Tag Archives: site slope

Post Footing and Site Leveling

Post Footing and Site Leveling

Reader KEVIN in PAOLA writes:

“I’ve been working with Cory on my building design and had a question regarding leveling my site and setting my posts. The plan is a 40′ x 60′ building with a 17′ eave height. On the south side, there will be a 12′ attached shed that is open. Based on the elevations I’ve shot, I’ll have to add approximately 4′ of fill on the east end of the building and it gradually tapers all the way to the west end. Now, rock on the property is rather shallow. I dug a test hole on the east end which will require the most fill and the rock is about 2′ below native ground level. I’ve encountered solid limestone that is approximately 2′ thick when digging corner posts and I’ve found locations where the rock is fractured and can be dug out with an excavator. The county requires poles be installed at a minimum depth of 4′, but will allow 30″-40″ if due to rock and if the holes are backfilled with concrete.

· How would you design the foundation for the poles?
· Does the 4′ of backfill count when measuring post embedment?
· Would you set the posts first and then add the fill?
· Do you change post foundation design as you move from the deeper fill for elevation on the east end to fill on the west end that is replacing the top soil?
· Does the post foundation design change for the open shed on the south side?

I’m attaching the design doc from the county. Foundation information is listed on pages 8 and 9.

I hope all of this makes sense and thank you for the help.”

Thank you for reaching out to me. With your permission, I would like to treat your building as if it was my own (in other words, What Would the Pole Barn Guru Do?).

Project# 05-0211Starting with your door end (which I will assume is uphill), I would add enough fill so this end could have holes dug to 40″, filling balance of site accordingly. All fill should be compacted in no less than six-inch lifts to a minimum of 90% of Modified Proctor Density (you may need to invest in a Geotechnical Engineer to verify compaction).

Foundation would be embedded columns to 40″ depth and would be same for all areas (our engineers will seal holes at 40″ depth) Properly compacted fill can be relied upon to be equal to undisturbed soil Fill first – it is so much easier than trying to work around columns.

On door end, you will want to grade away from doors, so water coming down hill does not end up running into your building.

Uneven Ground, Granting Wishes, and Recommendations

This Wednesday the Pole Barn Guru discusses foundation for a uneven ground with 4-5′ “fall” in the back, granting three wishes, and recommendations for building/footing/slab.

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 ANDREW: I would go with an ecology block (read more here https://www.hansenpolebuildings.com/2015/04/ecology-blocks/) retaining wall several feet beyond my building footprint. Then backfill with suitable fill compacted in no less than six inch lifts. This would allow for construction on a flat level site with embedded columns.

 

DEAR POLE BARN GURU: Please grant me 3 wishes o guru, you are better than a genie!!! Do you have a crew put the building together? Do they put the grounding strap on the ground and on the building? Do you have pictures of the workshops? KEITH in PORT CHARLOTTE

DEAR KEITH: Thank you for making me smile! I will answer as many questions as you need answers for.

We are not building contractors. Currently (and for the foreseeable future) there is a nationwide shortage of building erectors. Many high quality erectors are booked out into 2023. We would strongly encourage you to consider erecting your own building shell.

For those without the time or inclination, we have an extensive independent Builder Network covering the contiguous 48 states (https://www.hansenpolebuildings.com/find-a-builder/). We can assist you in getting erection labor pricing as well as introducing you to potential builders.

A CAUTION in regards to ANY erector: If an erector tells you they can begin quickly it is generally either a big red flag, or there is a chance you are being price gouged. ALWAYS THOROUGHLY VET ANY CONTRACTOR https://www.hansenpolebuildings.com/2018/04/vetting-building-contractor/
Your electrician will (should) properly ground your building.

Please click on any of these photos at https://www.hansenpolebuildings.com/gallery/ to open gallery to more photos in same categories.

 

DEAR POLE BARN GURU: If I’m a belt and suspenders overkill kinda guy, what’s your recommendation on a pole barn construction/footings/slab. I would like to use steel instead of 4×4 posts if that isn’t a bad idea. JOHN in LITTLE ROCK

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.

Site Slope, Gable End Exhaust Fans, and Setting Trusses

Today’s Ask the Guru blog answers reader questions about building on a slope, a recommendation for gable end exhaust fans, and setting trusses into columns.

DEAR POLE BARN GURU: I always see pole barns being built on level ground. is there any reason my concrete slab, perimeter board, and exterior grade can’t slope 1/4″ per foot from the back to the front of my pole barn garage? I realize the bottom of my metal siding would probably have to be cut at an angle to match the slope. DAVID in WESTFIELD

DEAR DAVID: Could and should are two different animals.

Everything is going to be far easier working from a level site, where grade can be sloped away from building at 5% or greater (a 5% slope is six inches in 10 feet). You don’t want to have water from any direction running towards your building.

