The crown is junk and bricks are spalling

[ikessky]

Well, I have officially decided it's time to do something about the portion of my chimney that extends above the roof line. Portions of my temporary crown fix have already fallen off and I know some of the bricks are spalling. I'm looking into my options, but here is what I'm really contemplating doing.

Completely remove the junky crown that is currently on and replace it with a precast piece.
Coat/cover the exterior of the bricks with cement/mortar to seal any cracks and prevent further crumbling.
Install stone veneer over the outside of the bricks that I coated.
Seal up any gaps between the veneer and flashing and crown with silicone.

What do you guys think? I think I've also convinced myself to dump some insulation down around the liner. Not sure how much I'll actually get down, as it's a tight fit, but it shouldn't cost much and whatever I fit in won't hurt anything.

 

[begreen]

If the design looks good with the house, maybe have a mason come out and rebuild the crown?

 

[Todd]

I have a similar problem but my crown wasn't too bad so I just recoated with crown repair. The brick is spalling and I tried a temp patch of mortar in spots and it didn't work, it's falling out just like the brick face. I was told best thing to do is replace the bricks I think it's called point setting or tuck point? And then coat the whole chimney with a sealer.

 

[dvellone]

Getting that leaking crown replaced will go a long way toward preserving what's below.

Perlite is a fine-grade pourable insulation for masonry and chimney applications. Be sure to buy the moisture-resistant grade.

 

[Shari]

Depending how 'bad' is 'bad' you might be able to chisel out the offending brick and then tuck point new brick back in place. I believe you can purchase an entire new crown and just break out the old one and replace it. Warning! A crown is very heavy to get up there! I've never done this but my Dad was a mason contractor - I was his 'ground crew'. Given the weight of a new crown and trying to chisel out brick it just might be time to call a pro.

Shari

 

[ikessky]

I'm not really concerned about getting the precast crown up to the roof. If I can't carry it, I've got a couple different options.

I think that if I were going to coat it with mortar/cement, I would probably have to sand or etch the bricks so that it would have some tooth to hold on to. Maybe wrap it in wire mesh or something like that.

Then again, maybe just cutting back the mortar joints and tuck pointing it all would just make it last that much longer with less cost. Then I could put a sealer on the whole thing and not touch it again for a few years. I would think that adding the perlite would also help as less heat would be transferred to the brick.

 

[Astrolopitec]

Don't use regular mortar ($4-6 a bag) for this type of work. There are point work mixtures with amazing sticking properties around $18 a bag.
I've also seen masonery primers but I have no experience with those.

 

[ikessky]

Thanks for the advice on the mortar. I'll definitely look for some of that once I start.

Looks like I'm just going to opt for a new crown and then I'll tuck point the chimney and put a good coat of sealant on it all. Found a product by Defy that looks like it is just what I need. Allows moisture out but doesn't let anything back in. I think this work and adding the perlite will help out greatly.

 

[dvellone]

Then again, maybe just cutting back the mortar joints and tuck pointing it all would just make it last that much longer with less cost. Then I could put a sealer on the whole thing and not touch it again for a few years. I would think that adding the perlite would also help as less heat would be transferred to the brick.

One thing to keep in mind is that once spalling occurs the brick loses it's protective face. The outer surface of a brick by nature of the firing process is harder, and provides a protective surface giving a brick it's ability to withstand weathering. Without that outer surface the brick absorbs water at a much higher rate and continues to deteriorate faster.

 

[ikessky]

My repairs really only have to last less than 5 years. At that point, I'm going to be reroofing my house and rebuilding at least the top half of the chimney anyway.

 

[dvellone]

My repairs really only have to last less than 5 years. At that point, I'm going to be reroofing my house and rebuilding at least the top half of the chimney anyway.

In that event, and if you can heft the precast crown up there, I'd put the crown on, and after removing the loose material and cleaning up the brick parge the surface of the chimney with a surface bonding cement. You'll easily get your 5 years and it'll be well protected and you'll save your money for the rebuild. Set the crown on a bed of masonry compatible urethane caulk so you can reuse it for the rebuild.