psychedomination
Structural
- Jan 21, 2016
- 114
Hi there,
I recently got called to a job site where excavation has already occurred for a basement extension project.
The excavator has excavated very close to the existing house wall. It appears that the house wall was sitting on a limestone chunk that was resting on a soft sandstone type material. See image below :
I question whether the sandstone can take the weight of the wall/roof with the excavated material removed in front of it? The main wall is about 8" away from the basement wall. I recommended that the owner stabilise the wall as a matter of urgency. Am I being overly cautious or is there some contribution from the existing basement wall that can be utilised?
As part of the permanent basement extension works they will be looking to install a beam under the existing main house wall to stabilize it (see architects intent in sketch above), which they have asked me to design. However, I am wondering how they will be able to get the beam installed? I know for basement underpinning they typically excavate the length in about 1m sections but I'm not sure how the contractor will go about doing this when installing a full length beam (~8' in length). They don't have any specialist equipment only a few prop jacks. If you can provide some guidance on how walls are propped in situations like this to facilitate a beam install that would be very helpful.
Any other advice would be greatly appreciated.
I recently got called to a job site where excavation has already occurred for a basement extension project.
The excavator has excavated very close to the existing house wall. It appears that the house wall was sitting on a limestone chunk that was resting on a soft sandstone type material. See image below :
I question whether the sandstone can take the weight of the wall/roof with the excavated material removed in front of it? The main wall is about 8" away from the basement wall. I recommended that the owner stabilise the wall as a matter of urgency. Am I being overly cautious or is there some contribution from the existing basement wall that can be utilised?
As part of the permanent basement extension works they will be looking to install a beam under the existing main house wall to stabilize it (see architects intent in sketch above), which they have asked me to design. However, I am wondering how they will be able to get the beam installed? I know for basement underpinning they typically excavate the length in about 1m sections but I'm not sure how the contractor will go about doing this when installing a full length beam (~8' in length). They don't have any specialist equipment only a few prop jacks. If you can provide some guidance on how walls are propped in situations like this to facilitate a beam install that would be very helpful.
Any other advice would be greatly appreciated.
