Building new house and need beams to support flat roof trusses

Hi, I have searched the forums looking for my solution but cannot find the right fit. I readily find single load point data on loading of I-beams, but not on distributed loading.

Originally, I was going to repurpose hand-hewn beams removed from my early 1800's barn to build a post and beam straw bale home with a flat living roof. My wife and I decided to use several sliding patio doors in our south-facing wall to assist in our lighting, summer cooling and winter heating needs. As a result, a span in our south-facing wall has increased from a practical 10 feet to a more daunting 20 feet. I have several steel I-beams and need to be sure that if I use one of them instead of a wooden 10" x 10" x 19' oak beam. Can I safely support 600 lb solar panel installation, 2 lb/ft2 insulation, 2 lb/ft2 roof trusses, 3 lb/ft2 3/4 plywood sheathing, 25 lb/ft2 living roof load and 60 lb/ft2 snow loads. The area that the I-beam will need to support is 19' x 10'. So, from my figures, a 92 lb/ft2 load or a distributed 18,080 lb load. My I-beam is 231" long, 13 3/4" tall, 5" wide and has web 1/4" and 5/16" flange. This beam would be supported at each end, but if required, could get additional support from a box beam above the sliding patio doors. Any assistance would be greatly appreciated.

Please read the stickys up top on posting, and titles.

Moreover, this is a more appropriate forum for your question:
Eng-Tips Engineering Forums

Oh, okay. I'm sorry for posting in an inappropriate place. I will look over there.

Thank you.

W14 X 22 - the very lightest of the 14" W shapes

aefriot said:

Hi, I have searched the forums looking for my solution but cannot find the right fit. I readily find single load point data on loading of I-beams, but not on distributed loading.

Originally, I was going to repurpose hand-hewn beams removed from my early 1800's barn to build a post and beam straw bale home with a flat living roof. My wife and I decided to use several sliding patio doors in our south-facing wall to assist in our lighting, summer cooling and winter heating needs. As a result, a span in our south-facing wall has increased from a practical 10 feet to a more daunting 20 feet. I have several steel I-beams and need to be sure that if I use one of them instead of a wooden 10" x 10" x 19' oak beam. Can I safely support 600 lb solar panel installation, 2 lb/ft2 insulation, 2 lb/ft2 roof trusses, 3 lb/ft2 3/4 plywood sheathing, 25 lb/ft2 living roof load and 60 lb/ft2 snow loads. The area that the I-beam will need to support is 19' x 10'. So, from my figures, a 92 lb/ft2 load or a distributed 18,080 lb load. My I-beam is 231" long, 13 3/4" tall, 5" wide and has web 1/4" and 5/16" flange. This beam would be supported at each end, but if required, could get additional support from a box beam above the sliding patio doors. Any assistance would be greatly appreciated.

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Just a suggestion from a guy who has a house with a flat roof section, don't. Flat roofs are extremely prone to leakage. Any pitch will help, but in an area that actually gets snow I'd want enough to shed most of it. Originally both the living part of my house and the shop (it was a store / marina shop) out front had a flat roof, but at some point in the past an A roof was placed on top of the living area. The front shop section is still flat, and I've been ten years trying to correct problems from bad initial design and the fact that the water just lays there.

aefriot said:

Hi, I have searched the forums looking for my solution but cannot find the right fit. I readily find single load point data on loading of I-beams, but not on distributed loading.

Originally, I was going to repurpose hand-hewn beams removed from my early 1800's barn to build a post and beam straw bale home with a flat living roof. My wife and I decided to use several sliding patio doors in our south-facing wall to assist in our lighting, summer cooling and winter heating needs. As a result, a span in our south-facing wall has increased from a practical 10 feet to a more daunting 20 feet. I have several steel I-beams and need to be sure that if I use one of them instead of a wooden 10" x 10" x 19' oak beam. Can I safely support 600 lb solar panel installation, 2 lb/ft2 insulation, 2 lb/ft2 roof trusses, 3 lb/ft2 3/4 plywood sheathing, 25 lb/ft2 living roof load and 60 lb/ft2 snow loads. The area that the I-beam will need to support is 19' x 10'. So, from my figures, a 92 lb/ft2 load or a distributed 18,080 lb load. My I-beam is 231" long, 13 3/4" tall, 5" wide and has web 1/4" and 5/16" flange. This beam would be supported at each end, but if required, could get additional support from a box beam above the sliding patio doors. Any assistance would be greatly appreciated.

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Sliding doors for winter heat? Never seen a slider that didn't leak air like it was open.

moonlight machine said:

Sliding doors for winter heat? Never seen a slider that didn't leak air like it was open.

Click to expand...

