Roof geometry question

[Dennis J. Bonner]

Two story home. mostly hip. one gable in front(20'), and small flat(10x10) on top of a hip. the flat is def less than 10%. the roof perimeter is 240+/-(major pain in the a** to measure) Its so damn close.. Do you guys count the edges of this type of flat section while factoring other? Feedback appreciated

[Dennis J. Bonner]

Btw, the flat section is on top of the garage on left side

[dquigley]

Not exactly sure what your asking --- but --- rule for flat roofs - if more than 100 s.f. of total roof area is flat or if greater than 10% of total roof area is flat, whichever is greater - then the roof would classify as flat -- the greater here would be the 10% of total roof area - you don't have a flat roof by definition if the total roof area is at least 1000 sf. Also, the gable of 20 lf is less than 10% of the total roof perimeter of 240 lf, so your roof should be classified as "hip". You do not count the lf of the flat portion of the roof in your total calc of roof perimeter, that would be double dipping since it was already counted on the lower edge of the hip -- if i understand things correctly. Does that reduce your total roof perimeter to 200 lf? If so you are still just barely ok as a "hip" classification. One more thing, the gable roof lineal footage should be measured as a horizontal distance across the bottom chord of the gable. Do not measure it up and back down the rake (or fascia) -- Hope that helps

[Robert R. Hanson]

Do you think the flat roof is ten % of the entire roof?

[Dennis J. Bonner]

no i know for sure the flat is not greater than 10% of roof area. My situation is that im between hip and other. the gable is 20', the total roof perimeter is over 200 lineal feet(just the foot print, actually) . The underwriter is saying that I need to figure the 10' sides of the flat sections on top of the hip roof while calculating other. I have the same understanding of this as D.Quigley stated above, so i went to the bill york manual page.124 -in the table, second bullet down- it says to count roof edges which are flat as other, but would this circumstance count as a roof "edge"-since its not the end or fascia board?

[dquigley]

Hmmm - Now i see your delima - This should be a Wind Mit Scenario.
This one might need to be sent to Bill York for a review. The fact that the flat portion does not have a fascia and it appears to butt up to a wall on three sides makes me think that only one side should be considered. This roof being protected on three sides does not have the same uplift properties that a conventional flat roof would have. Most flat roofs are a problem when the wind blows across creating neg pressure at the surface resulting in uplift on the roof. This won't happen here if i'm reading the photo correctly.

[Dennis J. Bonner]

i, know right, 6 months ago, it was an "other" slam dunk

[John Shishilla]

The Flat/hip portion would be counted as other. It is not all flat and not all hip.

[Dennis J. Bonner]

other or non hip? non-hip specifically excludes flat roofs

[Brian C. Hoagland]

Once again we will make it up as we go along, then change it later on as some new expert weighs in. I'm having deja' vu or maybe it's a bad acid trip flashback whoa it's worse... it's reality. Need new form this one does not work.

[Dennis J. Bonner]

Originally Posted by dbonner

i, know right, 6 months ago, it was an "other" slam dunk

This is the right intrepretation, according to the experts. Thanks John