Marking and cutting hips :)
- Thread starter Sonnypaul
- Start date
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Hi Sonnypaul,
its not really on to try and describe roof cutting on a DIY forum.
If you are replacing a hip then use the old hip as a template.
If its new work then draw out on a clean deck/floor in full size or 1/2 size a diagram of: first a common rafter, then the hip.
This will show your top plumb cut and the birds mouth(notch?) that sits on the wall plate.
There are books on roof cutting but it can be a bit of a pain to learn.
its not really on to try and describe roof cutting on a DIY forum.
If you are replacing a hip then use the old hip as a template.
If its new work then draw out on a clean deck/floor in full size or 1/2 size a diagram of: first a common rafter, then the hip.
This will show your top plumb cut and the birds mouth(notch?) that sits on the wall plate.
There are books on roof cutting but it can be a bit of a pain to learn.
We pull a tape measure off the last full common rafter.
We drop the tape on both sides of the common so that we can transfer two marks onto the hip blade, i.e. one will be higher up the hip than the other.
We keep a templated section of the bottom birds-mouth and the soffit overhang from previous common cutting.
We measure from the highest mark up the hip down to the outer edge of the wall plate and what will be the crook of the birds-mouth.
We prepare a jack rafter with the correct compound cut done at one end. We then take our measurement and pull the tape from the peak of the compound cut along the side of the rafter and mark off our birds-mouth crook.
We then use our saved templating piece to mark out the birds-mouth, aligning the crook of the b/m with our mark and also pencil around the rafter end soffit/fascia cut also.
We drop the tape on both sides of the common so that we can transfer two marks onto the hip blade, i.e. one will be higher up the hip than the other.
We keep a templated section of the bottom birds-mouth and the soffit overhang from previous common cutting.
We measure from the highest mark up the hip down to the outer edge of the wall plate and what will be the crook of the birds-mouth.
We prepare a jack rafter with the correct compound cut done at one end. We then take our measurement and pull the tape from the peak of the compound cut along the side of the rafter and mark off our birds-mouth crook.
We then use our saved templating piece to mark out the birds-mouth, aligning the crook of the b/m with our mark and also pencil around the rafter end soffit/fascia cut also.
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Hi noseall good to hear from you, you have answered a few of my posts in the past.
Im literary at a knifes edge trying to scribe bird-mouth commons.
I jumped the gun abit asking about hipped roofs i think, i still cant even do a basic lean to, ive bought goss roofing ready reckoner and a few other books but still cant get it in to my head!
Ive been trying to practice etc in the garden but i keep having the same problem.
The only way i can manage to get it all sitting nice is to put another piece of 4x2 on top of the existing wall plate, ive tried scribing and it fitted nice but the top angle was well out!
I also dont want to move the top wall plate down.
I remember someone saying something about stringing a line and using a bevel?
pictures to follow.
Cheers noseall
30 Degree pitch im using
The Arrow at the top indicates top of wall plate
You perhaps need to remember also that your seat cut is exactly 90 degrees to your plumb cut.
So if your plumb cut is 30 degrees (which also denotes the roof pitch) then your seat cut is 60 degrees. You can sometimes do both the seat cut and the plumb cut on the bench saw depending on the saws' limitations. Mine will swivel around to 60 degrees one way, so i can do 60/30 b/m cuts.
You can also position the pitching or pole plate (the vertical wall timber on a lean-to) so that it is under the rafter end and not at the rafter end.
If you do position the pole plate beneath the rafter end, B.C. do like to see the rafters either b/m'd onto it or use something similar to a truss clip to anchor it.
So if your plumb cut is 30 degrees (which also denotes the roof pitch) then your seat cut is 60 degrees. You can sometimes do both the seat cut and the plumb cut on the bench saw depending on the saws' limitations. Mine will swivel around to 60 degrees one way, so i can do 60/30 b/m cuts.
You can also position the pitching or pole plate (the vertical wall timber on a lean-to) so that it is under the rafter end and not at the rafter end.
If you do position the pole plate beneath the rafter end, B.C. do like to see the rafters either b/m'd onto it or use something similar to a truss clip to anchor it.
Hi noseall.
My seat cut is exactly 90 degrees, i used my square and then checked it on the chop saw with a bevel.
I know what you mean about moving the pole plate beneath and maybe notching the top but i cant seem to find anyone to tell me this method that im questioning.
I mean if a chippy turned up on site and the wall plate was on and the pole plate was up at 30degrees what does he do?? see what im getting at noseall its driving me insane.
Looked at roofing courses and there a rip off, silly money.
you Dont know anyone who lives in kent by any chance lol
If you were to place a 2" thick piece of timber vertically against that foil insulation and butt it against the rafter then strike a pencil line down the rafter, this would give you the thickness of material you would need to remove in order for your rafter to be the correct length for a butted pole plate..
You bed the wall plate (bottom) but do not do the (vertical) pole plate until you have rafters (at least a pair) temporarily in place. You always cut a rafter so that it butts directly against the brickwork THEN decide what you are going to do with the pole plate.
I use trigonometry to get the exact length of the rafter and it's relatively straight forward once you have done it a couple of times.
Depends how you have set out your 30 degree pitch If you have taken a line from outside edge of ledger plate to outside edge of wall plate then it will not be 30 degree pitch.
Your pitch line is the hypotenuse of the triangle and is two thirds down at a 90 degree angle from the top of rafter. The pitch line is also the internal angle of your birds mouth (the crook). If we try to explain any further you will get confused.
Therefore if you post the following information we will give you all your angles and cuts plus a way of scribing all yout cuts with a rafter thrown up the wall
The following measurements must be exact, and we have assumed this will not be vaulted but a coupled lean to.
House wall to outside edge off wall plate.
Height of bedded wall plate to top of ledger plate.
Width and depth of ledger plate.
Depth of rafters.
We note that old nose wrote.
I use trigonometry to get the exact length of the rafter and it's relatively straight forward once you have done it a couple of times.
We are more up to date than old nose bless him, we use a ball of string, bit of chalk, passing cloud and a nearby tree
Regards oldun
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