Tag Archives: structural integrity

Additions, Notching Posts, and Stem Walls

This Monday the Pole Barn Guru answers reader questions about adding to an existing pole barn, the possibility of notching girts into posts, and use of a stem wall on an uneven site.

Hansen Buildings TaglineDEAR POLE BARN GURU: I have an existing 36x36x12 pole barn and would like to do an additional 36-48 roof only build off the back. I used the Oregon ready build plans for my existing barn, built in 2019. My 2 over head doors are on the end wall. I was told by my county official that the ready build plans cannot be added onto because they are stand-alone buildings, but maybe with engineering they could be. Do I need to consider building a separate barn 12′ behind mine or can I possibly get it engineered to be attached? Thank you. CLAYTON in SCAPPOOSE

DEAR CLAYTON: Your county official is correct in stating your existing pole barn is a stand-alone building. It is likely we could engineer and provide your proposed extension, however it may require some modifications to your existing building. A Hansen Pole Buildings’ Designer will be reaching out to you to further discuss your building needs.


DEAR POLE BARN GURU: If a DIYer had all the time in the world to build a post frame, could the posts be notched for the girts? MARK in KNOXVILLE

DEAR MARK: My lovely bride and I spent a fair amount of time in Knoxville as our oldest son got his Master’s degree at U.T., lived in Maryville and taught high school at Lenoir City. His youngest sister, used to play summer basketball for Pat Summit (she has a piece of championship basketball court signed by Pat for being best player one year). Beautiful area!

Could and should are not necessarily the same. Sound engineering practice limits notch depths in columns to 1/6th of direction being notched, without requiring more complex engineering review. On a 6×6 (actual dimensions 5-1/2″ x 5-1/2″) this would allow notches to be only 7/8″ deep for an externally mounted girts, or if one was doing bookshelf girts, 7/16″ deep on both sides of column. With externally mounted girts, this could pose challenges with aligning other wall framing members such as splash planks, door headers, etc. For bookshelf girts, nail or screw connections would have to be angled, reducing lateral strength of this connection so as to require extra fasteners.


DEAR POLE BARN GURU: My site is not level. Can you build in a stem wall? CHRIS in SEQUIM

DEAR CHRIS: You can either excavate and have a stem wall on the formerly high side, or have a stem wall on the low side and fill. Stem wall can be poured concrete, ICFs or concrete block with wet set brackets, or we can incorporate a Permanent Wood Foundation wall between columns. A Hansen Pole Buildings’ Designer will be reaching out to you for more information about your new post frame building.



I Like Building Officials

For those of you who are not Building Officials, stop laughing, I am serious. Building Officials have a job – to protect those who use structures (which include buildings).

In Chapter 1 of the IBC (International Building Code), under Purpose of the code, it states, “This code is intended to provide minimum requirements to safeguard the public safety, health and general welfare through structural strength, means of egress facilities, stability, sanitation, adequate light and ventilation, energy conservation, and safety to life and property from fire and other hazards attributed to the built environment.”

How would you like it if this was your job description?

This is not an easy proposition, by any means. The IBC itself has been simplified to roughly 800 pages – which might be manageable, if it were not for the literally hundreds of other texts and documents which the building code now incorporates by reference!

There is just no possible way for any one person to know all of this information, and how it applies.

An example from just this morning: A Building Official from a township in Michigan was doing a review of the plans we had provided for one of our clients. This particular building has a design ground snow load of 25 psf (pounds per square foot). With a 6/12 roof slope, and the other appropriate factors applied, the roof live load is 18 psf. The building has a 29 gauge steel roof and 2×6 #2 roof purlins on edge spanning a distance of 11’ 7-1/2” from center of joist hanger to center of joist hanger.

In Chapter 23 of the IBC are provided basic tables for rafter spans, which the aforementioned official was attempting to apply to the roof purlins. While these tables may be handy as a reference for rafters in a “stick frame” type of construction with shingled roofing over sheathing, they just do not apply for the design of purlins.

The closest the official could get was a table with a 20 psf roof live load (11% higher than our case) and a 10 psf dead load (833% higher than actual). Using these much greater loads, the tables would only allow for a span of 11’7” with a spacing of 24 inches on center.

The Building Official contacted us, and we provided full calculations to justify the design as submitted. These calculations easily extend for over a full page, typed without spacing between lines. The calculations include footnotes as to the sources of all data and calculations, as a verification they are indeed correct and complete. Checked in them are strength in bending from snow, and wind loads. Also verified is… does the member meet shear and deflection criteria and the connection of the purlin to the trusses?  Yes, it does, calculations were provided.

Should the official have known enough structural engineering to have been able to calculate these himself? I think not, and even if he would happen to be a registered professional engineer (which most Building Departments do not have the luxury of having on staff), unless these were calculations he was performing on a daily basis – no.

The Building Official was doing due diligence in requesting backup information on something which just did not look quite right to him. From our aspect, we are always able to provide and glad to assist.