June 1, Preparing for the Slabs

Rain, Rain go away!   It never seems to end, so I am doing what I can in preparation for the pouring of the floor slabs.  There are two places where the floor needs to be thicker, with more steel.   One where the masonry stove will be placed, and the other where a masonry wall will separate the great room from the master bedroom.   Hence I have formed the deeper  spots with 1″x5.5″ lumber, and will put the rebar on “chairs” to put it 2 ” above the grade.   The slab thickness in these spots will be 10″.    In addition the masonry stove needs an external air supply via a 6″ duct which goes below the floor connecting to outside air.    I rented a 3/4″x14″ masonry drill and put in a hard couple of hours on the business end of my hammer drill punching a 7″ diameter  circle of holes through the foundation wall.  The fiber-reinforced cement in the block cores is really hard and strong, as my aching muscles testified.   This was followed by a mini sledge hammer and cold chisel to pop out the core, and trimming with a diamond blade on my right angle grinder to get the hole to accomodate the 6″ ID “big O”.     A 1.5″ x 15″ duct rises from the big O to feed air into the firebox of the masonry stove.  Was fabricated from flashing aluminum, and a block of polyurethane foam keeps it from collapsing when the cement is poured around it.   The top of the duct represents the approximate level of the floor surface.

Below are the pictures of the forms and the air duct.

Form for the base of the great room wall.

Form for the base of the great room wall.

Form for the base of the masonry stove and the air intake duct.

Form for the base of the masonry stove and the air intake duct.

The air intake duct passing through the foundation wall.

The air intake duct passing through the foundation wall.

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3 Responses to “June 1, Preparing for the Slabs”

  1. Scott Rookes Says:

    Thanks for the great site. I am trying to build my own passive solar home in Manitoba but can’t get the engineer to approve the block walls. Any advice on this?

    • tedspassivesolarhouse Says:

      Scott,
      Are you proposing dry stack concrete block? Not sure why the engineer would object to concrete block, since the like has been used for building structure virtually forever. There is a whole body of published engineering studies using drystack blocks with surface bonding cement demonstrating their superiority to mortar jointed blocks, which as far as I know are still widely acceptable as a structural mode. If it would be useful I can dig back into my materials and point you to some of these studies. I consulted briefly with an engineer in Windsor, who has had experience with drystack technology marketed there by a local firm, which I used in my project. I am curious as to his justification for rejecting block walls in your house plan.

      • Scott Rookes Says:

        Yes weird I know, as everything I read is exactly as you say. Heck they are even supposedly earthquake proof in California!

        His rationale is that, as I am a beginner at this, he doesn’t want the liability, but would approve if I had hired a contractor….. So I will Limey consult a local engineer anyways at stages, but I am wondering if your plans had been stamped/approved at some point by an engineer, and if so maybe I could purchase them off of you. Not so much for those plans, but just more to discuss with the engineer.
        Thanks again Ted, great work.

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