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We are looking at a number of properties and a fair amount of them are 2 bedroom/1 baths of varying square footage.
If we decide to do a room addition of a 3rd bedroom and possibly a 2nd bathroom, does anyone have experience as to what the usual procedure is regarding the basement for the addition in relation to the foundation? That is, assuming the additional structure is not located on top of a rocky ledge, is it normal to build on a slab foundation when adding on to a house which has a regular basement, or is the basement typically extended under the new construction. I would guess the former, but am not sure, coming from CA, the land of slab foundations.
One other question would be if anyone has experience in costing out the ballpark, per square footage $$$ figure for a room addition?
Thank you once again for your insight!
Until you get a backhoe or excavator to moving dirt you simply do not know what you will find. Maybe sand, clay and loam; maybe rocks the size of houses; maybe ledge; maybe you will open an aquifer; maybe a mixture of all these things.
A slab is pretty safe.
This summer I dug a lot of holes for footings and with each hole it was completely random the things I found.
I do know it depends on the area of the state on "what you may find under the first layer or so".
In the "area where Princeton,Maine is.... my folks tried for a basement and they were only able to go half way down due to "ledge"
Lots of ledge in their area. Digging a mail box post was like wanting to dig to the "center of the earth."
Where I am about 20 so miles away I have a mixture and I too (have high hopes for an addition with a basement. I wonder too what it may cost, and what I will really find too.
I do know it depends on the area of the state on "what you may find under the first layer or so".
In the "area where Princeton,Maine is.... my folks tried for a basement and they were only able to go half way down due to "ledge"
Lots of ledge in their area. Digging a mail box post was like wanting to dig to the "center of the earth."
Where I am about 20 so miles away I have a mixture and I too (have high hopes for an addition with a basement. I wonder too what it may cost, and what I will really find too.
Isn't there some high tech way to get some idea what is under the surface before you dig?
Location: 3.5 sq mile island ant nest next to Canada
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Originally Posted by OutDoorNut
Isn't there some high tech way to get some idea what is under the surface before you dig?
We had an outfit here on the island that had the DEP doing soundings to find any possible contamination areas on the property. They found areas where they needed to dig quite deep (deeper than a basement) to remove concrete pads to search beneath. The equipment they used was so good it increased the acreage of the property by 4 acres or so.
Here, you could dig on one lot and hit ledge and go a few lots down and not hit anything but dirt.
The front part of my house has a basement built in 1900. The recent addition before I bought it, done in 1996, has a slab. Sometimes bedrock is pretty close.
Isn't there some high tech way to get some idea what is under the surface before you dig?
Maybe... I can call in MPBN's "History Dectives"..
Seriously.... will find out when the times come. Having people come in to find out would be a "cost" on top of a cost.
If I couldn't dig a full basement, I'd use a Rubble Trench Foundation with an insulated slab inside. The Rubble Trench would go to the ledge so no issues with poor load bearing soil. A slab can have issues with frost getting under the outer edges unless properly built. Instead of a frost wall of concrete, look at the Rubble Trench design. Frank Lloyd Wright used them so I'd say they work. Lay out the foundation, have the excavator dig trenches where the walls will go. If no ledge, dig the entire foundation. If ledge is hit, go with the rubble trench. Never built on though...but everything is about drainage and the rubble trench seems to have the answer.
You never know what you will find when you begin digging.
Our plans called for a full basement. The site-work contractor does not like opening holes until they are needed. His reasoning is that all too often an open hole will fill with water. So he scheduled the work with the foundation contractor. The hole was opened on the day that the foundation contractor's first crew arrived to setup the foundation forms. Apparently this is standard procedure in this area.
For half of our home's footprint the digging went fine. But at about half-way they hit ledge. The grade in this area is flat level. The ledge is 4 foot below grade. The ledge has a drop-off to it, the drop-off runs through the center of our house. So half of our house was able to get a 8 foot basement, and half was only able to get about 4 foot.
The foundation contractor's crew sees this routinely. While they arrived on site with forms for an 8-foot foundation, they also brought with them other forms just in case. So when setting up their forms they merged the two depths of forms.
Also in the deeper area where we decided to install a sump, it turns out is an aquifer.
You just never know what you will find when you begin digging.
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You never know what you will find when you begin digging.
