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Discussion Starter · #1 ·
is a small bump out in a concrete slab necessary at an exterior door? (those without some sort of masonry detail) i don't recall seeing this as a common detail. maybe I've simply not noticed.

I understand that a 2" bump-out would help support a threshold, but i just don't recall seeing this as a common detail.

thanks in advance
 

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I've never seen it in school or hospital work where one encounters some of the most detailed oriented funny papers you will ever see.
 

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When we pour a floor, for a slab on grade exterior door, we extend the floor 1 1/2 to 2" to support the threshold. In a std PH exterior door the threshold extends about that far past the wall line. Without the extension, the exterior slab would extend under the threshold and make it susceptible to frost heave in our climate.
 

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When we pour a floor, for a slab on grade exterior door, we extend the floor 1 1/2 to 2" to support the threshold. In a std PH exterior door the threshold extends about that far past the wall line. Without the extension, the exterior slab would extend under the threshold and make it susceptible to frost heave in our climate.



We do the same here,N.W. Indiana.:thumbsup:
 

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When we pour a floor, for a slab on grade exterior door, we extend the floor 1 1/2 to 2" to support the threshold. In a std PH exterior door the threshold extends about that far past the wall line. Without the extension, the exterior slab would extend under the threshold and make it susceptible to frost heave in our climate.
We typically have frostproof edges on stoops or slabs at entry doors to eliminate the need to extend the slab under a threshold.
 

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This was not a slab on grade situation, but the detail we do is pretty much the same. See door opening...

We bump out the slab 1-1/2" to give the door sill something to set on. If this were at grade, you would want to have a step from the house slab to grade.

Better to have it and not need it, than get kicked around because the sill is sticking out in the wind.

 

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That looks correct to me.

Now, if it were the same level, I'm gonna disagree with the others. I always like to hold my edge form in a couple inches, so the sidewalk extends under the threshold. It won't heave-it's still splitting the foundation wall. The reason I do this is because I've been burned too many times on punchlist for the edge of the interior finished slab showing an inch or two outside before the sidewalk starts. That looks terrible, and is hard to sell. As far as threshold support I don't install thresholds until after the sidewalk is done anyway, because nobody protects it from the sidewalk mud and I'm stuck cleaning it off.
 

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I've been in the biz for 35 years and have never seen a slab poured out into a doorway. It sounds like a great idea though. We always have to go back and hilti a pt board on under the sill to support it.
 

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Discussion Starter · #13 ·
good photo. in this instance you have the brick ledge that allows an easy way to extend it at the threshold. what we do in this instance is hold the slab down and lay a course of bricks, like one under a window sill.

as some have mentioned, in what i was describing, there would be a small section (width of the threshold) that would extend beyond the outside edge of the stud wall / foundation.

so it looks like, as always, there are several ways to skin a cat.

thanks for the input guys.
 

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We extend the slab about 6", similar to the pict tgeb posted.

Our homes are slab-on-grade with stemwall foundations. The top of the stemwall is broken out at the location of the door, the slab is continuous to about 6" beyond the stemwall.

Frost heave is not an issue, the soil is very dry and we don't get much frost.

It looks better, it supports the threshold better.
 
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