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Thermally breaking a threshold

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?

Asked by Peter L
Posted Thu, 03/06/2014 - 23:09
Edited Fri, 03/07/2014 - 08:58

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8 Answers

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2.
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Pemko also has thermally broken thresholds.

Answered by David Meiland
Posted Fri, 03/07/2014 - 10:46

3.
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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.

Answered by Peter L
Posted Fri, 03/07/2014 - 14:02

4.
Helpful? 0

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?

Answered by Malcolm Taylor
Posted Sat, 03/08/2014 - 00:52

5.
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Do you mean a mono-slab, or are you pouring stem walls first and then slab within?

Answered by David Meiland
Posted Sat, 03/08/2014 - 01:25

6.
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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)?

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Insulated slab.jpg
Answered by Martin Holladay, GBA Advisor
Posted Sat, 03/08/2014 - 06:10
Edited Sat, 03/08/2014 - 06:11.

7.
Helpful? 0

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.

Answered by Peter L
Posted Sun, 03/09/2014 - 11:28

8.
Helpful? 0

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.

Answered by Martin Holladay, GBA Advisor
Posted Sun, 03/09/2014 - 11:34
Edited Sun, 03/09/2014 - 11:35.

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