Tag Archives: soil bearing capacity

Footing Diameter, Non-Ground Contact Columns, and Ceiling Insulation

This Wednesday the Pole Barn Guru answers reader questions about the required footing diameter for a 20’x24′ pole barn garage, use of non-ground contact columns on a concrete stem wall or thickened edge, and Insulating a cathedral ceiling in a barndominium.

DEAR POLE BARN GURU: I am looking to build a 20ft x 24ft pole barn garage. The footings are going to be drilled and filled with concrete now, with the structure being completed at a future date. My city engineer requires 30″ deep footings. He was not able to say for sure what diameter footing I needed to drill. Do you have any insight to what diameter footing I should expect to need for this size structure? JOE in CINCINNATI

DEAR JOE: Ultimately required diameter will depend upon soil bearing capacity and imposed loads. If you are single story, chances are good an engineer would specify 18 inch diameter.

 

DEAR POLE BARN GURU: I was fortunate to have acquired enough columns for a building. My question as these are not ground contact columns and I prefer at this time to not pour a concrete floor is it allowable to pour a perimeter of concrete ( 2’x2′,3’x2′?) thickened edge if you will and set the columns to keep them off the ground? I was thinking partially setting rebar perpendicular in the concrete leaving 1-2′ protruding towards the buildings center to tie a future slab possibility into what would be the existing edge ( foundation). This is a cost driven situation as you may have already surmised. Really appreciate your knowledge and time. RICK in TWO RIVERS

DEAR RICK: To save further on costs, you can pour concrete piers to support engineered wet-set brackets. This would be much simpler than pouring a concrete perimeter. Bottom of piers should be at or below frost line. https://www.hansenpolebuildings.com/2019/05/sturdi-wall-plus-concrete-brackets/

 

DEAR POLE BARN GURU: Insulating a cathedral ceiling in a barndominium. It is house wrapped and single bubble beneath the metal roof panels. Girts and purlins are on 2 ft centers. Was planning on using Rockwool and Siga Majrex with the appropriate air gap. Building is vented through soffit on all sides. Also planning on using soffit baffles( and should I take them to the peak) , along with plastic vapor barrier above stone before concrete. Is there a better way, other than spray foam, and would that be in the ceiling over top of the single bubble also? Thanks. CHAD in DILLINER

DEAR CHAD: Thank you for the photos. You need to seal any venting coming in from endwalls. This can be done by placing 2×4 blocking flat between purlins on top of end truss. Install baffles between trusses and run them “uphill” to beyond depth of your insulation to be blown in. Do not use a vapor barrier between ceiling finish and truss bottom chords. Ideally blow in granulated Rockwool above ceiling (second choice would be fiberglass).

You Have to Get It In

Disclaimer – this and subsequent articles on this subject are not intended to be legal advice, merely an example for discussions between you and your legal advisor.

Please keep in mind, many of these terms are applicable towards post frame building kits and would require edits for cases where a builder is providing erection services or materials and labor.


PREMISES: Purchaser will be responsible for personal injury or property damage sustained by anyone entering the jobsite, as well as security. Purchaser warrants soil is of bearing capacity to meet what is stated in the Agreement. Seller has not made any soil studies, and the determination of any need for a soil analysis, as well as the costs of the same, shall be made by and paid for directly by Purchaser. In the event soil bearing capacity is less than as stated, any and all costs of redesign, redrafting or reengineering shall be paid for by Purchaser.

This version of “premises” is written specifically towards built buildings and is, for practical purposes, a ‘hard rock clause’:

PREMISES: Purchaser will be responsible for personal injury or property damage sustained by Purchaser or third parties who enter the jobsite, and for all security at jobsite. Upon completion, Seller shall remove all of Seller’s tools, construction equipment and machinery from the building site. 

Purchaser warrants that all soil is clean, unobstructed, of adequate bearing capacity and meets a minimum of 95% compaction. Seller’s price allots a maximum average of 30 person-minutes per column hole for hand-digging or 10 equipment-minutes per column for auguring, with excess time to be paid for by purchaser pursuant to Section xx of this Agreement, “Change Orders”. 

Purchaser to absorb all costs associated with underground water or unexpectedly high water table including, but not limited to, diversion of flow or removal of water from column holes. 

