One of the greatest challenges we face in the business of historic preservation is controlling unwanted moisture in and around our structures. Water will find a way down. When it gets down and is trapped in between things made of wood, it can cause serious deterioration and rot. We have found evidence in the Stone House that there has been a history of serious water leaks where the roof over the stone side meets the south gable wall of the log addition. Sheet metal flashing has been the method used to prevent and repair leaks in this part of the house for over a hundred years. This has certainly been the case ever since the metal roof was installed over the stone side of the house. Before the advent of rolled metal roofs, wood shingles were tucked under weatherboards in places like this, where a roof met an exterior wall. The weatherboards were cut in relief to the profile of the shingles. This would leave a sawtooth pattern on the bottom edge of the weatherboards. We have an example of this kind of woodwork in the attic of the Steele & Bro. Store. (See image below.)
In this instance the weatherboards of a former exterior wall were left in place and were encapsulated under a new metal roofline that was installed above. Even though the old wood shingle roof and its supporting structure was demolished in the 1880s, its profile remains in the surviving weatherboards.
We are using this method of tucking our wood shingles under the bottom edge of relief-cut weatherboards on the south gable of the log addition. To minimize potential damage to the wood shingles over the stone side of the structure, we began by having our roofing contractor Frank Stroik, and his crew at Country Homestead, install a few courses of the side-lap wood shingles in that place where they abut the south gable wall of the log addition, leaving the remainder of the roof structure over the stone side covered with temporary tarps. This made it possible for Vintage Inc.’s crew to install the weatherboards above without requiring them to walk on any new wood shingles. After the abutting shingles were installed, they were painted with a red linseed oil paint mixed with copper naphthenate. There is historical evidence for red paint on wood shingle roofs, but the copper naphthenate is a modern compromise to extend the life of the shingles themselves. When the rest of the shingles are installed, they will also be painted with the same mixture.
The installation of the weatherboards over the shingles required careful measuring and the leveling of each board in relation to its vertical alignment. Every effort was made to ensure that the gap between the top of the shingles and the bottom of the weatherboards is about the width of a carpenter’s pencil. This allows both the shingles and the weatherboards to “breathe” and prevent water from getting trapped.
This method of weatherboard and shingle installation works because water does not run uphill. By sealing the end grain of the weatherboards and the shingles with paint, we are also significantly reducing the capillary action and absorption factor of the boards themselves. In our next installment we will unveil the finished roof over the stone side of the house. We have been looking forward to this for years.