what is the minimum degree of elevation for the roof to allow a good rain water flow??

Question

what is the minimum degree of elevation for the roof to allow a good rain water flow??

Answer 1

The most common roofing material in most parts of the USA is the three tab asphalt shingle. Most manufacturers go to great lengths to get across the point that these shingles are not designed for roofs with less than a 3" in 12" pitch. They will leak. Furthermore, most waranties are voided if installed on such a roof. Most builders will not install these shingles on a roof with less than a 4" in 12" (33.3 degree) pitch for a variety of reasons.



Therefore, a 33.3 degree elevation is the minimum elevation for most roofs. Other roofing materials offer the option of constructing near flat roofs, but are uncommon in most parts of the country for residential construction.



Good luck with your roofing project.

Answer 2

I do not know of anything in the international building code, international residential code, or uniform building code which almost everyone uses here in the states that dictates minimum slope, heck it allows for flat slopes. However, there are some homeowner associations and covenants, conditions, and restrictions in some neighborhoods that require a certain pitch roof so all of the houses will look similar in the same neighborhood. Like someone answer earlier, a 4 in 12 pitch roof would be the minimum you would want if you plan on using regular shingles and if you want the roof to last longer. If you use less than a 4 in 12 pitch you need to use rolled roofing and overlap the joints a minimum of 4 " with a layer of roofing tar to join the seams. There are very few instances that I can see why someone would want to use less than a 4 in 12.

Answer 3

I suspect,,given that I don't have my protractor at hand, that 20 degrees would be adequate. Certainly roof pitch may vary on the same house, IE: Entries, style, etc.



You don't state if you are building, or just questioning, but the style of the house and size largely define roof pitch. I have to believe there are specific codes and standards no matter where you live.



I live in Central FL, and there are still many FLAT or minimal pitch roofs, some still in gravel.



Good Rain Flow is a subjective phrase. What is it you wish to achieve, within reason? Do you have gutters? Does the pitch and the drainage from it cause damage to the ground beneath?



Rev. Steven

Answer 4

Depends on the materials you choose to build with, raining will weigh down the roof and cause leaks and creaks for plywood or any wood. The height doesn't matter as long as the material will sustain the weather changes and not wear away easily, and there is proper drainage. Flat roof have pvc's angled below the landing of the roof from inner wall to the outer wall. Also depends on your local building restrictions and regulations, you may have to clear it up with a contractor or even visit or call your neighboring hardware store for a workshop.

Answer 5

In the construction trades, roof slopes are considered as a run of inches for each foot of elevation. So 4 inches of run per 12 inches is called a 4/12 pitch. If you go with less pitch than that, then shingles aren't effective.

Answer 6

18.4 degrees, which is a 4 in 12 or 1/3 pitch. This is about minimum for regular three tab shingles as stated earlier.

Answer 7

I'm not an engineer, but I'd say 30 degrees.