I need help with roof measurment

[pourfolkes]

We are thinking of building out own home and I am estimating the materials. For the life of me, I can not figure out how to estimate the amount of material needed for the roof...... duh.... It is going to be a 40x40' home, gabled roof. I am trying to determine how many feet it will be from the center of the roof to the end of the eave. The rest, I think I have figured out. Does anyone know how to do this? Thanks

[PyroDon]

what pitch do you want the roof to be . how many inches drop in one ft
have you figured in your over hangs . 40x40 flat would be a 16 square roof but when you add the pitch and over hangs every thing changes

[pourfolkes]

I want a 4/12 pitch and a 12" overhang... Thanks

[hillsidedigger]

How wide is the overhang (eve) and what is the pitch?

[hillsidedigger]

1.0541 X 21 X 42 X 2 = 1859.42 square feet of roof surface.

Centerline top of roof frame to edge of eve would be 22.14' or more commonly 22', one and 3/4 of an inch +/-.

The 1.0541 comes from the (square root of (4X4 + 12X12)) divided by 12.

[hotzcatz]

The other option is to draw it to scale and then measure it out. I have AutoCAD measure it after I've drawn it but you gotta have the program first.

AutoCAD comes up with 22'-1 5/8" long at a 4 in 12 pitch and 21'-10 1/4" at a 3.5 in 12 pitch.

[YuccaFlatsRanch]

A squared + B squared = C squared.

[PyroDon]

58 sheets of 4x8 decking ten rolls of 30 pound felt, 19 and 2/3s squares of shingles (have to remember starters and ridge) 15 pieces of rolex ODE roof edge . misc pipe flashings and two rolls of ridge vent .
or you can always go with metal

[Bearfootfarm]

http://www3.telus.net/selkirk99/selk...s/rafters.html

Posts #5 and #7 are the only ones that came even CLOSE to answering the actual question

[Columbia,SC.]

1022 this transmission,lol

[Columbia,SC.]

if it is 40'x40' that is 1,600 sq feet. a square of shingles covers 100' square feet that is 16 squares, 40x20 = 800 + 40x20= 800 more ( front side plus back side) plus 1' x's 12" ='s 160 extra square feet or 1.6 extra squares add in the hangover (due to the math ,hahaha),
plus the ridge and starter shingles (upside down along the perimeter), just go crazy and add one more square. Then add 10% for waste. I would figure 20-21 squares, my math does not add up but but it should be pretty close. remember that you also need 15 # felt paper and it covers 3 squares also. so there goes another 6-7 rolls in the mix of the cost. Also remember you need vent caps and flashing as needed, plus nails, caulking ect.
Also you can take back what you do not use, but be sure to keep one or two bundles for repaires for the future! You will be glad you did!

[haypoint]

Yup, A squared+ B squared = C squared, but you need to know how that relates to the question. From what I've read on this thread, it has been explained several ways, but not in a way for the beginning builder to understand.
With a 4:12 pitch the rise from the side wall to the center of the house is figured like this: Since this 40 feet wide house is 20 feet to the center, divide 20 by 12 and you get 1.66666. Take that and multiply it by 4. (If you had a 6:12 pitch you'd multiply it by 6.). You come up with 6.6666 feet ( that's 6 feet and 8 inches, but let's keep it simple for now). This is the "rise" or the height to the peak. The A square(times itself) + B square (times itself) is the length of the triangle that forms half of the roof. In this example you multiply 20 feet by 20 feet, then multiply the rise, 6.6666 by 6.6666. Now add the two together and get 444.444. Now hit your square root button. You get 21.08 feet. Add the amount of overhang you want and you get the length. In figuring your sheeting, it is 21.08 X 2 X 40 feet, plus the overhang on all 4 sides.
Generally cheaper to have a truss company build your trusses, plus many building codes require an engineered truss for homes.

[Columbia,SC.]

Originally Posted by haypoint

Yup, A squared+ B squared = C squared, but you need to know how that relates to the question. From what I've read on this thread, it has been explained several ways, but not in a way for the beginning builder to understand.
With a 4:12 pitch the rise from the side wall to the center of the house is figured like this: Since this 40 feet wide house is 20 feet to the center, divide 20 by 12 and you get 1.66666. Take that and multiply it by 4. (If you had a 6:12 pitch you'd multiply it by 6.). You come up with 6.6666 feet ( that's 6 feet and 8 inches, but let's keep it simple for now). This is the "rise" or the height to the peak. The A square(times itself) + B square (times itself) is the length of the triangle that forms half of the roof. In this example you multiply 20 feet by 20 feet, then multiply the rise, 6.6666 by 6.6666. Now add the two together and get 444.444. Now hit your square root button. You get 21.08 feet. Add the amount of overhang you want and you get the length. In figuring your sheeting, it is 21.08 X 2 X 40 feet, plus the overhang on all 4 sides.
Generally cheaper to have a truss company build your trusses, plus many building codes require an engineered truss for homes.

uuhhhh, I would go by what he said or something...lol
I am sure he is correct! I only have a couple (23) years doing this, and as I said before buy extra and carry back what you don't need. If it was me I would figure the amount that I stated above but what do I know? I am flying by the seat of my pants here.

[Columbia,SC.]

I forgot to add 56 pcs. of 4x8 sheeting, add 10% and figure 62 sheets
I don't know the calculus to figure the amount of nails....or the number of school books to hammer them in with..LOL I would go with a 50 pound box of nails each to start with.

[haypoint]

62 sheets that Columbia suggested is 1984 square feet. The figures I offered ( 21.08 X 2 X 40 feet, plus the overhang on all 4 sides.) is 1686.4. If we allow a 12 inch overhang, it will take 42+42+44+44=172 more. So 1686.4 + 172=1858.4 square feet. By these figures, you'd use 58 sheets if you had no waste. An extra 4 sheets seems normal. So, Columbia is right on. I don't know anyone that's still using nails. Staples hold better and are cheaper and faster to apply.
I don't recall much of my High School Algebra, but A squared plus B squared = C squared is one I use all the time. I think it was part of the residential Contractor's Licenseing test.

[Columbia,SC.]

I also took the Residential Contractor's Licenseing test 10 or so years back, proud to say I passed it the first time around, (material take off and codes) Many of the old timers I know/ learned from had to go back a couple times.....It upgraded to only allow 10% wrong answears the year I took it instead of the 15% they allowed in the years before I got my license. This was a 6-8 hour test and we had to sign in and out if we needed a bathroom break.
I do it the simple way, this side times that side equals the total square footage.
A square of shingles or siding is 10'x 10' = 100 square feet, plywood is 4'x8' = 32 square feet. Always throw in 10% for waste and a little extra depending on the 'pitch', it should work out prety close.
That is my country boy math lesson for today.