Replies

1. 
   calvin | Dec 10, 2020 07:30pm | #1

   Matching a slope and or cutting a roof for an addition etc, it is what you say it is. The only real answer is that it is all the same on that slope so every connection fits like a glove....

   Or close.

   When framing new houses, never did layout in the point five.
   Remodels, repairs and additions, plenty of times. A tapered line on two gables a foot apart, one below the other?.....ugh.

1. 
   ragnar704 | Dec 10, 2020 09:03pm | #2

   I can understand that with remodels you have to just make due with what is there. But with new construction you have always used whole (exact) numbers?

1. 
   calvin | Dec 10, 2020 10:23pm | #3

   Yes, but I have not built thousands of homes either. I suppose there would be a reason to fraction it but why?

   Now, with a very low slope roof, easy to understand. Perhaps even to make your roof look good with the mountain range under or behind it.

   Why do you think?

2. 
   ragnar704 | Dec 11, 2020 12:26am | #4

   Oh! Perhaps I should have said why I was asking. I'm producing as-built drawings of a house for a remodel. The house was built in the 1920s and has sloping ceilings in parts of the upper level. Based on what I'm seeing, it looks like the slope is closer to 7.5/12 than 7/12. So I got to wondering if it was common to break away from whole numbers when laying out slopes.

1. 
   calvin | Dec 11, 2020 06:48am | #6

   Yes, it’s common for a question to not have all the info and responders often have to pull out the bits and pcs to be able to answer.

   1920’s? It probably started out at least an 8/12. A hundred yrs of sitting doesn’t mean there wasn’t movement. From seeing those tapered reveals several times on additions, I’d guess there are some builders that might follow a pitch called out on a drawing as gospel. Even then, you’d think they would hold a pair of rafters up to check fit against the existing structure.

   That’s for stick built. Trusses are a different story. Somebody had better crawl up there and check before order. So, to cover your rear I’d call out pitch to match on the drawing. You know, sort of like the label “ may contain peanuts” on packages.

3. 
   jlyda | Dec 11, 2020 02:44am | #5

   On new builds an odd slope is not common and truthfully the designer would probably be laughed out of business if done so. The only time you will see it is when tying into an existing structure or unique situation.

4. 
   andy_engel | Dec 11, 2020 06:58am | #7

   I've done it with very low slopes. Some shingle manufacturers allow their products to be used on 2.5/12 pitches, but not 2/12, for example. And when you're trying to balance roof pitch with building width and the elevation where a new roof meets an existing wall, fractions can become meaningful.

5. 
   ragnar704 | Dec 11, 2020 09:59pm | #8

   Thanks for the input, guys. I was already planning on putting a note on the drawings that things would need to be "verified in field" following demolition, but I'm obviously going to try to get things as accurate as I can from the start.

   For academic purposes, I'm going to go with the assumption that most (new at the time) roofs were framed to whole numbers UNLESS there was a compelling reason to deviate.

6. 
   user-6164958 | Dec 12, 2020 10:52pm | #9

   I have done it more than once. When the main roof line has an intersecting roof line and you want the ridge height to match. The main would be a whole number but the intersecting could be anything.