Projects: Prospect Place, Pt. II - "The Earth Moved"

 
When you're adding a 3 story extension to a house in Prospect Heights - and one of those stories is underground - you've got yourself some Earth to move!  In our latest look at the project on Prospect Place that Cousin John is letting us follow, the task at hand was creating the space for the new foundation and cellar beneath the garden level.  This required excavating enough dirt from the backyard to fill 9 dumpsters, one bucket at a time.

It takes approximately 4,000 buckets of dirt to fill one dumpster!  And even more when the buckets are lighter, as they were when the hole got too deep to lift full buckets up the flight without steps.

It took weeks of manual labor to move just over 6 tons of Earth, until a step out the backdoor of the house became a steep drop into one big pile of dirt.

It reminds us of the door hanging over the sand dunes in Beatlejuice...

Now properly excavating in these tight confines is a lot more complicated than just digging.  The neighboring extension on one side had to be propped up with underpinning, which begins with one initial pit...

And then additional columns are added in a strategic order of segments, ultimately 4' of support underneath the foundation of the adjacent extension.

Underpinning can be a huge issue when not anticipated and not executed properly, as other cases we've seen show.  On the opposite side of the excavation that has no neighboring extension, supports had to be used to prop up the yard, but underpinning was not required.  An L-shaped footing of concrete poured over steel & rebar suffices.

 
With a vapor barrier underneath and 4" concrete slab with radiant heat as the flooring of the basement, this cellar will be as comfortable & quality as any other finished space.  Afterall, when you're doing it fresh from scratch, might as well do it right.  We asked about this carpetfoam-looking substance along the wall between the yards, which Cousin John says is a waterproofing material that melts and fuses to the concrete between the basement of the renovation and the adjacent yard.

Now when you go digging up holes like this that risk disturbing the structure and foundation of the neighbors, not only do you have to get the engineers to do it all right, you've gotta have the forensic documentation to prove you didn't step on any neighboring toes.  Engineers do a detailed report on the existing conditions of the neighboring structures, and even install crack monitors to track even the tiniest disturbances.  These crack monitors are actually mini seismographs that measure whether 'the Earth moved under my feet' on the adjacent properties.

Looking ahead to the plans for the floors above, we're excited about a glass floor detail to let light from the parlor to the garden level, just over 1" thick and roughly 4' x 6'...

Get a bit of this effect going on, perhaps...