The pitch of a roof - Roofing Talk

English Roofer · 01-04-2009, 05:37 PM

Hi guys, i have a question, you guys ,when you talk of pitch of a roof say the pitch was less than 4:12 etc, im not sure what that actually means we say in degrees as in a 33 degree roof, can some one explain please?
Cheers
Dave

Mike Lamb · 01-04-2009, 06:24 PM

http://roofgenius.com/roof-pitch-degrees.asp

It's the inch rise of the roof every horizontal 12" or one foot run. It's probably a US thing. For instance, I didn't know 50 mm is about 2". I had to go to a metric conversion chart. A 4:12 = 18.5 degrees.

Grumpy · 01-05-2009, 12:58 PM

4:12 means that for ever 12" horizontally I travel, I am moving 4" vertically. If you take a right-triangle and the base is 12", the side will be 4". the sidSame thing Mike said above, but I felt like typing it too

English Roofer · 01-05-2009, 05:10 PM

Cheers Guys that explains it!

Ed the Roofer · 01-06-2009, 10:55 AM

It would still translate the same way in metric versus US standard, by the way.

Ed

GreenTree · 03-14-2009, 02:39 AM

And you convert slope (4:12) to degrees using tan. So, tan(x) = 4 / 12 where x is the slope in degrees.
tan(x) = 0.3333
x = atan(0.3333)
x = 18.4 degrees

English Roofer · 03-14-2009, 10:14 AM

Quote:

Originally Posted by GreenTree

And you convert slope (4:12) to degrees using tan. So, tan(x) = 4 / 12 where x is the slope in degrees.
tan(x) = 0.3333
x = atan(0.3333)
x = 18.4 degrees

Thanks for that!

01-04-2009, 05:37 PM	#1
English Roofer Roofing Expert Join Date: Dec 2008 Posts: 104	The pitch of a roof Hi guys, i have a question, you guys ,when you talk of pitch of a roof say the pitch was less than 4:12 etc, im not sure what that actually means we say in degrees as in a 33 degree roof, can some one explain please? Cheers Dave

01-04-2009, 06:24 PM	#2
Mike Lamb Junior Member Join Date: Nov 2008 Location: Chicago Posts: 7	http://roofgenius.com/roof-pitch-degrees.asp It's the inch rise of the roof every horizontal 12" or one foot run. It's probably a US thing. For instance, I didn't know 50 mm is about 2". I had to go to a metric conversion chart. A 4:12 = 18.5 degrees. Last edited by Mike Lamb; 01-04-2009 at 06:26 PM.

01-05-2009, 12:58 PM	#3
Grumpy Senior Member Join Date: Oct 2008 Location: Chicago, IL Posts: 464	4:12 means that for ever 12" horizontally I travel, I am moving 4" vertically. If you take a right-triangle and the base is 12", the side will be 4". the sidSame thing Mike said above, but I felt like typing it too __________________ -Grumpy Chicago Gutters Chicago Roofing

01-06-2009, 10:55 AM	#5
Ed the Roofer Super Moderator Join Date: Sep 2008 Posts: 503	It would still translate the same way in metric versus US standard, by the way. Ed __________________ Just Wait A Minute, I Will Be Right Back With A Link For That. http://www.rightwayroofingcompany.com/ www.rightwayroofingcompany.com Roof Estimates, Roof Repairs, Roofers, Roof Leak Help, Elgin, Carpentersville, East Dundee, West Dundee, Sleepy Hollow, Algonquin, South Elgin, Huntley, Lake In The Hills, Illinois

03-14-2009, 02:39 AM	#6
GreenTree Jason at Green Tree Join Date: Mar 2009 Location: Vancouver, BC Posts: 14	And you convert slope (4:12) to degrees using tan. So, tan(x) = 4 / 12 where x is the slope in degrees. tan(x) = 0.3333 x = atan(0.3333) x = 18.4 degrees __________________ www.greentreeroofing.ca Roofers who care about the environment

01-05-2009, 05:10 PM	#4
English Roofer Roofing Expert Join Date: Dec 2008 Posts: 104	Cheers Guys that explains it!

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