# porch roof



## Willie T (Jan 29, 2009)

You either let the 5' roof hang 1' long, or you compromise, and split the difference on the overhangs.... 6" long on the 5' side... 6" shorter on the 6" side.


----------



## Kurt1968 (Oct 15, 2009)

What i'm asking is the rises are different. So how do i get the rises the same.


----------



## 12penny (Nov 21, 2008)

I dont get it either. If you want them the same then make them the same.


----------



## Kurt1968 (Oct 15, 2009)

I guess i just wanted help in figureing out the length of the rafters and where to cut the birds mouth.And what angle to cut the top at. Because the length of the rafters is different . I think i'm just over thinking it.


----------



## Willie T (Jan 29, 2009)

You are not going to be able to have equal rise on both sides unless your rafter bottoms are all landing at the same distance from the house wall. That's what I was trying to express in my earlier post.


----------



## Kurt1968 (Oct 15, 2009)

ok thanks can i change the angle where it mounts to the house to make them the same?


----------



## Kurt1968 (Oct 15, 2009)

I gonna just make the other side 6' also to make it easier.:thumbup:


----------



## Willie T (Jan 29, 2009)

Kurt1968 said:


> I gonna just make the other side 6' also to make it easier.:thumbup:


Sounds like a plan. :thumbsup:


----------



## Wildie (Jul 23, 2008)

Kurt1968 said:


> I gonna just make the other side 6' also to make it easier.:thumbup:


 Yah but, the beam for the short section will have to be higher as the birds-mouths will be further away from the rafter butts.
How are you going to support this beam? 
It may be easier to maintain the beam heights and have a different rise for each roof!


----------



## Gary in WA (Mar 11, 2009)

Just put a ceiling joist under it to raise the heel height at the bird's mouth level cut whatever the rise per foot is. Example - a 2x4 under the rafter if a 3-1/2" rise per foot, a 2x6 under if a 5-1/2" rise, etc., and make up some of the difference at the depth of the b-mouth height cut, just so you have minimum 1-1/2"level cut for bearing. . That is how to do, not what I would do... I would use a 24" overhang at the 6' beam, a 12'" overhang at the 5' beam. The unequal pitch would be on the 5' beam but the tails would line, though the hip would be offset also. Be sure to solid block all rafters for rotation and positive connection to plate or beam (Simpson H-1 or 2.5). 
Be safe, Gary


----------



## Willie T (Jan 29, 2009)

Being a bit on the lazy side, myself, I think I would just either build or order triangle-shaped trusses (all of the same size) and install them all around. Straps and hangers. Yeah, you'd need a hip setup in there, but that's not a big deal.


----------



## Joe Carola (Apr 14, 2006)

Kurt1968 said:


> I gonna just make the other side 6' also to make it easier.:thumbup:


That's the easiest way to frame it and keep the pitch/overhang and height the same. You can also frame it with a 6' and 5' run with the same overhang and height. You will just have a "Bastard Hip" offsetting the corner towards the 5' run side which is the steeper pitch side. This is very common and framed every day.

What pitch were you looking for on the 6' run or the 5' run? What is your overhang? What size rafters are you using?


----------



## Kurt1968 (Oct 15, 2009)

Alright now how do i figure the rafters its not coming out right. My run is 5'-10 3/4 the rise is 32". Thats what the rise has to be. I know its going to be some bastard size. Thats what you get when you own a 105 year old house.


----------



## CookeCarpentry (Oct 17, 2009)

What is not coming out right?

You know your rise and run.


----------



## Kurt1968 (Oct 15, 2009)

Ya i have a program that tells me what i need to cut for a 5/12 but the angle seems wrong but i think maybe it just looks wrong until i cut the birds mouth. I drawing it in autocad right now to see what i'm doing wrong. Both runs are 5'-10 3/4 now no more 5' and 6' made them the same . ​


----------



## elkwd7 (Oct 14, 2009)

this is a gable or a hip, the math will be hard to figure when the center is not exact, but an eyebrow hip is in a sense adjustable!!


----------



## Joe Carola (Apr 14, 2006)

Kurt1968 said:


> Alright now how do i figure the rafters its not coming out right. My run is 5'-10 3/4 the rise is 32". Thats what the rise has to be. I know its going to be some bastard size. Thats what you get when you own a 105 year old house.


