A slate roof challenge

Hey, I took some more pictures the other day and put them into the same folder. I was going to update the file and post it here, but the computer did it for me already. The only thing I didn't do was able them, but the pictures show some of the masonry wear and also the hot tub on the roof of the building. It looks over the city from the highest point in the city. Quite a view! A lot of work too. Neat!

That looks like a real challenge, OS. I think the turret would look better without those clunky add-ons.

The pictures bring to mind a question about permanent roofing. After 100 years how much of the original roof needs to still be in place to be considered a permanent roof? What percentage of this roof is currently still in place and what will that percentage be after your work? Will you be trying to make all the slates on every side match?

Wywoody, the definition of the word "permanent" keeps coming up. These days, definitions are pretty subjective. I got my interpretation of permanent roofs from Joe Jenkins in the Slate Roof Bible. He uses the words permanent and temporary to separate two different types of roofing and roofers.

I believe he refers to permanent roofs as those lasting over a century. We have several well documented, proven examples of such roofing.... Certain natural slates, several types of clay tile, some hardwoods and copper, lead, brass, gold, etc...

Slates can be very different from one another. This is based on the geology of the slate. Slate is a metamorphic rock and the base elements determine its strength, water absorption and overall lifespan. Slates with a higher quartz content tend to last the longest. Some slates such as welch, peach bottom and buckingham are still unclear as to how long they last properly installed on a roof because a limit has not yet been found.

Clay is similar in that the clay itself has different properties. Then from there, how it was baked, at what temp, duration, cooling, curing, duration, etc determine the lifespan of the installed product. Clay tile is so far the longest lasting roof known to man. There are roofs over 400yrs old still functioning and in some cases still looking new!

With both of these, roof structure design also plays a huge roll. For instance, an "up and over" gable roof or a 4 sided hip roof with no valleys, flashings or penetrations will always last longest. Flashings, valleys and penetrations are always the weak link in a permanent roof. Most often these can be repaired by replacing the flashings and relaying the slates or tiles.

Sometimes the structures dont last as long as the roofing. I have witnessed this with ludowici "book" tiles. These tiles are usually found on gov buildings, churches and fine homes. Ive seen 200yr old structures fail, the tiles removed, the structure rebuilt then the tiles reinstalled.

The best quality slate i ever touched was a 100yr old peach bottom i installed on a 100yr old home. This slate was quarried, delivered, installed, lasted over 100yrs, taken down, transported and was still the strongest slate ive ever seen. On a compatible structure, i believe this slate would last several centuries. Actually im certain.

However the components to these roofs are even more critical for maximum lifespan. Things like plywood decking, monolithic underlayments, incompatible details and weak structures such as metal studs or dimensional pressure treated lumber make permanent roofing impossible. In these cases its important to leave permanent materials be and install compatible materials as it is important not to be wasteful with natural materials.

Those Add Ons" are original, but they were reroofed a while back and that is the result When and if we do this, I will take everything off and redo all of the flashings, the gutters, fix the masonry and redo the slate roofing. There will also be painting, wood repairs to trim and window sills etc. and everything else from the ground up on the outside of the house. Yes it will be a challenge. It is amazing how well the building is holding up to the abuse it has endured. A real fine example of quality w=hen it was built. The slates they used were shot 40 years ago though. Not good, but very steep and hard to get to so they haven't had people trying to walk on them. Again, a challenge.

What Branden said about the "Lifetime roofs"