ICF Castle (Scott's Castle)

Scott's Castle

At last, someone has really built a castle of sorts using ICFs.  they obviously didn't do this themselves, but some folks have asked about building a castle with ICF materials, so here's proof it can be done.  The structure here is  over 11,000 square feet, so this is not an inexpensive venture.  Photo from site.

CMUs are the way to go...

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.

Concrete Walls?

Something I really hadn't considered too much as an option was a solid concrete wall. I'd always figured concrete would be prohibitively expensive, but that prejudice was probably instigated by looking at how much a bag of pre-mixed concrete costs at the local big-box hardware store. I made a couple of posts over at Ownerbuilderbook.com just as feelers for the cost and merits of various materials (CMU, ICF, SIP, etc...) for an owner-builder. One of the posts recently got a reply and referenced that many CMU walls would likely require reinforcing by filling some of the hollow cores with concrete and re-bar. This was something I knew, as it is likely a requirement by many building codes especially if you live in a hurricane or earthquake area. The post made a quick reference to something I didn't know though, which was that the cost wasn't as high as I thought for reinforced concrete. A quick internet search brought up a site for a software designed for building cost estimation called Goldenseal. I'm not really interested in the software, but the estimates it gives for a solid concrete wall vary between $6-$9 an hour per linear square foot of wall, the upper end being for a twelve inch thick wall. Sounds expensive, but here's the real savings: This includes the cost of formwork! Assembly and disassembly of all wooden forms needed to pour the wall. If that is correct, a poured concrete wall is a considerable time savings over a DIY CMU wall, especially if you can get it at the cheaper price. This needs more research...

As a side note, I just found Perma-Form ICF block offering a $6.99 form block which puts their cost per square foot of wall at $1.99 per square foot of material. Wow, look for one thing, find another; questions begetting more questions!

AAC block, ICF and CMU, oh my!

I spent some time the other day looking for "cost per square foot" calculations to have a guess as to what it might cost to build a structure yourself. Starting from the bottom, my assumptions were that a professional would have to pour a slab foundation, but that you'd do most of the site prep work on your own. So for a 6" thick, 3000 square foot slab it would cost around $4200 for the concrete (professionally trucked in and poured) and around $12,500 for the labor. One could see immediate cost savings if there were ways to eliminate the labor costs, but I figure most folks lack the ability to successfully pour, screed and float 3000 square feet of monolithic slab themselves. I'm sure one could pour sections, but still...for the square footage of floor space needed, you'd have to mix a LOT of bags of concrete by hand. If you had a lot of friends that you could rope in for a slab-pouring party, that could be a lot of fun too and save some cash, but I guess that depends on how much food and beer they consume!

On to the walls. I had a little difficulty here. Calculating wall costs using materials like AAC, ICF, and cement block using the information on the internet isn't very easy. Most places want you to call or submit your plan for an estimate, and considering the structural numbers I'm using for guesstimates is completely arbitrary at this point, I have nothing to submit. Many places don't list cost per unit, cost per foot or cost per cubic yard for their materials anywhere on the site; they want you to call or talk to a local distributor who also wants the same info - how big is your structure? How many doors/windows?

I wasn't able to come up with what I thought might be a reliable estimate for ICF construction. I was quite interested in it and thought it might be the way to go, but after seeing that the builder will need to purchase the block forms (these forms come in a limited number of shapes) that are the outline of the structure, and that the form must be complete in order to bring in a ready mix truck every time you need to fill the form, it doesn't look so attractive. Not to mention that the ICF form blocks vary widely in cost, and all seem to have different methods of assembly and unique hardware that would take some learning for a DIY builder. Not to say this still wouldn't be an option, it all depends on your build timeline.

Then there's AAC block. After looking at several sites, this material looks to be a good possibility for the DIY builder to use with good results. No specialized foam block forms. Cuts with regular hand tools (no special stone saws like you'd need for concrete block), so you could make curved doors or window spaces fairly easily. Builds like cement blocks. Don't need to hire professionals and a truck to pour cement in your walls. Lighter weight block. Very good insulation qualities, though not quite as good as ICF. (8" wall, AAC=R-22, ICF=R-22-46, climate dependent) You could assemble your structure one block at a time, as you have time. Cost for plain 12" thick AAC block seems to be around $197 per cubic yard of block. Plain cement block (CMU) is around $190.

There's another option as well; sort of an in-between - insulated concrete block. Couldn't find a whole lot of information about it. It's similar to regular concrete block except that instead of having empty, hollow cores in the block, the structure of the block is altered to incorporate an insulating foam insert, or the block itself is foam filled. While this does provide better insulation than standard block, it still has "thermal bridges" (where heat or cold can travel through a wall due to the exterior surface being connected by material directly to the interior surface) that reduce the efficiency of the structure.

Edit: I found a site here that has to do with educating consumers and builders about ICF construction. Good information, somewhat hard to wrap your mind around at first, but an eye opener. I also discovered that not all AAC blocks are created equal; one site mentioned the difficulty an owner-builder had with her AAC block- they weren't milled true! She couldn't get her walls perfectly straight, and upon calling the manufacturer to find out why, discovered the fine print: block size "nominal".

*Pictures: The colorful ones are ICF blocks, the string of blocks are AAC, and then there's the regular CMU or "cinder" block.

