Get the Ground Ready
You know that work on the foundation for the addition is imminent when a BOBCAT rumbles up your driveway. This came to pass last week, and I was so happy to see the pea patch scraped down to fresh dirt by Friday! The orange tree is gone, but so is the DIY concrete blob and a lot of mulch and weeds that I had grown really weary of looking at.
A peaceful pre-work morning scene last week. Electrical demo was about to start—clearing out all the 1910 knob and tube wiring. The porcelain knobs themselves were left behind for future industrial archaeologists to discover (at least, that’s how I think of it).
Mini earth-moving equipment
On Monday (8/30) they started trenching for the new foundations for the addition! The amazing thing about this (an overused adjective to be sure, but I really was amazed!) is that you can now stand in the spaces where the rooms will be!
More progress!
A few days later they’d started to build the formwork for the concrete, but this is as far as it got before the crew was called off to another job.
So we can see that those new foundations will be nice and deep. How about the foundation of the existing structure, which has been out of sight and mind for 111 years? Much less reassuring (arrow below)! I guess that’s all you got for your $2,000 back in 1910.
The red arrow is pointing at the existing foundation. Yes, that is IT! The depth of the trench below the arrow gives you an idea of how much deeper the new foundations will be than the existing!
What we are looking at above (at the arrow) is a shallow concrete shelf about one foot deep—also known as our existing foundation (I use the word loosely). That’s right. You may have noticed (it took me seven years, and it hadn’t really occurred to our contractor till it was all exposed, either) that THIS is what our house is resting on. The cripple wall—the space between the underside of the floor plate and the ground—is also just WOOD. Not brick or concrete, as one would expect in better construction from this period (and by better, I mean better than this—not necessarily “good”). The plywood with the circular holes was installed from inside the crawlspace and open basement area when we moved in and had the foundation retrofitted.
Along the bottom of the wall here you can see the sill plate—a length of wood attached along the top of the concrete foundation to which the wood members are nailed. You can see the series of raking boards that lean out from the wall surface. These are used as a guide to define the flared profile of the shingle cladding at the bottom of the wall. Horizontal battens such as you can see at the arrows in the picture below were attached to the raking pieces (continuing up the wall), and each course of the shingles was nailed to those.
The new plywood will extend all the way down the wall to the sill at the ground, stiffening the whole structure. The plywood is the same thickness as the battens (all removed now); therefore the wall thickness won’t change, even with the addition of all this new material. The shingles will be nailed to the new surface of 3/4” plywood. The relative profile of the windows, casing, and shingled surface will remain as it was once the whole thing is put back together. Yea!
I just found this diagram which depicts pretty accurately the existing lower structure of our house. It’s from the National Center for Preservation Technology & Training (NCPTT) of the National Park Service, so I feel a little more legitimate now! What we have is not unheard of (at least the part above ground). I’m sure folks from NCPTT have seen it all.