Seller has not made any soil studies, and the determination of any need for a soil analysis, as well as the cost of the analysis, shall be paid directly by Purchaser. 

Should asbestos or other hazardous waste be discovered during the course of Seller’s work, Seller will promptly notify Purchaser, who must advise the applicable governmental agencies. It shall thereafter be Purchaser’s responsibility to contract a certified hazardous waste removal contractor in order to perform all asbestos or hazardous waste removal. 

For extended reading on ‘hard-rock’ clauses: https://www.hansenpolebuildings.com/2014/03/hard-rock-clause/

TRANSPORTATION/SHIPMENT: Other than ferry charges, freight and transportation charges within the Continental United States are included in sales price unless otherwise expressly stated in the Agreement. For projects outside of the Continental U.S., shipment is made to a mutually agreeable port, or is available for “will call” at one of Seller’s distribution points. If needed, Purchaser will provide any permits and/or pilot cars for oversized loads, and equipment and/or labor required to unload trucks. 

Purchaser shall make access to the building site available at all times to Seller’s agents for purposes of delivery. 

Materials delivery challenges: Once any material leaves the truck bed it becomes responsibility of the Purchaser and all risk of loss, damage, and other incidents of ownership shall immediately pass to Purchaser, but title to such materials will be retained by Seller as security interest for Purchaser’s performance until payment in full is received. This security interest constitutes a “purchase money security interest” pursuant to the Uniform Commercial Code. 

Signed delivery slips shall be proof of receipt of materials in good order. Acceptance by common carriers shall constitute delivery, therefore, the freight carriers are liable for materials lost or damaged in transit and (in case of loss or damage en route), Purchaser must immediately notify the carrier’s agent at destination, in order to establish a formal claim when presented, and no claims for damages shall be made against Seller.

PROTECTION OF WORK: It is agreed Purchaser shall be responsible for replacement of any stolen or damaged material after delivery in good order.

DELIVERY ACCESS: Purchaser shall provide clear, level site, with sufficient area and adequate access (at least 10 feet in width and up to 14 feet of height) for trucks to make delivery without danger to property or equipment, and shall assume, pay and hold Seller harmless from all claims of damages to property of others. Delivery trucks may be semi tractors pulling 48′ or longer trailers. If a site does not have adequate access, it is the responsibility of the Purchaser to find a suitable alternative delivery location. 

Drivers are instructed to not risk themselves, their loads, or their equipment in an attempt to make delivery to a location driver deems as unsafe. The final decision as to adequacy of access shall be determined by the truck driver. Should, for any reason, adequate access is unavailable and Seller’s truck must make another trip to the job site, Purchaser agrees to pay the cost of an extra delivery at $5 per loaded mile, with a $250 minimum. 

In the event Purchaser instructs a driver to access over a particular route or area and the truck becomes stuck, requiring towing, or causing damage, Purchaser will absorb all expenses, including a minimum of $120.00 per hour truck standby time for each and every hour, or partial hour, truck is stuck or delayed. Purchaser shall be responsible to provide safety jackets, warning signs, whistles and persons to direct traffic, if necessary, to allow access to the jobsite. Should materials NOT be able to be delivered and properly stocked, the Purchaser agrees to absorb all costs of moving materials.

Building Department Checklist 2019 Part II

BUILDING DEPARTMENT CHECKLIST 2019 PART II

Yesterday I covered seven of what I feel are 14 most important questions to ask your local building department.  This not only will smooth your way through permitting processes, but also  ensures a solid and safe building structure.

Let’s talk about these last seven….

#8 What is accepted Allowable Soil Bearing Capacity?

This will be a value in psf (pounds per square foot). If in doubt, err to side of caution. As a rough rule – easier soil to dig, weaker it will be in supporting a building. A new post frame building will only be as solid as it’s foundation, and it’s foundation will be only as strong as soil it rests upon.

Some jurisdictions (most noticeably in California and Colorado) will require a soils (geotechnical) engineer to provide an engineered soil report, spelling out actual tested soil strength.  Other states may have requirements as well, so be sure to ask ahead of time.

#9  Is an engineered soils test required?

If so, get it done ahead of time.  Don’t wait. It’s easy to do and there are plenty of soil (geotechnical) engineers for hire.

