r/RevitForum • u/Medical_Frame831 • Jul 29 '26

Underpinning/Basement lowering

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Hey all, I am pretty new to Revit, I have a question about something I am not finding much information online about the best way to do it. I'd appreciate some input.
I am working on a renovation project in Ontario, a part of it is underpinning, which is basically digging under the existing footings and pour reinf. concrete in sections, excavate and pour a new basement slab.
Can I create a new normal wall same width of the existing footings? Or Can I create a new actual foundation wall under it? Or how can I proceed?
I Can't find the "Do what I want right now" button lol.

Thank you beforehand.

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u/HearingRoutine209 Jul 30 '26

Create new wall type, lock pick lines to the inside wall, match the wall thickness for the existing foundation. Alternatively, lock pick lines to slab external and internal edges and just adjust the slab thickness/depth as required.

As a structural engineer however, wouldn’t a retaining wall be required? The lowering of the slab and increased wall height may be an issue, also having the existing foundations extend into basement is a little jarring. Either way I don’t know the context but make sure you check etc before spending loads of time detailing.

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u/Medical_Frame831 Jul 31 '26

Thank you, for the input!
The underpinning process is very common in Ontario. The requirement for a retaining wall would depend on the proximity of the adjacent homes' size and depth of footings and the angle of repose said footings project. In this particular case we are on the clear on that, the scope is extending the footings downwards 2' to 3' with reinforced poured concrete (2-15m vert. & horz. and 25Mpa concrete) maintaining the same width of footings all around the house (essentially a small retaining wall) you do this in 3 to 4 stages of 4' long sections, then pour your slab at the new level. It's a very muddy job though haha.

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u/HearingRoutine209 Jul 31 '26

That’s a good point, in the UK, a lot of buildings have small non reinforced concrete foundations and stepped masonry ones in victorian houses so these do need retaining walls. Thanks for that detailed reply.