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Hip roof on a wraparound porch

Woodie_Krugel's picture

I am adding a porch onto three sides of the house. On the front and side, the porch will extend out from the house six feet, and in the back it will extend out ten feet. I'd like a hip roof. What input can I get on building a hip roof with different pitches coming into the hip? The ten foot side will have a pitch of approx 4 in 12.

Thanks, Woodie

(post #89204, reply #1 of 29)

What input do ya want ? Are you looking for someone to figure out the pitches, tell you how to frame it, or what ?

Dual sloped hips should be no big deal for an experienced framer.

(post #89204, reply #2 of 29)

Woodie, it may look better to keep the same roof pitch around the corner. Instead of the hip rafter hitting the corner of the house, it would land somewhere on the side wall.

If you go with the option of different slopes the underside of the rafters won't be at the same elevation on the different pitches. If this bothers you, rip the lower-slope rafters to match the others.

As the Boss says, no problem for an experienced framer.

(post #89204, reply #3 of 29)

Woody - for planning purposes (drawing a plan) the angle of the hip = InvTan (pitch 1/pitch 2) in degrees. If 4:12 and 6:12 (say) it would be represented as InvTan (6/4). That will tell you where the hip will land.


(post #89204, reply #4 of 29)

Mike or anyone
I am putting a porch on a custumers house and he would like drywall on the interior part of the cieling. the local lumber yard has exterior drywall but does not know if I need a special mud.
Any one used this exterior drywall and if so what did you finish with?
Thanks in advance

(post #89204, reply #5 of 29)

Perry, if you start your own thread, you'll have a chance of someone answering you.

(post #89204, reply #6 of 29)

Hey Woodie,
The two different pitch hip roof is known around here as a "bastard hip". I would make the hip go from the corner of the porch to the corner of the house. In a normal hip roof, the hip rafter is at a 45 degree angle when seen from a bird's eye view. In your case the angle will be different. You will probably find it helpful to draw a top view (bird's eye view) of your house and the proposed porch. Connect the corner of the house and the corner of the porch with a hip. Check out the angle with a protractor from the front wall and the side. Might be something like 30/60 degrees. This means your jack rafters will not meet at the hip together. Draw in some 16" o.c. rafters and you will see what I mean. I make my 60 degree cuts by (my saw only goes to 45*) cutting my angle with the saw set at 90* and then tilting the saw to 30* and cut on the end of the rafter. If you have an 8" saw this works really slick. If a 7 1/4" saw, you can run a sawzall down the last 1/4" of material.
The other tricky part is that you need to have the top edge of the rafters line up (both sides) and the soffit cuts. The only way I have found to do this is to make two different size soffits. Usually it is something like a 10" on one side and a 12" on the other.
WHEN IN DOUBT, DRAW IT OUT. This is my motto and it works for me. I usually sketch on a piece of plywood with a framing square to scale.

Sorry for rambling guys.
Woodie, If you need me to further confuse you give me a shout.

(post #89204, reply #7 of 29)

Woodie you can have the same overhang at the same fascia hieght by changing the heel hieght of the two different pitches and swinging the hip off the corner. Ask Ken Drake for the skinny on this technique.


(post #89204, reply #8 of 29)



(post #89204, reply #9 of 29)


Ideally you would "change" the plate or wall height and not the "heel" or H.A.P. cut.

(post #89204, reply #10 of 29)


Will the porch rafters be exposed from below?

How about the rafter tails? Will they be exposed? Or will there be a soffit to cover them?

Will there be fascia?

These are questions that need answers before someone can give sound advice, IMO.


(post #89204, reply #11 of 29)

Found a neat little rafter layout program the other day. Should work great for this project. Download the demo & it'll tell you exactly how to cut your rafters.


(post #89204, reply #12 of 29)


Why not frame the roof with just one pitch? (See attached diagram)

The top end of the regular hip won't hit the corner of the house, but do you really care?
< Obsolete Link >

(post #89204, reply #13 of 29)

That's what I'm saying, Ken. I think it looks better and more interesting than fooling around with different pitches just to make the hip rafter land on the corner of the house. Nice drawing.

