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Hey DIYr’s

Let me jump right in and just explain why I ended up on here. Not meaning to sound unsociable. Just think this intro, for now, should serve more as a kind of sticky. I'll lighten up once you guys slap me out of panic mode.

Simply put, my arrival here is about specifying a pair of Wide Flange Beams for a very tricky addition to our home. The new space comes out off of house perpendicularly, then bends 40deg to right of that. I couldn’t even reach a nice 45 deg, even *after* the ledge got removed.

This project is much needed garage and shop space being added to a 1995 house with 2 symmetrical 4:12 roof pitches. The site lies at 1700’ and is far more exposed to the wind (treeless) than I would have preferred. But when the house was purchased a few years ago, my wife was the primary bread winner. She had by then also suffered a stroke. That forced her early retirement and after a year we both wanted to go rural. When she first saw the view here, she sighed, "It's just like in the Sound of Music". She got jazzed on that. And I got locked into an average 9mph breeze goin on for the rest of my life, with only a 2 bay under-garage, for shop space.

While excavating for the frostwall (foundation) for our first plan, a sheltered pad area, we got hit with a double whammy. At about the same time last summer we not only ran into some ledge (removed at a $4100 hit to the budget), we also learned that the property line setback, on the side where we were also planning to build a primary main level access barn idea, was prohibitively close to the house. Meanwhile our leach field ruled out the only other vehicular approach around from the driveway side, and the prop line buffer is only 25’ from the house. The narrow, 12’ wide, view-side lawn is the only other vehicular access to the main level. The wife does still drive (snowless months only). And for my part I can’t see an 80 year old me lugging 3 trips of groceries, through the winter winds, through the garage, and up the stairs, especially when my time is already taxed enough as it is. In the winter that narrow “lawn” on the view side of the house cannot be counted on everyday because it drops off steeply downward about 20 feet to the next nearest flat grade. It can also resemble a skating rink for anything without studded tires.

Enter the "wide flange beam" slash combine it all, solution. But with the BIG QUESTION being, which weight (lbs/ft) W16 will do the 36’ span at the deepest (outside bend) corner of the addition. Posts aren't much of an option because they would restrict access to the existing heated garage bays.

Because of the 40 deg angle every possible location for support posts fragments the lower level space. Am hoping for a 12x9' wide door and a walk-in at the front (actually a side profile of a basic saltbox).

I can attach acad screenshots and pics for anyone who could help me plow through the most critical formulas for determining the deflection of the two steel beams I intend to spec.

I am hoping that a W16-50ish, paired in parallel, 10 feet apart from, a W12-XX-ish will accomplish the desired Saltbox Garrison profile. The primary ?W16? would be directly under the rafter ridgebeam posts, 6x6's, 6ft on center, and the W12 will support another bearing wall, serving as a purlin of sorts for the rafters on the lengthier west facing roof. The front width of our Fall-2011-poured frostwall and foundation is 30 feet. The two W-beams are to be simply supported at either end, front to back in the Z axis. You are basically looking into the side of a Saltbox. The apex/ridgeline will run atop the first (left side) beam being 10’ over from the left side of the foundation. The beam will have to be trussed over the main door. I am hoping we can swing a good quality roll up door. I'm in a panic right now because the welder is going to have help design the truss we need for the front end of the beam. That beam's elevation of 12' is for accommodating any future automotive lift.

Forgive me for the long winded TMI details here.

This is actually my first property ownership ever. I am excited to be this close to having an unobstructed workspace for ripping wood, building prototypes indoors, etc.. Even if we go broke, at least the next owners (aka, prospective buyers) may regard the lift idea as a real god send. For which they will pay dearly. Maybe.

The bottom of the W-beam on the 12 feet high side of the saltbox shape, will need to rated/spec’d/built for typical residential storage loading. The rear ends of the beams will bear on 4 prefab footings set inside the frost walls prior to pouring the final pad.

Whole plan works so long as any W16 -- of one lbs/ft weight or another -- will suffice.

Wind loading is another consideration I need to – ahem – “nail down” prior to going back to our structural engineer. He is retiring this year, and last summer he was good enough to review and approve my first design (with a single W12-45, over a single center post) at no cost. So, with this second phase, dual beam, postless design, the least I can do is try to make sure my next W16-xx approach will pass muster. Anything taller and it’s back to the drawing board (ACAD) with contractors’ schedules filling up fast.

What's freaking me out is how there is no simple table you can go to for calculating Deflection, just based on a given Span and Wbeam-weight criteria.

Thanks to all in advance. And sorry for any eye or brain strains in trying to follow this.

If something is not clear then please by all means, email or PM me.


Registered User
11,730 Posts
Welcome to the forums! Sounds as if you need to hire a structural engineer....

Glad you found us.


Super Moderator
13,973 Posts
Wow, may I suggest posting this in another area, you will not get as many responses here in introductions as you will in "Building and Construction" or "Carpentry" not a lot of the fellows and gals come here to introductions.

Welcome to the forum
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