I am going to attempt to repoint my chimney and replace the crown. I'm fairly confident I can handle the tasks. Well, I'm confident on the repointing, a little less on the crown.
In anycase, my question is what should I do first, the repointing or the crown? My guess was repointing because if the bricks/joints are in rough shape and need to be reset then I would have to remove the crown anyway?! If anyone has any tips on the sequence it would be greatly appreciated. I'm no expert but I believe the bricks won't need to be reset. everything seemed stable. Just alot of cracked joints and even a few missing mortar on the corners.
Also, any tips on creating an equal slope when pouring the crown would be great. I know what I need to do with the form but not sure how I create the same slope on all sides other than eyeballing it as I go.
It appears that you have a handle on the repointing of your brick. I assume when you say the crown you are referring to the cap atop the chimney. I would imagine that the top is cracked and detoriating. You will need to remove the old. I have poured quite a few over the last few years but generally larger but the same procedure applies. Most flue's have a terra cotta liner. I usually build a form around the exterior (brick) out of 2X material. I tapcon the form in place dropping the top of the form 1" below the top of the brick. You can connect the form boards together to them self with deck screws in the corners. I then take an additional form and attach to the primary form raising it up 1-1/2 -2" above the primary form and attach with deck screws to the primary form.
For the concrete I mark on the terra cotta a point which is higher than the outside form to give adequate pitch to the outside so water will run off. I secure a few pieces of rebar inside that form area in both directions midways the thickness of my pour.
Fill your form with concrete and add to to gain the elevation you need. As you work the concrete with a trowel from the inside edge of the form board to the terra cotta you can create a a cap which virtually has no noticable angle lines from the corners to the liner.
An important detail is to make sure you have all the air pockets out from around your form board. Repeated tapping lightly on the form board will cause that trapped air to rise to the top of your concrete. Take your trowel before tapping and drag it along the inside edge of your form board pushing slightly to the center of your pour. That will move the aggregate back away from the form board so that when you take off your form 24-48 hours there will be no voids. If there is then use a griding or finishing mason stone to rub a slurry to fill the voids and take the sharp edge off of the concrete on the top of your pours outside edge. Then once this has had time to set up lightly brush removing the sand and grit with a soft bristle brush similar to a paint brush. Horsehair is best but others will work.
Hope this helps
Thanks, that is helpful. Does it matter what I do first? repointing or crown?
Here is a detail of what I was planning. 2x4 secured to a 1x6. Also a shoe molding secured to 1x6 for the drip edge. The 2x4 will sit tight around the top row of brick creating an 1-1/2" overhang. 2"Deep crown. It's a small chimney. I was also going to put cardboard or other material around the flue to leave room for an expansion joint. Once I remove the forms I will fill in the gap with high temp expansion caulking.
Looks Doable. I would not place the cardboard around the flue. Your rebar should take care of the expansion. Just another place (void) for failure and leaks. Still caulk even if poured tight.
Make sure if you put shoe mold that it is well below the top of your brick. Water will run back in between the concrete and brick and freeze bust.
I believe that I would tackle the repointing first. If you find that you have to replace some brick(loose or broken) your cap might have to be removed to build up from that damaged area.This message has been edited. Last edited by: redoverfarm,
The shoe mold would create a recess in the crown at the bottom so the water would drip before it reaches the chimney. or at least that was my understanding.
Attached is a side view detail of the crown/drip edge.This message has been edited. Last edited by: BasementDweller,
That will probably work but you will not have much space in that you will only have 1-1/2" from the brick to the edge of the cap(squared 90 deg) then up to your finished concrete top. As I stated before make sure that it is well below the top of the brick. You might consider something a little smaller in scale (1/4"). You could also cut the top of that form (2X) with a slight angle down to the front and eliminate that molding. Water will not run up hill. Oh that's not true mine does all the time in the winter (Ice Dams on gutters and eve's) Ha. Ha.
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