Contractor Talk - Professional Construction and Remodeling Forum banner
1 - 20 of 119 Posts

·
Registered
Joined
·
162 Posts
Discussion Starter · #1 ·
Does everyone cut their hips 1/2" less than the common rafter plumb cut at the plate line and the valleys the same as the plum cut of the common rafter?

So if the plum cut of a 2x8 common rafter at the plate line is 6 1/4" than the hip at the plate line is 5 3/4".....and valleys would be 6 1/4".
 

·
KemoSabe
Joined
·
14,233 Posts
I always keep the heel of the hip equal to the common heel. I bevel the cut to make it easier to guage the hip during installation. The valley heel will change depending upon the pitch of the roof. In any case the valley needs to plane out to the center, which will actually cause the heel at the valleys edge to be lower than the common rafters. Unless the top of the valley is ripped to the slope of the roof, in which case the heel will remain the same.:thumbsup:
 

·
Pro
Joined
·
506 Posts
this is roof framing 101.


hip always needs to be dropped - the severity of the drop depends on two things..

1. the pitch. steeper the pitch = more drop.
2. the thickness of the hip. thicker hip = more drop.

here's a simple way to know exactly what to drop your hip. (for regular hips only, bastard hips are a different animal.)

using a framing square scribe a hip plumb cut on a piece of wood. then step half the thickness of the hip (3/4" for 2x, 1-1/2" for double and so on) using the square. measure the height difference at the top of your board. that is the drop.

on shallow pitches and short overhangs the difference is negligible and you can drop the hip, say a quarter, and get away with it. on deep overhangs and drastic pitches your drop has to be dead-nuts on, otherwise the tail will either be riding high or swooping low.
now....
if you're beveling the tops of your hip you will avoid the drop completely given you have the right bevel.

valleys are framed to center so there is no drop.
 

·
KemoSabe
Joined
·
14,233 Posts
this is roof framing 101.


hip always needs to be dropped - the severity of the drop depends on two things..

1. the pitch. steeper the pitch = more drop.
2. the thickness of the hip. thicker hip = more drop.

.
If the hip gets dropped lower than the common it will not plane out at the plateline. If your fascia line doesn't match, it's because the math done for the placement of the hip at the ridge is wrong. The centerline of the valley needs to match the common therefore the layout for the cut on the side of the valley will need to be lower.
 

·
The Duke
Joined
·
14,746 Posts
Roof Framing 101

The seat cut, or what most people call the HAP, of a hip/valley is 100% exactly the same as the common seat cut.

A. You must determine where your vertical plane measurement is located, i.e., usually the outside face of the frame of the wall.

B. Your seat cut at that plane is exactly the same for commons as it is for hips and valleys. Otherwise, your plywood is not going to be on the same plane. For hips, this plane I refer to is located on the side of hip, not the center (theoretical). Valleys are measured to the center, not the side. When laying out your hip, your seat cut (HAP) is marked on the face, which is exactly the height of your common HAP. The length of your hip rafter has to be shortened to accommodate the theoretical measurement, which in another viewpoint would be your dropping of the hip.

C. Don't randomly pick a measurement to raise or drop just because "this is the way I've always done it or was taught". This is the thought process of a lazy man and usually ends up one day being called a hack.

Think. Learn. Be.

Tune in tomorrow for another philosophical viewpoint of Framing.
 

·
Super Moderator
Joined
·
10,711 Posts
Roof Framing 101

The seat cut, or what most people call the HAP, of a hip/valley is 100% exactly the same as the common seat cut.

A. You must determine where your vertical plane measurement is located, i.e., usually the outside face of the frame of the wall.

B. Your seat cut at that plane is exactly the same for commons as it is for hips and valleys. Otherwise, your plywood is not going to be on the same plane.

C. Don't randomly pick a measurement to raise or drop just because "this is the way I've always done it or was taught". This is the thought process of a lazy man and usually ends up one day being called a hack.

Think. Learn. Be.

