Chalkboard/slate. Would it last outside in the extremes of Minnesota weather?

I’m planning my build of a Little Free Library (see thread about those here) and have a design in my head how I want the one I’m building to look. The architectural feature would include slate chalkboards on the sides so people could write or draw on the library.

The look and feel of slate would be great, but someone mentioned that it can be brittle. That’d be a concern as I want this to last. But I also think back to schools growing up and I don’t remember seeing chips in those boards and they make roofs with slate shingles, so they should be able to weather extremes of Minnesota weather (from -40F to 105F or so). Right?

Bonus question, if slate would work, where could I get some sheets that are smooth and not already mounted in a chalkboard?

Lots of slate roofs around here in PA. My family home, built in 1865 has one. It rarely needs a new tile slate or two. In the back yard is a slate blackboard (the scoreboard for a shuffleboard court) that my grandfather made in 1965 and it is still used every summer; there is a wooden frame around the blackboard. Not 40 below around here, but 20 below is not unheard of.

Google “chalkboard paint” for some alternatives to the real thing.

I did, but all of those call it an indoor paint. So I don’t think they’d last long in the elements.

How is chalkboard paint going to do in a Minnesota winter (or even in the summer)? I doubt it will do well, so actual slate might be best for the OP.


I have a sheet of chalkboard slate in my garage that you could use. I am located about ten miles from downtown St. Paul. It’s about 1/4 to 3/8 in thick, and the thickness is not consistent throughout the sheet. I think the smallest piece is about 24 x 60 inches.

It can be cut with a “wet saw” used for tile. It’s a little awkward doing this with a large piece, but I’ve done it.

PM me if you’re interested.

I get that roof shingles have to withstand extreme weather changes … but what significance does a school’s chalkboard hold? It’s not like they’re outside exposed to the elements. :dubious:

I believe the main issue with chips or cracking is if water gets into minute existing cracks in the stone and then freezes (expands).

Thanks, Malden! PM sent.

Sorry, my thoughts probably ran over each other. I was trying to say that the chalkboards/slate never seemed brittle in class.

A client of mine had a beautiful old slate patio table made of a single 1.5 inch thick piece of slate 7 feet in diameter set into a wrought iron frame. When she died her daughter wanted to load it up and take it home so me and 5 guys got a good grip on it and picked it up and watched it shatter into a thousand little pieces. We figured it had been horizontal so many years soaking up rain and freezing and also expanding hot summer days that it was basically rotten. Don’t think a big slate set vertically in the weather would suffer so much.

Many of the early one-room schoolhouses in rural Minnesota had real slate blackboards. And those buildings often were heated by wood stoves, but only during the time school was in session. The teacher had to arrive early, and stoke up the stove to heat up the building. And students sometimes kept their coats on for the first hour of so of classes, until the building warmed up.

The schoolhouse was completely unheated overnight, and on weekends. And given the minimal amount of insulation in many of those old buildings, it soon cooled off to just as cold as it was outside. So the blackboards probably froze every night during the winter. Yet the slate blackboards in most of them was still in good shape when the schools were consolidated, and the old schoolhouses converted to other uses, or demolished. Many of those blackboards were recycled then, and used for many more years.

One of our horse barns had a chunk of blackboard near the feed room, that was rescued from the old country schoolhouse. It was used there for another 30-40 years. And come to think of it, tht barn was never heated either, all tht time. Slate blackboards weem to do just fine in freezing Minnesota weather.

A friend in Duluth has some (chalkboard paint) on an outside playset he made for his kids. It’s protected from actual rain/snow by an overhang, but is otherwise open to the elements. It’s lasted a couple of years, anyway.