What size rafters are you using? That will determine what the pitch is since you have a fixed height of 32" because of the HAP cut (Height above Plate). This is the Vertical measurement after you make the seatcut on the birdsmouth at the 5'10-3/4" run. 

This is where Architects will make mistakes when calling out a certain pitch and a fixed ridge height but they don't allow for the HAP cut height and the rafter with, whether your using a 2x6, 2x8 or 2x10. This all makes the difference right there.

For example, you have a 5' 10-3/4" run and you want to use a 5/12 pitch. This would give you a 29.47917" rise if it was just a simple triangle. Now depending on what size rafter you use and if you layout a 3-1/2" level seatcut, adding the vertical HAP cut height can put you over your 32".

If you use a 2x6 rafter and layout a 3-1/2" level seatcut, that will give you a 4-1/2" HAP cut. Add that to the 29.47917" rise and you will have exactly 33.9375" or 33-15-16"" rise. Add another 5/8" -3/4" for sheathing if using 5/8" sheathing.

If you use a 2x8 rafter and layout a 3-1/2" level seatcut, that will give you a 6.666667" or 6-11/16" HAP cut. Add that to the 29.47917" rise and you will have a 36.14583" rise. Add another 5/8" -3/4" for sheathing if using 5/8".

The first drawing is a 2x6 rafter and a 5/12 pitch. The second drawing is a 2x8.


----------



## Kurt1968 (Oct 15, 2009)

Thanks dude your awesome. Not to be a pain but can you give me the lengths of the rafters and where to make the cuts. I'm using 2x6's. For elk this roof is attaching right to the house its a wrap around porch.


----------



## Joe Carola (Apr 14, 2006)

Kurt,

There are many ways to figure this out mathematically and they will always work. In your situation, all you have to do is nail your ledger board onto the house about 3/4 lower than your fixed height which would 31-3/4". That's not including the sheathing. If you can't be any higher than 32" including the sheathing and roofing with proper flashing do to windows above, you have to lower the ledger.

Once you have the ledger in place and the girder set, all you need to do is take a rafter pattern and scribe a 5/12 plumbcut for now and cut that because it's close enough. Set yourself up and someone else up with a ladder at the girder and ledger at the end. 

Take the 5/12 plumbcut end and stick it past the ledger until it hits the sheathing with the top of the rafter flush to the inside of the ledger. Have your helper hold the bottom of the rafter flush to the inside of the top of the girder and scribe the level seatcut on the top of the girder and scribe the vertical HEEL cut on the outside of the girder. This will give you your birdsmouth and full seatcut. You will scribe the inside of the ledger and that will give you your plumbcut and pitch of the roof.

Doing this gives you the exact length and pitch of the rafter. You will then add whatever you overhang is past the HEEL cut. Use that rafter as the pattern and scribe every common rafter for the entire roof.

Depending on what size rafter you use, the pitch might work out to be a 4-5/8;12. If it is, the plumbcut on the hip at the top and the birdsmouth will be 4-5/8:17.

Hope this helps


----------



## Kurt1968 (Oct 15, 2009)

Thanks joe for all your help its starting to make sense now. I just makes me feel stupid. I cant figure this out . If i was a carpenter instead of a tool & die maker. It would be easier.


----------



## elkwd7 (Oct 14, 2009)

*math*

all that it is , math. Wrap around will give you 2 outside corners do deal with and thats where the hips will be.........The house wall are high enough that the porch roof attaches with ledgers and your plumb cuts nail into those but many variations here good luck dude!!


----------



## Joe Carola (Apr 14, 2006)

Kurt1968 said:


> Thanks dude your awesome. Not to be a pain but can you give me the lengths of the rafters and where to make the cuts. I'm using 2x6's..


Kurt,

Using 2x6 and a 5' 10-3/4" run from the sheathing, your pitch will be 4-5/8:12. That will give you a total rise to the bottom of the sheathing of 2' 7-13/16". Add your 2x8 ledger which will reduce the run by 1-1/2", that will set your ledger height at 2' 7-1/4". Your rafter length from the back of the ledger to the outside of the girder will be 6' 2-13/16" not including your overhang because I didn't know what it was.

Add your overhang in and use that rafter as a pattern. Tack your ledger up at the height I said and cut a few rafters and make sure they fit. Make sure your girder is straight because if not your rafters can be up and down a little at the ledger. Always nail the birdsmouth tight to the girder so that the overhang stays the same.