+1 Went over to decent 'Atrium' doors, vacuum pane, wood framed, problem went way, and we still have a decent opening, near as dammit same looks. "Pella" ISTR.

As to the clear span?

Place a few support pillars, that problem is reduced, too. Engineer in a measure of safety.

Folks can adapt to a few columns changing the looks far better than to a load of building materials crushing theirazz into Mother Earth.

Thank you all for the input. I should have been more specific in my description of my situation. Your input has not gone unnoticed.

gadget73 said:

Just a suggestion from a guy who has a house with a flat roof section, don't. Flat roofs are extremely prone to leakage. Any pitch will help, but in an area that actually gets snow I'd want enough to shed most of it. Originally both the living part of my house and the shop (it was a store / marina shop) out front had a flat roof, but at some point in the past an A roof was placed on top of the living area. The front shop section is still flat, and I've been ten years trying to correct problems from bad initial design and the fact that the water just lays there.

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I apologize for my post. I wasn't clear as to the style of roof since it was not my primary engineering question. The roof is an inclined flat roof. The house is a one story house with a horizontal ceiling and sloped flat roof truss. There will 3/8" per foot slope sheathed with 3/4" plywood and covered with tar paper and a single membrane solid EPDM membrane covering the entire roof. A layer of smooth pea gravel covers the membrane and is used to allow water to drain. This is covered with a silt barrier to allow water to penetrate to the drain layer from the 4-6" soil layer above. Grasses and wild flowers keep the soil from blowing away. The roof will shed water with no pooling and there are no roof penetrations. Roofs fashioned like this have kept homes dry and have lasted for far longer than I or my wife expect to be alive.

moonlight machine said:

Sliding doors for winter heat? Never seen a slider that didn't leak air like it was open.

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I am making the doors and frames myself with either solid black cherry or hard maple from our property and the insulated glass modules in the purchased doors. The winter heat will come in the form of solar gain. Thermal mass in the floor and walls absorb and retain heat during the day and release heat at night. Automatic insulating panels cover the glass when night falls to retain heat. The post really wasn't to decide on the type of door, but to determine what is needed to be sure of the proper support since the height of the ceiling is 11 feet so I could install two of the I/W beams (not sure how to distinguish between the two) if I need to have more support above the doors.

Monarchist said:

+1 Went over to decent 'Atrium' doors, vacuum pane, wood framed, problem went way, and we still have a decent opening, near as dammit same looks. "Pella" ISTR.

As to the clear span?

Place a few support pillars, that problem is reduced, too. Engineer in a measure of safety.

Folks can adapt to a few columns changing the looks far better than to a load of building materials crushing theirazz into Mother Earth.

Click to expand...

I have 50 aged wood beams and 40 I-beams so materials are not the concern...keeping the wife happy is! If she wants it, I try to get or do it (within reason). If it ends up being that a large opening cannot be designed into the house, so be it. We are not wealthy, but I can be very resourceful when it comes to obtaining building materials. As I stated before, the beams came from my barn and I was fortunate enough to acquire the steel beams at auction for a very reasonable sum.

aefriot said:

If she wants it, I try to get or do it (within reason). If it ends up being that a large opening cannot be designed into the house, so be it.

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Get an experienced structural Architect/Engineer and see what you might be able to do with cantilevering support for the 'view' area from stout, but not necessarily even visibly exposed, support well back of it, then. Think multiple trusses, fully triangulated, probably inclined, not level, etc.

This sort of challenge has been solved before, more than once, and within the strengths of common materials without undue risk.

And if you can DIY high-grade custom hardwood doors, and a low store-bought-energy input home... successfully?

You ARE 'wealthy', even if not 'rich'.

Monarchist said:

Get an experienced structural Architect/Engineer and see what you might be able to do with cantilevering support for the 'view' area from stout, but not necessarily even visibly exposed, support well back of it, then. Think multiple trusses, fully triangulated, probably inclined, not level, etc.

This sort of challenge has been solved before, more than once, and within the strengths of common materials without undue risk.

And if you can DIY high-grade custom hardwood doors, and a low store-bought-energy input home... successfully?

You ARE 'wealthy', even if not 'rich'.

Click to expand...

Yes, it does, this conversation is pretty common over at eng-tips.com

As well as any codes that need followed....

The best reference book for any sort of structural steel design work is the AISC Steel Construction Manual. It has just about every imaginable loading situation one would ever encounter.

Price is in the $300 range but they're discounted heavily in tech college bookstores. IIRC when I bought mine about 15 yrs ago, it was about half the retail price. That said, its worth every cent of the retail price for anyone doing what the OP has described.

AISC also publishes a couple other manuals with similar titles. They are more specialized to specific types of design, and are widely available for 20 bucks or so in the used book market. But the one you want is titled exactly as I listed it above.

