hip rafters cut too deep.

[Jsmithy]

Hi all,
I have been framing my extension roof but unfortunatly cut my hip rafters too deep, they are resting on the wall plate at the point where the cut is around 50% of the width.. they are 11 by 3".

my question is can i double up my ceiling joists on either side and make a support to take some weight of the hips, the joists are 6x2" and span a distance of2450mm.

or is it a case of biting the bullet and buying new hip rafters? any solution to this will be greatly apprieciated thnx for help on this.

 

[tony1851]

As the cut is right at the end (making it 5 1/2" x 3"?), you don't need to worry.
The bending stress at that point is nil and the only criterion is the shear stress across the reduced section. And even this will be well below the maximum allowed. You don't need to double up anything, or provide any additional support to the hip.

 

[catlad]

I am not sure I understand you correctly but you can span both walls at a 45 degee angle and support it off that, a sort of dragon beam arrangement but it would probably wise to buy new rafters.

 

[theprinceofdarkness]

If I understand you correctly, the horizontal distance across the hip rafter at the top of the wall plate is 11/sine of roof slope inches, say 15" and you have had to cut away 7" of this to allow the rafter to sit on the wall plate. This would give a couple of inches of hip rafter overhanging the wall plate and so unsupported.
I would think that if you got a joist hanger, flattened it out so its like a rectangular "U" and fitted it on as tight to the loose end as possible. This then would be like the bottom edge of the hip rafter "hanging" of the rest of it, which would actually be overkill, but quite quick to do.
If you fitted your 6" X2" ceiling joists it is unlikely that you could get enough fixings in to actually strengthen the overhang unless you glued it as well, because its only the bottom 2" of the hip rafter that requires support.

Are you sure your angles are right?
Frank

 

[Jsmithy]

hi thanks for replys my roof pitch is irregular one side pitch is 42 degrees and the other the pitch is 33 degrees.
can i put a 3x6" across the corner of the wallplates like a dragon tie to help support the rafters at the bottom would this be sufficiant.

 

[Jsmithy]

hi tony, thanks for your input, can i let you know that the depth of the cut at its thickest is around 5" at the point the hip rafter meets the wallplate and around2.5 at the front is this ok thanks for your time on this.

 

[Jsmithy]

tnx catlad would 3x6 be sufficiant for the dragon tie arrangement? or thicker.
3 would be the depth and 6 the width which sat on the wallplate.

 

[Jsmithy]

just to say thanks again for input any extra clarification would be nice and i will be able to reply later as im off out for a bit thanks again.

 

[noseall]

The hip blade always ends up with an uber-deep cut in order to lie through with the commons and jacks.

As said not a problem

Just remember to fit a dragon tie and all will be ok.

 

[Jsmithy]

Thanks alot everyone for the replys always good to get the expirienced to help out, great forum and great members cheers.

 

[theoldun]

Hi all,
I have been framing my extension roof but unfortunatly cut my hip rafters too deep, they are resting on the wall plate at the point where the cut is around 50% of the width.. they are 11 by 3".
.

Due to the fact that we are thick, we can make no sense of your post what so ever.
Are you saying that you have cut your birds mouth to deep and left your HAP low or are you saying that your secant was to short and your heel cut and seat cut does not now extend over the 45 degree cut on plate corner,

QUOTE
hi thanks for replys my roof pitch is irregular one side pitch is 42 degrees and the other the pitch is 33 degrees.

Sorry, but once again do not understand. Have you got an of centre ridge with Queen and commons on one side at 42 and ditto other side at 33, or is major roof, centre ridge at 42 both sides and King rafter and hip at 33 making irregular pitch hip.
A dragons tie is not a load bearing member, but purely as assistance to lateral restraint Depending on depth of hip and pitch, if you use a dragons tie, you nay have to notch hip over the tie . These days we obtain lateral support from the joists. If we have the information we will advise you.
Regards oldun

 

[noseall]

.....are you saying that your secant was to short and your heel cut and seat cut does not now extend over the 45 degree cut on plate corner,

...and by the sounds of it he will have to bolster off a 45 degree chunk of masonry also.