(post #89204, reply #14 of 29)


Mike Maines and I are suggesting a method to frame your roof that is considered "standard" in the trades. There's absolutely no need to get into double pitch irregular roof framing in this situation, especially if you are inexperienced with irregular roof framing.

I've framed a ton of corners like this Woodie, and I'm sure there will be more to come. Set your saw bevel at 45º for all bevel cuts on the jack rafters and hip rafters.

The 4/12 common rafter that butts the end of the ridge board, should be exactly the same length as the other 4/12 rafters on the 10' side. These 2 rafters should be the same distance from the corner of the beam. Layout the remaining common and jack rafters using them as your starting point.

Cut a double 45º bevel at the top of the hip rafter and you're good to go. If the rafters are exposed from below, the jack rafters will match on the hip rafter, and you can ooh and aaah when you finish.

(post #89204, reply #15 of 29)

Can you give us a sketch of the side view of the house? That's the side that will look funky. Why a DOUBLE 45 degree bevel on the top of the hip? Wouldn't you just cut a simple 45 degree at the 4/12 pitch?

(post #89204, reply #16 of 29)

Hey Guys -
Thanks so much for all the messages and input. Responding to some specific questions/comments:
1. I've drawn this project out and convinced I want to start upper end of hips at the corner of the building.
2. One question I had was cutting jacks beyond 45 degrees. Message #6 Ricky Espo addressed this, Thanks.
3. I am going to have a ceiling on this porch, the underside of rafters will not be exposed. The tails will be exposed & I'm aware the length of tails will be different from side to side.
4. I was lost with Jeff Clarke's (message #3). Talking about InvTan?
5. Yes, There will be Fascia.
6. DanPat (Message #11) I agree - neat program. Thanks!

Reading all the messages you have sent has made me stop and ask what was I actually wanting from you? It's simply a situation I had not been exposed to before but I felt like I had it pretty well figured out. Just needed a little confidence builder that others have "been there, done that". Thanks
I look forward to any more input.

(post #89204, reply #17 of 29)

A safer method of making cuts beyond 45 degrees with a skil saw,
especially when you have to make a lot of cuts. I have tilted the saw table as far as it would go (45)and then tilt the whole saw while sighting the blade against the angle you need. I drilled two small holes in an old skil saw table and screwed a piece of wood (measured while sighting the angle) to the bottom of the saw table. This tilts the saw well beyond 45 degrees, almost like when you put your fingers under the table to get 50 degrees. This method is only practical if you have more than one saw.

(post #89204, reply #18 of 29)

excellent, ken.

i, as an inducted volunteer, had to frame an irregular hip roof for one side of a building (patio cover). had never done this before. no big deal because it was only one side. but i was left wondering about what i would have done if the cover had wrapped around the building while maintaining the same pitch. you provided THE answer. very clear.

very happy now,

(post #89204, reply #19 of 29)


If you put a common rafter at the end of the face of the ridge board, as well as one that butts the end of the ridge board, it's necessary to make a double 45º cheek cut at the top of the hip rafter so it can fit properly against the 2 common rafters. The reason that I suggested to do it that way, was to keep the jack rafters matching up on layout in case the framing was exposed.

I'm not sure why you feel that the roof plan that I suggested would look
i funky.
This type of roof framing is very common and occurs whenever the first floor roof dies up against the side of the house, and the offsets are not equal. I specialize in roof cutting and find this situation showing up over and over again.

Here's what it might look like in elevation

< Obsolete Link >

(post #89204, reply #20 of 29)


I would tend to disagree with that assessment. If the roof is a double hip like this one then sure but just a straight corner with a long wall well. . . . . . . You can see about this roof here.

If you want to know how to control the plate and fascia heights then you can read this.

