In my last post “Let’s talk ICF For Our New Off-Grid Home- Part 1”, we discussed what this ICF material was about and how easy it was to build with. Although ICF is an easy, straight forward method of building, there’s a lot to it if one is going to do it properly. We had 6 courses of forms up at the time of my last post so let’s continue on with the building process. Winter is coming and we are longing to move out of the tent. Let’s talk ICF For New Off-Grid Home- Part 2
We Utilized a Detailed Floor Plan
A detailed floor plan is a must in order to properly lay out the house. We knew we wanted a couple of doors and lots of windows. Some windows may have some leeway in location while others will need to be located dead on. The kitchen window is an example where a window location needs to be dead on. Johanna has a kitchen cabinet that will be hung on one side of the window and a refrigerator on the other side. We had to know exactly where that window would be placed before cutting any block or pouring concrete.
Energy Efficient Windows and Doors
Speaking of windows, it doesn’t make a lot of sense to have well insulated house walls and then furnish it with poor quality, low energy efficient windows. So our windows will be triple glazed and argon filled. There are lots of technical specifications associated with windows and doors. One of the most important in terms of comparison between window manufacturers is Energy Rating (ER). The higher the number, the better.
We were pleasantly surprised to find out that windows can now be made pretty much for any rough opening subject to the confines of the window style. So in other words, there doesn’t seem to be standard sizes any more. The manufacturing process is so flexible these days, we can build an odd sized window buck and then order a window to easily fit it. We simply supply the rough opening and we can get a window made to fit.
We chose single hung windows this time. Our last house in Saskatchewan had awning windows and we had trouble with the crank system. It was a drag to open the window in summer with the screen in and then have to remove the screen to close the window because the scissor arms attached to the crank got hung up on the window frame so the window wouldn’t close fully.
All 3 of the homes I’ve built or am building has been non-standard as far as wall height. I like a 7 foot 3 inch interior ceiling. Considerably less volume of air to heat in the winter, less draft and it makes for a more cozy home. But it does force us to be careful in kitchen cabinet planning and what size windows we can install. Not at all a big deal for us. It just requires a little extra thought.
A Great Engineer to the Rescue
The area above windows and doors is called a lintel. Typically, as long as we have space above the windows to pour roughly 9 inches of concrete at a minimum, we don’t need the services of an engineer. Anything less than about 9 inches may require an engineer to make sure the house is stable.
We ran into a problem over our doors. Because of the height of the door versus the height of our wall, we only had 3 inches over the doors. No point in placing only 3 inches of concrete over the door. That layer is not strong enough to do much good. It was time for some professional help. At the suggestion of Jeff, the Bird Stairs ICF sales specialist, I contacted Pat Griggs of Griggs Engineering. Pat is a gem! I contacted him in the afternoon, sent him the requested information along with a couple of ideas I had and the next morning Pat had an answer for us. Great service and an easy solution. I understand Pat is closing in on retirement but if you need an excellent engineer in Nova Scotia, my experience with him was superb.
Building Window and Door Bucks
In regards to window and door bucks, I simply built wooden boxes out of pressure treated 2 X 12 material the proper size for the windows we wanted to have in the house. The inside of the box is the rough opening we gave to the window and door manufacturer and they build the windows to set in that rough opening with a little slack thrown in just in case the boxes are out of square or level.
In our case, we wanted to be as consistent as possible by making all of our windows (except the kitchen window) the same height. That made it easy for me to cut and frame everything in. All my windows were the same measurement from the floor and terminated the same height from the ceiling. The only difference in our windows is the width.
I pounded nails around the outside of the window and door boxes in a random pattern, Those nails were within plus/minus 3 inches of the center line so the nails didn’t interfere with the ICF foam once the boxes were placed in the wall. I only hammered the nails deep enough so they did not protrude back into my rough opening. Their purpose was to lock the window and door boxes into the concrete. The nails gave the concrete something to really bond with.
This was a good use for any bent nails I had laying around. And I had lots. Lest you think my hammering skills are poor, my abundant supply of bent nails was more a function of weak, lazy nails unable to withstand the strong blows being rained down upon them or defective nails. Certainly wasn’t due to an errant hammer whack on my part. 🙂
Working with ICF
Working with ICF requires no special tools. The standard carpenters tools such as a good carpenters level, framing square, tape measure, chalk line, a sawzall, 4 foot steel or aluminum “T” square and a keyhole hand saw are all that’s required.
I used the key hole saw to make the majority of my cuts in the ICF foam. The narrow blade allows for curved cuts which I needed to make when I had to form fit window bucks into the wall. I used the sawzall when I had to make cuts across the sheet and encountered the hard plastic ribs every 8 inches or sometimes the small metal hinge pins. I was meticulous in laying out and cutting my forms to fit pretty tight around the windows and doors. Not only can I take pride in the workmanship, but the tighter the fit of foam around the windows and doors, the better insulated those windows and doors will be. Otherwise, there will be solid, exposed, uninsulated concrete from exterior to interior which would be a glaring thermal bridge.
Score lines are conveniently in place on the foam exterior every 2 inches. That makes it so easy to locate and then accurately cut out foam to accommodate windows, doors or whatever needs to be fit in the wall like perhaps a fan opening. I cut right on the lines, paid close attention that my saw blade was perpendicular to the face of the foam so that all my saw cuts were true and I took my time. Measure twice, cut once really applies here. Any mistakes and the piece is somewhat ruined. “Somewhat” ruined in that I could perhaps salvage a chunk off of the length if I needed a short piece somewhere. In desperation, the piece might be glued back in place with PL premium or similar and strapping applied as reinforcement but I wouldn’t do that. Best to set the mis-cut piece aside and continue on with a better cut and see if there isn’t a way to salvage something from the ruined piece.
