in the afternoon each day, and then to just extend my work day by a couple hours… I am very glad that my job is flexible enough to get away with that kind of time management so I can save my vacation days for actual construction.
One of my pet peeves is how secretive the contractors are about where the costs come from. The GeoThermal guys are the worst because they have big chunky components that should be the easiest to quote. They want to make it seem like they need to do this big fancy energy audit before they can possibly work on the quote. But in actual fact, they only have 3 hydronic units (for radiant floor) and I want the small one. Then they start to say that the load requirements determine the feet of pipe they need to bury, but later admit that hardly changes the price at all so they always put in more than they need… 
Still, the price is a mystery. This is particularly annoying when I am trying to decide if I need an add-on. For instance, I am not sure I need AC, but wanted to check the cost of adding the air handler. They only have one model that would be compatible with the rest of the system I need, so I asked for the price… They gave me a range that was so wide that the high number was double the low number… As I have said before, I find informational asymmetry frustrating.
I had planned to avoid spending money as long as possible, so I was going to wait on the permits until after I got the bids in. Also, many of bids I had already received included that they would file for the permits. This is probably right for some of the permits (well, pluming, electrical, mechanical), but the septic field size needs to be set by the county based on some formula that takes the number of bathrooms and bedrooms into account. Apparently this size is specified in the permit, which the excavator needs before it can be accurately estimated… So we need to take care of that sooner rather than later.
Fortunately, my wife has taken over the permit stuff. She recently spent a couple hours following the daisy chain of permits and printing them out as she goes. I will let her explain it better in her own post if she ever finds the time, but it doesn’t seem like a nice clear set of paperwork. Instead, it is more like a branching tree. Each permit needs several other permits filled out first and she is following it to the bottom. We joked that our county is very “liberal” which is why there is so many restrictions and complicated paperwork is required to do anything. She has already covered a large desk in forms organized into some sort of hierarchy. Now to fill them all out. ;^)
Sorry, none today. This post is already too long. But I will come back soon and do a special Eye Candy edition this coming week.
This first one is about Englands abandoned Rock Houses. It appears that these homes were abandoned after hundreds of years of continuous use due to shutdown of the local industry. Many believe this underground villiage inspired Tolkein to include them in The Hobbit. The very old homes are still in great shape, although some are inhabited by endangered bats.
This one is for a partially built earth sheltered home in California… This typical Terra-dome home is more bunker than beauty (to each his own), but the site is still interesting for seeing the construction process. Its also for sale, if you want to live in that area.
