With the last few storms we've had I've noticed some water in the basement at the base of the masonry chimney (terracotta lined) for my oil burner. The house was built in the 1920's and the chimney has never been touched other than some minor maintenance at top. I got up on the roof this afternoon and thought I might find the parging cracked but surprisingly it wasn't. Just a few tiny gaps between it and the terracotta. The top terracotta sleeve has a few cracks but nothing too severe. The flashing is all in good shape as well. The chimney has never had a cap on it and I've never noticed water in the basement until now. Should I throw some exterior silicone on those gaps and put a cap on it?
They make a product specifically for coating an old chimney like that...can't remember right at the moment what its called...let me mull it over for a bit...or maybe someone else will recall...I think it is a brush on product? Edit: I think its called Crownsaver And yes, I'd do a cap too...
Always install a cap. Without a cap it's a giant rain gauge that drains into your house. The moisture absorbed into the chimney stone, clay, mortar will evaporate when hot flue gases are exhausted. Too much moisture and a hot fire can cause spalling and cracking. Moisture and creosote make acids. I just sealed some small cracks on my chimney crown with cement crack sealant caulk. Looking to use a brush-able crown repair this weekend.
A good chimney cap is a must and super easy to do. I had trouble with the top cap cracking on mine and had good results sealing between the cap and liner with a butyl caulk for masonry. Eventually the cap, done on site was pretty bad and I broke down and put on a precast cap with a cast in drip edge and caulked around the liner - that was the ticket!!!
Yes, get a cap on that chimney, and use some hi-temp furnace caulk around that clay pipe. Wouldn't hurt to clean and seal the cement up there with a siloxane sealant either.
Thanks for the advice guys. I threw a cap on it this evening and i just have to wait until I can find the correct caulk and sealer in stock somewhere. Don't want to have to mess with it twice. We're supposed to get some pretty good rain tomorrow so I'll see how much just the cap helps.
That probably would have been a better idea than the Butyl caulk I used. I will keep that in mind next time. Thanks.
Chimney RX is the best product I have ever found for crown repair or seal. They make a brushable or trowelable. I bought mine from Northline Express but I believe Amazon and EBay has it too. As far as silicone, if you are using that you do not really need to be concerned with high temp at the top of the chimney. Any silicone will handle the amount of heat you will have up that far away from the appliance.
