> >
>

# Metal roof question.

## Metal roof question.

#1
04-02-08, 06:54 PM
Member
Join Date: Oct 2005
Location: New Hampshire
Posts: 231
Metal roof question.

Hi, i will be framing a shed roof with a 4/12 pitch. (4" rise to 12" run). The outside of my top plates measure 11' 6" from exterior side to exterior side. My rafters will have an 8" hangover on each side. Can someone tell me the length of each metal panel (it must be custom ordered). I realize I can easily frame it first and measure, however, I own my mobile home but I am in a MH park. There is a 10 day lead time needed to order the metal panels and my park rules do not allow us to use tarps or leave exposed sheathing for more than 3 days. So, I'm asking so that I can have all materials on hand before construction to comply with park rules. I asked this question at the big box stores contractor counter and they looked at me like I was from mars.
-THANKS
Bob

#2
04-02-08, 07:06 PM
Group Moderator
Join Date: Dec 2004
Posts: 26,816
If I'm not mistaken, the length from the center of ridge to the edge of the fascia would be 81 3/16. You'll likely have some gap between panels at the top and some overhang over the fascia at the bottom, so you might want to get them 82 / 83" or so.

Maybe someone else will check my math.

#3
04-02-08, 10:20 PM
Member
Join Date: Mar 2008
Posts: 14
What about the overhang?8" overhang,plus overhang at eaves,I got around 94"?Just my calculations,correct me if I'm wrong

#4
04-03-08, 01:36 AM
Group Moderator
Join Date: Dec 2004
Posts: 26,816
11' 6" is 138". 8" of overhang on each side is another 16". 138 + 16 = 154. 154/2 = 77. A triangle with a 4:12 pitch would have a rise of 25.77 and a run of 77. The hypotenuse of such a triangle would be 81.165. Unless I'm missing something.

#5
04-03-08, 07:06 AM
Member
Join Date: Oct 2005
Location: New Hampshire
Posts: 231
Thanks XSleeper.....your calculations seem right on the money. Now, can you figure out the delegate count so I can predict the next election! Thanks again.
-Bob

#6
04-03-08, 10:42 AM
Member
Join Date: Apr 2007
Location: Richmond, Va.
Posts: 154
Sleeper is right. You might want to add 1" to be able to box the pans at the top and another 1-2" to allow for a dripedge and an inch over it to lock the panels.

If wrong, it's sure easier to cut an 1" or so off than to add it.

#7
04-15-08, 10:31 AM
Member
Join Date: Oct 2005
Location: New Hampshire
Posts: 231
Greetings to all. I have had to do recalculate my rise. Xsleepers calculations are right on the money. The information I gave is wrong. After checking all the other mobiles in our park 99% of them have a 48" rise at the center ridge. If homewidth is 138" and I want eaves to overhang another 8" (138 + 8 + 8 = 154). Then my rise to the top of the ridge beam is 48". So now I need to recalculate my pitch # (8:12?) and my new rafter length. This will allow me tomake my "birdsmouth" cut properly without ruining the first 10 rafters! Thanks to all you great folks who can jump in with some help.
-Bob

#8
04-15-08, 11:06 AM
Forum Topic Moderator
Join Date: Mar 2005
Location: USA - N.E.Tn
Posts: 45,490
An 8/12 pitch is fairly steep. Most MHs have a roof on a 3/12 pitch.

#9
04-15-08, 11:16 AM
Member
Join Date: Oct 2005
Location: New Hampshire
Posts: 231
HI, thank you for a quick reaponse. That is why I put a question mark next to my 8:12 figure. I know I am not calculating right. However, my measurement of a 48" rise is exact for most of the MH in this park. So, span of 138" plus 16" for (2) rafter tails = 154". My run then equals 1/2 the span or 77" and my rise will be 48". With these figures can you calculate for me the pitch # and rafter length? THANKS.

#10
04-15-08, 11:26 AM
Forum Topic Moderator
Join Date: Mar 2005
Location: USA - N.E.Tn
Posts: 45,490
I'll leave that to XSleeper or one of the other carpenters it might tax this painter's brain too much

A 3/12 pitch = 3" rise for every 12", 4/12 = 4" rise

#11
04-15-08, 01:06 PM
Member
Join Date: Oct 2005
Location: New Hampshire
Posts: 231
Exactly, the 4:12 pitch only gets me a rise of 25.77 inches and I need to get to a rise of 48", so my pitch will definitely increase....but to what....well that's why I'll wait for XSleeper.
THANKS AGAIN!

#12
04-15-08, 05:54 PM
Group Moderator
Join Date: Dec 2004
Posts: 26,816
Ha ha, you guys are killing me... but it's nice to feel needed!

The closest standard pitch given your measurements would be 7 1/2:12, which would mean your rise would actually be 48 1/8". The hypotenuse of a triangle with sides 48.125 and 77 would be: 90.8, or roughly 90 13/16.

7 1/2:12 does seem steep for a trailer. The ones you checked that are 48" high are just as wide as yours is?

So you'd want your metal to be about 91" or so. Dropping the sheets 1" down from the top would give you something like a 1 1/4" overhang at the bottom. (assuming your fascia is included in the 8" overhang).

Don't forget to order foam closure with your sheets of roof metal. (upper and lower)

#13
04-15-08, 06:39 PM
Member
Join Date: Oct 2005
Location: New Hampshire
Posts: 231
You're great....I knew i would be punished someday for sleeping the whole semester of geometry class. Yea, just about everyone here in New hampshire has steeper roofs on their sheds and MH's....the steepness helps with the snow loads. Have a great nite.
-Bob

#14
04-15-08, 07:09 PM
Group Moderator
Join Date: Dec 2004
Posts: 26,816
No problem! I thought Geometry was great. I slept during Shakespeare. Maybe I just thought Geometry was great by comparison. LOL