Trickle Down Arch Design

Our latest design challenge is a brick arch with recessed accent courses that tie in to the recessed accent courses of the running bond of the building.  Here is a building in Baltimore with a similar style arch.

What complicates the matter further is the 32" soffitt and the question of how we will prefabricate the arch.  When designing a normal radial brick arch the measurements that we need to determine are the circumference, angle, length of the outside arc, and brick size.  

circumference x angle  =  length

360    

But in this case the masonry opening arc is half round and the outside arc is elliptical.  Also we are limited by the size of brick because the joints of the accent course must line up with the running bond.  Here is where it gets tricky.  Instead of starting with the arch, I started with the running bond and accent course, and started at the top of the arch.  To pass the eye test the arch cannot be too tall in the center, but also the 2 1/4" brick size must line up to the same number of courses in the arch.  The only way to get the desired effect was to start with 3 5/8" closure size brick towards the top of the arch, then work our way smaller towards the bottom.  This is how we came up with the ellipse.

I am no math wiz, so if anyone knows a better way to reverse engineer this thing send me a message.  What has me mixed up is the length of the elliptical arc combined with the size limit of the radial segments.  

You say Palladium, I say Palladian

A palladian window is a large window divided in three parts: a central sash that is arched at the top and two sashes on each side of it that are smaller than the central sash; the smaller sashes are rectangular, topped with flat lintels.  This style of window is also called a palladium window depending on where you look on the internet.  Needless to say, this window is very common in the D.C. metro area with some of the production home builders like NV homes, Winchester homes, Pulte homes, and Toll Brothers.  The challenge for a bricklayer is how to cross over this style window with a brick arch.  Cast stone commonly is used.

Here is a palladian surround we did for Plus One Masonry @ Pulte homes.  As you can see the lines are clean and the look maintains it's colonial architecture.  There are several examples of historical palladian/colonial buildings in Annapolis Maryland one of which is the Hammond-Harwood House

And a modern example in Baltimore is a multiple building project at Johns Hopkins University for Henry J Knott Masonry.  Here it is 3D google maps.

Getting back to the residential palladian window, here is the design we use for a brick arch.  There are two  tricks to making it look good in my opinion.  First is how the radial arch and the lintel jack arch come to a natural meeting point on each side of the 1/2 round window. Second is to avoid small brick pieces if possible.  You do this by starting with a 7" long radial brick, and by the time you are to the 5th course on the 1/2 round center, the bonded arch meets up with the bonded lintel wing.

My vote is for calling it a palladian window.