#10 What is your Seismic Category (such as A, B, C, D-1, D-2)?

While rarely do potential seismic forces dictate design of a post frame building, there are instances where they can.  A high seismic potential, with high flat roof snow load and low wind load will be one case. Other case will be when you are considering a multiple story structure.

#11 Are wet-stamped engineer signed and sealed structural plans required to acquire a permit?

Some Building Department Officials will say no to this, yet during plans review process they request structural engineering calculations to prove design, or (worse yet) they make wholesale changes to plans, based upon how they think a post frame should be constructed.

Engineer sealed pole barnMy recommendation – invest in engineered plans. It becomes an assurance a registered design professional has verified your building will meet Code mandated loading requirements. In some cases, insurance companies offer discounts for buildings designed by an engineer. It’s certainly worth asking your agent for one!

In some cases, Building Permits will be granted with only requiring engineer sealed truss drawings. We do not condone this practice, as it creates a false sense of security.

Are exterior finished (showing roofing and siding) elevations required with building plans? Will more than two sets of drawings be needed for permit submittal?

#12 Verify Building Risk Category.

Most buildings not frequently occupied by public (not a home, business or municipal building) represent a low hazard to human life in event of a failure and are ASCE (American Society of Civil Engineers) Category I. This information can be found by Building Officials in IBC Table 1604.5 (not to be confused with Use and Occupancy classifications from IBC Chapter 3).

#13 In areas with cold winters, is frost depth greater than 40”?

All building columns or foundations must extend below frost line to prevent heave. We don’t design for any depth less than 40”, and have designed for up to seven feet deep in some areas!

#14 Does the Building Department have any unusual Building Code interpretations, amendments or prescriptive requirements for non-engineered buildings which could affect this building?

If so, get a copy from your building department for us, or anyone else whom might be considered to be a provider for your building project.

Even though “the Code is The Code”, there are a plethora of local folks who think they have better ways or better ideas than world’s smartest structural minds, who have actually written the Code. And once again, I can’t stress enough: build only from plans sealed by a Registered Design Professional (architect or engineer). It will make life easier all around when it comes to getting your permit, even if you have been told seals are “not required”.

No one inside or outside of a permit office wants a construction process to be any more difficult or challenging than necessary.  Being armed with correct information (after doing homework of course) will be a solid step in the right direction.

 

How Should I Backfill My Pole Barn Holes?

How Should I Backfill My Pole Building Holes

This is a subject which is repeatedly brought up. Usually it is ones who are constructing a post frame building which was not designed by a registered design professional (RDP – architect or engineer). The wrong answer could easily lead to a catastrophic failure of the building!

Reader JOE in ROCHESTER writes:

“I am in the process of building a relatively small pole building. 16x24x8. I’m having trouble finding the right answer to the back filling the pole question. The local Inspector will be coming to measure the depth of the holes (42” to the top of the footer) but other than that they didn’t give me any spec on back filling or diameter and thickness of the concrete footer. My question is what do you recommend for footer size and how should i back fill the holes around the poles? 42” of concrete around the poles seems like excessive to me and just back filling with earth doesn’t seem right either. Any advice would be much appreciated. Thanks.”

Mike the Pole Barn Guru advises:
My educated guess is the local building authorities issued you a permit to construct without requiring you to submit engineer sealed plans. All this ends up doing is leaving things to chance – which you are quickly finding out. Column embedment (depth and diameter of the holes), thickness of concrete footing, concrete collars, etc., are a function of many different variables.

Among these variables include – the soil bearing capacity of the earth at your site, weight of building with a code minimum snow load, design wind speed and exposure, building eave height and roof slope, is it fully enclosed, roof only or some or all of a wall open? Any one of these could affect the outcome.

Ultimately you should have a registered professional engineer or architect design the column embedment for you. From judicious experience, assuming a fully enclosed building with wind rated doors and properly tied into a four inch nominal concrete slab on grade, your engineer would probably require these as minimum: eight inch thick 18 inch diameter concrete footings. Two sticks of 1/2″ diameter rebar driven through the lower portion of the column, one each direction and sticking past the column four to six inches each side. A Concrete bottom collar probably 10 inches tall and the same 18 inch diameter, with the balance of the hole backfilled with compactable materials well compacted.