I threw a lot of loose brick scraps around. And after having reached rock solid layers of brick, I was ready to test my masonry skills again.
I learned early on in the project that the combination of a 100+ year old building and Chicago common brick requires not just any mortar, but a special kind of mortar – the Type O kind.
The mortar joints in these masonry walls are meant to be the sacrificial layers – because they are easy to repair through tuck pointing. Replacing damaged bricks is much more involved and labor intensive. To prevent brick damage or spalling, and to assure a functioning sacrificial joint, the mortar needs to be softer than the brick. That is where the Type O comes in handy, if used in combination with our common brick.
For more details and rationales on the Type O mortar, read my earlier post: Bricks and mortar.
To make the mortar work and have it properly cure, I had to prevent it from drying out. The common brick is a very effective sponge, and can suck the moisture out of mortar within a few minutes – unless the common brick is already wet.
Before I could slap any mortar onto the bricks, I needed to spray down the existing masonry wall and soak the replacement bricks in a bucket of water. And believe me, one quick spray or one quick dunk won’t do it. Common brick is a sponge, and it needs wetting like a sponge.
Once the tedious due diligence is out the way, I was ready to slap mortar on the bricks and start rebuilding the top of our south wall, so that we could get to building the roof level of our new back porch.
I am glad that the time lapse doesn’t provide any close-up view, because my masonry skills are OK yet still basic. In other words, my work is not that purdy! Do I care? No! Not as long as the work is sturdy. That part of the wall will be covered with a big old ledger anyways.
Edgar, our carpenter, and I had a number of conversations this spring, thinking through the process of rebuilding the back porch. Back then, he pointed out that we would encounter a lot of loose bricks right at roof level.
That prediction didn’t surprise me because this section of the masonry wall isn’t that dissimilar to the parapet. And boy, that parapet was in bad shape, until we rebuilt it.
Removing the loose bricks was somewhat of a déjà vu with some subtle differences.
The only whole bricks I encountered were on the outside. The inner wythe was almost completely composed of brick scraps. This must have been the last bit of masonry work when they raised the walls. Was this resource efficiency or did they simply run out of good bricks? Whatever it was, the extensive use of brick scraps didn’t produce very solid masonry.
I had to pull out all those loose bricks until I was down to solid masonry again.
When we insulated the second floor, I didn’t insulate behind the last roof joist. There simply wasn’t enough room to get into those two inches between the joist and the masonry wall.
Now, with the brick removed, I had all the space I needed to get into that space and insulate it with pieces of two inch thick XPS boards. I can’t lose sight of the air tight building envelope principle. So I made sure to seal around all the XPS edges with spray foam.
The west facing kitchen window is so tall (or reaches so low for that matter), that any cabinet with a countertop would partially block it. I assume that the original kitchen layout must have been such that no counter was located at the window – which wouldn’t have left much room for countertop space.
Or, the previous owners were content with the countertop partially blocking the window. This is a scenario I dislike as the window sill hidden behind the kitchen cabinet is hard to reach and would just accumulate… well – let your imagination roam.
I really am curious as to what the original kitchen layout may have been!
Anyway, we already solved this problem in the 1st floor kitchen, and were to repeat it on the 2nd floor – by raising the bottom of the window above the countertop height.
This means getting rid of the existing window altogether and calling our mason.
The masonry work was a big deal for me, but not so for the mason. “Just half a days’ work…” Great, then I can spend the other half day on building and installing a new window buck.
The process is similar to the range hood exhaust installation. I use the hammer drill with a masonry bit to drill out the mortar joints and set up a perforation line across the brick. Once that is done, I can grab a hammer and chisel and carve out the joist pocket.
In the kitchen at the chimney, the two joists stop short of the masonry wall. I placed a sister joist mock up along the roof joist, which allowed me to mark the exact location for the joist pocket. As for all the pockets, it was a tight space to work in. Nevertheless, the pockets turned out all right, and a test placement confirmed that the sistered joists would fit right in.
There is a laundry list of masonry repair items on the 2nd floor waiting for me. Not just the masonry pockets from the ceiling joists, but re-pointing and brick replacement too.
As with the basement and 1st floor, we will install a layer of polyurethane spray foam (SPF) across the interior masonry walls. The SPF will help with the insulation and air sealing of the building envelope. Before we install the spray foam, I need to get those masonry repair items done. Once the SPF is installed, I won’t have access to the brick any longer.
Damage to the masonry wall is almost always moisture related. A quick inventory showed that most of the damage was confined to the attic area. This included efflorescence and crumbling mortar joints.
This damage had been caused by water infiltrating into the masonry wall through the parapet, until we fixed it back in the fall of 2009.
I ground out the damaged mortar joints for re-pointing and removed all bricks that showed some level of spauling. Most of those bricks were along the north wall – the front of the building.
I suspect that I still have some water infiltration into the masonry along the north wall, right behind the cornice, where I can’t see it.
Fixing that problem will be a very interesting task, and probably requires me to take off the cornice and reinstall it.
For now, I had our mason come in to repoint the mortar joints and install the replacement .
That took care of the masonry work. Well – almost…