In February of 2017 the City of Winnipeg released its most current information bulletin regarding their approach to helical screw piles. If you click the link below you can download a copy of the bulletin:
What should you know about screw piles (augered piles, helical piles, ground anchors, etc.) within the City of Winnipeg?
There is good news and bad news for screw piles in Winnipeg.
The good news is that the City is now paying attention to screw piles and recognizing that they are an effective foundation solution for a wide range of projects. Yes, that’s right, you can build your addition, new home or commercial structure on helical screw piles.
The City has now recognized the significance of a CCMC report and proper screw pile engineering. This means that company’s approved for use in the City will need to verify claims with engineer supervised tests and satisfy National Research Council that the use of their products is acceptable within certain guidelines.
It appears that the criteria for engineering is excessive for screw piles but in reality much of the requirements for engineering apply to any pile including concrete. A home addition built on concrete will still need sealed plans and an engineer’s certification but it wouldn’t require the geotechnical report. The good news is that Postech has a unique geotechnical solution that is cheaper and faster than traditional methods – the need for a geotech therefore only adds 1 week to the timeline and will cost ~$1,000.
Note that if you have a commercial project,a geotechnical report will be required no matter the piles included in the design. Therefore, on commercial projects, screw piles, depending on the soil, could be a viable option that won’t create additional hoops to jump through.
In our opinion, the City’s information bulletin is a step in the right direction and it is very nice to see minimum requirements that will set a higher bar which weeds out companies that really aren’t providing a product or installation that is congruent with generally accepted engineering principles for helical screw piles.
However, the bulletin still lacks guidelines to reflect the local frost penetrations of up to 8 feet; allowing for piles that simply meet the 6 foot National Building Code criteria to be installed. Screw piles in Manitoba should have a minimum of 8 feet embedment measured to the top of the helical and not simply from the base of the screw pile; anything less will risk failure due to frost heave.
Engineered torque installations should also be a minimum requirement. The City appreciates rating screw piles based on soil capacities but without torque to confirm capacities, one is simply hoping the soil will provide sufficient bearing strength. As they say assume makes an “ass” out of “u” and “me” and comprehensive engineer led tests have confirmed time and time again the merits of torque installation for micro piles (screw piles with shaft diameters of 3.5″ or less).
If considering the use of screw piles for your project, Postech Screw Piles Manitoba and NW Ontario is here to help you make a solid decision. We have a CCMC evaluation already and can coordinate matters to satisfy the engineering requirements of any project. Most importantly, we are well experienced installing screw piles in all areas of the City for a wide range of projects from decks to home additions, garages, commercial structures, footbridges and more. Armed with our experience we can provide you with a realistic understanding of the costs and benefits or even short-comings of screw piles as they relate to your unique project.
Contact us at 204.793.0653 or toll free 1-855-4-PILING or check us out online at www.screwpiling.ca.