Tag Archives: retaining wall

Supporting Fill When Considerable Grade Change Exists

Supporting Fill When Considerable Grade Changes Exist

Everything in post frame (pole) building land seems to be predicated upon a clear level site. While many parts of our world (Upper Midwest) are fairly flat, most live where ups and downs, swirls and contours exist.

Reader ROBERT in RIVER FALLS writes: 

“I have a considerable slope from front to back where I want to place my garage. I will need to haul in considerable amounts of fill to bring to level. My question is what is the best way to support the fill on the back side. A concrete wall is expensive. Hauling in enough fill so it supports itself seems like it could lend itself to problems of erosion. Any suggestions?”

Our eldest son was faced with this situation 10 years ago when we help to construct his two story 24 by 30 combination garage/shop/in-law apartment near Maryville, TN. In his building’s small footprint he had just over five feet of grade change. His cure for this was to have a concrete block wall built on one side and one end to reduce how much fill would be required. With his lot continuing its precipitous fall in these two directions, it would have been impossible to ever bring in enough fill to have had a stable site.

Back in my post frame building contractor days, I erected a shouse (shop/house combination) at our property near Spokane, WA. With a dozen feet of grade change across 40 feet of building width, our solution began with digging (and digging and digging). You can read more of this story here:  https://www.hansenpolebuildings.com/2012/02/grade-change/.

In many instances the best scenario is to cut away from a high side, fill on low side. High side should be cut far enough back from building to allow for a 5% downward slope away from building and to allow equipment to get past building. Provided adequate space exists, the bank can be tapered to slope down towards the edge of slope away from the building. If space does not exist, a retaining wall (or terraced walls) can be placed to hold the hillside from caving towards building.

Ecology blocks can make for low cost retaining walls as well – https://www.hansenpolebuildings.com/2015/04/ecology-blocks/

Whether your site is level or sloped, Hansen Pole Buildings can assist you in arriving at as close to an ideal of a solution as possible. Please dial 1(866)200-9657 to speak with a Building Designer today.

Concrete Considerations from the PBG!

DEAR POLE BARN GURU: Is concrete included in price? TRACEY in SUMTER

DEAR TRACEY: No, we do not include concrete in the price and here is why:

Most familiar, as well as most available is the Sakrete® general purpose High Strength Concrete Mix. When mixed per the manufacturer’s instructions, this mix affords a compressive strength of 4,000 psi (pounds per square inch) at 28 days.

The instructions are: Empty the contents into a mortar box, wheelbarrow, or mechanical mixer. When mixing by hand, form a crater for adding water.  Add water a little at a time.  Avoid a soupy mix.  Excess water reduces strength and durability and can cause cracking. A 60 lb. bag should be mixed with three quarts of water, an 80 lb. bag four quarts.

Now the realities of using bagged concrete for post frame building footings….

treated postIt is not unusual to have concrete encasements of 24 inches or larger in diameter and 18 inches or more in depth, in order to prevent building settling and uplift issues. One hole this size would take 4.71 cubic feet, or about 700 lbs. of concrete! Even a very small building with 18 inches of diameter and depth takes 2.65 cubic feet or about 400 lbs. of concrete.

With either 60 or 80 lb. bags, it is going to take a lot of bags! An average building could easily have 20 posts, and if looking at 700 lbs. of concrete per post, we are talking about 7 TONS of concrete (3-1/2 yards).

Ignoring the huge number of bags involved, there are some other realities.

Ever looked at the pallets of readi-mix bags at the lumberyard? Take a peek, next time. Notice how many of them are broken or leaking.

Due to weight, it may very well mean another delivery and another delivery charge. Trucks do not run for free.

Bags can (and will) break when being handled during delivery, unloading and being moved around the jobsite. It is going to happen, just plan on it.

From experience, lots of projects are not begun immediately after delivery. It is not unusual for delays of weeks, or even months before actual construction begins. Improperly stored, bags can get wet or absorb moisture and become solid before time for use. This equals a total waste of money, other than the chunks of concrete make for solid backfill.

Then there are the builders who insist upon throwing the entire bag (usually including the bag) into the hole. Their idea is ground water will cause the readi-mix to harden. Why does this not resemble the manufacturer’s instructions?

Readi-mix must be mixed thoroughly and evenly. How does mixing over 200- 60 lb. bags of Sackrete® by hand sound? Add too much water (three quarts exactly per 60 lb. sack) and the strength is reduced.

Use too much? As holes are always perfectly round (not), it is going to happen.

Save time, effort and money. Often all three can be saved by having the local pre-mix concrete company deliver concrete for holes (even if a “short load” fee is charged), as opposed to mixing on site.

