Any thought on how to screen off a stone chimney that has a slate cap on top with four slate posts in the corners. (sorry no pics until Saturday)

Steve,

First thought is to make a screen that would be slid down over top of everything. It should look good and can be anchored to the chimney at the bottom.

similar to this one

Try Hy-C Co. @ 314-241-1214. They've been in the cap business for ~70 years and are very helpful.
Had a similar one a coupla months ago, only it was brick, and so rotten it wouldn't hold a nail. The top slab was cracked into three separate pieces; I told the owner to have a mason rebuild the chimney, THEN I might be able to screen it.

Steve:
Pull out your copperfield catalog and purchase the correct high + 2"
of stainless mesh from them, it comes in roll stock.

Cut every piece of mesh 2" bigger than the opening both ways.
That is height + 2" and width + 2"

Measure every opening since they will vary!!

What you are going to do is cut a 1" x 1" corner
out of each piece and fold with a brake, so that
you form a cake pan. That gives you anchor points
on three sides and the top is left so you can set
the slate cap on it

I have attached on three sides only, bottom and both sides with
liquid nails, if the property owner needs to clean the flue at a
later date the slate cap can still be pulled off.

I know that this may be a problem this time of year so you may have to
go to tap-cons if the chimney will take the drill etc.

Best of luck!!

pick65

Just a quick question about the screen you guys are using. What size do you use to keep bats out. I know the ones that you are talking about and it will keep birds, squirrels, and coons out.

I have used the 1/2" which is a CA requirement or the 5/8", but if bats are the problem
I have backed it up with 1/2" x 1/2" galvanized wire, hog nose ringed to the stainless steel mesh,

Why back it up with addition mesh, so I do not get a call back!!

pick65

Now I've got a question. In 25 years, I believe that I have had a total of two bats ( I'm sure they were on drugs ) inside of a chimney. Now I realize that if there are cracks in those stones, bats will love crawling in there from the outside but that has nothing to do with them going down the flue.

Do you guys commonly find bats in chimneys and if so, are the species other than our small and large browns?

Bats in a chimney is not a common thing, but it does happen.

Like the house next door that replaced the entire roof, because it was cheaper
than bat proofing the house. The following bat season the bats that
were evicted ended up in the house next door. Brick chimney with slate
slab on top. I used the method as described above and solved the problem.
Till we had a wind storm that actually lifted the slab off of the chimney.

Little brown bats were the problem.

pick65

Thanks a lot for the input guys. I appreciate it!

Be aware of fire codes when building a chimney screen . A poorly-designed screen can be big trouble, even lethal. You don't need that kind of liability. Check with your fire marshal, or at least Hy-C or Copperfield.

Or Ed Crankshaft.