We live remotely and finding contractors can be extremely expensive and unpredictable. After reaearching the product, we felt we could give this a try. Product arrived quickly, DTEPs was wonderful to work with. Our chimney is made of rock, has two flus and is 50+ years old. There is nothing squared or organized about it. After some trial and error, found the right ways to apply. We are very pleased with the result, have ordered a couple more Chimney RX products thru DTEPs to finish the repairs. Clean up was easy with soap and warm water. With the left over product, have repaired some cracks on our front porch concrete. We are very pleased with this product!! And we are way a head of what hiring a contractor would have cost!