DEAR POLE BARN GURU: I am building a 36 x 40 pole barn and I’m on a grade that drops approximately 4′ over the span of the building footprint. A home builder friend, a structural engineer, and my concrete guy have recommended traditional foundation with wet set permacolumns, but the builder I’ve contracted with wants to set columns on footers 3′ to 5′ in the ground and not use the permacolumns. The pole barn builder doesn’t think I need a retaining wall and should just have an excavator level what i need with a slope off the back. Seems a retaining wall in the back is better, which my concrete guy will pour, but still recommends foundation to eliminate frost heave. Use for building is car storage and shop with a lift.
Thank you in advance for your time and help. CHRIS in ST. LOUIS

DEAR CHRIS: This reminds me of a joke I once heard – a home builder friend, a structural engineer and a concrete guy enter a bar…….

Oops, kind of off track!

Some of the answer is going to depend upon what you want your yard to look like.

In any case – the actual pad of the building is going to need to be properly compacted (emphasis on proper) so those costs will be fairly even in any case. You’ll want to be reading about proper site preparation and compaction here (it is lengthy): https://www.hansenpolebuildings.com/2011/11/site-preparation/

What might appear to be the least expensive would be to just order columns long enough to get the required embedment depth as shown on the engineered plans, then fill afterwards, sloping away from the building. In order to keep the fill from sloughing off, it will probably result in a slope next to your building which will stretch out as far as 20 feet. You could easily invest in several hundred yards of fill!! If you can live with the look, might be the answer.

Building on top of a foundation – this is going to be the most expensive and certainly not the choice I would probably be making. It is also going to be tougher to build upon, due to the height of the walls plus the foundation.

Which leaves – build a retaining wall. I like this idea. Columns do not have to be longer (as long as fill is properly compacted).

By the way – there is no reason for ANY of these versions to frost heave as long as the site has been properly prepared. Read more about how to avoid frost heave issues here: https://www.hansenpolebuildings.com/2011/10/preventing_frost_heaves_in_pole_building_construction/

DEAR POLE BARN GURU: How much is the drip stop application for labor/material? Usually it comes already attached to the metal paneling. Do you figure it by square feet? JOSH in MANKATO

DEAR JOSH: For materials you are going to be looking somewhere in the neighborhood of 53 cents per square foot of roof surface. As a builder, if you are anywhere it is typically windy, I am going to give you a decent discount on my labor for having invested in it, because I don’t have to fight rolls of insulation flapping in the breeze.


Ecology Blocks

Hansen Pole Buildings Designer Rick is an avid stream fisherman. Near one of his favorite fishing holes, is also one of his favorite after fishing watering holes – The Castle Rock Inn. Last December 16, the Inn burned to the ground:


Castle Rock InnThe owners of The Castle Rock Inn chose a pole building to replace the structure, saving months of time by not having to wait for spring in order to excavate and pour the continuous footings and foundations which would have been needed in other forms of construction. While the pole building was sadly not provided by Hansen Pole Buildings, Rick stopped by to take some photos of the new construction. Among the photos might be one of the saddest examples of a retaining wall which I have witnessed.

Retaining walls are built for both functional and aesthetic purposes. A majority of the retaining walls built today are of the type called Segmental Retaining Walls (SRW). A segmental retaining wall is built using interlocking concrete blocks.

For retaining walls over 3 to 4 feet in height, building codes generally require a building permit and structural wall design prepared by a qualified engineer. Independent civil engineers (P.E.) licensed in the state of the project must prepare these final wall designs. Design professionals who aren’t doing the structural engineering of the wall (such as a site civil engineer, architect or landscape architect) can retain a SRW engineer to provide the wall design.

Ecology blocks are often used in SRW systems. These are large concrete blocks, which are manufactured from left-over or unused concrete. Concrete, which in years gone-by would have been dumped and wasted or hauled to a land fill site, is saved and turned into a useful construction product, hence the term Ecology Blocks.

The blocks are cast into either a half block or a full block and use nearly a half or a full yard of concrete respectively. The dimensions for these blocks are 2’ x 2’ x 3’ for a half block and 2’ x 2’ x 6’ for a full block. Each block is cast with a 3” radius tongue and groove, for interlocking stability, in stacking applications.

Full ecology blocks weigh approximately 3850 lbs. and the half blocks are 1900 lbs. There is a picking eye of #5 rebar located in the spacing between the tongues in the top of each block. This picking eye is suitable for loading, unloading and for placing the blocks with a crane or backhoe capable of lifting and moving 4000 lbs., in the case of a full block.

Generally the blocks are made in three finished styles; scratched & framed, plain and cobble. The color and appearance of the blocks is fairly random and inconsistent, due to the nature and mix of concrete which is being returned from jobsites.

According to one of the Castle Rock Inn owners, “Our site actually sank a couple of inches so we had to bring in more fill to bring to grade.” Whether the sinking feeling may be attributed to the retaining wall is a decision for the experts to resolve, however it could very well be a suspect.

Have grade change near your future pole building site, which is best solved by a retaining wall? Don’t guess. Invest in a professional engineer to design the wall, then follow their plans!