Tune in tomorrow for another philosophical viewpoint of Framing.
Framerman

While this is 100% true, one of the previous threads was describing how to do it "by the book" This would be for simple roof stick ins using a framing square and calculating the hip length as well as the amount to drop to allow it to lign up correctly. By calculating the length of a hip, you are actually figuring its length at the center of the rafter. Its impossible for us to lay out the hip rafter from the center, so therefore it must be "dropped" appropriately to make up for this. That being said, myself. I usually don't calculate the hip length. I usually measure it in place, being sure to measure at the edge of the rafter where it planes at the wall. Sounds like you do it this was also. While knowing all the math of roof framing is important, many times in the field we come up with more practical methods that allow us to adapt to situations as they arise.
 

·
Registered
Joined
·
162 Posts
Discussion Starter · #10 ·
that is exactly why i am asking the question. thsnks for your time


Roof Framing 101

The seat cut, or what most people call the HAP, of a hip/valley is 100% exactly the same as the common seat cut.

A. You must determine where your vertical plane measurement is located, i.e., usually the outside face of the frame of the wall.

B. Your seat cut at that plane is exactly the same for commons as it is for hips and valleys. Otherwise, your plywood is not going to be on the same plane. For hips, this plane I refer to is located on the side of hip, not the center (theoretical). Valleys are measured to the center, not the side. When laying out your hip, your seat cut (HAP) is marked on the face, which is exactly the height of your common HAP. The length of your hip rafter has to be shortened to accommodate the theoretical measurement, which in another viewpoint would be your dropping of the hip.

C. Don't randomly pick a measurement to raise or drop just because "this is the way I've always done it or was taught". This is the thought process of a lazy man and usually ends up one day being called a hack.

Think. Learn. Be.

Tune in tomorrow for another philosophical viewpoint of Framing.
 

·
Registered
Joined
·
1,571 Posts
Does everyone cut their hips 1/2" less than the common rafter plumb cut at the plate line and the valleys the same as the plum cut of the common rafter?
No, because it is different for every pitch and what size hip (width)you are using.

So if the plum cut of a 2x8 common rafter at the plate line is 6 1/4" than the hip at the plate line is 5 3/4"
No, that's not correct. It might work for a 12/12 pitch using a 2x hip. It's slight different for each pitch lets say starting at 4/12 - 12/12.

.....and valleys would be 6 1/4".
Yes, valleys HAP cut is the same as the Common HAP cut. You mark the length to the outside corner and then make the same HAP cut as the common rafter without coming in 1/2 the thickness of the hip.

The fastest and easiest way to mark the hip HAP cut without any math is to just mark the length to the outside corner and make a plumbcut mark and move the mark in towards the top 1/2 the thickness of the hip and mark another plumbcut. Come down from the top the same 6-1/4" common rafter HAP. Scribe your seatcut measurement out to the outside corner plumbcut mark (which is the outside corner) and cut to that mark.

You have to drop the hip or adjust the HAP mark because the hip outside corner length measurement running at 45° twists the side of the hipoff the corner. That creates a small triangle ayt the plateline with a run and rise. At the plateline is where the outsides of the hip has to have the same HAP cut as the common rafter HAP cut. Coming in 1/2 the thickness of the hip and marking the HAP cut the same as the common HAP cut planes the outside of the hip in perfect wity the common HAP.
 

Attachments

·
The Duke
Joined
·
14,746 Posts
Framerman

While this is 100% true, one of the previous threads was describing how to do it "by the book" This would be for simple roof stick ins using a framing square and calculating the hip length as well as the amount to drop to allow it to lign up correctly. By calculating the length of a hip, you are actually figuring its length at the center of the rafter. Its impossible for us to lay out the hip rafter from the center, so therefore it must be "dropped" appropriately to make up for this. That being said, myself. I usually don't calculate the hip length. I usually measure it in place, being sure to measure at the edge of the rafter where it planes at the wall. Sounds like you do it this was also. While knowing all the math of roof framing is important, many times in the field we come up with more practical methods that allow us to adapt to situations as they arise.
Absolutely agree, especially with adapting. I figured I may have been vague and debated whether to CAD it out and post it to give some visuals, but being in the morning and busy, I didn't have time. I may do it in a few minutes so I don't confuse everyone.

