Sealing Exterior Chimney

[PabloK]

Prior to having my wood insert installed last February, I had a guy clean the chimney. The exposed portion on the roof had a lot of moss build up. He recommended we clean and seal the bricks and a new crown be installed. I recently cleaned all the moss off with a wire and stiff bristled brush. Being that the crown looks ok to me, I'm wondering if the brick sealing is another unnecessary task that he was just trying to sell some services. We don't have any water leak issues that I am aware of.

1. Should I seal the bricks?

2. Does the crown need to be replaced?

3. Should I do any repointing on the bricks?

I would likely do the seal and repointing myself and hire someone to do the crown in necessary.

 

[blades]

Cream city Brick? a little touch up work and then seal it - i have seen better and worse leaking like a sieve. A little concrete resurfacing on the top and a bit of pointing here and there. Then seal it - not Thompsons though. Soloxthane or similar. Just make sure what ever items you use that all are compatible with each other.

 

[bholler]

I really don't like to seal masonry unless it is really needed. If you have a good crown and the mortar is in good shape sealing is an unnecessary step that adds expense

 

[PabloK]

Cream city Brick? a little touch up work and then seal it - i have seen better and worse leaking like a sieve. A little concrete resurfacing on the top and a bit of pointing here and there. Then seal it - not Thompsons though. Soloxthane or similar. Just make sure what ever items you use that all are compatible with each other.

I don't think it's cream city brick. It might just be the photos looking lighter. I think someone called it Chicago brick.

 

[bholler]

Those brick are pretty typical sandmold brick. Tons of places make them

 

[blades]

only reason I was asking if Cream city type is that is fired on the out side but is pretty soft and somewhat porous internally. the last chimney I had to seal was about the late 80's ( late 50's build) . it was solid as a rock but water was weeping through the joints to the flue blocks which were acting like sponges until they could not hold any more and then it became Niagara falls. at that time a gallon of the sealer I used was apx $50. applied with a pump up garden sprayer, looked like water, did not affect the coloration of the brick. fast forward to 2011 different home that chimney I had to tear down and rebuild - you could just lift the bricks off the mortar beds and then the mortar off the next row.(1960 build)

 

[Nick Mystic]

My chimney had some similar issues as in your photos, but not as severe. I used some masonry caulk to fill any open seems between bricks and mortar and then on similar cracks on my solid crown I used some clear silicone caulk. I used some quality masonry sealer that I applied with a pump up one gallon garden sprayer. The sealer is really thin (seems thinner than water), so be sure to have a rag handy to soak up any sealer that runs down the bricks. I really soaked the bricks with multiple coats (while it remained wet) because I was having some leakage in the house from rain water soaking into the bricks and then running down the exposed interior bricks. After this treatment I never had another leakage problem, so it apparently worked well.