This article was originally posted at A Prepping Homestead:
We’ve been hard at work on the pit greenhouse trying to beat cold weather and snow. The footing was poured in early October, and we thankfully had warmish weather through the first week of November to get the mortar work with the walls done. The warm weather is important when pit garden wall building with concrete blocks as you don’t want to be trying to cure concrete or mortar if the temps are dropping below freezing. Laying block will quite honestly be the most time consuming, and back breaking part of this project assuming you don’t dig the hole by hand. Our design required building the exterior walls up to 11 courses and a shorter interior wall. Yikes! This ended up requiring 20 man (or woman) days of work. Although 5 people helped put up block over the three weeks this part of the project took, 13 of those were mine!
Just like the old adage of measuring twice so you only have to cut once, I highly recommend laying out your block at least each course at a time before you mortar anything. This will ensure you don’t have any surprises after a wall is half constructed.
Once you’ve developed a plan and technique you may not have to lay out every block for each course, but at least lay out the corners so you can ensure you won’t end up with non-overlapping seams.
After laying the corner blocks, run a string around the corners to assist in making a straight course.
Often people build their corners up to full height like a pyramid, and then fill in the middle later on. I chose to build roughly one course at a time as for a non professional block layer it seemed easier and more efficient, and also because we were doing a reinforced wall with rebar on the horizontal plane. It varied, but every 2-3 courses we cut a groove in the blocks, and then laid out horizontal rebar for the entire wall.
I found a diamond saw blade for the angle grinder was an essential tool for this! Once two grooves were cut about the depth of the rebar, it was easy to take a pry bar and hammer to break out the groove. When this is done, cut, bend, and lay in the horizontal rebar tying it into each vertical rebar as it passes.
Once the rebar is installed fill all the cores that contain vertical rebar with cement.
As the walls got taller we had to create some makeshift scaffolding to ensure that the initial drop of the block, all so important for leveling, was from shoulder or below level.
Finally with the walls complete we added a sill plate on top of the finished concrete block walls. Laying the pre cut boards on top of the wall, pounding with a hammer was the best way to mark where to drill the holes for the bolts. Make sure to put a foam seal between the wall and your wood sill plate.
There’s much more to do before this pit garden is ready for gardening. The next step is adding rigid insulation to the outer walls and back filling. A door, stairs, fill, framing, roofing, decking, etc. all await and will be detailed in further posts. Stay tuned!
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