Developing an inner city basement has a number of elements that must be carefully orchestrated into the finished product;
- the hole has to get dug in the right spot, so the surveyor is essential before work begins
- the excavator must get the hole level and at the proper depth at the bottom of the footing
- the engineer must take the sample for soil bearing and sulphate content of the soil, this will impact concrete selection later (the mix is variable depending on the project requirements)
- the engineer must already have developed plans for the footing rebar detail and thickness, and wall rebar pattern. This is variable based on soil bearing, depth of backfill, and the weight of the structure above
- the lumber yard supplies the package necessary for the work, usually lumber, stakes, weeping tile and rebar
- the cribbing crew sets the footing forms in place
- concrete placing crew, pump truck and mix trucks are now called upon to pour the footing
- the cribbing crew arrives back on site to set the forms and rebar
- the engineer usually requires a site visit at this point to inspect the foundation wall detail
- the same concrete placing crew returns to pour the basement
- a form stripping crew is usually brought in to peel off the forms and load the trailer
- waterproofing is applied to the basement walls
- gravel and weeping tile is delivered to site and installed
- the city is called in for a pre-back fill inspection
- the excavator returns to backfill the basement
- to add another step, at some point the sewer and water lines can be brought in, in our opinion the sooner the better for this specialized task.
Our semi detached project is currently midway through the process, with the footing having been poured today. Let's hope our cribbing crew can get the walls up right away. Here are some photos of the footing stage of the basement project with captions to provide further detail on what is happening.
This is the centre form that divides the two buildings, it is both wider, at 30 inches, and deeper, at 10 inches than the typical perimeter forms. The middle footing also receives five rows of 10 mm rebar. the perimeter footing will receive only three rows.
The cribbing crew is beginning the rebar install in the footing forms.
the rebar is hung approximately in the centre of the form, it must be at 2 inches from the edge of the concrete, this offers some protection of the rebar from rust
The pump truck and placing crew arrives, and less than an hour later the concrete is poured. This job used about 10 cubic metres of concrete.