Access Holes Through the Walls
Johanna and I spent a great deal of time pondering exactly where access holes needed to be accounted for in the walls. We made a list of every cable, wire, vent etc. that would need to go through the walls. I marked their locations on the correct wall. Then I cut appropriately sized holes and installed pipes which will be used as conduit. All this was done prior to pouring the concrete. I highly recommend making a list of every outside fixture, outlet, fuel line, cable, electrical line, sewer, and water pipe that needs to get through that concrete wall so nothing is overlooked.
I used a hole saw to make my cuts and then I chose a pipe sized for the application. I made sure any pipe I placed through the wall had plenty of length extending out both sides of the wall. It can all be cut to the right length at a later date after the concrete is poured.
I made a couple of holes in the basement wall for an oil backup stove if we should ever care to have one. One hole had a small tube where the oil fuel line would come in and the other hole was much larger for the exhaust pipe. Since we didn’t have the stove or the stove pipe that comes with the stove, I had to make a hole that would accept a chimney pipe perhaps years down the road. I did an experiment that worked quite well. The chimney pipe that comes with these oil stoves is generally 3” diameter. So I took a piece of 3” PVC pipe and lathered the outside generously with a product called “Never Seez”. Next I wrapped the PVC pipe with a thin piece of sheet metal longer than the thickness of the wall. Then sheet metal and PVC pipe were shoved through the pre-made hole in the wall. A couple of days after the concrete was poured, it was relatively easy to slide the PVC pipe from the sheet metal collar. Once the PVC pipe was out, I wrestled with the remaining sheet metal collar and voila, I have a properly sized hole in the concrete ready to accept a chimney pipe if we ever buy an oil stove. For the time being, I’ll just plug the hole with foam.
The last thing I want to mention in this post is the importance of bracing. The longer and higher the walls, the more unstable the wall will be without some form of support. There will be a lot of thick, viscous concrete in those walls which will exert much pressure on the rigid foam board. Without some bracing and support, the walls could be misshapen or worse, a section of wall could completely collapse.
Just as I take pride in a level foundation and floor, I also want to see plumb walls. Bracing can be rented from the ICF dealer which is what we did. This bracing is great stuff. It not only makes a wall vertical and plumb but it also acts as a scaffolding support system. Generally, every 54 inches I had a brace set up with 2 X 8 planks for my scaffold. Additionally there are turnbuckles on the braces that allow one to push the wall in or out.
To secure the braces, for the basement, I pounded short pieces of scrap rebar into the earth to anchor the feet of the turnbuckles. For the upstairs pour, I took scraps of 2 X 8 or 2 X 10 and screwed them to the floor with #10 screws. Then I lag bolted the feet of the turnbuckles to the scrap wood.
Full walls of wet concrete are heavy and it is much easier to push a wall outward than it is to try to draw it in via the turnbuckles. So prior to the pour, I ran string close to the top of my interior walls. I screwed pieces of scrap wood at the top of the wall at each of my 4 corners. (2 pieces of scrap 1 X 4 screwed in each corner) I measured out 4 inches and used an eye hook to attach my string. I knew my corners had very little flexibility and must be right so if the string is 4 inches from my corners, anywhere along the rest of the walls, the string should also be out 4 inches.
Tweaking the turnbuckles easily aligns each section of wall. Knowing that it’s easier to push a wall out, prior to the pour, I purposefully brought the wall in slightly concave since the wall has a tendency to naturally bow outward during the pour due to the pressure of the concrete. After the pour, it’s easy to go around with a tape measure and measure out 4 inches from the string along all 4 walls. A person on the ground can adjust each turnbuckle as necessary which in turn trues up and straightens the wall.
Now let me tell you about dodging a concrete bullet. It was almost a huge mistake! I used an online concrete calculator to calculate the amount of concrete to order. By inputting a few numbers, the calculator spits out the necessary quantity of concrete. I added a half yard as extra and away we went. I completely forgot to take into account the windows and doors on this last pour. Obviously, volume needs to be subtracted because these areas won’t get concrete.
As a result I ordered too much. The concrete man asked me where would I like the extra dumped. Time was of the essence since the concrete was approaching the point where it was close to setting up and couldn’t be worked anymore. Hence, there was no time to think this through. I asked the driver how much concrete was on board. Two yards was his response. Oh… well that didn’t sound like much. I asked the driver if he could chute it through the basement door and so I could simply wheelbarrow the “tiny” couple of yards of concrete around to make a concrete floor in the basement. The concrete truck’s chute just made it to the doorway. And out came the concrete. And it just kept coming and coming and coming.
I had a mound ten feet in diameter and about 20 inches high piled up just inside the basement. And it was flowing back out the basement door. I couldn’t even get out the door without wading concrete. Talk about the proverbial set of “cement shoes”!
By this time it was dark, the stuff was ready to set and I was working feverishly to move this stuff before it hardened like a rock. Fortunately, we had hired a couple of guys again for the afternoon to help with the pour and they took mercy on me and grabbed shovels and helped out. It took us a couple more hours working by flashlight and a drop light to move that mountain of concrete. I could barely move the next day. What a disaster that could have been to have a solidified mass of concrete at the basement door. I wonder how much fun it would have been to master the jack hammer.
Moral of the story… a yard of concrete is a lot of material. Two yards is brutal when it is poured in a heaping pile on the ground and it all has to be shoveled into a wheelbarrow and moved. I don’t want to try that stunt again.
Until next time, keep the dream alive! We wish you a great day!
Ron and Johanna
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