- Today, we're learning how to frame a hip roof
using a framing square and a calculator.
Hip roofs like our mock-up here today
are made up of common rafters, hip rafters,
and jack rafters.
In order to frame a hip roof,
you must have already calculated
and installed your common rafters.
Now because I've already done two videos
on how to lay out and cut common rafters,
which I'll link below,
I'm not gonna get into too much detail in this video.
However, I will give you a quick overview
demonstrating yet a faster way to calculate common rafters.
When using a construction calculator
to solve for common rafters, you only need two numbers,
the run and the pitch.
The run is half the distance of the total span
minus half the thickness of the ridge material.
For example, this mock-up has a total span of four feet,
which is measured from its outside edges.
So half of that is 24 inches.
The ridge is an inch and a half wide.
So half of that would be three-quarters of an inch.
Therefore, 24 minus three-quarters
leaves us with a run of 23 and a quarter.
Pitch is how much the roof rises per 12 inches of run.
For example, for every 12 inches of horizontal run,
our roof rises six inches.
This number is completely dependent on personal preference,
codes, or specified by a designer.
On the calculator, type 23 and one-quarter inch
and press the run button.
Then type six inches, and then the pitch button
followed by the diagonal button
for a measurement of 26 inches.
26 inches is the rafters diagonal measurement
which is from this tip here down to the black line.
And it does not include the overhang.
So, let's go over and do some layout to figure this all out.
The majority of our layout will be done today
using the framing square,
that's actually attached to a piece of wood
with some simple clamps.
What this will do is allow the square to move freely
and accurately over the lumber.
To set up for a common rafter,
line up the six mark on the tongue side
with the edge of your wood.
This represents the pitch or rise.
Then line up the 12 inch mark with the other side
and clamp it in place.
Again, this represents our run.
Now slide to square up to the top of the rafter,
trace the tongue angle, and cut the angle with a saw.
From there, measure down from the top of the rafter,
26 inches, make a mark and draw a second line.
So far, we've laid out this part right here.
And now we need to lay out
and cut for the birdsmouth, the soffit, and the fascia cut.
The seat cut for the birdsmouth
is to the right of this line.
And it's four inches long for this mock-up.
So line up the four and draw a line.
And that gets cut out.
Next is the overhang, which is five inches from this line.
So line the tongue back up, measure over five,
make a mark, and draw another line.
The last line to mark is the soffit cut,
which forms the four-inch fascia.
Measure down four inches, make a mark,
and then draw a line.
And this all gets cut out.
Once everything is cut out,
you now have a finished common rafter.
Because we're focusing mainly on building a hip roof today,
we're actually gonna use this common rafter
that we just cut to start forming today's hip roof.
Once installed here, there common rafter
becomes known as the king common rafter or just king rafter.
And it gets lined up with the ridge at the top
and on the center line down on the plate.
And you may be wondering,
how do you know where the common roof ends
and the hip roof starts?
Well, it's actually pretty simple.
The hip roof starts 23 and quarter inches
back from the edge of the building,
which is exactly our run.
Moving on, let's start working on the hip rafters,
which go from the bottom corner here
all the way up to the ridge.
If we look back at our calculator,
you can see that it's still showing our common rafter length
of 26 inches.
From there, all you have to do
to find the length of the hip rafter
is to push the hip and valley button
for a total length of 34 and seven-eighths.
Again, this measurement does not include the overhang.
So we'll need to add that
just like we did for the common rafter.
There's one more number that we need to figure out
before we clear the calculator out,
and that is the jack rafter lengths.
Still on the screen is 34 and seven-eighths.
And all we have to do to find the first jack
is to hit the jack button until you see jack number one,
which for us is eight and an eighth.
If you hit the button another time,
you can see the jack two is zero inches.
And it's zero because our roof is so small
that there's no other jacks needed.
If you had a larger roof,
you would just continue to hit the button
and cycle through all the jack rafters needed for your roof.
Because hip rafters are at a 45 degree angle
to the ridge board, they rise slower
or more gradually than the common rafter would.
Therefore, we need to account for this
by changing the run of our square from 12 inches
to 17 inches.
Just make sure that when you make that adjustment,
double check that the tongue measurement of six inches
is still right on.
The other thing to note before we begin layout
is that hip rafters along with ridge boards
are generally one size larger than the rafters themselves.
So for our example back here,
we're using two by six rafters.
So the ridge and the hips are two by eights.
All right, with the framing square set to six and 17,
mark out the top cut by drawing a line.
And this time adding two more lines
three-quarters of an inch to the right and to the left.
We will use these additional lines
as guides to make our double bevel cut
at the top of the rafter.
If we look back at the two rafters in our mock-up,
you will see that the hip rafter
has to be pointed in order to fit tightly into that space.
With the saw beveled to 45 degrees,
cut the right line first, which is the waste side,
and then cut the other side.
When you're done, your cut should look like this.
From there, take your tape measure
and hook it over the point
and measure down the rafter length,
which is 34 and seven-eighths.
Make a mark and draw another line.
On common rafters, the seat cut which is this part here,
is generally the same thickness of the exterior wall.
In this case, it's four inches.
However, we can't use that same seat cut measurement
for our hip rafters.
