Dear Pole Barn Guru: What Size Glulam Should I Use?

Welcome to Ask the Pole Barn Guru – where you can ask questions about building topics, with answers posted on Mondays.  With many questions to answer, please be patient to watch for yours to come up on a future Monday segment.  If you want a quick answer, please be sure to answer with a “reply-able” email address.

Email all questions to: PoleBarnGuru@HansenPoleBuildings.com

DEAR POLE BARN GURU: I’m building a 32’x40′ pole barn using 6×6 treated posts on 8′ centers and would like to use a glue-lam beam across the 40′ length, but am not sure how to calculate the size needed to support the roof or if I need to increase the support post size.

This will be the ridge beam. I live in a sparsely populated area of Alaska, but plan on a trip to town soon to look at other similar sized buildings. There are no building regs out here, but I have looked at some large metal buildings blown down by 90 mph winds we had two years ago and another built out of rough cut spruce logs (ridge beam type) that looked pretty simple to build. I planned to use posts sunk 6′ and set in concrete. I always like to err on the safe side, so overkill is OK. MUSHING

DEAR MUSHING: Even in the remote areas of Alaska, there are probably much safer and practical methods to design a pole building rather than trying to utilize a ridge beam 40 feet long. I’d seriously recommend rethinking your design and using prefabricated ganged (two ply or greater) wood roof trusses placed at each sidewall support. This will be much more efficient than the use of a huge beam.

In any case, you need to determine the design load for your site. Here is one possible source: https://www.groundsnowbyzip.com/

The International Building Code also provides a table of ground snow loads for Alaskan locations: https://publicecodes.cyberregs.com/icod/ibc/2012/icod_ibc_2012_16_sec008.htm

You might want to consider getting an engineered pole building kit package, which could be easily shipped out of the Port of Seattle or Tacoma. This would take away your guessing at how to construct it right.

Back to your question….assuming a relatively low roof live load of 40 psf (pounds per square foot), your beam has to be able to support somewhere in the area of 30,000 pounds of weight (this will depend upon the dead loads – what is being used for roofing, etc.).

Assuming the snow will remain on the roof for an extended period of time, a Duration of Load of 1, is probably realistic. This means you will need a 2400f rated glulam with a Section Modulus of around 800 (for information on Bending Moments and Section Modulus read more at: https://www.hansenpolebuildings.com/blog/2012/09/bending-moment/).

In the above scenario, you would be looking at a 6-3/4” x 27” deep glulam beam!! Not only will this be amazingly expensive, but it will also result in the need to hire a crane to set it in place.

DEAR POLE BARN GURU:  HEY MIKE…………COULD YOU GIVE ME THE NAMES  AND ADDRESSES OF A COUPLE OF YOUR CUSTOMERS IN NYS HUDSON VALLEY AREA?  THANKS! NEW YORK NICK

DEAR NICK: Thank you for your continued interest in a new Hansen Pole Building. Among the thousands of building kit packages we have provided are hundreds in New York (as well as every other state in the U.S.A.). We are VERY protective of the personal information of all of our clients, just like we will be of yours. Most people feel very uncomfortable with having “strangers” visit their homes and buildings. It is a security and safety issue, as it would be all too easy for an unscrupulous person to use this method as a way to case things out for “less than helpful” activity.  Please click on the Free Product Guide and we will be happy to mail you a very nice 32 page “showroom” of our buildings.

Here is what a few of our clients have to say: https://www.hansenpolebuildings.com/testimonials.htm

DEAR POLE BARN GURU: You have provided a tremendous amount of information and have given us a lot of questions that need answering – Thank you.

One of the major questions we have, what is code to make a living space (studio) type apartment inside one of these structures?  The second floor load being 40 psf, can this be increased for living space?

Do you have contractors that can assemble this on our site?  What kind of cost would be associated with assembly?

We are in the process of obtaining a VA construction loan with our local credit union and the above questions may be answered through that process.

I’ll take your questionnaire to our building department next Friday to get all those questions answered.

Thanks for your time and patience as we are just starting down this unfamiliar road.

WANTING IN WALLA WALLA

DEAR WANTING:  You are very welcome, we try to assist our clients to be as educated as the want to become, so as to make certain the choices they make in the end, are the right ones.

A 40 psf second floor live load would be Code loading for a residential living space. You will need to meet the Washington State Energy Code for level of insulation in relationship to the number and area of openings (doors and windows) in the conditioned space. Whoever designs your HVAC (heating, ventilation and air conditioning) systems can assist you with the proper recommendations to meet the requirements.

While we are not contractors, we do deal with builders who may be able to assist you with your project: https://www.hansenpolebuildings.com/find-a-builder.php

Fair market value for assembly varies greatly depending upon geographical location and the costs of doing business in any particular state. In my mind, a competitive labor quote should be around 50% of the cost of the materials being installed. As it begins to creep upwards from there, I think about strapping on my old nail belt and doing the work myself.

Please do not hesitate to contact us at any time we can assist you.

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