While the common description is to say to "drop the hip", my procedure is essentially the same, but my previous explanation may be confusing. The "by the book" method is what I was taught as the "theoretical", the calculations and such. The dropping of the hip is essentially moving your theoretical measurement half the distance of your hip member. This would make the face of the hip line up with your vertical measuring plane, thus when you mark and lay out your hip, the HAP is the same as the commons.

It's a different method with the same results.

The reason I do it this way is so I can have someone on the roof, that may not be as talented as I am, installing the hips in the correct place. My method of laying out the hip places a visual plumb line where the face of the plate is. All they need to do is match the vertical line with the face of the plate.

The method of dropping the hip usually indicates that you are laying out where the corner point of the house is on your hip and dropping the HAP to plane the hips in with the commons. This gives you a vertical layout line for the theoretical and you would have to do either 1) make a few more layout lines so the tard on the roof knows where to put the hip, or 2) assume the tard can figure out where that point is under the hip.

I chose my method because it eliminates a few unnecessary steps in laying out a hip and to try to eliminate the confusion for the guys on the roof. Two lines laid out on a hip and the guys are asking "which line?"
 

·
Registered
Joined
·
1,571 Posts
If you didn't want to come in 1/2 the thickness of the hip and wanted to use math, a simple way to do it is like this:

Pitch ÷ 16.97 x 1/2 Thickness of Hip.


Using a 2x hip.


4/12 Pitch.

4/16.97 x .75 = .176783" or 3/16" Drop.


8/12 Pitch.

8/16.97 x .75 = 353565" or 3/8" Drop.


12/12 Pitch.

12/ 16.97 x .75 = 530348" or 1/2" Drop.
 

·
Registered
Joined
·
189 Posts
Am I losing something in translation here? When I originally posted I assumed he was beveling the top of his hip to match the pitch on either side. Are we talking bevel vs. non-bevel or are the guys that suggested dropping the measurement still speaking on the terms that even when you bevel you have to drop your hip?
 

·
Super Moderator
Joined
·
10,711 Posts
Am I losing something in translation here? When I originally posted I assumed he was beveling the top of his hip to match the pitch on either side. Are we talking bevel vs. non-bevel or are the guys that suggested dropping the measurement still speaking on the terms that even when you bevel you have to drop your hip?
Who bevels their hips??

And why??
 

·
Registered
Joined
·
189 Posts
I can't answer definitively who but I've always beveled mine. I suppose it's just to get a cleaner look, and I realize it's not structurally necessary. Maybe I'm just a product of my environment and how I was taught. That's the great thing about this site, it breaks you from from the singular mode you learned in. I'm not saying it's wrong or right to bevel that's just the way I was taught and maybe I've wasted a lot of time doing it since. Warren, where are you at in NE Ohio? I'm in Cleveland right now doing a major reno( haven't done a new build in a year... market and all) and if you're doing a new one I'd love to at least drive by it. Fresh new wood kind of gives me a boner and if I can't do it I'd at least like to see it.
 

·
Registered
Joined
·
189 Posts
I think the McAfee blocked it because I got a strange message that I've never seen before on my desktop. I'm not computer literate enough to figure out how to view that message. How far east? I grew up in Geauga county and like I said I'm working up here, sleeping on an air mattress, and after I shut it down for the day I have a lot of time on my hands after hours. It's either get on this website and chat about the trade or sit in boredom. I'd love to come see it and at least hang out with my own kind. My two employees quit on me in May so I spend way too much time by myself and, while I'm not someone who pleads for company, I'd love to see a new build site again. This past winter I thanked God I wasn't in framing but now that it's summer I miss it like you wouldn't believe.
 

·
Super Moderator
Joined
·
10,711 Posts
Framing is life. I will be starting a new frame in the Barrington allotment next month. Its not a giant but is probably about 4600 sq ft. We have done a few monsters in that allotment throughout the years.
 
1 - 20 of 119 Posts
Top