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Any trick to getting chimney counterflashing to “hug” tight to the chimney and over the step flashing? Seems regardless of whether I step it up or use a continuous piece it always wants to stick out at the bottom and pull slightly out of the joint. Also, whats the preference, mortar or sealant in the joint.
Dave
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Mortar is the correct material. Strike out the joints about 3/8 of an inch and tuck the top lip of the counterflashing into the joint and mortar it in. There should never ,never, never, be tar on masonry.In fact, there is no place on a shingled roof where tar should be visible.If the flashing is done correctly, there is no need for tar. And don't use tar on slate.Also,step flash the counterflashing. One single piece defeats the purpose.If water gets into the top of a single piece of counterflashing,it 's in.
*Well Creature ,you may not want to listen to my advice on this topic.The last time I discussed my method for counterflashing chimneys on this forum I was told I was " ARCHAIC" Stick a masonry blade in a circular saw and cut a nice neat saw kerf in the mortar joint where you want the flashing to insert. Usually the cut is about 1/2" to 3/4" deep.With your brake bend the top of your flashing 90* to insert into the kerf. This bend will have to be a bit deeper than the kerf to account for the brick layer having struck the joint and the mortar not being flush with the brickwork.Use a heavy weight metal,not that tissue paper thin mill finish "handy flashing coil" commonly sold at lumberyards etc. Get some good stock from a roofing supplier .Actually you want to slightly OVERBEND the metal past 90*. That way, when you insert the bend into the kerf it will help wedge itself in place , tight top and bottom. I then nail into the kerf pinching the metal between the nail and the bottom of the kerf. (bottom of the kerf is usually the top of a brick course).If the kerf you cut is not straight ,when you force the metal into the kerf it will pucker at the bottom as the top tries to conform to the crooked line.smaller pieces are easier to keep flat. I try to keep each piece shorter than 9" from roof to top of inset bend.Blow all the dust out of the Kerfs. I seal the joints usually with GEOCELL.All horizontall and verticall joints. If the mortar is very soft I use wedge shaped Cut masonry nails. If it is very hard I use pointed ,fluted,masonry nails.Sometimes I will even predrill a hole for each nail.I have done hundreds of these as repairs on old roofs,plus our new roofs.I take my time. On an old roof it usually takes me about 1/2 day counting removing old flashing and surrounding shingles and putting every thing back together.Flashing chimneys this way is a tremendous sales tool. customers see the care and effort you put into this detail and they refer you to others for larger projects.. I have got countless roofs because the customer liked the way I flashed his neighbors chimney.Price.... single flue chimney about $400I did one about 2 weeks ago. House was only 3 years old. Builder had not installed ANY chimney flashing. Not even any caulk. I could stick my hand into the attic between the chimney and the edge of the roof.the mortar was so soft I was able to cut the kerf with my roofing hatchet by rubbing the blade back and forth along the joint. $200-300,000 house in an allotment recently part of a " Parade of Homes" tour. Perhaps it should have been a "Parody of Homes" tour.Good Luck,Stephen. If you want anymore details let me know
*Stephen:Sounds like we have pretty much the same method, so I guess Im archaic as well!! Are you using one continuous piece on the sides of the chimney, with one long cut, or cutting each induvidual joint and stepping up the chimney? It must be my 90 bend that is making the metal stick out a bit. Thanks for the tip.I always try and use copper for my chimeny flashing if the budget allows, never the "handy coil." I use small wedges of bent copper to secure the flashing in the joint. Have been sealing wih PL concrete and masonry sealant. Getting a good view of the fall trees....Dave
*Dave, I step the counter flashing up the chimney. That way I can keep all the peices small and laying flat.I make masonry cuts at one time and then take written notes and sketches while I am still on the roof. Back on the ground I bend all the metal peices in one tripThe copper wedges are a good idea,prob. prevent corrossion of the fastners. I have not noticed any nails corroding to the point of failure on any old tear-offs,but your method sounds like a good way( I have done it in a pinch when I have run out of nails!)Copper is virtually never used here. Also ,on the back pan ,I like to project the ends about 3 or 4 inches out past the corner of the chimney and bend down the "ears" at a 45* angle. That way any water running around from behind the chimney drains about 4" away from the sides of the chimney and never even touches the step flashing. I like the geocel sealant cause it works well and I can match the color of most metal workIf you have a problem with a vertical joint wanting to pucker,try drilling a pilot hole through the metal and into the mortar about 1/2 way down the joint. Then you can drive a copper nail into the hole and gently pull the flashing snugg. If you are worried about that puncture leaking even on a vertical surface you could seal it with your sealant. If you keep all your peices pretty small,none of this paragragh will be needed.Good Luck, Stephen. Ps,are you the guy that mentioned earlier in the year you had to shingle a turret? If so How did it work out?
*Here is one more for archaic flashings. I'll consider new developments in chimney flashings next season maybe. After helping my friend the HVAC guy redo his roof, I've tried his tin banging techniques on my own. Soldered upper pan flashings that are positively waterproof. These resemble the head flashings supplied by skylight manufactors. I've used both vulkem caulk and mortar, prefer mortar but both are probably acceptable. Counter flashings are best bent on a break in my opinion.Joe
*I didn't know there was another way to flash a chimney than the one described by Stephen. I extend and fold the top flashing on skylights the same way he describes too. - sign me "archaic"