Help with framing an offset lean to roof


Hi forum,

I've encountered some framing problems drawing up some plans for my office for a future extension. I don't really have any to ask so I thought I'd turn to you guys! I've tried extensively researching on google but can't find any examples specific to my needs.

Currently we have an existing build with a 30d roof pitch. I'm looking to put a lean to roof at 6d attaching around half way up the roof. This is better explained in the photos I've attached.

I just have a few questions;

1. How would I frame the roof where the new roof and valley rafter joins? Can I somehow just attach a fascia board to the valley rafter and cantilever the distance I need? 

I've got 2 options for this roof, one large cantilever to keep the roof shape rectangular and another where i've put in gnome walls on top of the existing walls and just roofed to there.

2. How would I go about the change in roof pitch framing? I've given it a shot but it just doesn't look right and I can't figure it out.

Existing roof is clay tile, new roof will be steel sheet roofing.

Plans are rough so please dont worry if things look messy / out of place etc! Thank you for any help in advance!

Mar 7, 18 7:55 pm

Are you licensed?

Where did you go to school?

Mar 7, 18 10:26 pm

Irrelevant to the initial question, but no I am not licensed and have attended no university.
Just drawn plans and hand them over to a registered architect when he is available.

Mar 8, 18 7:24 pm
Non Sequitur
Completely relevant. Why not ask the actual architect to do the work?
Mar 8, 18 8:29 pm

Costs are significantly reduced to get him to just check over and correct what I've drawn, then lodge the plans after they're complete and competent.

Really just needing help with the two roof details as the architects response time is usually 5-7 days with trivial questions and will only respond with sketches (not a phone conversation, which is fair enough). Anywhere else I could post where someone may be able to help?

Mar 8, 18 8:44 pm
Non Sequitur

So, you're looking for free advice from real professionals who actually make a living answering such questions? Good luck.


But the basement draftsman needs help

will only respond with sketches (not a phone conversation ...




I'll respond with trivia questions and answers in less than two hours. If that helps.


Here is my tip for you......  Skylights leak

Mar 9, 18 11:05 am
Non Sequitur

just the skylight? what about that low slope roof connection? Hopefully this junior draftsmen is not in a climate with heavy rain and/or snow.


Skylights are necessary as windows aren't an option along the boundary, and windows on side walls need to be set back 3m from the boundary for fire safety. This is in Australia, with no snow and ice loads needed as there is no snow and negligible ice.


Normally the standard response to someone looking for free advice is to rip them apart.

Based on the drawings here I think you'd really be better served hiring someone who knows what they are doing.  It'll save you a lot of time now and aggravation.  If you can't afford that then you can't afford the project.

You're on the path to an expensive and and long lasting head ache.

Mar 9, 18 11:13 am
Non Sequitur

The Op is less than a year removed from technical school. It's probably in their best interest to quit the drawing farm and move into an office where they can rely on real staff architects.


I see, thought this was a home owner.


Is this a single family residence? Keep costs down by not hiring an architect at all. 

If you don't know what you're doing, stop trying to play architect to "keep costs down." You're not helping, and even if you find a good Samaritan here willing to give you free advice, your costs (which are being kept down) should have been paid to the professional you are actively trying to stiff.

Mar 9, 18 11:43 am

Three skylights but no windows on the long wall of the addition? What is with that?

Skylights leak, virtually always, you need to delete those.

The 'catslide' roof intersection is asking for snow and ice build-up. Even areas of the deep south can have ice storms.  

Mar 9, 18 1:55 pm

Australia has no snow and ice requirements


Is that the property line?  Are you allowed to build that close to it?  Have you considered there may be fire ratings required if you build that close to the property line?  You may require the services of a professional.

Mar 9, 18 3:18 pm

Boundary wall is within rescode. No windows along the long wall as the neighbouring house is less than 3m away and windows are not allowed on the boundary.


Here's a guy who thinks knowing AutoCAD makes someone an Architect... lol!

So let me see if i understand your section correctly... you are proposing a new column to support a new beam on which you are stubbing up to support a roof? How messy... I agree with the above comments... why not just hire an architect? Why do you do the drawings and hand them off to a registered architect? 

Mar 9, 18 10:13 pm

Also, why are all your dimensions in mm?

Mar 9, 18 10:15 pm
Non Sequitur

mm is typical for most of the world. I exclusively produce drawings in mm.


Australian Standards


Sorry- one last comment... where is this project located? Don't see any insulation... you also need to meet residential energy code...

Mar 9, 18 10:18 pm

Here's a hint...

Shore the existing joists that support the attic. Cut those joists and re-support them via a new beam that spans the length of the new addition. Frame a new load-bearing knee wall on top of that beam to support the existing rafters that will be cut to accommodate a new opening whose length is the length of your addition. The top of that knee wall will also support new rafters that will be the framing for your new roof. The angle of your roof will be determined by the hight of the new wall opposite that new opening.

Mar 9, 18 10:24 pm

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