Roofing Math

[JOEX]

I need some help with figuring the amount of materials I need for the roof of a shop i'm building. I've looked up a few online calculators but they keep asking for measurements I don't don't know:ermm:

It's a hipped roof and the demensions including the eaves are 22' x 32'

Pitch is 5/12

I'd like to know how much sheathing, tar paper and shingles I need.

If you can show me how to do the math that would be great too:D I can do the standard gable roof but the hipped roof is throwing me off:(

Thanks:)

[wilkin250r]

What kind of measurements do you need?

I plugged your measurements into AutoCAD, and then laid it flat to get the square footage.

You know what I came up with? It's almost IDENTICAL in square footage to a simple Gable Roof design.

The top is a Gabled roof design, laid flat, 22' x 32' Notice that once it is laid flat, 22' becomes 22.83'.

The bottom design is the same 22' x 32' in a hipped roof design, laid flat. With this visual, you can see the square footage is almost identical.

[Giz400ex]

22x32=704, then if both sides of the roof are the same then x2 which is 1408. So as shingles goes you can get 15 sq and cut it close or be safe than sorry and 16sq. I always add a sq to be safe. It also depends on what type of shingle you'll be using. Arc's have less waste but if you go with the reg 3 tab shingle there's gonna be more than the Arc's. As for anything else, you can just tell them what you numbers and they'll hook ya with sheathing and paper. The paper covers alot area so you won't need many of those.

[bwamos]

ROOF SUMMARY REPORT
New Project 09212007
New Order Unit Unit:1 Alt:0 Rev:0

Panel Surface
Roof Area Area Eave Ridge Hip
sq-ft sq-ft ln-ft ln-ft ln-ft

R1 284.63 250.25 32.00 10.00 32.43
R2 284.69 250.25 32.00 10.00 32.43
R3 168.68 131.08 22.00 - 32.43
R4 168.67 131.08 22.00 - 32.43

Tot 906.67 762.67 108.00 10.00 64.87




I work for a pre-engineered metal buildings manufacturer. You can ignore the "panel area" column. That includes our panel scrap at the hips.

For a quick calc you can simply multiply your flat roof area by 1.0833 to get the sqft on slope for a 5:12 roof area.

[sqrt(rise^2 + run^2)]/12 = slope factor.

Sqft of a hipped roof, gable roof and single slope roof on 5:12 will all be exactly the same. However you'll need more scrap material on a hipped roof.

[JOEX]

Thanks for the replies, algebra 1 was 25 years ago and I barely survived:ermm: :p

If i'm figuring correctly i'll need about 8 squares of shingles.

Giz400ex, why did you double the 704 figure?

[Giz400ex]

Originally posted by JOEX
Thanks for the replies, algebra 1 was 25 years ago and I barely survived:ermm: :p

If i'm figuring correctly i'll need about 8 squares of shingles.

Giz400ex, why did you double the 704 figure? Are there 4 sides to the building?

[JOEX]

Originally posted by Giz400ex
Are there 4 sides to the building?
Yea, but what does that have to do with the roof:confused:

[Giz400ex]

Originally posted by JOEX
Yea, but what does that have to do with the roof:confused: So, 2 sides measure 22 and the other 2 sides measure 32....right?

[JOEX]

Originally posted by Giz400ex
So, 2 sides measure 22 and the other 2 sides measure 32....right?
Correct.

To figure area it's length X width---

32x22=704 then to add the pitch it's 704x1.0833=762.64

= 8 squares

Unless we're thinking two different things:p

[Giz400ex]

Originally posted by JOEX


Unless we're thinking two different things:p Yep! I'm frigin idiot!!! I was thinking of a different layout:mad: Sorry about that but.....at least our post count went up:D j/k

[Giz400ex]

Your gonna have alot of waste, you might want to grab some extra bundles to save a trip back to the store. This I do know:rolleyes:

[86 Quad R]

Originally posted by Giz400ex
Your gonna have alot of waste, you might want to grab some extra bundles to save a trip back to the store. This I do know:rolleyes:

yuppers and almost always the bundles in a pallet were from the same run. which means that if ya need to go back for more. you'll be getting a mismatche in color. if that is a concern to you. lol