I am planning to construct a completely underground separate storage cellar about ten meters from my house, and will be doing everything from scratch with quite limited resources and knowledge. I basically have very little knowledge, but hopefully, I make up for it in the desire to learn.
First and foremost, I will dig a large pit of about 35 square meters, 3.5 meters deep. Then I will cast a separate foundation along the edges of the pit using wooden molds. After that, if I have understood correctly, I either get pre-made cement blocks and build with these, or I set up molds and cast the concrete walls myself. Personally, it actually feels both more stable and cheaper to cast the concrete myself. After that, I'll cast the floor separately, on top of the "protruding" part of the foundation frame.
My questions are these:
I know that you can use wooden molds to cast house foundations, but when I check around for people who have cast concrete walls with homemade wooden molds, I don't find much. Most seem to use rented metal molds, which both seem expensive and not sufficiently do-it-yourself.
Should I be worried that the wall will bulge and not be even if I build my own molds?
How do I then cast the concrete roof? I want a solid construction if possible, but the roof must still be cast separately, right? Is there information somewhere on how to build and assemble the mold for the roof?
Apologies from a novice beginner. I would be very grateful if someone would help me a bit with this project!
Edit: I can add that I plan to reinforce the concrete, and that the cellar will be about 40 centimeters below ground level at the roof's highest point.
First and foremost, I will dig a large pit of about 35 square meters, 3.5 meters deep. Then I will cast a separate foundation along the edges of the pit using wooden molds. After that, if I have understood correctly, I either get pre-made cement blocks and build with these, or I set up molds and cast the concrete walls myself. Personally, it actually feels both more stable and cheaper to cast the concrete myself. After that, I'll cast the floor separately, on top of the "protruding" part of the foundation frame.
My questions are these:
I know that you can use wooden molds to cast house foundations, but when I check around for people who have cast concrete walls with homemade wooden molds, I don't find much. Most seem to use rented metal molds, which both seem expensive and not sufficiently do-it-yourself.
Should I be worried that the wall will bulge and not be even if I build my own molds?How do I then cast the concrete roof? I want a solid construction if possible, but the roof must still be cast separately, right? Is there information somewhere on how to build and assemble the mold for the roof?
Apologies from a novice beginner. I would be very grateful if someone would help me a bit with this project!
Edit: I can add that I plan to reinforce the concrete, and that the cellar will be about 40 centimeters below ground level at the roof's highest point.
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It takes a lot to build a form for the walls that can withstand the pressure from the concrete. Likely, rented forms are significantly cheaper than building forms yourself (though I have no idea what it costs to rent). I had help here to cast a retaining wall for a new basement staircase, about 4m long and maybe 1.6m high. It was cast with a form of formplywood and a solid network of studs. Form ties were also used (a sort of steel rods used to "bind together" both sides of the form; the rods are cast in. I recall that more than 100m of 45x120 studs were used for the form.
I can't remember what the material cost, but surely at least 10,000 for the form. I would think a good benchmark is about 1500 kr per square meter of form.
I can't remember what the material cost, but surely at least 10,000 for the form. I would think a good benchmark is about 1500 kr per square meter of form.
How expensive the forms will be and whether you can build them yourself also depends on how thick the walls should be. If you have plenty of stone in the ground, you can build as much as you can with stone in a wooden form (slipform stone masonry), reinforce it, and then pour the last bit. The easiest way is to look at a construction site and see how they do it. My neighbor just removed the wooden forms from his cast garage, with walls maybe 20 cm thick and heavily reinforced. He, as described by the home enthusiast above, had plywood sheets and tons and tons of form ties.
But if you don't have time to build with stone (which is super easy but extremely time-consuming) and don't have enough knowledge to fix concrete formwork, isn't it easiest to go with masonry concrete blocks? You can then fix the roof with roof beams and simply pour over it, similar to when you cast a regular slab on the ground.
The drainage... you've already thought about that, right? A lot of gravel is needed there.
But if you don't have time to build with stone (which is super easy but extremely time-consuming) and don't have enough knowledge to fix concrete formwork, isn't it easiest to go with masonry concrete blocks? You can then fix the roof with roof beams and simply pour over it, similar to when you cast a regular slab on the ground.
The drainage... you've already thought about that, right? A lot of gravel is needed there.
Rent system molds and cast the walls. Reinforcement mesh and concrete. If you try to build something yourself with studs and form plywood, it will most likely not be straight and will be more expensive than renting system molds. On the other hand, you probably shouldn't attempt that type of project if you consider yourself a novice in the field. Are you even going to mix the concrete yourself to get that true DIY feel?