After sitting down with a pen and paper alongside my Sketchup castle design with the purpose being to calculate costs per foot of wall, a clear winner showed up immediately. CMUs are by far the least expensive and most forgiving material to use to build the shell of a structure. I don't mean "fancy" split faced or other decorative type blocks, I mean plain-old flat faced standard blocks. A quick look at a 1' thick wall 1000' long full of cement 8' high at $2.78 per foot is over $22,000 at $75/cubic yard of cement, and I've seen many prices for cement over $100/cu yd. Take the same dimensions using $1.30 a block and the cost comes out to be considerably less, even if you raise the cost to $1.50 a block it still wins. Throw in concrete core reinforcement on top of the CMU construction and yet again, the CMU is still cheaper.
Now, folks will argue that one needs to throw insulation in on top of the CMU cost, and I want a stone interior/exterior for the most part, so now we're approaching the costs of ICF. The decision here isn't too difficult either. Due to the unusual design of a castle and the height of the structure, most ICF will not work. Many of the sites only allow for 2 floors of standard height (from the limited information I could find), none mentioned 3 floors of greater height. Gridwall ICF is right out the window. To have these companies engineer something, or to find a specialty ICF, that would meet my needs plus the cost of poured concrete, exterior and interior finishing, ICF gets taken out of the running.
So, in a nutshell, the basic structure of the building will be reinforced CMU with a stone exterior facade; and on the inside, something along the lines of foam board insulation with a stone facade tied in to the main wall. That's pretty much it. This method will allow for rapid construction of the shell and the decorative extras can be added later.
http://www.icfmag.com/how-to/ht_big_walls.html
ReplyDeleteThanks for the link, Kirk. I read the article, and I'm still favoring CMUs. There were many points in the article that stated the method used cost quite a bit more (at least initially), and there are the additional expenses of multiple concrete deliveries plus the actual cost of concrete as well. There was also a lot of specialty scaffolding and bracing being used as well. This also appears to be more for commercial/apartment complex type of building, so I stand corrected that multi-story ICF isn't available, but it looks to be unsuitable for my modest residential needs and budget.
ReplyDeleteI do wish ICF were cheaper, and as it becomes more and more widespread and costs fall, I may be convinced to switch to it. CMUs, for the time being, still allow the most flexibility and best cost for the self-builder of a castle.
Have you looked at pre-cast and/or tilt-up walls?
ReplyDeleteAbsolutely. The costs are very high there as well; now in addition to the cost of the concrete, one must pay for the labor, specialized forms, and the heavy equipment needed to move and position the units.
ReplyDeleteIt'd be nice if I had the cash to take advantage of some of the more efficient methods of concrete construction; but until I win the lottery, I'm stuck with the DIY, not as pretty methods to get the job done.