That is such a good question. I've been debating on asking too. We're designing a living/dining room with a vaulted ceiling with wood beams. I just can't visualize it. Our room is 16 x 28 with 9ft plate ht. Our designer says our wall will be 14ft to the peak. I don't think that is tall enough.

I hope we both get a good education on vaulted ceiling ht.

I don't mind a vaulted ceiling if it's not extremely tall.. So it sounds like I want the opposite of what you want..a shorter ceiling, lol. That's why I'm trying to figure out how tall this would be. Not even sure we are using this plan yet.

maybe we can get a visual for you too. 14 sounds about right to me. I would rather not go any higher. What is the pitch on that part of the roof?

Mathematically speaking it's rise over run. So on graph paper-10/12 pitch would be (from your starting point) up 10 and over 12. 12/10 would be up 12 over 10. So no they are not the same. Draw it out next to each other and you can see the difference although it would be crude vs seeing a ceiling in 3-d.

That is a 10/12 pitch shown on both sides of the diagram. Roof pitch is ALWAYS expressed in /12 proportions. Halve your distance to the room and multiply by the rise in that distance. That gets you the external.

In your case, The roof will rise 80" on the exterior over that 8'. That is on the exterior. Exterior roof pitch often can have be unrelated to interior ceiling slope because of the required insulation and ventilation before you get to the interior finish of the ceiling. The two are not always identically sloped. And that insulation and ceiling cladding has height and dimension o be accounted for in your plans. Your center of your room could be anywhere from 15'6" to 16".

I could hug you Sophie. So are you saying that if I go forward with this...I can adjust the height of this room no matter what the outside pitch is of the roof?

I would love to have some height in this room with a wooden ceiling, whitewashed look but I do not want an extremely tall ceiling.

And what I should google image search is "10/12 pitch rooms from inside"? Perhaps I will find more examples than when I was looking for 12/10.

thank you!! You always have all the answers.

Autumn..thank you too :-)

Ha - mine was the simpleton version. Sophie has some meat in there that you can actually do something with. :D

What Sophie is saying is that the exterior roof pitch may...may...may be different from the interior ceiling pitch depending on how the roof framing and interior ceiling joists may be designed. However--and this is important--in the two photos which are posted above the roof design is an exposed plank and beam design (there is no attic, no attic insulation, and no separate ceiling joists), and thus the interior pitch is exactly the same as the roof pitch since the roof structure is exposed. Do you understand the difference? If the supporting roof structure is exposed, the pitch on the exterior and the interior will be identical.

12/10 means that the roof increases 12" in a 10" space; thus, it's more steep.

10/12 is the opposite: the roof rises 10" in a 12" space -- less rise, more space; thus, less steep.

Here is a chart showing the different roof pitches.

Write it 12/10 as in the chart by cpartist or the normal 10/12 but it is the SAME thing. The lateral distance is always 12" and the other number is the rise. mrspete example would be correct if it worked another way but it doesn't. 12/10 and 10/12 roofs are just two different ways of saying the same thing: the roof rises 10" over 12" run.

The OP's picture shows a 10/12 pitch roof which is show as 12/10 in cpartist chart. It is still the same thing.

Sophie got it right; a roof pitch is traditionally expressed as the ratio of rise to run (not run to rise) and the run is traditionally expressed as 12". Writing it any other way is likely to be misunderstood by the framer. It is traditionally written as 10/12, 10:12 or 10 in 12.

if you are researching the ceilings shown above, try using the term "cathedral ceiling"; a "vaulted ceiling" is sometimes used for this ceiling shape but in architectural terminology it refers to an arched ceiling.

Framers always put the rise before the run. a 6/12 roof means 6" rise in 12" run, Which becomes 6 in 12, which becomes 6/12. We have our own shorthand.

It appears oriented two ways on that elevation drawing, but you will notice the 12 is always on the horizontal leg of the square symbol, because it's designating the run.

12" should always be used for the run because it is how we gauge our framing squares. The only time we use something other than 12 is when cutting stair stringers, where we use the actual rise/run sizes in any proportion imaginable, like 6 7/8 in 10 1/4, or 4 1/2 in 15 1/2. God help the framer who is compelled to use a "base 10" format.

Casey

The ceiling must follow the framing or the end gable window head would have to be lowered.

As my math teacher always said....slope is rise over run. So you take the rise (up and down number) and put it over the run (side to side number). That is your slope.

I like your pictures! :)

Come on, guys, measuring slope is 10th grade Geometry. Remember that X and Y axis stuff? And while I don't know roofing, I am a math whiz, and I do know that 12/10 and 10/12 are not the same thing.

If a roof's slope is always supposed to use a 12 as the denominator, then the upper number should be adjusted accordingly (you can't just flip the numbers and think you won't change something significant). The resulting equation should be 12/10 = 14.4/12. I doubt roofers ever work with fractions, especially if we're talking about pre-made trusses.

I am inclined to think someone has made a mistake on the image that started this conversation.

Virgil..."However--and this is important--in the two photos which are posted above the roof design is an exposed plank and beam design (there is no attic, no attic insulation, and no separate ceiling joists), and thus the interior pitch is exactly the same as the roof pitch since the roof structure is exposed. Do you understand the difference? "

Yes, I do now that you explained it. I live in the Midwest and certainly could not do a room like this with no insulation. Thank you for making this clear. I would love to do a ceiling that looks like this but has insulation, etc. ??

