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Concrete/General homebuilding questions
August 10, 2011 9:15 AM   Subscribe

Looking into building a house near Golden/Boulder CO area. Planning on using ICF's. Looking for suggestions of almost any kind. Would like the house to be about 2000sqft. Am a teacher and worked construction for several summers (but only w/ stick built houses) a few years ago so I will have some time and rudimentary knowledge. Trying to keep the house as simple as possible to keep costs down. Simple rectangular shape and roof and trying to avoid the need to any custom building supplies. If we keep it under $300,000ish we won't need financing. Is it possible?

Any good home building blogs to read?
What would you do differently if you built your house again?
I like the look and idea of concrete floors. I understand they can be cold(considering a radiant heat system but not sure about cost) and loud, and hard but I still think I want them. Bad idea?
Best type of insulation to use on the roof?
We love windows. Will this completely defeat the purpose of using ICF's even if we use low-e windows?

Anything else I should consider, let me know. Always up for some good reading too. Thanks!
posted by no bueno to Home & Garden (4 answers total) 1 user marked this as a favorite
 
You probably already know this but get a subscription to fine homebuilding magazine and see if Taunton (the magazines publisher) has any books on building with ICF on their list and also check amazon for good books. I would recommend working alone (book title) as it has lots and lots of labor saving tips. They focus on stick building but I think it will still be relevant. This website has some discussion for modern building techniques and lots on newer technology.

I would pay lots and lots of attention to passive cooling and heating techniques like clerestory windows, deep porches, house orientation to sun and wind directions for your area. I would try to incorporate an easy to use cistern for the rainwater coming off the roof so you can water landscaping cheaply year around. I would at least plumb it, if not install a solar hot water heater. The benefits of PV solar are questionable from a purely economic view point but not solar thermal, they are clear and obvious. With the right system you might be able to heat the whole house with a solar hot water heater and hydronic radiators throughout the house for a lot of the year. Boulder has very good solar exposure ratings and this might be a huge energy cost saver down the road, I bet payoff is measured in a few years if not a couple for this one. A lot of this stuff is expensive or impossible to retrofit but easy to do from the beginning.

Concrete floors are tough to finish to a high polish and no cracking. I am not sure they are cost effective. Radiant heat systems are great but i would only try for concrete floors in the Kitchen and utility areas, for obvious reasons. I would go with wood or carpet in the rest of the house. I prefer wood but that is a personal choice. And you can use radiant heating with either. You could probably use radiant heat with a solar hot water heater actually and not have to devote room space to a hydronic radiator (they look like baseboard heaters).

For the roof I would use Structural Insulated Panels (sips) and build it with a rafter frame so you have usuble attic space, even if you don't finish it off. Sips are well suited to rafter framing and easy and quick to install. They automatically provide really good insulation and just using them will go a long way to preventing ice dams. I would also go with standing seam metal roof over shingles. You don't have to replace this roofing, you have to repaint it. Much better over the long haul than asphalt shingles. I would also get it in a light color. This will keep your roof cooler and make everything last longer.

ICF does not like large continous window openings(or any large unsupported opening), for technical stuctural reasons that amount to concrete is weak in tension so you have to use lots of extra rebar to keep it from cracking and moving. Extra rebar is what makes ICF really, really expensive. If you don't need it the cost can be kept under control. Along these lines I have seen multi story ICF construction turn into a nightmare due to the extra rebar issue. So work with the ICF supplier to avoid extra rebar. You can still have a lot of windows you just need to keep concrete between them so you will have a series of windows, not a whole wall of windows.

The last thing to keep in mind with ICF is once it is in, it is in, and you can't easily change the house or do things like change the plumbing or wiring. Leave extra conduit for future wiring needs and make really sure you are happy with where the bathrooms are and how they are arranged. This also depends on the foundation system you use. If you are using a slab on grade for the house (or some other solid method) what I would do is leave the rooms about 6" bigger in every dimension so you can fur out a shallow 3" wall to run all the utilities and hang drywall and do every single wall out of ICF (if you can afford this). It will cost some more in terms of materials but get a much more flexible house (the plumbing will still be unmovable though). If you are on a stem wall or perimeter foundations system with conventional stick built interior walls your house will be almost as flexible as stick built house but not as solid or well insulated.

I would hire a local structural engineer to do the special inspections required for this type of construction. Every piece of rebar has to be checked by an engineer to be in the correct location (part of the extra rebar comment above) and this is due to the nature of concrete. The rebar really does have to be just right for the house to be built right. If it is built right reinforced concrete is really, really strong and resilient. If it isn't is will be worse than a cheaply built stick home. Build a good relationship with an engineer who is willing to explain why stuff has to be done a certain way. Once you have that knowledge, this type of concrete construction is pretty easy and you can do it(or anyone who is reasonable intelligent and handy). Finishing concrete is a tough skill to master. Correctly placing rebar and tieing it off ain't nearly as hard, and pouring it into the forms is even easier, once someon shows you how.

Before you spend any money on materials or plans I would talk to you local building and planning department to find out what requirements you will need to meet on this one. Boulder has a reputation of one of the enclaves in this country where people are pretty snooty and picky about what is built next to them, sometimes this can be good for unconventional methods sometimes it can be really, really bad to get something permitted. So check it out first and make sure the permitting requiremetns are going to make the cost spiral out of control. Most of your controllable costs are going to be in the kitchen and bathrooms and fixtures in general. Keep these reasonalbe and moderate. Buy ready made stuff like cabinets and sinks and countertops. Your dishes don't care how much the cabinet costs or what the counter is made out of. Spend your money on the best quality stuff that isn't custom made. you will get a lot more value for you money and can spend the extra on furnishings and enjoying your whole house, not just the fancy carrera marble bathtub and granite counter.

Wow that was quite the diatribe. Good luck and have fun with this.
posted by bartonlong at 11:11 AM on August 10, 2011 [1 favorite]


Ana White is currently working on building a house for her mother and mother-in-law in Alaska. They are also using ICFs and are doing a lot of DIY to keep expenses down.

She's been pretty thoroughly documenting the process here. It's in the very early stages and probably won't answer most of your questions, but she does spend a lot of time explaining the choices she's making along the way and why she's making them.
posted by stefanie at 11:24 AM on August 10, 2011


Wow barton. Thanks so much for all the info. Knew rebar was extremely important so I'll make sure I'm extra careful about that. Been researching passive solar a lot lately as well. I've been considering the fine homebuilding subscription because from what I've read so far the articles were great. Good to hear someone vouch for it though. Again, REALLY appreciate all the info!

stefanie - thanks for the link. quite an extensive blog it looks like. great!
posted by no bueno at 11:35 AM on August 10, 2011


Breaktime Classic is a good resource. You have to register to post, but it's free and they don't sell your e-mail address.

Regarding what bartonlong wrote about the permanence of concrete, read Stuart Brand's book How Buildings Learn.
posted by Bruce H. at 1:48 PM on August 10, 2011


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