Part 3 – The structural parts of the house

Before I move on to the basement, I need to explain a couple of things.

When we bought the house, among the many things that needed to be decided was how we were going to use the house. Were we going to leave it as a very large single family home? Or somehow divided it up into different living areas? The house as we bought it had about 4000 sq ft of living space, which after our planned energy retrofit modifications would be reduced to about 3750 sq ft (the loss of living space due to the addition of insulation). This included a virtually unusable basement, and equally difficult attic space. After some discussion we decided that the best option was to leave the upper floors as a single family unit, and to make the basement area (which in reality is a walkout) into a self contained suite that could be rented or used by family members.

And there was another very important issue.   Structural integrity. This goes to the very heart of what we were going to do to the house and how we were going to do it. As mentioned before, the floors where a mess, structurally the interior of the house was a disaster and there never had been any insulation in the house, evidenced by the 175,000 BTU boiler that was probably struggling to keep up with the demand. So, when you combine all these factors, our plan to massively improve the thermal characteristics of the exterior walls and replace the entire interior floor structure made perfect sense. But how exactly do we do this? In a prefect world we would dismantle the interior floors from the top down (to create an empty shell, essentially a hollow cube) and then rebuild from the basement up. Unfortunately, this approach has some serious problems. The way some of these old homes were built involved creating a structure that was built as an entire assembly as the house was being constructed. After some very invasive examination, we discovered that, for example, the floor joists on each floor, were actually supported on the inside wythe (a wythe is a row of bricks in construction. So a “double brick” house would be termed a “double wythe” house) of bricks, and then the areas between each joist were bricked up, and then the inside wythe would continue up to the next floor. There was also a wooden ledger block installed into the inside brickwork as well. This meant that the floor joists were actually an integral part of the structure of the house and were partially responsible for keep the exterior walls from moving in or out.

 

Looking closely at the above pictures, they really show the whole story. The picture on the left shows the cross bricks (my terminology). These were trimmed whole bricks that were placed cross-ways periodically along and through the height of the wall. It effectively created a monolithic structure that prevented the 2 wythes from separating over time (or during construction). As you can also see from this picture, there is virtually no space between the wythes. No insulation could ever be installed, and the only thing between the wythes is lime mortar. The middle picture shows one of the floor joists. It appears that it has been inserted into the wall,  but in reality it was probably installed in a specific sequence. An outside course of bricks were installed. The inner wythe was installed to a certain point, and then the wood ledger was installed to be flush with the inside wythe. The joists were seated onto the wood ledger (they only sit about 1-2″ on the ledger board) and toe-nailed. The remaining bricks were installed to complete the inside wythe between the joists, and once high enough, the inside and outside wythes continued upwards in tandem with cross bricks. The right picture shows the cavity of where we removed the joist. The toe-nails are still there and could only have been installed before the bricks on either side. All this to explain that the house, including all the floor structures was built from the ground up, and everything was an integral part of the house.

An important consideration arose. It seemed imprudent to simply gut the whole inside, as there could never be any guarantee that the brick structure would be able to stand up by itself, with all the lateral bracing removed, and only a roof sitting on the brickwork. I questioned numerous Engineers and Designers (and my own common sense), and everyone had mostly the same answer. Yes, it “should” stay up, BUT, its unclear what other forces may be exerting pressure on the upper walls (perhaps pushing out), so it would be better not to remove everything all at once. The problem seemed to revolve around creating an extended vertical gap between lateral bracing points. In other words, creating a 20′ gap between the foundation and the second floor (to remove the 1st floor) wouldn’t be a problem because the walls would be braced at the foundation and at the second floor. Then, to remove the second floor, the same 20′ gap would be braced by the new first floor and the existing third floor.  But removing both floors simultaneously would create 30 or more feet of unbraced brickwork, and anything could happen.

Not wanting to experiment with the “anything could happen” scenario, I came up with a plan to replace each floor separately. Of course, the next question was how exactly we were could do this. It would have been completely pointless to remove any of the floors without any bracing, as this would mean that the unsupported floors above could drop (even marginally) and potentially draw the brickwork inwards, cracking bricks and mortar. So no question: the floors above had to be braced so they would not move when the lower floor were removed. Basically each upper floor had to be braced to the second lower floor so the floor in the middle could be removed and replaced.

pillar plan
As shown to the left, the plan was pretty simple. To remove and replace the 1st floor “all” I needed to do was install a beam (or as it turned out multiple beams) under the second floor joists, and then brace the whole beam to the floor below the one I was going to remove. This beam had to “catch” the majority of floor joists to prevent any sagging from the floor above. The pillar that was holding up the beam had to pass through the floor we wanted to remove and rest on the floor below. The beams turned out to be 28′ long and the pillars were a box design that went 19′ to the basement. Everything was done with 2×6 lumber.

As shown above, one of the main horizontal beams (28′ long) was installed to hold up the second floor, with vertical pillars that go through the 1st floor and rest on the basement floor. I used some techniques from our trucking days to jack up the pillars, making sure that there was lots of positive pressure on the second floor joists, and then blocked up everything tight so nothing would move. At this point it was safe to remove the 1st floor framing, as the second floor was resting entirely on the basement floor!

I should mention at this point that I have gone somewhat out of order. The problem is that to explain what we had to do next, required me to explain the purpose of what we had to do next. But, once I understood conceptually what we had to do, I had to figure out how we were going to do it. The understanding that we would have to use the basement floor to hold up the 2nd floor was only one of the pieces. We also knew that we were going to develop the basement. We also knew that the 1/2″ water line in the basement was insufficient for the house. AND we also knew that when we rebuilt the 1st floor, we needed a flat perfect structural surface to build and support the 1st floor.   In reality, we first fixed all the problems in the basement and  then installed the beams and pillars. But first things first. We had to, before anything else, deal with the basement, because like any normal house, you have to start from the bottom and work up!

On to part 4.

 

 

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