I’ve bought a house in Vermont with a steel roof. There is a cement-block chimney near the center of the roof, and a rain leak has developed alongside the chimney. I haven’t been on the roof yet, but looking up from the attic crawl space, I could see daylight through a gap (perhaps 1/8″ wide) along one side of the chimney. There are long gobs of dried clear caulk hanging from the edges of the crack, so it’s apparently an old problem that someone tried to cure by squeezing a tube or two of silicone into a hole.
I’ll be up there this weekend, and weather permitting, will get onto the roof to have a look at the flashing situation. In general, the house was very well-maintained, and the remainder of the roof installation seems fine. I’d like to deal with the problem on this visit, but I’m not familiar with metal roofing. I’d appreciate any suggestions about how to handle this. I’m not even sure what additional tools to bring up with me – grinder to try to cut a groove for flashing into the block? metalworking tools? And if I need to add flashing, what flashing is recommended against a steel roof (electrolysis)?
Thanks very much in advance.
Replies
a rain leak has developed alongside the chimney.
Does that mean water is running down the face of the chimney or on the sheathing/rafters nearby?
I could see daylight through a gap (perhaps 1/8" wide) along one side of the chimney.
Do you see water coming through this gap? It's not unusual for daylight to penetrate where flashing overlaps masonry. Might be a problem, might not.
As far as what to do to remedy the situation, I can't offer much help without some pictures. There are several ways to flash and without knowing exactly what's been done, it's impossible to advise further. Your description has raised more questions than it has answered.
>> Does that mean water is
>> Does that mean water is running down the face of the chimney or on the sheathing/rafters nearby?
Well, to be honest, I'm not sure - I'd guess both. It wasn't raining when I was up there, but there is a spreading water stain on the sheetrock of the ceiling of the room beneath, running right to the side of the chimney itself, and the stain had grown since the previous visit. And the strings of dried silicone caulking were hanging from both the roof structure and from the masonry at the edges of the gap.
I'll know more in a few days when I get back up there, and will try to get some pictures as well (should have done that last time!). Thanks for the reply.
the strings of dried silicone caulking were hanging from both the roof structure and from the masonry at the edges of the gap.
That sounds like someone tried to caulk it from the inside.
I assumed that they had tried to fill too wide a gap from above, and the caulk had just flowed through. But I see what you're saying, and it certainly could have been attempts from below. I won't know until I see it from above, I guess.
As a separate issue, what material is recommended for flashing against a steel roof? Something nonmetallic, or do you have to insulate a dissimilar metal from the steel, or is it not a problem?
Without seeing it it would be hard to say, but it sounds like you need to install some step flashing into the grout joints of the chimney. Then you will need to counter flash from that to the roof. Can you get a picture and upload so we can see it maybe?
I was thinking of some sort of step flashing. What material is suitable for use with a steel roof, however? Is electrolysis a concern with metals that don't match the roof material itself? The roofing has a very hard dark grey finish, perhaps some sort of baked enamel or powder coating.
The rest of the roof seems well done and has no leak problems, and the house was very well maintained without evidence of cutting corners on construction costs, I wondered what sort of seal might typically have been originally intended at that point, In any case, I'll try to get some pictures this weekend, if weather lets me get up onto the roof. Thanks.
I was thinking of some sort of step flashing.
The "step" flashing is the base flashing when shingling. The "counter" flashing is cut into the chimney to shed water over the step or base flashing. This gets confused because counter flashing looks like stair steps in some applications.
We can guess and guess, but until we see how the roof is installed around the chimney and what type of flashing exists and what doesn't, it's still all just conjecture.
The counter flashing should be the same metal as the roof in this case. We can come close to determining that when we see some pics.
Can you see the chimney from the ground? It may not be necessary to go up there to provide a useful photo.
The chimney is set near the center of the roof, so the junction with the roof is not well seen from the ground. I'll be going to the house this weekend, so will try to get some photo's then. Perhaps a piece worked loose - the house is on Lake Champlain and periodically gets some pretty fierce wind storms.
Thanks for your comments in any case.
telephoto image of chimney
I got on site late today, and rain kept me off the roof. But I did get this much of a picture of the area that is leaking, using a telephoto lens and digital enlargement.