But what we can use is the height above plate.
Height above plate is this measurement right here.
It's a straight line
that goes right up to the edge of the rafter.
And in our case, it's four and a 16th.
If we now go back to our layout,
we can measure down four and a 16th,
make a mark, and draw the seat cut.
Now we're not quite done with the seat cut yet.
Because if we were to cut that line right here,
the rafter would fit, but it would be too high.
Again, because the rafter is coming in at a 45 degree angle,
it needs to sit down or be dropped
so that the rafter edges meet like this.
The amount of rafter drop
is based on half the thickness of the hip material.
So in this case, it's three-quarters of an inch.
Back at the layout,
measure to the right of this line three-quarters of an inch,
and make a short mark.
Then remeasure down our four and one-16th,
which is our height above plate, and make another mark.
The distance between these two lines
is the amount of rafter drop needed for this roof.
All you have to do then is slide the square
up to that new line and draw a new seat cut.
Next up is the overhang amount.
Because this is a hip rafter,
we can't simply measure out five
like we did with a common rafter.
Rather, we need to figure out
how far down the slope we need to go
in order to locate the correct amount of overhang.
I know that's a little confusing.
So let me draw a picture.
What we're trying to figure out
is how far down the slope we need to go
to get the correct amount of overhang.
So we don't know this number.
However, we do know the other two numbers in this equation
and that is the overhang amount of the common rafter,
which is five inches,
and the pitch of our roof is six inches.
Therefore, on the calculator type five inch run,
six inch pitch.
And because this is a hip rafter and not a common rafter,
we're gonna hit the hip and valley button
for a total of seven and a half inches.
If we go back to our layout,
we can measure down now seven and a half inches,
make a mark, and draw our overhang.
Again, because this is a hip rafter,
this cut needs to have a double bevel cut
just like at the top.
So like before,
we're gonna measure three-quarters of an inch on either side
and draw two lines.
Remember, once both lines are cut at a 45 degree bevel,
the center line will end up being the tip
of those two bevels.
The last thing to lay out would be the soffit cut.
And in order to do that,
we need to first extend our seat cut line
over to meet the overhang or fascia cut line.
And now, it's back to the common rafter
to measure the distance between the seat cut
and the soffit, which is two and five-eighths.
Transfer that measurement
down from our extended seat cut line,
make a mark, and draw the soffit cut line.
Again, there's a lot of lines here,
so let me darken them so you can see more clearly.
First we're cutting the fascia, the heel cut,
and the seat cut, which makes up the birdsmouth.
And then we're cutting the soffit.
But remember that the center fascia line
is cut using two 45 degree bevels.
Cutting the waste side first and then the other side.
Be careful to position (indistinct) material safely
as you work through making each cut.
With the hip now cut,
it's a good idea to lay out the 45 degree angle
for the rafters.
So, you know exactly where it fits.
Once installed,
double check it's fitting tight to the exterior.
And the top corners of the hip
are lined up with the other king rafters.
Because this hip fits,
use it as a pattern to cut out the remaining hip
and install it.
The last thing to do is lay out and cut our jack rafters.
Because this roof is laid out 16 inches on center,
let's pull a tape from the left side of this king rafter,
measure our 16 inches, draw a line,
and mark an X where the rafter gets installed.
Because this roof is so small,
it only needs one jack rafter.
And if you remember the length of that rafter
is eight and an eighth.
Now there's one thing to note
about the Construction Pro Calculator
and that it doesn't take into account
the thickness of the hip when calculating the jack rafters.
Therefore, because our hip is an inch and a half thick,
we have to add seven-16th
to the overall length of the jack rafters
in order to get them to land exactly 16 on center.
So all we have to do is simply add seven-16ths
to our eight and eighth to get a total jack rafter length
of eight nine-16ths.
To lay out the jack rafters,
you have to put your square back to a six, 12.
Again, because we're not cutting hips anymore.
Jack rafters also have 45 degree bevels at the top
and a common rafter seat cut and tail assembly.
Therefore, you can lay these out individually if you want,
or you can make a copy of the common rafter tail
simply by tracing it out and using it as a pattern.
It starts by laying out the top angle
set to your six and 12.
Set this all at a 45 degree bevel and make your cut.
Measure down from the long point of that bevel
eight and nine-16ths and draw another line.
From there, line up your pattern,
trace it out, and make the cuts.
Now because some of the jack rafters
are on the opposite side of the hip,
you'll have to make mirrored copies
so that the 45 degree angles
are going in the right direction.
To do that,
simply lay one jack down with a long point facing down
and trace the whole jack out.
And now when you cut this new jack,
just make sure that you're cutting
with the saw beveled in the opposite direction
so that you're making a mirrored copy.
With everything cut,
install the remaining jacks to finish the roof.
As a reminder, this is just a mock-up roof.
So you need to make sure
to check with all of your local building codes
so you can find the correct ways to attach
and size all the framing members.
Now, we went over a lot of information really quickly.
So I broken down this video into chapters
so you can go back and do each step easily.
So, if you have any questions,
hit me up in the comment section below.
You can find me on Instagram.
That always works as well.
Thank you so much for watching today.
See you in the next video.
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