Barn Renovation

[Phil McKrakin]

I'm new to the forum & I'm a big DIY'er. I'll try to introduce myself in another category shortly.

Here's where the fun begins. I'm going to start a running Post / Thread outlining a project's progress, including pictures. I think you people are going to love this one.

I've just recently acquired some land with several outbuildings on it. One of which is a Dairy Barn that measures 32' 2" X 111' 6". If it all goes well, this 3,586 Sq. Ft. building will soon be home for my Family & I. I've have always wanted to convert a barn into a home since I was 16 yrs. old. I'm now only 42 yrs. young.

This Dairy Barn has high curved roof trusses with a curved roof line. The entire hay loft is wide open. There is absolutely no support beams &/or other support trusses within the hay loft area. The entire roof load is transferred down onto the masonry block perimeter walls.

There are (2) support beams that run the entire length of the barn that support the perpendicular floor joists of the hay loft. These (2) support beams are approx. 12' ft. from each side walls with approx. 8' ft. width between them. These (2) support beams are supported with 4" (+) sq. posts approx. every 7' - 8' on center. This main "ground" dairy level has approx. 7' ft. ceilings to the bottom of the hay loft floor joists.

This barn needs to be raised & supported while I have new footings & walls poured. The current footings are poured over sand, gravel & rock. I needed to have these footings replaced with frost-line footings. Since the walls are currently masonry block, they will have be replaced as well. I plan on poured walls with reinforcement if necessary.

Since the barn has to be raised & supported for this work, I'd like to replace all the current support beams with either steel "I" beams or laminated wood beams if structurally safe & feasible.

Since the outside wall perimeters will be poured walls, I’m only having to deal with loads that will be placed on the hayloft floor joints from above & within the perimeter of the walls.

I would like to span at least the width of the barn, (approx. 30' inside dimension), with no support posts. If this cannot be done cost effectively or without having to add significant height to the support beam(s), then so be it. I can easily handle support post on 10’ or 15’ ft. centers in my designs if necessary.

I'd also like to span the depth / length of the barn with support posts as far apart as possible. Again, if this cannot be done cost effectively or without having to add significant height to the support beam(s), then so be it. I can easily handle support post down the length of the barn as well. Here is where I’d like to see at least 12’ ft. or more on the support posts.

What are some of your thoughts?

I'm looking for information &/or links to helpful information on determining loads for Steel I Beams &/or Wide Flange Steel I Beams. I would also like to learn as much as I can about engineered / laminated support beams as well. Prior to I contacting an engineer or local building supply center regarding this aspect of the project, I’d like to get feedback and input from some of the professional out their to help me determine a path that is not only practical, but cost effective as well. I also want to be able to determine some rough cost estimates for these different options.

I'm also looking for any information or contacts on who might have, or know someone who might have, new &/or used support beams for sale that will fit my application(s).

If anyone would like to share their thoughts on this project, please free to post replies to this Post / Thread or contact me directly through this forum.

I look forward using this forum. I’ve never used one before.


Regards,




Pat
Phil KcKrackin (Alias)

[Don_P]

You'll need an engineer, insert standard speech here :)

The AISC Steel Construction Manual would be a good place to start. You can probably get it on interlibrary loan if you don't want to purchase it (google and you'll see why). The 9th edition is still fairly current and easy to follow.

The APA website will probably be a good resource on engineered beams and connection details.

This may be of some early design help, I'm no engineer.
http://www.ls.net/~windyhill/Calcs/steelbeamclc
Imagining running I beams across the 32' width every 12'.
I entered;
384" span
144" tributary area
50 psf load
50 ksi steel (modern, not recycled)
I got the deflection to pass with a W16" x 40 plf beam.
Floor joists would then run beam to beam 12', longways down the barn. you lose the existing floor and need to check the rafter connection but its open below.

Replacing the existing girders with heavier ones will allow you to keep the existing floor if its in good shape and move the posts further apart on center within each of the 2 rows. That would not require steel, built up solid sawn headers, LVL's or glulams could all do that.

[Phil McKrakin]

Thanks Don,

Replacing the existing girders with heavier ones will allow you to keep the existing floor if its in good shape and move the posts further apart on center within each of the 2 rows. That would not require steel, built up solid sawn headers, LVL's or glulams could all do that.

The floor is in great shape. The family is going to have a great time playing floor hockey up there until we start finishing it off.

When you say "girders", I assume you are referring to what I called the "support beams" that run the length of the barn in (2) plcs? And yes, your right. They would have to be replaced. They are short pcs. Most of them are butted / joined every 7' - 8' ft. over the center of the 4" (+) support posts.


Thanks Don,



Pat
Phil McKrakin (Alias)

[Phil McKrakin]

I entered;
384" span
144" tributary area
50 psf load
50 ksi steel (modern, not recycled)


Hi Don,

Is 50 psf a little excessive or high for a residential application?

I see that a W18" X 40 psf Beam selection with the criteria that you used would allow a Total Load on the Beam of 20,480 lbs. 10.24 Tons? Is this correct or am I miss-understanding something?

With a Tributary width of 144", am I correct in figuring that (1) beam would then be able to support 20,480 lbs. over 768 sq. ft. of floor space? (144" X 2 x 384")/144 sq. in?

Also, is the W18" classification on this beam the width of the flanges, depth of the beam or both?

We eventually plan to convert some of the upstairs hayloft area to bedrooms & open family areas. With the exception of some dormers, I intend to leave walking space between the roof trusses and any outside bedroom or family room walls. Kind of like a house inside a house.


Thank you for your input.




Pat
Phil McKrakin (Alias)

[Don_P]

The 50 psf combined load is reasonable for a non sleeping area. Any point loads or transfer of wall loads from above would need to be looked at. I'm missing why you are trying to span this direction if you want to preserve the existing floor though. Replacing the 2 runs of support beams (girders) with something that can span further post to post is the real goal, yes? Their method of loft support is classic barn construction.

Or are you wanting to run the I beams under the 2 rows of new girders and eliminate the support posts without removing the floor? If so we need to be looking at a different steel beam formula. Third point loading instead of uniform loading. This can certainly be done but isn't the way I would do it without a good reason.

To answer the I beam questions this far though,

The 16" is the depth the 40 is weight per foot of beam (remember you buy steel by weight, in a beam "deeper is cheaper") Once a size is selected the beam can be looked up in a table for its other dimensions. Notice the same depth can come in many weights, they vary in thickness, flange width, etc. The flange is 7" wide on that beam. That 16" deep beam can be manufactured as heavy as 100 lbs/ft. You can see why it might be necessary to bump up the dead load portion of the load once the beam size is known.

The tributary area is 6' of floor width supported on each side of the 32' long beam, so 12 feet x 32'= 384 square feet x 50 lbs per square foot= 19200 lbs. The Steel manual lists allowable uniform load for that beam as 44,000 lbs at a 2.18" deflection. I was limiting deflection to the code allowed 1/360, so at about half the maximum load the long beam is under deflection limits. Some people advocate limiting deflection on such a beam to L/600 to avoid vibration problems in long spans. The L/360 is to avoid cracking drywall. Just for more info, the W16x100 is allowed 120,000 lbs uniformly distributed on that span with the same deflection.