Triangular lath from the old farmhouse on the Michael Korns, Sr. Somerset County PA family farm. Lath from the old farmhouse on the Michael Korns, Sr. Somerset County PA family farm.

Triangular Lath from north wall of the house on the Michael Korns, Sr. farm

The enlargements (above) are from a 1998 photograph of the north wall of the east end of the house. The photographs show plaster attached to what I interpret to possibly be split (as opposed to sawn) lath, which suggests an early house construction date. Note the triangular shape of the lath, which is unusual. The timber the the triangular lath is attached to clearly shows reciprocating saw marks, as opposed to circular saw marks. To see the photo that these enlargements were taken from, click here. The thick plaster over the triangular lath is also notable in that it appears to be a single material, rather than the typical white coat over a brown undercoat.

The crude plaster and lath suggests an early construction date, and in my opinion makes it more much likely that the house was built during the lifetime of Michael Korns. Click here for a 1989 statement on the history of lath from the National Park Service.

Although more modern sawn lath, apparently prepared with a circular saw, was found on another part of the house near a later addition, this presence of triangular lath with crude plaster tells us that the sawn lath was probably part of a remodeling job that occured well after the house was built. The photograph below, enlarged from the same 1998 photograph as those above, shows triangular and sawn lath in the same room, and the sawn lath is coated with the more typical white finish plaster over a brown plaster subcoating. This presence of both types of lath and both types of plaster in the same room suggests that some of the plaster and lath was replaced as part of a remodeling job.

The plaster remodeling job was probably a necessity due to faulty placement of the triangular lath, causing plaster failure at a later date. The proper way to place lath is to leave space between the strips, so that the plaster will flow through the cracks and form "plaster keys" on the interior of the wall to mechanically hold the plaster to the lath. It seems apparent from the photo that the triangular lath was placed too close together, preventing the formation of robust plaster keys. The thick plaster would have compounded the mechanical retention problem by adding considerable weight. In short, I believe that we not only know that the house was replastered, we know why it had to be replastered.

The thickness of the plaster over the triangular lath reminds me of the thick plaster that I once observed on the nearby Lepley stone house, which by local tradition was built circa 1810. That plaster was thick by necessity, being placed over rough stone walls. Given the isolation of the area at the time, it isn't surprising that an evidently similar plaster technique (i.e. thick) would be used in both houses. In fact, if you look closely at this photograph of the house on the Michael Korn farm, you will see some of the double-coat plaster (believed to be remodeling) applied directly to the stone wall lining, without lath. It isn't hard to imagine that before the time of the double-coat plaster, the thick coat plaster would have also been applied directly to the stone wall lining. In this enlargement of the same photograph, it appears that the brown undercoat is applied over a fragment of the original plaster, which seems to confirm the remodeling theory. The plaster over stone, the thick coat plaster over triangular lath, and the double-layer plaster over conventional sawn lath, all occur in the same room of the house.

The split lath that I have seen in the literature that I have reviewed is rectangular in cross-section, and not triangular. Even if I am mistaken about the triangular lath being split rather than sawn, it is still not a modern type of lath even for the early nineteenth century, the plaster attached to it is unusual in being a single thick coat, and the faulty placement of the triangular lath explains why more modern sawn lath was installed elsewhere in the house.

The second photo from the top provides additional insights if studied. We can determine that this was the location of a doorway even though that section of wall has fallen away, since the plaster is roughly broken at the top (above the height of a doorway) but the plaster, the lath and the clapboard siding terminate relatively smoothly throughout the height that is compatible with a doorway. From this, I infer that the plaster and lath terminated at a vertical board that edged a doorway. One can also see the nail holes in the side of the vertical member where the door trim was attached. Better yet, if you look at the full picture, you can see a dangling piece of siding that is cut out for the missing doorway. The second photo above also reveals the configuration of the clapboard siding. Notice how the boards are beveled at the top and bottom edges to facilitate overlapping.

L. Dietle
July 29, 2007

Lath from the old farmhouse on the Michael Korns, Sr. Somerset County PA family farm.

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