Valley Jacks

Higgs

hey,

does anyone know how to calculate hip and valley jacks. its been a while since i have and i can't remember for the life of me.
thanks

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Higgins
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neolitic

"The Full Length Roof Framer"
It's cheap, and fits in your pocket.

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KentWhitten

and the construction master, cheap and fits in your pocket.

Usually, find your longest one, then the jack table on the side of a framing square would finish it for you. Geometry concept is helpful to figure it out.

Jacks are the same as commons, just different input for run.

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cleveman

buy a speed square with a little book and a magnifying glass.

Joe Carola

The framing square has the jack difference right there. There are many ways to figure them, it depends on what way you're comfortable with. If it's the first jack you want, one way is to go from where the hip hits the top plate and measure over to your first 16" center. Do you have a Construction Master Calculator?

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A W Smith

so sad. no one reads framing squares anymore,

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neolitic

Even stranger.
I was going to show a kid
how to do it a few years ago.
And his square had no tables.
Since then I've noticed that
lots of them don't have
them anymore.
Maybe the same companies make
those calculators.

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Joe Carola

The cheap framing squares don't have the tables. All the good ones do.

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Joe Carola

wink

don't let any of your fellow carpenters see you do this but you could run a string from point a to point b and measure it, it will even give you your angles. i watched a guy do this to get a hip rafter once, it worked but seemed to take awhile.

Joe Carola

Why would you need to do that for a regular hip running at 45°? If you have a 8/12 pitch roof, your framing square for the hip will be 8/17. If your talking about a Bastard Hip, I can see people doing that who don't know how to figure out a Bastard Hip pitch.

The Construction Master Calculator by far is the fastest way to figure a roof, but you have to know what to put into it first. Knowing how to read a framing helps you with that.

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justagrunt

I have yet to figure out how to cut a side cut on the valley rafter, say for an 18/12 cut. Looking on my square it says 6 11/16ths. Doing this the way the book says, ends up with a 60 degree cut at a 45. Using my circ. saw this is near impossible, I've thought about my radial arm saw but thats not the easiest tool to haul around. Any advise would be appreciated

KentWhitten

If you have a flat plan in front of you and the pitch on either side of the valley is the same ie, in your case the 18/12 pitch, on your saw it will still be 45°. The sharper the plumb cut, the more sharp that angle becomes, but it still will be only 45° on your saw table.

That's assuming your valley is 45° on the plan of what your jacks are coming into the side.

Edit: I just noticed you said valley rafter, not jack. Same still applies. If your valley board is 45° on the plan of where your rafters/top plate are, then you will be setting your angle on your saw to the 45°.

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Salmon Falls Cabinetry

neolitic

And the plumb cut is 56¼º.

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A W Smith

you need this saw
http://www.whitecapdirect.com/products/106HD5860

OR..Make the cut in two passes. Mark both sides for the cut. Cut 45 degrees on the long side first. flip the rafter over. cut on the line but tilt the saw to cut or skim the excess off. Another way is to cheat the saw by shimming up the the edge of the foot with scrap 5/8 or 3/4 plywood. I bought a reconditioned Skil 8 1/4 sidewinder for that purpose that cuts at a 60 degree angle but the saw had a vibration problem from the start that i swear was a bent shaft. skil couldn't fix it. I parked it.

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oldfrt

We'd always take physical measurements from plate to hip/ridge rafter laying out our 16"OC,Take the nearest(straight) common rafter to lay out the hip.This way if ,there is a bow in the hip ,the rafters don't come out short.

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FRAMERBEN

Man I cant Imagine handeling and 18.5 lb saw everyday, none the less $230.00 Crazy

KentWhitten

OK, we have gone from talking about valley jacks to valley rafters. I'm getting a bit confused to the problem you have with the saw cut not making it. If it is a 2x, it doesn't matter what the plumb cut is, it will cut it with no problem.

Forget about the side cut for your rafter for now. You need to answer what I said above. What is the angle of the valley in plan view? Is it 45°? If it is, then you want to put a 45° angle on your saw. It's not going to be 60° on your saw. It will be 60° on the top edge of your board.....or whatever this angle comes out to.

This is where the theoretical length of your rafter come in. You draw the angle listed from your side cut to figure out where the start of your theoretical measurement it.

If it is a simple 45° common valley, then make a plumb cut on one side of the valle board, then flip it and make the same plumb cut on the other side. This will give you a bullnose with a sharp point on the end. This is your start point to place the end of your tape measure on to measure the length of your valley.

If this doesn't make sense to you, you might go through a few boards before getting it good enough. Like I said before, you need a good concept of geometry to understand what is necessary to make things work on a roof.

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If you correct your mind, the rest of your life will fall into place ~Lao Tzu

Custom Cabinetry - Portland, Cape Elizabeth, Scarborough, Kennebunkport, Yarmouth, Falmouth, Cumberland, Ogunquit, Maine

Salmon Falls Cabinetry

A W Smith

thats why i bought the 8 1/4 inch sidewinder,

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wallmaxx

Here's the basics of how I do it with a scientific calc to run the numbers

Joe Carola

Forget the sidecut tables on the framing square because you don't need them unless you're cutting with a handsaw. Whatever way your hip is running in plan view, that's the angle you set your saw at to cut the jacks and hip/valley. If your hip is running at 45° then your saw is ALWAYS set at 45° no matter what the pitch is when cutting the jacks and the hip cheek cuts.

For a bastard hip, if you have an 8/12 and 12/12 combination, you will set the saw for the jacks at 33.69° on the 12/12 side because the hip is running at 33.69° on the 12/12 side.On the 8/12 side you set your saw at 56.31° because the hip is running at 56.31° on that side.

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