Hi everyone need help, iam doing a single storey extension on the back of the house an it comes out 10 ft . The pitch roof has to be 17 degees. How can i work out the pitch in 12, as i want to do it myself. Any help would be really apreciated on the birds mouth ect. Thanks Carl.
17 degree pitch
- Thread starter benuover
- Start date
Sponsored Links
What do you mean by this?
Ditto to noseall but if you mean the perpendicular height at the top of the pitch you'll need a trig calculator which can be found on google
OR
use the tried and tested estimator method with a piece of paper, protractor and a ruler, lot quicker and easier
OR
use the tried and tested estimator method with a piece of paper, protractor and a ruler, lot quicker and easier
If you mean going out 12 foot instead of 10 foot then a 10 foot wide extension at 17 degrees will give a rise of about 36" whereas a 12 foot wide fella will give a rise of about 44".
Working out all the cuts is done by using a bit of math's, a compound saw with angles on it, a bevel, a square, a tape measure, a pencil, a spirit level, an angle finder, a bit of trigonometry, a bit of pythagoras, and a fair bit of trial and error.
Working out all the cuts is done by using a bit of math's, a compound saw with angles on it, a bevel, a square, a tape measure, a pencil, a spirit level, an angle finder, a bit of trigonometry, a bit of pythagoras, and a fair bit of trial and error.
Sponsored Links
We believe that, when the OP says 12 he is referring to the American system of working in twelve’s i.e. 17 degrees equals rise of 3.7 in 12. We used to work this way back in the 50s
If you care to post the measure from the existing house wall to the outside of the wall plate either in metric or imperial, we will post all the angles, birds mouths and measures that you will require.
oldun
If you care to post the measure from the existing house wall to the outside of the wall plate either in metric or imperial, we will post all the angles, birds mouths and measures that you will require.
oldun
Iam at the house 2morrow,i will measure from the wall to the outside edge of the wall plate. The wall plate is 4*3 and the timbers will be 8*2 and the ridge plate will be 6*2 and i will be having a 100mil over hang for the sofit an fascias for spot lights. If you can do my calculates on the birds mouth, angles and measures ect it will be really apreciated thanks very much your a star.
8X2 RAFTERS WILL NOT SIT WELL ON 6X2. SORRY ABOUT TYPE NOT SURE WHAT I HAVE DONE
yes i mean the height at the top. Been lookin on youtube and they call it run in 12. I want my slope to be 17 degrees thats what it says on the drwings. I am putting redland groveburys on with three velux windows in. All the help would be really apreciated
hi i have measured from the wall to the outside wall plate an its 115 inches it needs to be 17 degree pitch an im putting a 300 mil facia an sofits on. hope u can sort it out for me. thanks Carl.
Pitch 17 degrees. Angle of cut to seat 17 degrees. Angle to plumb cut ridge and heel 73 degrees
Wall to back edge of plate = 115ins
115ins = 2920mm
2920 less 47mm width of ridge plate = 2873
2873 run gives rise of 878 on the pitch line (hypotenuse) plus HAP (height above plate). Come back to this in a minute.
Slope of rafter from ridge plumb cut to heel plumb cut will be 3004 plus what ever overhang you require.
If rafters are 50x200 these will be delivered 47x195.
Pitch line and birds mouth plumb cut will be one third up rafter depth = 65mm. Seat cut will be approx 210 long. Save your cut our, reduce and stick back on to cut to continue rafter down to plate.
On 47x195 rafter, length of plumb cut at 73 degrees will be 203mm less 65 = 138mm which is HAP.
As above rise to pitch line on 17 degree was 878 plus HAP of 138 =1016 therefore top of ridge plate is 1016 above wall plate.
Would suggest that you use 47x195 for ridge plate to collect full depth of rafters.
Make sure plates are level and parallel.
Not being negative, but if you have windows in wall above roof, then you will not get a 17 degree pitch in due to height of rise.
If you do not understand what we have wrote then PM us your address and we will put a self explanatory drawing in the post.
All measures are based on 47x195 rafters.
oldun
Wall to back edge of plate = 115ins
115ins = 2920mm
2920 less 47mm width of ridge plate = 2873
2873 run gives rise of 878 on the pitch line (hypotenuse) plus HAP (height above plate). Come back to this in a minute.
Slope of rafter from ridge plumb cut to heel plumb cut will be 3004 plus what ever overhang you require.
If rafters are 50x200 these will be delivered 47x195.
Pitch line and birds mouth plumb cut will be one third up rafter depth = 65mm. Seat cut will be approx 210 long. Save your cut our, reduce and stick back on to cut to continue rafter down to plate.
On 47x195 rafter, length of plumb cut at 73 degrees will be 203mm less 65 = 138mm which is HAP.
As above rise to pitch line on 17 degree was 878 plus HAP of 138 =1016 therefore top of ridge plate is 1016 above wall plate.
Would suggest that you use 47x195 for ridge plate to collect full depth of rafters.
Make sure plates are level and parallel.
Not being negative, but if you have windows in wall above roof, then you will not get a 17 degree pitch in due to height of rise.
If you do not understand what we have wrote then PM us your address and we will put a self explanatory drawing in the post.
All measures are based on 47x195 rafters.
oldun
hi old thanks for your reply got 8*2 delivered today and 6*2 for the ridge an 4*3 wall plate. not sure what u mean is there any chance u can e-mail it to me. my e-mail is [email protected]. If not how do i pm u. Thanks Carl
Is this a lean-to roof or duo pitch.
I assumed lean-to, hence my second post.
Old Codge has given you a comprehensive answer. Short of actually providing diagrams there is little else to convey. If you don't understand what he is saying then you really should not attempt the roof build.
If it is a duo pitch then 6" x 2" will not be enough for the ridge. If it is lean-to then a 6" x 2" can be bolted below the rafter (top) end.
Despite all the info' that can be provided on here, there will still be uncertainty and trial and error will still come into play. You should not for example, just cut all the wood up to the dim's written on here.
You will need to "mock-up" part of the roof, make a pattern rafter, then if you are happy cut all the others. Things like soffit overhang, soffit boxes etc, are largely cosmetic and can only be decided on site.
P.S. You is spelt y.o.u. Txt spk is irritating to read.
I assumed lean-to, hence my second post.
Old Codge has given you a comprehensive answer. Short of actually providing diagrams there is little else to convey. If you don't understand what he is saying then you really should not attempt the roof build.
If it is a duo pitch then 6" x 2" will not be enough for the ridge. If it is lean-to then a 6" x 2" can be bolted below the rafter (top) end.
Despite all the info' that can be provided on here, there will still be uncertainty and trial and error will still come into play. You should not for example, just cut all the wood up to the dim's written on here.
You will need to "mock-up" part of the roof, make a pattern rafter, then if you are happy cut all the others. Things like soffit overhang, soffit boxes etc, are largely cosmetic and can only be decided on site.
P.S. You is spelt y.o.u. Txt spk is irritating to read.
SM PPL JST HV NO GRMMR SKLLS WHTSVR NSEALL. THY HV TH GRMMR SKLLS AKN 2 A MNKY.
DIYnot Local
Staff member
If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Are you a trade or supplier? You can create your listing free at DIYnot Local
Sponsored Links