Your hip will be cut with the framing square held on 4-5/8:17, or 15.24° with a speedsquare. The Hip length will be 8' 5-1/2". I'll show you how to mark the HAP cut on that because it's a little different.


----------



## Joe Carola (Apr 14, 2006)

Kurt1968 said:


> Thanks joe for all your help its starting to make sense now. I just makes me feel stupid. I cant figure this out . If i was a carpenter instead of a tool & die maker. It would be easier.


Kurt,

There's no reason at all to feel stupid. It's not what you do for a living. Your asking the right questions. That's the smartest thing to do right there. Hope I can help you more.


----------



## Kurt1968 (Oct 15, 2009)

My overhang is going to be 1'.


----------



## Joe Carola (Apr 14, 2006)

Kurt1968 said:


> My overhang is going to be 1'.


Here you go.Are you using a 2x sub-fascia and a 1x6 fascia?


----------



## Kurt1968 (Oct 15, 2009)

Yes on the fascia. What program are you using for this?


----------



## Joe Carola (Apr 14, 2006)

Kurt1968 said:


> Yes on the fascia. What program are you using for this?


I'm using SketchUp 7. Free download.


----------



## Kurt1968 (Oct 15, 2009)

Thanks again for all your help. I will post pictures when i get the rafters up there.


----------



## Wildie (Jul 23, 2008)

Joe Carola said:


> I'm using SketchUp 7. Free download.


 I notice that you have shown a 2X4 plate on top of the laminated beam.

I recently finished a similar project like this. My beam was laminated using 3-2X10's. I didn't use the 2X4 plate for mine.
I fastened the rafters to the beam directly using 'Hurricane Clips'.
Was this a mistake on my part?


----------



## CookeCarpentry (Oct 17, 2009)

Wildie said:


> I notice that you have shown a 2X4 plate on top of the laminated beam.
> 
> I recently finished a similar project like this. My beam was laminated using 3-2X10's. I didn't use the 2X4 plate for mine.
> I fastened the rafters to the beam directly using 'Hurricane Clips'.
> Was this a mistake on my part?


You would have had to use something wider than a 2x4, msot likely a 2x6 ripped down (unless you had 1/2" packing between each 2x10).

Anyways, standard practice would dictate some type of top plate over a beam/header. If you toe-nailed the rafters to the beam and used hurricane clips - you will be fine. Yes, a mistake, but nothing that would compromise the integrity of the structure.


----------



## Wildie (Jul 23, 2008)

CookeCarpentry said:


> You would have had to use something wider than a 2x4, msot likely a 2x6 ripped down (unless you had 1/2" packing between each 2x10).
> 
> Anyways, standard practice would dictate some type of top plate over a beam/header. If you toe-nailed the rafters to the beam and used hurricane clips - you will be fine. Yes, a mistake, but nothing that would compromise the integrity of the structure.


 Thanks for the reply! The job was passed by the inspector. His concern seemed to be more to do with 'lift'. No comment was made about the plate!
In this case, what purpose does the plate perform?

( my beam has 1/2" plywood between the 3 2X10's to conform to the 6X6 posts.)


----------



## Kurt1968 (Oct 15, 2009)

I think my whole problem is I'm reading the speed square wrong. To cut the angle that goes to the ledger. Do I use common or the hip valley.


----------



## richardballast (Oct 18, 2009)

Kurt1968 said:


> Thanks again for all your help. I will post pictures when i get the rafters up there.


Thanks. I'm anxiously awaiting these since I'm considering a similar project (but my porch is only on one side).


----------



## Joe Carola (Apr 14, 2006)

Kurt1968 said:


> I think my whole problem is I'm reading the speed square wrong. To cut the angle that goes to the ledger. Do I use common or the hip valley.


A 4-5/8:12 pitch is 21.07749° or call it 21°. Since your not using a framing square and using a speedsquare you will pivot the speedsquare until it hits 21°. You will use that for the plumbcut at the ledger, HAP cut and plumbcut for the facsia.

The Hip plumbcut marks will be 15.24°.

It's confusing using the speedsquare for this because the pitch is 4-5/8:12 and not a 4/12. If it was a 4/12, you would pivot the square until it hits the 4 where the "Common" numbers are and pivot the square until it hits the 4 where the "Hip-Val" numbers are.


