My roof is 18ft by 12ft - hipped four sides. That’s 18 ft around each side and 12ft from the middle of each side to the top - there’s no ridge. So far pretty simple. The square footage of each side is therefore 18 x 12 / 2 = 108 so x 4 would be the total sq ft: 432. How am I doing?
I’m using metal sheeting which is 33 inches wide - allow three for the overlap so you’ve got 30" for each sheet. The roofing company told me to bring the measurements and they would calculate how much I need. Well, it’s been days now and they havn’t managed to come up with the figures. They say it’s very complicated , having previously told me it could be done in minutes. After they come up with the quote it’ll then take days before they get around to cutting the sheets… I’m running out of time, so I want to just give them the sizes but I’m crap at maths.
The builder says to get 4 x 12’, 8 x 10’, 8 x 8’ and 8 x 4’ - that would be 224 ft in total. Isn’t this a lot of waste surely? I tried to figure out using less footage by cutting the angle on a longer piece (the builder is wanting each piece separately) which I worked out to be the following: 4 x 12’, 4 x 24’, 4 x 12’ and 4 x 5’ making 200 ft - a difference of 24 ft - just from using more efficient cuts. The last **three **measurements would then be cut on the angle in half. Am I missing something?
Any input would be greatly appreciated - I’ve even made a little origami roof to try to test my measurements!
You have waste in roofing so seams don’t line up, and you want minimum lengths because too short a piece is likely to give problems later. The intersection of roofs is another big waste. They also get damaged during installation or are damaged on delivery. You don’t want to run out or you will have grief. Shingles do come in lot numbers too. Most people want the roof to match and recognize the extra expense of an unfinished roof. You have the potential of rain damage and extra labor costs to come back to it and finish it. Most people want to keep a few shingles as repair pieces later so it comes close to matching the shingles already down. Most lumber yards will take back the unopened shingles if you didn’t damage them, but you need to ask them their policy.
What the heck are you building that is 18’ square and has a roof that doesn’t have a ridge? Does the roof rise to a point like a pyramid? In which case it sounds like your building a bell tower? Or are the metal sections your describing nearly vertical and the top of the roof is largely flat (called a mansard roof)? In which case it sound like your building a very nice shed. I kid this sounds like a free standing portion of a larger roof.
Regardless like Harmonious said you should plan for extra also known as over run or waste. At least 10% more like 20% on a roof that small. Is this copper? Is it standing seam or flat seamed? Who is installing it? All play into how much over run you need.
Thanks for the responses, guys, I really appreciate it. I’m not using shingles though I wish I could. Here we collect the rainwater to drink from the roof so shingles can’t be used - or rather you wouldn’t be able to drink the water from them without extensive filtering.
Harmonius - it’s a bedroom. This type of roof is pretty standard in the Caribbean. It’s 7 / 12 pitch, so yes I guess it’s like a four sided pyramid. You’ve answered my concern that indeed there will be waste which is unavoidable.
http://vixenhill.com/Merchant2/graphics/00000001/Cabana%2016x16_6_product.jpg
It looks something like the link above but without the hat.