Ashlar Stone

This would be the ideal construction method for a "real"castle, pure stone. There aren't many of us that have the knowledge, time, or money to purchase this stone and build with it. While it wouldn't be hard to use, you'd have a lot of mistakes and it would probably look pretty rough if you didn't have the help of a stonemason to keep you pointed in the right direction. There are several options available to those of us that are less able to make use of this method. There are ashlar stone veneers that look very realistic and cam be applied easily to concrete block or ICF structure. The building with blocks or ICF will eliminate most code difficulties because they are known, safe construction methods (to the inspectors, anyway), and you'll have less difficulty with inspections should you choose to build in an area where they are necessary. Building the structure rapidly to get some living space and temporarily ignoring the exterior finish allows you to move in and keep initial costs down, you can add the veneer over time. I looked around for sites offering veneers and was surprised to see such a variety of finishes available. Everything from pebble to block type finishes can be found, and the best part is, modern veneers don't have to have that cheap, monochromatic, and repetitive pattern that really make it look fake.

The point is affordability and DIY-ability. Take a look at veneers from Boulder Creek Stone. They look great.

AAC block construction

Information shamelessly lifted from the Rittersburg Castle website.

AAC block looks similar to standard cement blocks (in material) but has slightly different shapes. It appears to be something that an owner builder could use. Looking around on the internet and checking various cement block or other construction methods (such as ICF), the cost per square foot of wall doesn't seem to vary more than a few dollars ($9-$13/sq.ft.). Multiply a few dollars by a few thousand square feet though and it adds up. I think some of the variables are dependent on how much you do yourself, the quantity of material ordered, where your nearest supplier is and the experience level of your work force.

Insulated Concrete Forms (ICFs or SIPs).

I've made repeated mention regarding insulated concrete forms but had little luck with finding a way for an owner-builder to DIY a structure like this. There are a lot of benefits to ICF construction such as a rapid build time, very high energy efficiency, and good structural strength. Well, look no more; I found this site: BuildBlock building systems. They offer DIY homeowners avenues to financing and building their own home using BuildBlock's ICF system while making no payments during construction on their secondary site called BuildMax. Now, I'm sure there are strings attached such as the structure needing to be completed within a certain time frame and similar restrictions, but this does sound like a pretty good deal.

Here's a quote from the site:

"With BuildMax support, you can be a successful project manager, even if you're not handy with tools. We don't expect you to build your home yourself. You only have to manage the building process. But if you want to cut costs even more and build more equity, you can choose to do some simple jobs yourself, such as painting and clean-up. And if you're an experienced do-it-yourselfer who can handle substantial work on your own, you'll keep costs at rock bottom. Whether you stick to supervision or get right in there and do the work, you're building more than a house. You're building "sweat equity," a critical part of the owner-involved building plan to help you get a home of your own."

EDIT: After doing some research, BuildMax is not the way to go. Poor customer support, your loan is low priority if compared to the sure-fire high-credit loans, and is essentially a middle man fee for the very same loan you could get someplace like IndyMac.

Thoughts on castle construction.

After spending a lot of free time using Google to scour the internet for current owner-built castles I've come to the conclusion that the most popular method to build a castle is using cement blocks (or "CMUs"). I discovered that we don't actually have a lot of cinderblocks available anymore, apparently not since the 50s. I guess it's just a term that has become the common usage for any structural cement block. I found some information that said castles shouldn't be built with cinderblocks due to the strength of the block, but that doesn't make sense now that you're likely to be buying cement blocks anyway. Obviously it would be wise to make sure that whatever material you choose is strong enough to bear the weight of the structure you plan to build.

I suppose building with cement blocks makes sense, as very little specialized equipment is needed to use these. Really, what is necessary? To simplify: get a building plan approved, get the foundation built correctly, and then start stacking blocks one at a time...lots of time and hard work. You can erect a large building "rapidly" with this method. Without any further treatment to the structure the drawback is that it looks like exactly what it is: stacked cement blocks. One of the ways to get a better finished look is to take a look at what T. E. Breitenbach did (bottom row, next to last pic to get an idea), and that was to build with cement blocks and add a stone facade. Took a lot longer, but looks great. One thing I'd like to know about that method is how to bond the stone facade safely to the structure. Essentially it's a "cold" joint between the structure and the mortared stone. There are treatments available to use on a cold joint, but I'm not sure when they are necessary.

Another method would be to build using the "ashlar" method; basically building with pure stone. That'll take a while, and probably cost a fortune if you aren't able to DIY or find a free source of good stone. An even greater expense would be to have the folks over at Castlemagic do it for you. Their method appears to be a combination of ashlar, and rubble stone and mortar, but you can't argue with how it looks. I have yet to see examples of someone building a castle with the slipform or ICF method, but I'm still looking. Slipform is a perfectly acceptable DIY method of homebuilding, but unfortunately the ICF method takes some seriously heavy equipment to implement. So, for the vast majority of modern castlebuilders, it'll probably be cement block, slipform, and/or stone facade.

Just for gee-whiz factor, here's a calculator for the number of blocks or quantity of cement necessary for a wall or square footage. Here's another calculator for all kinds of structural component measurements, from blocks to walls and stairs. It even has a wall segment with different types of blocks shown, plus their positioning and uses. There's another site with an ICF calculator as well. Worth a look.