----------



## Kurt1968 (Oct 15, 2009)

Thanks again Joe.:thumbup:


----------



## Kurt1968 (Oct 15, 2009)

Hey Joe cut some rafters the other day you were right about the pitch and everything. They are not perfect. But I think the combonation of the house and my beams are the problem. Once the soffit and fascia are up you will never know. Thanks again for your help.


----------



## Joe Carola (Apr 14, 2006)

Kurt1968 said:


> Hey Joe cut some rafters the other day you were right about the pitch and everything. They are not perfect. But I think the combonation of the house and my beams are the problem. Once the soffit and fascia are up you will never know. Thanks again for your help.


I'm glad it worked out for you. Alot of times on an existing house you run into things not being straight/. parallel or level and that will throw the common rafter length off. Some houses every rafter has to be cut a little different because you have to set the ledger level and the house can be bowed in or out and in order to keep and nice level roof line with the windows and siding you have to cut every rafter different.

Take some pictures if you get a chance. Did you cut the hip yet?


----------



## Kurt1968 (Oct 15, 2009)

No I haven't cut the hip yet. I'm gonna work on it saturday.


----------



## What have I done (May 28, 2006)

Thanks for running all the numbers for me. Im gonna be doing this same project in the spring.

Make sure you post pictures!


----------



## Joe Carola (Apr 14, 2006)

Kurt1968 said:


> No I haven't cut the hip yet. I'm gonna work on it saturday.


What is the HAP cut height on the common rafter? What size hip are you using, 2x8?


----------



## Kurt1968 (Oct 15, 2009)

I was going to use a 2x6. Thats what im using for rafters. I think the HAP is 4 1/2 like you said .


----------



## Joe Carola (Apr 14, 2006)

Kurt1968 said:


> I was going to use a 2x6. Thats what im using for rafters. I think the HAP is 4 1/2 like you said .


Kurt,

Since your using 2x6 commons you have to use the next size bigger for the hip structurally. Uae a 2x8.

When you mark the length of your hip at the outside corner of the building and draw you plumbcut, you have to come in half the thickness of the hip and make another plumcut mark and mark the HAP cut from that mark and then scribe the level seatcut. 

This will make the top of the hip plane in at the plateline the same HAP cut height as the common HAP cut because the hip travels at 45° from the corner and if you mark the HAP cut at the outside corner it won't be the same height at the plateline causing the fascia to rise up at the corner.

Here's a drawing I did years ago showing you the plan view of the outside corner and how the hip travels at 45° and has a run (half thickness of hip) and rise. It will show you how to mark the HAP cut.


----------



## Gary in WA (Mar 11, 2009)

A very good book, second page: http://books.google.com/books?id=Z8...r=3#v=onepage&q=dropping a hip rafter&f=false
Be safe, Gary


----------



## Kurt1968 (Oct 15, 2009)

Here are the pictures of my porch. One is before and almost done. Thanks again Joe. Now I just have to tie it into the other little roof on the left. Supervisors in the window in first picture.


----------



## What have I done (May 28, 2006)

wow looking good. It probably says in your post but Im gonna sk anyway. How wide is the deck, Is it about 6' ? More pics when you can! It is exactlt what i will be doing in the spring.


----------



## Kurt1968 (Oct 15, 2009)

Yes it's 6 Feet wide. Just started shingling got one side done. Gonna get the other side done . Then the rest can wait till spring. Like the facsia and soffit. Ya it's not turning out to bad. Ok for a Tool & Die maker.


----------



## Scuba_Dave (Jan 16, 2009)

That's going to be a great addition to the look of the house


----------



## Kurt1968 (Oct 15, 2009)

Got it all shingled finally. Will post some pics as soon as I can. Done with it till spring . Will do soffit and facsia then. Now time to work on the man cave in the attic.:thumbup:


----------



## Kurt1968 (Oct 15, 2009)

Still working on this porch. Had some problems with the village that set me back. Will post some pictures tonight.


----------



## Kurt1968 (Oct 15, 2009)

Here are some pictures of my porch.


----------



## fixrite (Mar 1, 2009)

looks GREAT. I am sure you will be enjoying a nice cold one this summer on the new porch.
cheers


----------

