maths/trig/DIY question
Discussion
I've been helping my father in law put up an oak built, barn style second garage at his house. It is 6m by 6m and around 4m high, but we hit a bit of a snag yesterday so I thought I'd ask the PH collective how you would solve this.
The structure is built with a flat roofed 'box' base measuring 2.5m to the top of the horizontal beams. There is then 3 uprights that go vertical to this flat base which measure around 1.5m high, these are then used to put one longtitudinal beam all the way through the middle and then connect rafters to in order to have a pitched roof.
My question is, what would the angle be that we would need to cut the rafters to in order to achieve the correct pitch on the roof. (fyi - there will be an overhang on each side, but the rafters butt up straight onto the longtitudinal beam at the rop).
(my Microsoft Paint skills are world renowned for technical accuracy, so I thought I'd put a little visual aid into the mix, see if that helps!)
The structure is built with a flat roofed 'box' base measuring 2.5m to the top of the horizontal beams. There is then 3 uprights that go vertical to this flat base which measure around 1.5m high, these are then used to put one longtitudinal beam all the way through the middle and then connect rafters to in order to have a pitched roof.
My question is, what would the angle be that we would need to cut the rafters to in order to achieve the correct pitch on the roof. (fyi - there will be an overhang on each side, but the rafters butt up straight onto the longtitudinal beam at the rop).
(my Microsoft Paint skills are world renowned for technical accuracy, so I thought I'd put a little visual aid into the mix, see if that helps!)
This was the plan, thing is, where we need to have the overhang, we need to take a notch out so it sits flat on the beams and when we do this, the top angle obviously changes. We then take some more off the top angle which puts the notch out slightly. This then becomes a vicious circle and it ends up a complete mish-mash of cuts and plane marks!
The rafters are all over sized already so we have a bit of room to play with, but I'd rather not have to play with anything and just get it right first time!!
The rafters are all over sized already so we have a bit of room to play with, but I'd rather not have to play with anything and just get it right first time!!
if i have read correctly
You have a triangle with a length of 3 (half of the total width) and a height of 1.5 (the long side therefore is 3.35) the angle at the top will be circa 63.5 degrees (rafter to upright)Meaning if the rafters are to butt up to the cross beam they will need to be cut at an angle of circa 116.5 degrees
However I would cut one and try it first as none of my calculations take into account the thickness of the rafters etc
The angle at the bottom will be 26.5 degrees and therefore the cut for the notch (into the over hang) will need to be 153.5 (bit more tricky this as you will not be looking to cut all the way through)
You have a triangle with a length of 3 (half of the total width) and a height of 1.5 (the long side therefore is 3.35) the angle at the top will be circa 63.5 degrees (rafter to upright)Meaning if the rafters are to butt up to the cross beam they will need to be cut at an angle of circa 116.5 degrees
However I would cut one and try it first as none of my calculations take into account the thickness of the rafters etc
The angle at the bottom will be 26.5 degrees and therefore the cut for the notch (into the over hang) will need to be 153.5 (bit more tricky this as you will not be looking to cut all the way through)
Found use some calculators that may help you...........
http://www.pole-barn.info/roof-rafter-calculations...
http://www.pole-barn.info/roof-rafter-calculations...
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