Hello everyone, I'm trying to find out if it would be possible to build an interior circular ( or curved ) staircase out of ICF blocks. I'm hoping for an "outside the box" suggestion to help find a solution to a unique building situation. We are currently planning a Castle themed home build and have found several good products we are considering for use in the build, including APEX Block and Quad-Lock flooring, but have not been able to figure out a good way to construct a rather challenging staircase. The staircase is envisioned as the centerpiece of our open floor-plan, which includes a first floor Great Room. We would like to construct a center-less circular ( or curved ) staircase which will rise through a central opening in the ceilings/floors which would be 10 to 12 feet in diameter and would rise roughly 30 feet ( ceiling heights = 16 & 12 ft ) We've explored a number of building methods including log or traditionally build wood, iron / steel, & poured concrete but have been getting very high numbers on the cost cost regardless of the method used. One of the big factors affecting the complexity / cost is the fact that, with the open floor-plan we don't have any walls to work off of and therefore can't use cantilevered or attached treads. Since we are planning for a traditional stone staircase look ( which were most often build out of stone blocks ) it occurred to me that perhaps we could use ICF blocks to construct the stairs which would give us savings in both the cost and weight of the staircase, but I haven't come across any examples of this sort of item being built with this method. Any opinions or advice as to wether such a build would be practical & cost effective would be appreciated : ) Thanks, Rick

Hello, i have done a couple of circular walls not to bad to do but it is easier with a knockdown ICF system, in my opinion, otherwise you can order the cut pieces from the mfgr its a bit more expensive, but it doesn't sound like budget is a barrier? haha anyways here is the one example. go to search engine and type in casabelleverde it should come up. good luck!

I did a circular underground basketball court 2 years ago and before the job we were debating the best way to get the exact wall as drawn by the nit wit designer. My Fox Block rep. came up with the solution that will work on any size circular wall. You take the block and cut all the way thru the outside of the wall between each web. The inside you make 2 shallow cuts [about on inch deep] between each web. If it's a tighter radius the more shallow cuts. The gaps on the outside get filled in with PUF. We used about 8 cans from HD to fill in the gaps on the outside, strapped it with strips of 1/4 " osb, 16' high, no problem.

What is the rise and run of your stairs? If you can tolerate a 7-5/8" rise, you could construct the stair stringers using standard concrete blocks (CMU). To keep the rise to just 7-5/8" (the height of the blocks) rather than the typical 8" rise which includes a 3/8" mortar joint, you would have to do something like glue the blocks together with construction adhesive and then come back and fill the cores with grout, or glue and fill with grout as you go up. You could use 6" wide blocks rather than standard 8" wide blocks which would reduce the amount of grout needed to fill the cores and still provide plenty of strength.

If you really want to use ICF and keep your rise to a more typical 7", you could use a knock-down type of ICF block like LiteForm. These are individual EPS foam planks 2" thick x 8" tall x 48" long that have 1" deep slots every 8" top and bottom to place the plastic ties. To make stair risers 7" tall, you could run the EPS foam planks through a table saw and rip them down to 7" tall. You would then have also come back and cut the1" deep slots every 8" on the side of the plank that had the 1" ripped off. These slots can be cut easily with a circular saw (corded or battery powered) with a 1/8" thick masonry cutting abrasive blade installed. Just set the blade depth to 1" and cut away. LiteForm can also be purchased with ties that are only 8" across to accommodate a 4" concrete core which should be more than sufficient for stair stringers.

I have built radius form with both standard forms cut on site to make the curve, and with custom ordered forms (Nudura) which were spec'd to the radius we wanted. There was a small increase in cost for the custom form (around $1/sq ft if I remember correctly), but that was money well spent. You absolutely CAN build a straight for into a curve on site, but don't let a rep tell you it's quick and easy. The custom forms saved countless man-hours and made for an easier/neater/more professional finished product.

Hello Again Everyone, Thanks billnaegeli, smartwall, arkie6 & ICFBdr for your insightful posts, I really appreciate your suggestions. Please excuse me for not responding directly to them but my technical expertise is limited, and I've needed to do a lot of research to be able to appreciate the concepts. Thanks Again for all your good ideas - R

Fox makes radius blocks for 5,6,7,8,and 9' radius' . They would be great for a castle type detail or a circular stairway. They go together very nicely.

We made a spiral staircase form using 2# geofoam block. What type of anchor points do you have? In reinforced concrete it will weigh at least 10,000 lbs. The foam can be carved shaped and painted to look like rock. Most movie sets are built that way. These are fun projects to work on but usually require a lot more time than anything standard. We did that job based on time and material not a firm price. What kind of estimates are you getting?