Tag Archives: frost depth

How to Re-level a Garage

Auntie Em, Auntie Em My Garage Has Lifted 

Well, it wasn’t from a twister and this article has nothing actually to do with Auntie Em or actress Clara Blandick who played Auntie Em in 1939’s film classic The Wizard of Oz. For trivia buffs, Blandick also played a part in 1937’s original A Star Is Born.

Reader GEORGE in LAGRANGE might be wishing a twister had hit his garage, so insurance would pay for a replacement. George writes:

“Due to the freezing and thawing cycle my pole garage has lifted about 7 inches since it was built 12 years ago. You can now see the outside grass from inside the garage. And it has not lifted evenly so the garage is unlevel.”

George’s post frame garage has some challenges, none of them ones with an easy fix. How did his garage get this way? There are three possible major contributors to this garage’s current situation. These would include:

Inadequate site preparation

At a minimum, site preparation includes:
· Remove all sod and vegetation.
· For ideal site preparation, remove topsoil and stockpile for later use in finish grading. In frost prone areas, remove any clays or silty soil
from within future building “footprint”.
· Replace subsoil removed from around building with granulated fill to help drain subsurface water from building.
· Distribute all fill, large debris free (no pit run), uniformly around site in layers no deeper than six inches.
· Compact each layer to a minimum 90% of a Modified Proctor Density before next layer is added. Usually, adequate compaction takes more than driving over fill with a dump truck, or
earth moving equipment.

For more details on proper site preparation please read: https://www.hansenpolebuildings.com/2011/11/site-preparation/

Column Depth

Bottom of column encasement needs to be below frost line. This is a no-brainer.

Water

Read more about what causes frost heaving here: http://www.hansenpolebuildings.com/2011/10/pole-building-structure-what-causes-frost-heaves/.

There is going to be no easy or inexpensive fix to George’s situation. An investment into a geotechnical engineer who could provide a thorough site evaluation along with solutions might be money well spent.


Building could be brought back to level by excavating at each raised column to well below frost depth. Cut off columns at base of splash plank (while supporting building from falling), then remove embedded portion of column. Place an appropriately sized sonotube in excavation with top of tube at grade. Pour premix concrete into tube and place a wet set Sturdi Wall bracket – expertly placed to receive upper portion of column. https://www.hansenpolebuildings.com/2013/11/sonotube/

If all of this sounds daunting (it would be to me), a consideration could be demolition and start over from scratch.

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.

 

Help with Instructions? Correct Frost Depth, and Nailing Schedule for OSB

Today the PBG attempts to assist with finding some instructions, the correct frost depth, and nailing schedule for OSB.

DEAR POLE BARN GURU: A friend of mine gave me a cannonball track and hardware setup for my pole barn garage.  I have looked everywhere for INSTALLATION INSTRUCTIONS.  I cannot find anything on line.  Can you please tell me where to look.  I would appreciate any help you can give. Thank you. RAY

DEAR RAY: Your request could pose some challenges as Cannonball was acquired by one of their competitors, Western Products of Indiana January 1. We use sliding door systems from a Cannonball competitor, so all of the parts are not exactly the same. I’ve searched online for the installation instructions with the same results you have found – none. Best bet is to try to call Cannonball direct and see if they can assist. (800)766-2825

 

DEAR POLE BARN GURU: Hello , was wondering if you could tell me the depth I need to be at for a pole barn ( garage ) it is going to be 24’x32’. I’m using 4×6” PT poles and going to put them about 10’and 12’ apart on center. I live in Indianapolis on the north side. When I looked up the National frost depth for my area it showed 54”, thought it was a bit deep for here, but want it to be safe as well as lasting. Thank you for any advice you could give. ROBERT in INDIANAPOLIS

DEAR ROBERT: The column depths will be specified on the sealed plans produced by your RDP (Registered Design Professional – architect or engineer). If they are missing you should contact the RDP directly to receive clarification. In no instance should the bottom of the column holes be above the maximum frost depth, which in your case would mean 54 inch deep holes. When it comes to post frame buildings – the last place to scrimp on or cheap out is the foundation. With the correct diameter concrete footings, proper depth and provision for uplift resistance (all of which your RDP should have addressed) you should be off to a terrific start.

DEAR POLE BARN GURU: Your project # 18-0112F. Can someone show where I can find the nailing schedule for the OSB that goes on the roof?? Thanks JIM in KINGSTON

DEAR JIM: The nailing schedules for sheet sidings and sheathing is always found on the “A” pages of the engineered plans provided with your building. Usually they are in a tabular box.

For those who are reading and somehow did not invest in a Hansen Pole Building kit package – if the nailing is not found on your plans, do not guess or take a chance – contact your RDP (Registered Design Professional – architect or engineer) and have them provide a nailing schedule sealed by them.

 

 

 

 

Pole Building Footings and Frost Depth

“Except where erected on solid rock or otherwise protected from frost, foundation walls, piers and other permanent supports of buildings and structures larger than 400 square feet in area or 10 feet in height shall extend below the frost line of the locality, and spread footings of adequate size shall be provided where necessary to properly distribute the load within the allowable load-bearing value of the soil.”

Yeah, right….and what did this tell you?

Frost heave can do nasty things to pole buildings with improper or inadequate footing designs. When pressure preservative treated columns are embedded to an inadequate depth, or are encased in concrete where the holes are conical (wider at the top than at the bottom), they can be prone to heave.

In winter, ground freezes from the top of the soil downward. The depth of frost penetration depends on soil type, the severity of the winter, the amount of water in the soil and depth of an insulating blanket of snow.

The frost depth varies by region. In frigid northern climates, the frost depth can be 60 inches or more, whereas a warmer southern state frost may not even be an issue.

Your local building department can be called and asked what the frost depth requirement is. Then dig the footing holes so that the bottoms of the pole building footings are at or below the frost depth.

The mechanics of frost heave are complex, but here’s a quick primer. Water in the surrounding soil collects and freezes into thin layers of frost called “ice lenses.”

When water freezes, it expands (think of how ice cubes have a dome shape above the original water level in the ice cube tray). Ice exerts a pressure of about 50,000 lbs. per square inch—enough force to lift even a large building. A pole barn on inadequate footings doesn’t stand a chance.

The reason buildings don’t always return to their original height is that surrounding dirt sometimes fills in under the footing while it’s lifted.

Heavy clay soils don’t drain well, so they tend to have more frost heave problems than sandy, well-drained ones. But even if pole building footings are deep enough, ice lenses can latch onto the rough surfaces of wood and concrete and lift footings and posts from the side. This potential problem can be alleviated by increasing the diameter at the bottom of the holes.

Bottom line: make sure your pole building footing design extends below the frost line.  Frost acts randomly, so unless you are planning on selling tickets to “pole building at a slant”, make sure your building stays…exactly where you put it.