Smart move on the part of the OP in designing doors around stock sizes of insulated glass units for sliders. There's 3 or 4 stock sizes and all are dirt cheap as compared to anything of a slightly different size, like substantially less than half the cost. All about the volume of sliders used and broken glass replaced.

Frank L Wright would suggest laminated two by fours.

It's not the best perhaps, but it works and can make a very economical roof support.

If you have a building authority and you have an unusual construction, I can almost guarantee they will require a licensed engineer to sign off on the plans. Been there, done it.

Tom

TDegenhart said:

If you have a building authority and you have an unusual construction, I can almost guarantee they will require a licensed engineer to sign off on the plans. Been there, done it.

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Especially in a place like NY. They are sticklers up there.

That big of an opening will make it a soft story and you will have to add some major framing at each end like some big Simpson welded "strong walls" Probably have to add major diagonal bracing to the shed roof. You will run into issues on such a long beam of tieing the roof down so it stays attached to the beam in wind/sesmic action.
As far as Wrights ideas for a roof I am not aware of any building he designed that does not have roof problems. Either sagging or leaks or both
Bill D

Maximum deflection at mid span =(5WL**4)/384EI
Maximum moment at mid span =M= (WL**2)/8
Maximum stress at mid span =MC/I

W14-22 I beam
I=199 in**4

W=18080 lb/231 in= 78.27 lb/in

L = 231 in

E= (steel) - 30*10**6 lb/in**2
yield strength of A36 = 36,000 lb/in**2
C= 6.78 in

maximum deflection = .5 in
maximum stress = 18,000 lb/in**2
The beam also needs to checked for flange buckling
The beam deflection and stress are ok however


The unified building code will require fire proofing of the beam. The steel beams fail much quicker than wood in a fire.
The unified building code will also require at least 10 feet of shear wall for a 11 foot high by 19 ft long opening.
The local code may require that the beam sit on top of the shear wall to insure a solid connection. That means that the beam may need to be 19 + 4 ft long for example. In wood construction, the shear wall and beam are attached with plywood and a large number of nails. For these reasons a structural engineer will recommend a laminated wood beam rather than a steel I beam

Robert

I had a question almost exactly like this when trying to see how small a beam I could use to support a 17' opening.

I walked into the local professional (not Home Despot or Loads) lumber yard. Talked specs to a rep, he pulled out some books and in 5 minutes had calculated out a 11-7/8" x 5-1/4" Versa-Lam beam.

Sent his recommendation to our engineer and in about an hour with almost no effort had an approved certified beam for the princely sum of just over $300. They had them in stock, same day delivery.

Let professionals give you professional help. It's fast and easy.

Robert R said:

...
The local code may require that the beam sit on top of the shear wall to insure a solid connection. That means that the beam may need to be 19 + 4 ft long for example. In wood construction, the shear wall and beam are attached with plywood and a large number of nails. For these reasons a structural engineer will recommend a laminated wood beam rather than a steel I beam

Robert

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While the rest of Robert's post went by far above my head, this is something I have learned 11 years ago when built my house and needed to clear span
19' 8" of not only dead, but live load as well.
Also needed an appropriate beam for a 27' hip.

It is absolutely amazing what laminated beams are rated for and capable of.

In my area, it was sufficient to use the load tables provided by the manufacturer when submitting the plans, but of course you still have to use your calculations
and building code figures for the actual load requirements.

We've ended up using triple 20" LVL-s

This table might help in figuring the beam size and load capacities: http://www.weyerhaeuser.com/files/document-library/1484260463_TB-551.pdf

Flat roof and you are in snow country?

FORGET IT. The steeper the pitch, the better. And as for leaking, I guarantee it. I had a flat roof over a screen porch in my home in Florida. No snow. It leaked. Naturally the low spot was where it met the house roof, which was sloped. Big lake there. When I had a new roof put on the roofers strongly recommended that they build it up with plywood to prevent water from pooling. That seemed to help, but it would not do much for snow.

A good lumber yard can engineer your beam. Go talk to them. It will be a special order, not a stock item.

Robert,
You've got me curious about your statement that the beam would have to be "fireproofed" in single family detached construction. We use the IBC, not UBC, here, and there is no hard requirement for making a fire resistive assembly even in commercial unless the Code states that the wall or floor/ceiling or roof/ceiling assembly is required to be rated. Detached single family one or two story construction would actually fall under the IRC, and I can't think of any requirement for fire resistive construction there except for walls demising a garage space from the living space, and 20 minute doors on sleeping rooms.
I assume you said "fireproofed" as a part of vernacular, since that term isn't used in the codes. We have "fire resistive",since nothing is "fireproof".