Shed style roof - Span over beam

[midrover170]

Hi all -

First, I'm quite the rookie on here - forgive me for any obvious ignorance!

Next spring/summer I'm planning to start building a small 550 sf off-grid cabin. Wanting to do most on my own, so that's the reason for my simple design and layout. I have a number of questions about the framing, but one that worries and/or stumps me right now is at the roof where I anticipate using a glulam beam for mid-structure support. The cabin will have a 3:12 pitch running the distance. In the middle of the span is where I plan to frame in and install the glulam for rafter support (attached a couple pictures). As you'll notice in photos, I can't carry the angle of the rafters across the beam (unless I do some seriously strange notching).

What's typical here? Is the space (about 5 inches across) minor enough that the sheathing will provide strength? Do I need to have beam machined to match the 3:12 slope? I'm planning sheathing with metal roof, so there'll be strength for sure. Just want to avoid any major bonehead moves.

Thanks!

[new land owner]

I would cut a wedge out of some 2x material and cover that gap.

[John Raabe]

I would suggest dropping the beam down below the rafters which can be notched and lapped over the beam.

[midrover170]

Thanks John. I really like that approach.

[GSPDOG]

Mid rover,  I see what you planning, basic and very functional design. 

What are your planned dimensions?  It would appear to be simple lower level and open loft?
2x4 or 2x6 walls?

Keep in mind the roof has constant downward and outward forces working on it.  Type of wood lumber dimensions all play a part in how this has to be built.

So we need a little more information on dimensions because that is going to play a major factor in how to design that kind of roof.   So you thinking about something 32x16 for 512 sq ft + additional floor space in the loft?

[midrover170]

Hi Jim -

The cabin is scheduled for 14x32, and you're right: simple shed style roof running the length. I'm planning 2x6 construction for all the walls, and 2x10s for the rafters. The overall footprint is roughly 550 sf because there's a small bumpout for bathroom/utility. The loft space is roughly 9'x14'.

The foundation is really up in the air at the moment. An engineer friend is running the numbers, and isn't sure if post/pier will pencil. For this county in Idaho, they recommend working with a 100# snow load, and that's making things difficult. I might have to do a monolithic slab - even though concrete will be mighty difficult to get at this site.

Thanks for taking a look.

-D

[Don_P]

Have him check by replacing the piers with ~4' sections of 8" concrete wall, make 90 degree angled corner walls. If it checks that would be less concrete. I've poured sections that size using bags of portland, sand and gravel with a small mixer.

Have you considered platform framing the loft area and balloon framing the non loft area?

The bumpout appears to be cutting through a window.

Don't forget an egress window in the loft.