chimney cap mortar

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Old 04-19-13, 04:24 PM
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chimney cap mortar

Hello all. I'm new to this forum. I hope someone can offer advice. I've just replaced the flu pipe in my chimney. The top of the chimney also had to be repaired. It had an old metal piece welded to a round pipe that the flu went through. This metal piece had been cemented over and was rusted through. I've repaired this using 2 layers of cement sheeting with aluminium flashing sandwiched between. Now I have used mortar to cover this and adhere it to the chimney top. I have it sloped down a little so water will not stand on the mortar cap. I'd like to seal this mortar to prevent moisture from penetrating. I'm in Australia so a lot of the products available in the US may not be available here. I'd like some suggestions please. Also, How long will I need to wait to seal/paint this repair? We are just about to enter the winter season down here. Thanks for any advise. Amanda
 
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Old 04-19-13, 04:32 PM
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Welcome to the forums! Cement sheeting? Is that concrete backer underlayment like for tile floors? Would it be possible for you to safely take pictures from the top of this repair so we can see what you have? Sort of difficult visualizing a repair such as this, and advise regarding it. Thanks.
http://www.doityourself.com/forum/el...your-post.html
 
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Old 04-20-13, 02:56 PM
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G'day Chandler. Yes, cement sheeting is just like "cement backer board" used for tile underlayment. It's about 1/8" thick. Not sure if I can pull myself back up onto the (very steep) roof at the moment. It's supposed to rain for the next day or so. Hope it does as we really need it. I may try and do a drawing and scan it and send it in. How do I add an attachment to a reply? Amanda
 
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Old 04-20-13, 03:05 PM
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Hey, Amanda: Once you save the drawing you can upload it just like a photo using the instructions in my first post. Be sure to put some dimensions on the drawing so we will know how big things are. Thanks.

Oh, be very careful up there. Remember it isn't the fall, but the sudden stop that makes for a frowny day.
 
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Old 04-20-13, 04:26 PM
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drawing of project

Name:  chimney cap 2 001.jpg
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Size:  20.7 KBNot sure if it worked. I followed the instructions. If it did work and you can see the drawing, please accept my apologies for not being an artist, but I think you can see the idea. Amanda
 
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Old 04-22-13, 04:32 PM
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chimney cap

Hello all. Just wondering if my last post with the drawing was received. I've not had any replies. Cheers, Amanda
 
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Old 04-22-13, 07:20 PM
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Ooh, Amanda, sorry, I saw it, but got switched to something else. I know we are not talking a large chimney since your dimensions are so small. What is supporting your cbu at the flue? Or does the flue take up all the space. I am just not a fan of cbu in an external, rain beaten situation like this. If anything, I would have coated the cbu with RedGard or something to make it waterproof, then apply the cement. BUT, it seems you have taken all the precautions and have tapered your cap and flashed it, so only time will tell. Keep us posted

Your drawings were nothing less than super, BTW.
 
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Old 04-23-13, 01:49 AM
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chimney cap sealer

Thanks Chandler. The flu is only 6 inches so there's quite a bit of space between it and the brick of the chimney. As I mentioned, I did put aluminium flashing in between the 2 pieces of cement board. I was told mortar wouldn't adhere to the flashing if I put it on top. I was hoping that I could seal the mortar that I put on top with some kind of sealer to make it waterproof. How long would that mortar have to "cure" before I sealed it with something. I don't think what's available over there would be the same as we have here, but I was just wondering how long I'd need to let it sit before sealing it. We have actually had over an inch of rain since I did the repair. The water should have just run off the mortar, though as I made sure it had a slope away from the centre. I just don't want to go up there and coat it with a sealer if it's not cured or damp from rain. The previous cap just had a small piece of thin steel (not galvanized) and ordinary cement over it. The steel bit had rusted through. Thanks for the comment on my drawings, Amanda
 
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Old 04-23-13, 04:15 AM
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Once you get two or three days of non-rain, you would be able to seal it. It has been there long enough to chemically cure out. If it has absorbed any water, give it those days to dry up, then apply your sealer. Not sure what you have available down under for sealing, but I am certain local outlets would have it available.
 
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Old 04-23-13, 03:26 PM
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Thanks so much for your help and advise. I really appreciate it. I will look at the local hardware shop for some sealant and plan to finish the project as soon as we get a few days of dry weather. Thanks again for everything. I will return if I have any more questions concerning any of the projects I get involved in with this 100+ year old house. I'm sure there'll be many more and as a 66 year old living alone, with very little in the way of financial rescources, I have to do everything myself. Cheers, Amanda
 
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