Chimney cracks pictures added

[dvellone]

Okay, just so i know!!


When he removes the cracked chimney cap and flue, places the new flue in place puts on the new chimney cap he should fill in the void with a perlite and vermiculite mixed with the mortar.

No, absolutely not.

The void between the flue and any outer masonry unit, including the cap should never be filled with mortar regardless of it's perlite or vermiculite content.

I think that maybe your confusion comes from the advice to fill the void between the tile and the outer masonry structure with a mineral insulation such as perlite or vermiculite. This mineral insulation is added to the void alone - without mortar- to insulate the flue tile.

At the top of your chimney where the last tile will exit the cap, that joint which separates the flue tile from the cap and is as deep as the cap is thick at that point should be sealed with an elastic sealant to prevent water entry and also to allow for the expansion and contraction of the flue tile. No mortar here just a quality urethane caulk suited to this application. I also mentioned in my last post to you to first back the joint with a closed cell foam strip.

Your flue tile along it's entire length should have a space all around it separating it from the masonry structure it sits within. That space becomes exposed to the weather where the tile exits the cap so this is weatherproofed and protected against the damage of expansion by using the flexible sealant.

 

[branchburner]

At the top of your chimney where the last tile will exit the cap, that joint which separates the flue tile from the cap and is as deep as the cap is thick at that point should be sealed with an elastic sealant to prevent water entry and also to allow for the expansion and contraction of the flue tile. No mortar here just a quality urethane caulk suited to this application. I also mentioned in my last post to you to first back the joint with a closed cell foam strip.

Your flue tile along it's entire length should have a space all around it separating it from the masonry structure it sits within. That space becomes exposed to the weather where the tile exits the cap so this is weatherproofed and protected against the damage of expansion by using the flexible sealant.

This is very informative. All the chimney crowns I've seen (which isn't many) appear simply to be mortar sloped down from the protruding flue tile to the edge of the masonry. It sounds as if that is pretty old-school, and doesn't take any expansion into account, which could explain some of my experiences with water leaking in and around chimneys (I always blamed the flashing).

I did basically the same thing with my ss liner, simply sloped a couple inches of mortar down to the old existing mortar crown at the 12 x 12 clay tile. Then I put on the flat top flashing - guess I should have stuck with that. Good to learn about this stuff - I can keep an eye on it and bust it out easy enough for a re-do if needed.

 

[cyclone]

I will be heading to the store today, what quality urethane caulk do you recommend (flexible sealant). Please can I have the brand name and how much do you think is needed???



Thank You again

 

[branchburner]

I will be heading to the store today, what quality urethane caulk do you recommend (flexible sealant). Please can I have the brand name and how much do you think is needed???



Thank You again

How are you making out on this?

I'm a bit curious about the different functions of the various products. The liquid latex fortifier is for mixing with mortar to make a cap/crown, but does it then need to be sealed with a water repellant or anything else? Does it need the foam/caulk at the joint, or is that just for the prefab cap?

And would a cement-stable sealant be any urethane caulk at all, or only a specific type? I see "quality" and "suited to this application" - I don't like throwing those terms at the Lowe's and Home Depot guys!