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Thermally breaking a threshold

jackofalltrades777 | Posted in Green Building Techniques on

How does one handle door thresholds on the lower floor so that the floor grade slab doesn’t become a thermal bridge at each exterior door?

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Replies

  1. GBA Editor
  2. davidmeiland | | #2

    Pemko also has thermally broken thresholds.

  3. jackofalltrades777 | | #3

    I think you misunderstood my question. I need to thermally break the CONCRETE SLAB as it transitions from the exterior to the interior on a grade-on-slab condition.

  4. Expert Member
    MALCOLM TAYLOR | | #4

    Peter, How are you planning to thermally break the slab under the exterior walls on each side of the door? Could you not use the same detail under the threshold?

  5. davidmeiland | | #5

    Do you mean a mono-slab, or are you pouring stem walls first and then slab within?

  6. GBA Editor
    Martin Holladay | | #6

    Peter,
    I'm still confused by your question. Most slabs are insulated at the perimeter with vertical rigid foam insulation. Do you anticipate a situation in which you have a slab that extends continuously from the interior to the exterior (forming some type of exterior patio)?

    .

  7. jackofalltrades777 | | #7

    Martin,

    Yes, I am anticipating a situation in which I will have a slab that extends continuously from the interior to the exterior, forming an exterior patio.

  8. GBA Editor
    Martin Holladay | | #8

    Peter,
    That's a bad idea, for two important reasons. The first is one that you have identified: thermal bridging.

    The second involves water management. A patio slab will be soaked by rain (and possibly covered with snow), and that means that water will wick indoors continuously whenever the slab is damp.

    Fortunately, the solution is simple: pour these two slabs separately, and make sure that there is a thick layer of vertical rigid foam between the two slabs. Ideally, the exterior slab will be about 7 inches lower than the house slab, to manage water entry.

    1. Tim_E | | #9

      I have a monolithic slab with perimeter insulation and am not certain how to handle the transition from the garage to the driveway and keep the thermal break. I would also like help making the garage door as airtight as possible.

      Along these same lines i would like to know the best option with the other doors in the house. The windows are easy but how do we keep the thermal break with the doors?

      1. Trevor_Lambert | | #10
        1. Tim_E | | #11

          yes, i had a look and didn't really find a solution. garages are generally dropped to a stem wall slab arrangement so i guess we are asking about something that is seldom done...

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