(post #89204, reply #21 of 29)

Thanks for the drawings. It doesn't look as bad as I thought it would. I am used to going corner to corner with a hip, regardless of the angle. I guess it is all in what you are used to and what you think looks good. In my opinion it has cleaner lines going corner to corner. Is it that the hip is not at a 45 degree angle that you do not like the looks of or the fact that it is a little more work with the bastard hip? I have done quite a few bastards and after the first one they are not a problem. Most common application is when you have a wide house in relation to length. For example a 28 x 36 colonial. The ridge would only be 8' long. Looks funky. If you used a 10/12 for the front and back pitch and a 12/12 for the ends, your ridge length would increase to the neighborhood of 12'8" giving you nicer lines for the roof. Just my opinion and I realize that everybody has one. Anybody else have some input on this matter, sound off. I am not an architect but a framer. Some architects might shine some light on this subject.
P.S. Most "bastard hips" that I have framed have had a 2/12 differnce in the roof pitches. (8/12-10/12) (10/12-12/12)

(post #89204, reply #22 of 29)


> Is it that the hip is not at a 45 degree angle that you do not like the looks of or
the fact that it is a little more work with the bastard hip?

Most of the time, the roof plan is shown for the large custom homes that I cut the roofs for. If the plan shows a single pitch at such a corner, I cut it that way. If a double pitch is indicated, I cut it that way. Makes very little difference to me.

But even if a double pitch is indicated, the hip may still not run from the corner of the frame, to the corner of the main house. It still may look very similar to the single pitch drawing that I have shown, except 2 pitches will be involved. The architect isn't always going to change the roof pitch just to make the hip go from corner to corner.

In Woodie's situation, he has a
i choice
so he can go either way with it. If the rafters were to be exposed from below, which is very possible on a porch roof, then I would recommend the single pitch roof as I drew it. This will give you a much cleaner look all the way around, including equal overhangs all the way around.

As it turns out, only the rafter tails will be exposed, so he has opted to go for the corner to corner approach, using 2 pitches, which is fine.The only problem he'll run into is making the exposed cuts on the tail of the hip, which will look like this, if framed properly

< Obsolete Link >

(post #89204, reply #23 of 29)

Joe sure it would be easier to change "wall or beam hieghts" but what would that do to the finished look of the beams underneath the roof. They could tend to be offset a little too much to look good. Then again I guess you just fir one down to match the other. You're right and so am I.


(post #89204, reply #24 of 29)


Sure feels good when everyone is right. ;-}

(post #89204, reply #25 of 29)

There is a time and a place for everything.

IMO, this is neither the time, nor the place, to raise the plate (beam), offset the hip, to make the overhangs equal.

i The rafter tails are exposed

Finished result would look like dog squeezins

(post #89204, reply #26 of 29)

ken. you can lead a horse to water...

joseph. excellent online demonstration of your suggestion. i am much enlightened and thankful.

ken, mike, joseph. excellent discussion. interesting what happens when you alter your views to suit a client's preferences. the idea of raising the plates for an exposed overhang does seem off aesthetically, if structurally required. stick to your guns, unless you could persuade woody to add soffits and extend the ceiling out to the overhang.

ps. for the guy who asked about finishing exterior drywall, there is a moisture resistant drywall compound, but it is very difficult to work with out of the bucket. thin first. work with a small section in the garage first. the product i used could not really be called "sandable".


(post #89204, reply #27 of 29)


Regarding your comment,

> the idea of raising the plates for an exposed
overhang does seem off aesthetically

I couldn't agree more.

That's what I meant by dog squeezins.

Thanks for your input.

(post #89204, reply #28 of 29)

if we're still working this thread, how far outside the corner post is one permitted to set hip. 1' or does it vary by local or size of beam?


(post #89204, reply #29 of 29)

Woody - Sorry to lose you -

You have to draw the angle of a valley or hip in plan between two intersecting roofs. Assuming that the roofs meet at 90 degrees, that angle is calculated as the inverse tangent ("the angle whose tangent is ...") of one pitch over the other. Thus, when 2 roofs meet that have the same pitch, say 6:12, the result is invtan (6/6) which yields 45 degrees. We all know that all things being equal, you'll have 45 degrees, it just changes when the pitches change. "Inverse tangent" or "atan" is a standard button on many calculators.