To my untutored eye, it looks like the counter flashing has some gaps, but I don't see any mating step flashing under it. Maybe it shouldn't normally be evident in this view?
If weather permits, I'll get up there tomorrow and get some proper close-up pictures.
Is this a new roof on an old building?
I think the roof is about 8 years old, maybe a bit less. The house is probably about 20, most recently expanded and renovated at the time that the roof was done.
I'm guessing that when the roof was replaced the installers didn't know how to work new flashing under the counter flashing properly.
Hard to make out the details -- what's that thick area right near the chimney -- is that sheet metal or something else? How is it connected to the roof?
Not exactly what I expected to see. All the components are there. The roof material appears to be "R" panel and the counter flashing is lead. Looks like the caulk monster has been up there as well. Get some pics of the top and back side of the chimney when you get up there.
better pictures
Here are two shots. What my untrainted eye sees:
1. Lots of caulk between lead sheets of counter flashing.
2. Fabricated step on three sides, but no saddle flashing.
3. Depressions in tarred joint on "uphill" face of chimney, corresponding to the contour of the R-panel ridges, with at least one 1/2" pit that may penetrate as a hole.
The leakage damage is limited to below the "nearside-uphill" corner - which is where the tar depression is the deepest.(the dark linear shadow near the lower left corner of the second picture is just a shadow, not a crack in the tar)
Looks like the back pan (where the tar is smeared) is lapped under the base flashing on the sides when it should have been lapped over. See if you can lift the lead flashing on the back and loosen up the ridge piece. Bend a piece of metal (galvanized will work for this) slightly wider than the chimney up the back of the chimney and let it extend back up to the ridge.
Cut the excess length at the sides so the verticle part can be bent around the sides of the chimney. You may need to caulk the corners and bend the counter flashing back into place and screww the ridge back down.
found it.
On closer inspection, the pan is, as you guessed, not overlapping the sides of the base flashing. In fact, it is so dished downwards, I suppose from winter ice and snow loads, that it forms a very nice holding basin for water. Not only that, but the junction between the pan and the ridge extrusion had opened about 80% of the way across. As the water level rose in the "basin", it would eventually overflow at the back (i.e. ridge side) of the pan into this large gap where the tar had split, since there was little pitch at this point.
It is not visible in the pictures, and I didn't see it before. In the second photo, it is under the shadow from the dish cables, and not really very visible at all when you're looking from that direction. The gap is up to 1/4" wide and runs nearly the full width of the pan. It would certainly account for the leakage, I think.
So I've temporarily resealed it with cement, and on my next trip up here I'll have some sheet metal tools with me, and something suitable to install as you described.
Thanks for your help, and to all for their comments.
You will probably have to have some made to the contour of your roof-preferably made by the same or similar manufacture.
What kind of roof is it? "R' panel, standing seam or corrugated.? Whatever the flashing will be it will depend on your roof style. Is there no counter flashing at all on the chimney that you can see?
He won't be the only one gagging.........
Keep the tar in the can where it belongs.
It's called fibered roof cement-I don't see anything in the title suggesting "slop in on around where you think the leak is coming from"-repair goop.
While it may work for the first season, good luck next spring. Fix it properly the first time (not with silicone either) and you might not have any more leaks in that area.
just slop some fibered roof cement on the gap from the outside ..
C'mon Art - you're losing your edge. In the old days you woud have suggested making the flashing from flattened tin cans or some crap like that instead of store bought tar. I'm dissapointed in you......................
[the newcomer quietly steps aside, makes some popcorn, and pops a beer...]
I'm dissapointed in you ,,, "store bought tar..
You musya missed Nov '90 FHB "great moments, "a ten year roof"
where i describe mixing old cutoffs from mopped roofs with diesel for roll roofing sealer <G>
BTW. Mom still lives in the house where I was raised. Built in gutters, It is 107 years old. Built ins were tar. Tore off one side and replaced with epdm about 3 years ago (the south side- the one I talked to you about years ago)
Last year I did actualy buy a 5 gal can of fibered to repair the other side. Chimney to roof has been fibered seal for all those years, think Pop maybe redid ever 25 years or so since 1946.