DIY Crown

[Smoked]

For chimneys like that i typically take off the top 2 courses that corbel back in and pour the crown on top of that other wise it looks silly. If the customer does not want that I will do a wash crown. I will not pour an over hanging slab on a corbeled chimney like yours as is though.

Nice, well that would solve the short liner problem. If the top courses seem really solid, I may opt to just replace what is there. If it seems like it is compromised, then Ill pop the top off and do it right. Dang, this seemed easier yesterday! Have some time to contemplate...

Thanks for all the advice!

 

[webby3650]

If you just pour a mortar crown up there over the existing bricks without an overhang this will be the result in about 1 season.

That crack between the brick and the crown is main culprit in this whole mess you are in already. Don't do like most Mason's and simply restore it to its original condition that was doomed to fail from day1! Take a few rows of bricks down and cast a crown with cement.
The chimney pictured is only about 3 years old.

 

[Smoked]

No bond break either. Busted clay...ouch.

 

[bholler]

If you just pour a mortar crown up there over the existing bricks without an overhang this will be the result in about 1 season.

Not if it is done right. The reason you get that separation is the lack of bond break at the liners. I totally agree overhanging is way better but a wash crown can hold up fine for quite a while.

 

[bholler]

With a crown like that you dont want a break between the crown and chimney just around the liners

 

[Dover29]

Instead of pouring chimney crown, I installed a stainless steel chimney chase cover. You can get one custom made at Rockford Chimney Supply. (broken link removed to https://www.rockfordchimneysupply.com/chase-covers.php) This way I will not have to worry about the crown cracking.

 

[Woody Stover]

It is best to build a form so your crown will over hang the chimney by about 1.5" or so. You also want a bond break between the top of the chimney and the crown as well as around the clay liners.

Yeah someone posted a good youtube vid of pouring a crown a while ago. Just be careful there is some really bad info there too.

My crown is in pretty rough shape, with a few of cracks. I've got a few questions:

• How do you remove the old crown? I don't think I want to beat on the top of it, might separate some of the bricks from their mortar joints. Just beat from underneath the crown with a hammer and chisel, and remove the chunks of crown?
• Do you mix the mortar on the roof? I guess I could build a platform pretty close to the chimney, across the roof ridge. Or do you recommend a scaffold?
• I haven't done any serious concrete work; How do you make the form? You can see a piece of decorative granite in my pic...that looks like it could get in the way.
  
• How do you achieve the bond break between the chimney bricks and the clay liners? Some kind of spray?

• I've got a 5G cap on my data, I'd like to avoid searching through a bunch of vids on youtube. Have you got a link to that good vid you mentioned?

Thanks for your great advice so far! A lot of folks will benefit, I'm sure.

 

[bholler]

How do you remove the old crown? I don't think I want to beat on the top of it, might separate some of the bricks from their

I either cut it up with a demo saw or just break it up with a demo hammer. And yes there is a good chance you will have to relay some brick.

Do you mix the mortar on the roof? I guess I could build a platform pretty close to the chimney, across the roof ridge. Or do you recommend a scaffold?

Well you are not mixing mortar you are mixing concrete and no i do not mix on the roof. But you could if you had a platform up there

I haven't done any serious concrete work; How do you make the form? You can see a piece of decorative granite in my pic...that looks like it could get in the way.

Well we use metal forms usually but if we are doing wood forms i take 2x4s and screw them to the sides of the chimney with the top edge flush with the top of the chimney then take 2x8s and screw them to that giving you a 4" deep form with a 1.5" overhang. Then i lay plastic in the bottom of the form to act as a bond break between the chimney and the crown.

How do you achieve the bond break between the chimney bricks and the clay liners? Some kind of spray?

I wrap a layer of the sill plate sealer foam strip around the liner and tape it in place. Then when I come back to pull the forms i pull out that foam and caulk the top edge. You also should caulk under the crown where it meets the chimney.

Also a crown should have a groove on the bottom edge to act as a drip edge one of our sets of forms has this in it but the other ones we just cut a groove with a grinder after we pull the forms

 

[Smoked]

So basically, the whole crown is floating to a degree. Ill look at mine in a few weeks and figure out a plan. Thanks all!

 

[mellow]

Is it just me or is redoing the crown look harder than running the liner and installing the dang insert, I have this job to do on mine as well, been putting it off for the last few years filling the cracks with silicone.

 

[Woody Stover]

no i do not mix on the roof. But you could if you had a platform up there

Yeah, hauling bags of cement up and mixing on the roof sounds like a pain, and a mess. I tore off and re-roofed last fall. I hauled some 75# bundles up, but then started splitting the bundles. I'm getting too old to be doing that. So do you have a guy on the ground mixing, then send it up in 5-gal. buckets with a rope, or what? Have you done re-pointing or do you leave that to a mason? I've been using SikaFlex Mortar Fix on the little bit I've done so far, but it's pricey. I might go with your acrylic-and-fiber mix on the rest of it...

Is it just me or is redoing the crown look harder than running the liner and installing the dang insert, I have this job to do on mine as well, been putting it off for the last few years filling the cracks with silicone.

Yeah, it sounds like some work, and we don't have the procedure down pat like bholler does. But I figure with the acrylic and fiber, it should last a long, long time. They didn't have that stuff back in the day, I don't think.
I have a lot of re-pointing to do as well, and there's a bunch of granite chunks interspersed. Looks nice but I wish it was just straight brick. Hopefully we don't have a 'quake right after I get done.

 

[bholler]

So do you have a guy on the ground mixing, then send it up in 5-gal. buckets with a rope, or what?

Yeah we have a small mixer and then usually carry buckets up to the roof sometimes with a rope

Have you done re-pointing or do you leave that to a mason?

yes we do allot of repointing that mix depends on the brick. Softer brick needs softer mortar. We typically use 3 parts sand to one part type n with additive but softer brick needs a softer mortar.

I might go with your acrylic-and-fiber mix on the rest of it...

that is only for crowns

 

[bholler]

Is it just me or is redoing the crown look harder than running the liner and installing the dang insert, I have this job to do on mine as well, been putting it off for the last few years filling the cracks with silicone.

yes it usually is harder