Monday, August 23, 2010

footing detail




I have received some questions on what a waterstop and keyway are... This sketch shows my detail. The waterstop is a barrier to any moisture that finds its way in between the footing and foundation wall. The keyway is a little notch in the footing to pour the foundation wall into. And here you can also see how the footing is asymmetrical.  I am debating on whether to move all the insulation shown to the inside of the foundation wall [gasp!].

13 comments:

  1. What will you do with the insulation above ground if you move all of the insulation inboard?
    ~K

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  2. Above ground, there is cellulose insulation between the 2x4 stud walls. If the budget allows, I may add a layer of 1.5" rigid insulation on the outside for good measure, but at the moment, the 14" thick cellulose is creating a R70 wall.

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  3. I'd love to see the section...
    ~K

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  4. I'll send you the section. [addendum: tried to send it but got an email error- did you get it?]

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  5. Apparently it is easier to install- and the weeping tile trade doesn't have to do it. We are also putting more cellulose in the interior stud wall. I am learning about what trades will do what work at a reasonable price by all this!

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  6. Hey, its Tracey.

    Why do you extend your footing under the slab? I think its going to crack. I would float the slab.

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  7. Hey Tracey~
    You are right! what is likely to happen is that I'll move the rigid insulation up, so the slab will float about it on the footing. Shown as it is above, it is also a bit of a thermal bridge!

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  8. What does the "F/O" stand for in "Drainage Board to F/O Insulation"?

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  9. Oak Ridges National Laboratory in the U.S. assessed the most beneficial location for insulation in conjunction with concrete. The conclusion was that placing all of the insulation on the exterior kept the thermal mass of the concrete warmer and drier. This mass acted as a thermal flywheel to moderate temperature extremes in the winter and summer.

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  10. The Oak Ridges National Laboratory, in the U.S., assessed the most beneficial location for insulation in a concrete wall. They concluded that all the insulation should be placed on the exterior. It keeps the thermal mass of the wall warmer. The mass moderates the temperature extremes in the summer and winter.

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  11. I agree- it is best to have insulation on the exterior. In this application, however, the decision was driven by the ease of installation- and the experience of the Mill Creek Net zero home. I used this discussion as a basis for our choice: http://greenedmonton.ca/mcnzh-foundation-walls

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  12. F/O is short-hand for "face of"

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