Brick Hod

A brick hod is a simple tool used for tending brick and masonry materials and units. The picture below is from a pre-1930’s

In this blog post, we give a special thanks to Mark Stansbury, for permission to repost this image from his blog to ours. Stop by and check out Mark’s site at http://trowelcollector.blogspot.com

Today we commonly use a clamping brick carrier, a clamp with a handle to lift about a dozen bricks at a time, to pick up and tend brick to our masons instead. You may be able to get a sense from the image, but if not imagine the brick hod shown is attached to long pole, all told standing up to the full height of a man.

As one technology changes other technologies, in this case tools, are impacted. Brick hods are still commercially available today and even used in certain cases; however, with long boom rough terrain site navigable forklifts available today our simple industrial ergonomic efficiencies have changed as well. From about 150+ years ago up to about maybe 40 years ago, masonry units were delivered to site on train, cart or truck. Today, we can often get the masonry units loaded by machine much closer to the actual location of installation. However we still have to tend the masonry units to the Mason. Tending is the name for essentially handing the masonry unit to the Mason before the Mason carefully sets the masonry unit in place. Tending sounds very simple, almost unnecessary but it requires a lot of tough, backbreaking labor. Today we more commonly use the clamping brick carrier instead of a brick hod.

Historic Quarry Floor

The unglazed quarry pavers in the photos are understood to be up to 100 years old.

Quarry pavers such as these are unglazed kiln fired clay. Likely fired like brick at about 2000 degrees Fahrenheit. Here they are installed on a running bond pattern.

Modern Cement Mortar

Modern cement masonry mortar is the combination of modern cement mix, water, and a fine aggregate such as sand. There are also various types of pre-mixed cement have different ratings based on strength. Modern cement mortar may have many advantages over historic mortar: cost / volume ratio, market accessibility and availability, compressive strength, tensile strength, modulus of elasticity, permeability and resistance to moisture permeance, etc, etc.

While popularly used for modern construction, modern cement mortar should not be used to replace degraded joints in historic masonry. The modern cement is much harder than the traditional lime mortar and the inconsistency can cause serious damage to the structure.

Click here to go to the list of all items on Capitol Hill Historic Masonry.

Historic lime mortar joint with efflorescence

I like this picture for several reasons, in just this one photo you can see so many things.

This is a historic common brick, not a pressed brick.

It’s a wide mortar joint typical of plaster covered or exposed rear exteroor walls of the time, about late 1800’s.

There are subtle signs of efflorescence salts around the edge of the mortar joint.

You can see the large chunks of quicklime in the mortar joint.

A perfect example of terrible tuckpointing

The following pictures are from a chimney we repaired and Tuckpointed BEFORE we fixed it.

Some previous contractor went and tuckpointed the mortar joints with something that looks like the small batch cement sold in big box stores in small bags for floor leveling and the like.

It’s hard to tell what the previous contractor was thinking, the mortar is incompatible with the existing, too strong, not equivalently permeable, disimilisr modulus of elasticity, different tensile strength. You can see all of this from the photosexcept for the permeability which is an educated guess on my part because I know it to be a dark colored modern mortar.

One of the other main details about this mortar is the lack of sand grit is visually apparent. It is likely there is still a high silica content in this cement but likely at a much finer sieve, that is one of the reasons I suspect it might be a feather edge type of cement leveling product.

And of course, by the way, the previous contractor left messy mortar stains all over the face of the brick which look so bad you can actually see it from the street level.

Interesting Stone Masonry

In this stone masonry wall, some interesting looking stones have been used.

The stone in this photo looks as if it has been built like Swiss cheese around a lot of small pebbles.

Without having a mineralogist or geological background, I would guess this stone is one of two descriptions:

1. Igneous stone above the Earth’s surface (extrinsic) with vesicles and / or amygdales that over the millennia following formation filled with soluble stone deposits that moved through the stone.

2. Sedimentary or metamorphic stone that forms around the smaller stones.

Most stone forms slowly over time, neither possible explanation is a good explation for a passive creation of this stone, and that is why the stone is so interesting.

Reused old form boards as roof sheathing 100+ years ago

I was in a DC attic recently and noticed that every one-in-five or so of the roof decking boards had a cement coating.

The boards looked just like our modern day forms boards after being dirtied from use. This roof framing is original to the house. At the time of construction of much of DC row homes, concrete (and therefore concrete forms as well) was not yet in use. So, I had to think and try to figure out where the boards could have been used.

After spending a few minutes thinking it over I realized the boards weren’t concrete forms at all, they were likely scaffold planks used by the mason who built the demising walls (probably not the front lumper).

Tabby construction in DC?

We were on a jobsite last month where there was a section of concrete paving. The concrete paving was old and largely broken up. I wasn’t expecting this but I found old mollusk shells in the concrete, similiar to the old tabby walls common on the shores of the Carolina’s.

Tabby concrete construction is a method of building using fired mollusk shells to create a lime cement. Together with the resulting lime binder the shells themselves also were kept in the concrete as an aggregate.

Old rat slab

The photo below shows an example of an old rat slab, a thin layer of concrete applied on top of a dirt floor cellar in historic times.

These old slabs were intended for just three purposes:

1. Minimize dust of a dirt floor.

2. Keep rodents, like rats from boring through as quickly.

3. Reduce some of the subgradr moisture permeability.

A close look at at electrogalvanization

The picture below zooms in on a panel of electrogalvanized corrugated sheet metal, in this case used as a siding material.

The exposed layer of the metal panel shown in the photo above is zinc. The panel itself is steel, likely grade-5 mild steel which is easy to cut and less expensive than grade-8 or higher tensile strength steel.

In this case the zinc galvanization acts as a sacrificial anode to protect tge cathode, the steel substrate. Essentially the zinc coating protects against oxidation, rusting, when exposed to precipitation or air moisture, humidity.

Some obvious advantages of this type of steel protectant process are:

1. Electrogalvanized steel has lower cost than hot dipped steel, in most cases depending on batch process mill run lot sizes.

2. Thinner plating of electrogalvanized steel allows for better and tighter fit between mating parts.

3. The aesthetic of electrogalvanized steel has a cleaner, brighter, shinier look.

However there is one downside as well, the thinner coating of zinc in electrogalvanized process offer lower restance to corrosion than hot dipped process.