Posts Tagged ‘Rubble Trench’
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14 May 2010
Rubble Trench – Concrete Cap
The 10″ thick concrete cap on this rubble trench foundation represents a significant reduction in the amount of cement used as compared to current conventional building standards.
The concrete form work for this building addition uses rebar for tensile strength and is one foot wide and 10″ thick. The cap sits on top of the gravel in the rubble trench, and rebar will be placed vertically at the corners, extending above the concrete as anchors for the sill plate and posts of the building.
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11 May 2010
Rubble Trench – Gravel
The gravel in a rubble trench foundation allows any water in the ground under the building to flow to the bottom of the trench and away from the building through the drainage trench, preventing moisture problems or frost heave.
The trench was filled with 1″ to 4″ diamater gravel inside the rigid foam insulation. Outside the insulation, subsoil was simultaneously backfilled to maintain the rigid foam in a vertical position. The gravel was packed to nearly level with the surrounding grade, ready for the concrete cap form work.
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7 May 2010
Rubble Trench – Drainage
Concerned about the amount of embodied energy in concrete? An excellent way minimize concrete in the foundation for a building is to use a rubble trench.
We were recently involved in laying a rubble trench foundation for the small addition to a house near New Denver, British Columbia. The site for the building was marked using string, and a trench was dug to below the frost line, including a drainage trench running away from the building. The foundation trench was sloped towards the drainage trench to allow any water to flow quickly away and surface well beyond the building footprint.
Rigid foam insulation was placed vertically around the perimeter of the foundation trench, extending to below the frost line.