International Residential Code (2021 IRC) Section R309.1 and International Building Code (2021 IBC) Section 406.2.4 address concrete floor slope: “The area of floor used for parking automobiles or other vehicles shall be sloped to facilitate the movement of liquids to a drain or toward the main vehicle entry doorway.” Floor slope by IBC only applies to “U” occupancy buildings of 1000 square feet or less. Actual slope requirement is unspecified however a generally accepted minimum is 1/8” per foot. Grade inside of building should be gradually built up to create this slope.

As far as cutting bottom edge of your steel siding to follow a slope, cutting each panel to precisely follow slope would be a difficult, if not impossible task. This also would leave a raw field cut edge in close proximity to ground and it will rust.

 

DEAR POLE BARN GURU: I have a 30×48 pole barn. 13′ at eaves/overhang and 19′ center height because of scissor truss. No windows. One man door and one garage door. It has closed cell insulation. Brown roof. Used for trailer/camper storage. Not a lot of work going on in this building. It stays a little cooler than the outside temperature but is humid with musty smell due to no ventilation. I would like to install a gable end louvered exhaust fan but everywhere i search i come up with different answers. I don’t need fast air movement, just replacement. i would like to know what size fan and air intakes are required to do this. Some of this information may be irrelevant but it was asked for among other inquiries. Thanks for your time and help. WILL in WINFIELD

DEAR WILL: You should plan upon three to six air exchanges per hour. With 23,040 cubic feet of interior space, you need 1152 to 2304 cubic feet per minute (cfm) as an exhaust. A professional HVAC provider can confirm amount of air intakes required, as well as set you up with an appropriately sized exhaust fan.

 

DEAR POLE BARN GURU: I have a question on installing trusses on a 16×40 pole barn. The bottom of all poles are square and measure what they should on the print. Knowing that the 6×6 poles are probably not straight, is there a trick to making sure that I install the trusses straight and square at the top? Always want to double check before Ii start lifting these 14 feet in the air. Thank you for any help. BOB in MOORCRAFT

DEAR BOB: This is one reason I like to build with my trusses directly attached to columns (using notches cut into columns to provide full bearing). After verifying trusses are exactly 16′ in length, trusses can be placed into notches, with outside of truss flush to outside of columns. This solves any width issues. Using recessed purlins, joist hung between trusses, purlins can be pre-cut to length of space between trusses, solving length issues. Once framing is completed, each roof plane can then be squared (read how here: https://www.hansenpolebuildings.com/2020/05/how-to-square-a-post-frame-building-roof/).

Wall Framing, a Sloped Build Site, and Engineering for Slab

Continuing the week with more Pole Barn Guru, Mike discusses spacing of framing for wall steel, how to prepare a sloped build site, and if Hansen can provide engineering for slab on grade in Colorado.

DEAR POLE BARN GURU: If you have 2×6’s for walls in pole building that are spaced 16 inches apart, and want to put metal siding up, would I use like a wood girts every 2 feet apart in order to hang the metal siding up and down? JOSEPH

DEAR JOSEPH: I will read between lines and guess you have built stud walls between building columns. If this is your situation then you will need to have horizontal girts added in order to attach wall steel vertically. You should refer to your engineered building plans for size, spacing and attachment of these girts, as your engineer is most likely counting on your steel skin to provide needed wall diaphragm strength.

 

DEAR POLE BARN GURU: The area I want to put a pole barn has a severe slope of 6′ from one end to the other. Should I excavate this ground to make it level or build a masonry wall on low end to bring level? If I excavate I’m concerned about moisture getting into building from the high end. If I build a wall, I’m concerned about the pressure on the wall that could eventually fail or the back fill settling under the concrete floor causing cracks. Thanks so much for your help. DAN in EDDYVILLE

DEAR DAN: Well you have lots of possibilities. Given what you have provided, I would be inclined to cut roughly four feet from your high side (making your cut back another eight to 10 feet from your building) and then fill on low side, with a retaining wall eight to 10 feet beyond your building. This way you can slope grade away from building in both directions. Walls will be far enough away from building to not affect it. If you have clay in your soil, make sure to remove at least top 18-24 inches where building will be located and replace it with good, properly compacted fill.

 

DEAR POLE BARN GURU: Does your company handle all the engineering required for an interior monolithic slab? We are very interested in a pole barn home (about 1300 SQ ft) but are running into a lot of issues with the interior slab. We will be building in Fremont County, CO at 9400’ elevation. Frost heave is a huge concern. JEFF in FREMONT County

DEAR JEFF: We would need to have an engineered soil’s report as well as to know your intentions for heating (always heated or not always heated). With this information we would provide engineering for your slab on grade.