Door threshold height on Roof Deck: Is this a code violation?

shw001September 3, 2013

There is a flat roof (about 300 square feet) on a one-story part of my house. There is a door out to it from one of the bedrooms. The door threshold is 3 inches above the roof deck. I am thinking of adding insulation to the roof and a new rubber/plastic roof membrane which would reduce the threshold height to only 1/2 inch above the deck. Does anyone see any practical issues or building code issues with such a small clearance?

We do not use this roof, except for occasional maintenance, like gutter cleaning.

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Assuming a roof deck door is a means of "egress"--and it may not be--this section of the International Residential Code 2009 indicates no violation. Of course, IRC 2009 doesn't apply in all states. So you'll have to figure out what Code does apply.

This post was edited by worthy on Tue, Sep 3, 13 at 19:26

    Bookmark   September 3, 2013 at 7:25PM
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I don't know how big your typical rainstorms are, but 1/2" isn't much leeway if you get water pooling on a flat deck area. Depending on where you measured the height, it make take even less than 1/2" of water before you get infiltration into the bottom of the threshold.


    Bookmark   September 5, 2013 at 5:43AM
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I would not lower the threshold at all. Insulate from below or shorten the door and raise the threshold and take that opportunity to properly waterproof it. You will probably need to replace all of the wall flashing too.

    Bookmark   September 5, 2013 at 4:13PM
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Bruce, The threshold is concrete and does slope pretty well and extends out about 8 inches from the door. There is also a storm door that the threshold goes under and extends out about 2 inches past the storm door. The roof membrane will extend over the threashold, so there is no infiltration at the bottom. There is not likely to be puddling near the door because the slope of the roof is now 1/8 inch per foot, and after the new tapered insulation will be ü inch per foot.

Renovator, your suggestion might work, with a tweak. I could build a 3-4 inch curb under the storm door (on top of the concrete step) and shorten the storm door (it is wood). The innder door would remain unchanged at full height. The membrane would go over the curve and be properly adhered, sealed, and flashed. However, it would be a bit awkward, because to go out onto the deck, someone would open the inner door and be faced with a 4-inch curb to step over. I am not shure if this would be an accident-prone situation? Any thoughts?

Wothy, thanks for the reference. I have not had a chance yet, but will check the IRC. In my county, they use different editions for different parts of the code, so it takes some digging.

    Bookmark   September 8, 2013 at 11:00PM
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Never been to Maryland, but my concern would be snow...and heavy rains also; if the membrane will extend over the threshold, won't that create an easy route for melting water to enter under the door?

I'd insulate from below, and leave the present deck surface alone, with the possible exception of a new membrane if needed.

    Bookmark   September 14, 2013 at 9:44PM
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