Underpinning Waterproofing
Underpinning Waterproofing
(OP)
We will be underpinning an existing elevator shaft and the groundwater is almost certain to come into play. What is the best way of waterproofing foundation underpinning?
I was considering applying the waterproofing on the inside of the shaft with protection board. However, I am reconsidering this option after speaking to a manufacturer's rep who told me they don't have negative side waterproofing products. I am thinking blind side waterproofing might be difficult to install considering the underpinning will be done in segments.
Thanks in advance.
I was considering applying the waterproofing on the inside of the shaft with protection board. However, I am reconsidering this option after speaking to a manufacturer's rep who told me they don't have negative side waterproofing products. I am thinking blind side waterproofing might be difficult to install considering the underpinning will be done in segments.
Thanks in advance.






RE: Underpinning Waterproofing
RE: Underpinning Waterproofing
RE: Underpinning Waterproofing
RE: Underpinning Waterproofing
www.PeirceEngineering.com
RE: Underpinning Waterproofing
RE: Underpinning Waterproofing
PEinc, are the chamfer strips used to form the joint of the bentonite sheets? I can see extending the width of the sheets about 4 inches or so on each side and cover the extra 4 inches with 4 x 4 so that the concrete isn't placed directly against the extra width. Once the adjacent pier is excavated then the 4 x 4 can be stripped off revealing that 4 inches of the sheet which can now overlap with the new sheet.
Or am I overthinking it and this is means and methods that should be left up to the contractor? I just think that if am going to put something in the plans I should have an idea how it can be done.
RE: Underpinning Waterproofing
An underpinning pit should be shored on all 4 sides. The bentonite sheet (cardboard impregnated with bentonite) is nailed to the wood shoring boards at the rear face of the excavated, shored pit. The bentonite "chamfer strips" are nailed vertically in the two rear corners of the shored pit. These vertical strips provide additional bentonite along the vertical, cold joints between the poured concrete piers. The bentonite chamfer strips are cardboard tubes filed with bentonite. When building an underpinning pier between two previously built piers, the shoring boards on the common side only get removed. The rear shoring boards stay in place. The front shoring boards will be removed when excavating to subgrade in front of the completed underpinning.
www.PeirceEngineering.com
RE: Underpinning Waterproofing
Thank you all for your advice.
RE: Underpinning Waterproofing
www.PeirceEngineering.com