# Figuring ot the pitch of a roof with dimentions

Hello everyone and thank you for reading my post!

``````I have someone close to me who asks me to help her with her roof problem, so she emailed me the information including a couple of pictures. There is an original roof and the way she game me the measurements is like cutting the roof in two. So you end up with a triangle: The highest point is 12 inches, the horizontal side is 77 inches (of the triangle, the total length would be 77 inches x2) and the riser is 80 inches. Is there a way to find the pitch with this numbers?
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I seems to be a pretty flat roof so I wanted to know if it would be OK to have roof shingles which is what currently what the roof has.

That is half of the job. Someone before her, built a room 14 wide by 25 feet long, and they decided to built this roof flat! This roof is in very bad shape and needs to be replaced right away. The roof is 11 inches lower that the end of the original building’s roof, so I was planning in re framing the roof to match the original roof pitch so there is a continuation.

[quote=“jordan69s”]Hello everyone and thank you for reading my post!

``````I have someone close to me who asks me to help her with her roof problem, so she emailed me the information including a couple of pictures. There is an original roof and the way she game me the measurements is like cutting the roof in two. So you end up with a triangle: The highest point is 12 inches, the horizontal side is 77 inches (of the triangle, the total length would be 77 inches x2) and the riser is 80 inches. Is there a way to find the pitch with this numbers?[/quote]
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If I deciphered what you are saying correctly, those numbers don’t work.

Your looking at around 2 on 12, which is two low for shingles.

That sounds just right! What I did is I draw the dimensions in a large piece of paper at scale and calculated the pitch. I read that there is a composite shingle that can be use in this application as long as the nails are applied at the adhesive strip, sealing the shaft and the head of the nail with adhesive to form a waterproof seal. Is it this correct?

I don’t know of any nailable shingles that will warrant their shingle on that low pitch, but if you insist on using shingles. I would use a watershield, hot dipped galvanized nails and I would stagger the butt joints as far as possible. Since there is no warranty, I would let the seal strip do it’s job and not nail in the nail zone. I would place the nails at the top of the headlap. This is the only way that you can get a few more years out of it, before it leaks or blows off. Get right with God probably will be your best bet. Good luck with it.

ditto

Plus I would decrease the exposure by about an inch to provide more overlap.

Why shingles? Rubber is cheaper than shingles?

Great comments you guys and I thank you for them.

Why shingles? Perhaps because that is what I know what to do I never done a rubber roof before so I have not knowledge at all about it…

Do you get more years out of rubber?

Don’t you need to heat the rubber in order to seal the ends?

OK, I rather to the best job with the best materials… If rubber is the way to go, Could you guys provide me a few descriptive lines of how to install a rubber roof?

Do I still need to use ICE shield? (the job is upstate NY?

Is the rubber rated as shingles are?

I have torn a 20 year old roof off of a 3/12 with 1 layer of 15 lb. felt and seen not one spec of rotten sheathing. Now, a 3-12 is not a 2-12, but I have seen a 2-12 with 3 tabs and one layer of felt with very little rot on it, also close to 20 years old. Butt joints were staggered 6".

Keep in mind however that I do not live in upstate NY.

If your gonna use shingles i would use 3-tabs at that pitch.

You never done a rubber roof before so. Let’s get salf-edhered rools(base 2 sq and cap sheet+ color 1 sq/roll) It easy for first Stap.

What blacksquare is saying (I think) is that doing a Self Adhering modified bitumen roof may be the easiest for a first time install, and will be effective at that pitch. Rubber is good, but you will have to buy a big sheet of it (not sure how much you need) and a bunch of glue and screw caps and seam tape(if you have seams) etc…

Go to mulehide.com. They have good quality products and you can get them at ABC supply (probably one near you). They give you some specs and information on all the practical roofing materials for your project. Then you can make a good decision for yourself.

I have only ever done 2 self adhering mod bit roofs, both very recently. They are super easy to do.

Fairly i never nailed SBS base,sometimes used torch in could weather . that help stick better, after goes cap sheet. Never herd about any tape for that. i would like to see next tear off after me. alot of done.I use GAF liberty