Re: adding basement approach
Let's put it this way --- you want to remove the existing foundation that currently supports the house -- excavate underneath --- pour a new foundation.
Originally Posted by tonymsn
Somehow the house will need to be supported while all this is being done -- as well the house will need to be raised somewhat to allow the concrete to be poured into the forms.
Doing some preliminary homework will put things in perspective as to what's involved and the feasibility of the project.
Your first stage of planning should be consulting with the local municipal building department on what you wish to do. They will advise you all the requirements needed --- including permits.
Also , consider utilities like sewer , water , natural gas ( if available ) will likely be disconnected while construction is underway. There's a likelihood you may be forced to live elsewhere since the utilities will be disconnected and the fact the house will be temporally supported.
Next in the planning stage is to source out a foundation contractor experienced with this type of retrofit and have them visit the site to give you a ball park estimate. This is just for getting some numbers to work with.
The reason you want a contractor experienced with retrofits like this --- it's different to digging out a hole and pouring the foundation on an empty lot compared to excavating and pouring a foundation under an existing building.
With an empty lot --- an excavator comes in with a backhoe and digs the hole --- a crew shows up to form and pour the footings --- later they come back to setup the wall forms and pour in the concrete --- fairly straight forward and relatively quick.
In your case there's a building in place. This means after the building is supported they need to somehow excavate underneath. Depending on site conditions and accessibility will determine how that's done and will impact the price. If site conditions are favourable the excavation maybe done with a small skid steer and minor hand digging. Otherwise, if site conditions are tight the excavating may require hand digging which is labour intensive and slow.
Of course you also need to consider what will be done with all that dirt from the excavation.
Next , contact a structural engineer to inquire the cost of their services to design and provide certified drawings of the foundation. Again, this is just for getting the numbers together.
If you decide to proceed -- enlist the the service of the engineer to design and provide the certified drawings of the foundation. You will need this to submit to the building department anyway.
Once you have the drawings , have the foundation contractor provide you a quote based on the drawings .
After those are in place then submit your application for the permits --- once approved --- go to it.
2 cents worth.
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