JDS..I searched using cathedral and did find more images. Thank you.

ILoveRed, the houses in your(?) two early photos most likely did have roof insulation, but not in the attic, since there is no attic! When roof structure is exposed as it is in the two early photos, insulation has to be designed for installation above the roof framing and/or sheathing, most likely using rigid insulation panels of one type or another. There are a wide range of rigid insulation panels, materials and thicknesses available. Google "rigid insulation". One of the more recent technological developments in residential and light construction is using structural insulating panels (SIPs) for roofs and/or walls, or both. These consist of an outer layer of plywood or oriented strand board, an inner layer of perhaps 4"-6", or so of rigid insulation and another outer layer of plywood or OSB, an "oreo cookie" assembly, usually 4' X 8', or other modular size. This panel approach may speed up construction, improve construction quality (if installed by knowledgeable builders), improve sealing the exterior perimeter and overall envelope energy performance. Google "structural insulating panel". There's all sorts of ways to make a house!

Casey...very interesting. So you are saying the framers will NOT screw up, no matter how the ratio is written...that it is understood that the 12 is always the lower number no matter how it's written. The exception is stair stringers.

Mrs. Pete, I dont think its a mistake on the image. This is the pdf of the same architectural blueprint that has several areas with a number other than 12 on the bottom. Note the dormer with the 3 on the bottom half. So, I'm assuming that is a 3/12 pitch?? Anyone??

Greg Bradley...then why do they write it both ways if it's synonymous? It's confusing. Do all architects do this?

Virgil...thank you for explaining that so well. I wish we still had our "clippings" from the old gardenweb so I could cip your post. This is invaluable.

Don't confuse how a roof pitch is written as a ratio with how it is shown in a graphic symbol. On the graphic symbol, 12 is always shown on the horizontal leg and in a written ratio the 12 is noted after the rise and separated by a slash or a colon. As shown on the drawing above, both methods are typically used where appropriate.

JDS...I re-read your last note about ten times while referring to the image but I think I finally understand. The key was explaining that the 12 is always on the horizontal leg of the symbol. But if the same pitch is written as a "fraction" the 12 is always on the bottom. Is that correct?

Its a bit silly and I would always write it as the rise (vertical) in inches over the run (horizontal) which is always 12 inches. I would show a roof that rises 10" over a run of 12" as 10/12. Some people would write that as 12/10 but it is the same thing. ONE number will always be 12, which is the run. It IS confusing but architects are a strange group and not above making things confusing that could be simpler.

You can be completely sure that a roof pitch written as 12/10 is the same as one that is written as 10/12. Whichever number is 12 is the run UNLESS it is a 12/12 roof in which case only one of the 12s is the run. Clear as mud, right?

The continuing confusion in this thread is due to the fact that the rise/run is shown on opposite or opposing pitches on an elevation. The architect's notation is correctly shown. It's some of the folks on this thread that are misinterpreting what is shown. Looking at the elevations, the horizontal element is always shown as 12, regardless of the elevation side or direction of pitch. The horizontal element is consistently 12! 12! The vertical dimension is the pitch dimension and in the elevation it is consistently shown as 10! 10! Thus, on each opposing sides of the roof, the roof pitch is 10 in 12, but the geometry of the notation 10/12 has to be reversed to match the change in opposite pitch.

Just look at the elevations and the horizontal and vertical notations. Vertical is always 10. Horizontal is always 12. It's that simple!

10/12 is not the same as 12/10! Come on people! I don't know what experience that response comes from. The numerator is always the vertical axis. The denominator is always the horizontal axis. Thus, it's clear that 10/12 is not the same as 12/10! I have never seen a set of construction drawings or known a roofer that measures horizontally in less than 12 inches. Does anyone think a 4 in 12 pitch is the same as a 12 in 4 pitch? Come on! The denominator is always 12 inches. It's the standard of the trade. It's the way a framing square is marked!

As for architects being a strange group and not above making things confusing that could be simpler, just go back and re-read this thread, from top to bottom, largely made up of comments from non-architects. Now that's confusing! And inaccurate! Thus endeth the lesson on roof pitch and notation! :-)

ILoveRed, yes that is correct.

cpartist's chart is the first time I have seen a roof pitch ratio written as run over rise. I own more than a dozen framing books and none of them use that convention.

Also, the more traditional drawing convention and the one I have always used is a full triangle with the hypotenuse parallel to the roof slope (see below). It is always best to avoid showing the same information twice on a drawing so I only show the roof slope triangle on one side of a gable roof unless the slopes are different.

Thanks Virgil for explaining that folks were reading the blueprints incorrectly by focusing only on the numbers and ignoring the vertical and horizontal notation that was clearly part of the expression. Of course the oversight was compounded by reading from left to right instead of the std rise/run. The roof in question has a pitch of 10/12 (you may notice on the second picture there are slashes that are used at some points in which you can read from left to right but NOT where you have intersecting horizontal (run ( and vertical (rise) lines, in which case you need to read the rise before run.

"It appears oriented two ways on that elevation drawing, but you will notice the 12 is always on the horizontal leg of the square symbol, because it's designating the run." just realized you posted this as well up thread Casey. Thank you.

very educational thread.

yes it is. loved the roof pitch chart!