Four-Plex Home on Helical Pile Foundations

The Challenge

B2K builders were planning a four-plex unit in a relatively narrow site down a residential street in Winnipeg. Due to the tight space, steep ramp access, and general soil challenges, along with winter conditions, their team wanted to see if a helical foundation would be a good fit.

One of the assumptions about helical pile foundations is that they must be installed all the way down to till (bedrock) when supporting larger structures like a multi-family housing unit. However, in this case, the geotechnical report indicated till wouldn't be reached until about 60 feet which would increase costs.

Our team determined that if we could use a floating pile design instead, there would be a significant cost and time reduction for the foundation. So, alongside our engineering partner, we decided to challenge assumptions and come up with a new solution!

This had never been attempted in the City of Winnipeg, and we knew it would be a unique challenge.
Additionally, because this project was taking place during January, ground frost and winter conditions had the potential to impact construction timelines - which all parties wanted to avoid.
So, everyone rolled-up their sleeves and got busy.

Our Solution

We immediately engaged our trusted engineering partners and brought them the information we'd been given. It indicated the loads would be 15kips per-pile, so everyone got to work designing a solution to fit.

Unfortunately those initial figures turned out to be SLS loads instead of ULS, prompting communication with the customer to obtain updated information.

The revised loads turned out to be quite different, with per-pile capacities now ranging from 15kips to 31kips. This caused concern among our team that floating piles would not be able to handle the increased loads.

In order to gain site-specific data and avoid costly assumptions, we installed a test helical pile to derive valuable data for our engineering partners. After assessing our data, they concluded floating piles were still a viable option thanks to better-than-average soil conditions at site.

With this confidence backing the decision, engineering determined that 37 piles in total would be appropriate to achieve the load requirements.

Implementation

Before our team even had a chance to begin staging at the site, project owners were concerned about construction timelines as the severe frost conditions had caused delays during the excavation phase. They were in a time crunch to get the project back on track, so our team stepped-up to see what we could do to help.

Our first step was to show up a day before the pile install was set to begin and arrange materials, run string lines, and drill through upper frost layers in the soil. This ensured we could hit the ground running.

Bright and early the next day, in very cold conditions, a Glawson Piling crew showed up ready to make serious progress on the pile installation. Despite the relatively narrow confines, our careful installers navigated around the excavated trenches while installing piles at a steady pace.

Results & Conclusion

Over the course of 2 days (Thursday-Friday), we successfully installed all 37 helical piles. After installation was complete, our welding subcontractor arrived the next Monday to secure the pile caps which was done successfully.

By Tuesday, the concrete contractors were on-site and pouring beams that would be supported by our helical pile foundation.

In a mere 3 days this project went from having an at-risk schedule to being right back on-track - and even ahead of where they planned! Since helical piles do not require heat and hoarding, it greatly simplified the process and slashed timelines.

Because we floated the piles instead of going to till it saved more than $20,000 on the total foundation cost.

The client was thrilled to recover lost time, save money, and have the peace of mind that comes from knowing their project will stand firm on a durable deep foundation.

At Glawson Piling, our goal is always to identify the best solution for each project. Not one that makes us the most possible money. Value-engineer and site-specific designs are in our DNA, and we're extremely proud of the positive results on this project.

Looking to save time and effort while maximizing the economy of your foundation? Contact us to learn more about our helical foundations and get started today.

Four-Plex Housing on Helical Pile Foundation

The Challenge

Our Solution

Implementation

Results & Conclusion

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