Pole Barn on a Slope – Can I use ICFs?
Reader NATHAN in WASHINGTON writes:
“I am hoping to construct a pole barn with a garage with attic storage and an apartment on the back as well. I have a couple questions. First, the site is on a slope, so I think we need to pour continuous footings and a foundation. Would you recommend using ICF forms for the foundation? Also, would a 4 foot tall foundation be acceptable? Thank you for your consideration!”
Many years ago I was faced with grade change challenges for two different buildings on my property – although I had a much greater grade change situation than you.
On one site, I intended to build a 22′ x 24′ garage using bonus room attic trusses to be able to have an office above. In this case, I was faced with 14 feet of grade change. You can read the story of this building here: https://www.hansenpolebuildings.com/2022/11/a-post-frame-building-at-newman-lake/ and https://www.hansenpolebuildings.com/2022/11/what-to-do-when-the-old-post-frame-garage-has-issues/.
On my other site, I wanted to build a larger garage/shop. In this instance, grade change was ‘only’ 12 feet across 40 of width. Here is its story: https://www.hansenpolebuildings.com/2012/02/grade-change/.
These two buildings had differing design solutions due to direction they would be entered. In case number one, as we were entering from ‘high’ side, it made sense to basically do a “stilt” building – and have an elevated wood floor. Elevated wood floors can be done for an investment very similar to a concrete slab on grade, especially when one considers costs to form and pour footings and build concrete (or ICF) walls. For building number two, entering from low side, cutting and creating what amounted to a daylight (aka walk-out) made more sense.
Your ultimate design solution probably resembles one of these two. If an ICF wall ends up being your play, keep in mind footing for wall will need to be at or below frost-line for your location. If you have four feet of grade change, your wall on low side could end up having an overall height of seven or more feet! On end (or side) where grade change is zero, those columns can be embedded in ground or done with wet set brackets and concrete poured piers, rather than having expense of a foundation wall on all sides.
In any case, we can design, engineer and provide your building – including foundation design.
DEAR POLE BARN GURU: How wide and tall can a pole building be? TODD in ALLENWOOD
DEAR JENNIFER: Post frame barndominiums lend themselves very well to building on slopes. I solved a personal situation where I had 14 feet of grade change in 24 feet, by building on stilts: 
DEAR TIM and LOUSIE: This is where an ounce of prevention is worth a pound of cure. There are numerous product capable of being applied below rafters, trusses and/or roof purlins, however in order to be truly effective, you must be able to achieve a perfect seal (impossible in real life). If not, warm, moist air from inside your building is still going to rise, get through any gaps, and now be trapped with no way to escape. Even with a tight seal, unless there is a thermal break, chances are fair you will now have move the condensation from underside of roof steel, to underside of new product. There are some solutions – least expensive, highly labor intensive is to remove roof steel, install a well-sealed thermal break, reinstall roof steel or have two inches of closed cell spray foam applied to underside of roof steel.
DEAR MATT: I was born and raised in Spokane, owned a house on Newman Lake until just a couple of years ago. In the 1990’s I was the area’s most prolific post frame builder – one year we erected over 200 post frame buildings in Spokane county alone!
DEAR CARY: Very few clients have been willing to make an extra investment into full hip roofs, explaining why our website has no photos of them (we do rely upon our clients to provide photos). We can engineer traditional (and most cost effective) gable roof designs with wind speeds in excess of 200 mph. Our Building Designers can incrementally adjust design wind speeds to allow you to make decisions to best meet your concerns and budget.
DEAR POLE BARN GURU: Hey thank you for time. I am wanting to build a 50×100′ shop. I have uneven ground and about a 4-5′ fall in the back. What is the best foundation for a post frame building for that situation. Any help would be greatly appreciated! ANDREW in APPLING
DEAR KEITH: Thank you for making me smile! I will answer as many questions as you need answers for.
DEAR JOHN: 4×4 posts would not be adequate for even a very small post frame building. I would avoid steel due to its unforgiving nature (everything has to be spot on), challenges of thermal conductivity and connections between structural steel and wood. My preference (in my ideal dream world) would be glulaminated columns, embedded in ground, with a mono-poured concrete footing/bottom collar. This would provide greatest strength and reliability at an affordable price point.
