Slate roof replacement project

[DavidP]

OK, folks, here we are! The job was finished late Thursday and I have just added the last two blog ‎entries. I also updated the antepenultimate [your word of the day ] entry with some very cool pictures I ‎finally got from my contractor. Check out the gutters and copper as seen from the roof!‎

I’m going to add one more photo here but not on the blog, since it would have to go on the entry for the ‎second day and most people wouldn’t see it. At the start of the job, my contractor arrived with a couple ‎sheets of high-quality birch plywood, assuming he would have to replace some of the roof decking. But ‎he didn’t: that old slate roof kept the decking in perfect shape for 115 years or more. You can also see the ‎beams that stick up vertically at the top of each ridge. Their presence is the main reason that the copper ‎ridge caps have a larger radius than I would consider ideal from a visual point of view.‎ (Sorry for the weird angle; I had to rotate the original photo. The chimney and main ridgeline are at the upper right, and the west gable at the left center.)

2019-06-14_roof decking 846 rotated small-2.jpg (585.96 KiB) Viewed 1024 times

I’ve always thought my house was well built, but now I have even more respect for the original contractor. ‎I was given a copy of the plans for my house by the previous owners. A friend of mine who used to work ‎in an architect’s office looked at them and said “There isn’t much here for the builder to go on.” The ‎plans and elevations show what the roof is supposed to look like, but the contractor had to do all the ‎geometry and measuring to figure how to shape the rafters and other pieces (and the roof is not simple), ‎had to decide how many collar ties to install, etc. I thought even before starting the roof replacement that ‎there weren’t many ties, and they are only 2 x 4’s. Yet the structure supported the slate for 115 years, ‎with only one spot on the west that wasn’t 100% structurally sound. Raising the center of the roof by ‎‎3/16” put things back in place. I guess the guy really knew what he was doing. I think that the ‎craftsmanship that my contractor and his crew brought to this replacement is worthy of the original ‎builder.‎

My contractor will be here Monday and I will hand him a large check, and then we're done.

[Gothichome]

David, isn’t that roof a great thing. And the copper just sets it off nicely. Your raised edge on the troughs only adds to thecharm of the roof. I can see the logic of not bringing the slate to the bottom, with ice dams ect. But old slate did the job well for 115 years, but I guess even traditional techniques change with time and new materials.
You have all the tongues wagging now on your block, and maybe for several blocks in all directions. Folks will be going out of their way just to have a look and admire your home on their evening walks.
And cudo’s to your contractor for the extra effort and creativity in solving the problems.
As fare the skills of the old carpenters, many of the of building techniques would have been expected with out question by the designer so detailed hand holding was not needed. And that’s why our old homes are still standing.
Now write that cheque (gulp) and look up knowing you did the right thing.

[GinaC]

My goodness, that copper edging adds the perfect touch! Gorgeous!

I sure wish your builder had built my house -- they would have built it level!

[1918ColonialRevival]

Glad the project is finished. Vermont gray slate and copper flashing will outlive all of us. They did a good job.

The more I look at the pictures of your old slate roof, the more I'm wondering if the slate roof you replaced could have been the second roof your house had. The slate looks like the soft Central Pennsylvania slate that was very popular in this area from the Depression years up until about WWII. It was a cheaper slate than those from Vermont, Virginia, or from the Susquehanna valley of Pennsylvania, and was very prone to scaling. The average life expectancy of this slate around here was about 60-80 years, versus 150+ years for almost all other types of slate. These roofs started giving out in droves around 15 years ago and the few that are still around look terrible. I say this all because 115 years would be an exceptionally long life for PA soft slate, or "black slate" as it's sometimes called, in this area. I wouldn't think NY's conditions would be much better for a longer survival.

[DavidP]

Vermont gray slate and copper flashing will outlive all of us. They did a good job.

I agree on both counts. I wish more people in our society would take the "long view" when it comes to houses and other things. I'm glad I could do my bit.

The more I look at the pictures of your old slate roof, the more I'm wondering if the slate roof you replaced could have been the second roof your house had.

Interesting question. After being told by a man with extensive experience working on old houses that my roof was Pennsylvania slate, I did some research. What I found was that the "black" (really gray) slate from PA varied -- some was quite soft, as you say, while some was a more medium-hardness. The latter was popular because it was longer-lasting than the soft stuff but not as expensive as the really durable stone. I think that's what I had.

The family that I bought the house from purchased it in the 1950s, when it almost certainly had the original roof. They didn't mention anything about replacing the roof and I don't think they did (on the house; they did on the garage, as they told me). So I think my roof was the better-quality PA slate.

For anyone reading this who wants to learn more about various types of slate, here's an excellent link; scroll down about halfway for discussion of Pennsylvania slate and photos.

[1918ColonialRevival]

Interesting question. After being told by a man with extensive experience working on old houses that my roof was Pennsylvania slate, I did some research. What I found was that the "black" (really gray) slate from PA varied -- some was quite soft, as you say, while some was a more medium-hardness. The latter was popular because it was longer-lasting than the soft stuff but not as expensive as the really durable stone. I think that's what I had.

The family that I bought the house from purchased it in the 1950s, when it almost certainly had the original roof. They didn't mention anything about replacing the roof and I don't think they did (on the house; they did on the garage, as they told me). So I think my roof was the better-quality PA slate.

For anyone reading this who wants to learn more about various types of slate, here's an excellent link; scroll down about halfway for discussion of Pennsylvania slate and photos.

From the picture, I believe your old roof was Bangor slate, which was at its peak use in this area in the 1930s and has about a 75 year life expectancy, give or take. Bangor operated several different quarries, resulting in the different shades of slate. If your roof was Bangor slate, it almost certainly wasn't the original. Aside from the life expectancy, the company that quarried it was not established until 1907.

The most popular type of "medium" PA slate was Chapman, which gained popularity in the late 1800s and flourished from roughly 1890-1920, though it continued to be quarried up until about the start of WWII. Chapman has a distinctive diagonal "grained" appearance to it. A lot of Chapman roofs remain in good condition today and all in all it seems to age pretty well given it is a little "softer" than Peach Bottom or most of the Vermont slates. The slate site you provided says Chapman's life expectancy is about 100 years, but from the ones I've seen around here, it wouldn't surprise me if many of them end up seeing 125 or even 150 or more.

If the roof had been replaced circa 1930, the previous owners who bought the house in the 1950s may not have had any idea, as 20+ years would have passed between the new slate roof and the house coming into their possession.

[DavidP]

If the roof had been replaced circa 1930, the previous owners who bought the house in the 1950s may not have had any idea, as 20+ years would have passed between the new slate roof and the house coming into their possession.

I was told the house was built in 1904, although there is some evidence it might have been earlier. Even if it had been constructed in 1890, soft slate lasts 60 years or more, which would have brought it into the ownership of the second family from whom I bought it.