Chimney Flashing And Leaks

I knew the man up on the roof
He moved so slowly, step by step
Until he reached the parapet
Then gripped it tight between his thighs
The fear now vanquished from his eyes
He turned and looked at me, aloof

Then rose with trowel in trembling hand
And waddled forward, like a duck
His bucket filled with mortar muck
Until the chimney he did reach
Intending to repair a breach
Where brick had crumbled 'way like sand

He called me then (I'll not forget)
To fetch to him a pail of brick
My knees grew weak, my stomach sick
But from the ladder I did pass
And scurried upwards, on my ass
He'll be forever in my debt

We topped the last course with a crown
Then looked about, and called "Hello"
To people passing by below
And for a time we felt at ease
Relaxing in the evening breeze
Then wondered how we'd make it down.

MR

Yes, I know I'm using parapet loosely, but try rhyming with "step" with "ridge". In any case, chimney repair requires a mixture of skills, including masonry and flashing, not to ignore the ability to work off a ladder or balance at heights. I suspect one of the reasons there's such a limited selection of chimney rework videos on YouTube is it's tough to find somebody who wants to play cameraman or find a place to put a tripod:-) The following short video offers a view of a flashing job that includes what looks like a cow catcher to prevent buildup of leaves behind the chimney.

Run Time 0:15



I spent a couple hours yesterday morning patching up a leaky chimney but didn't make my own video, in part because I didn't want to get gunk all over my camera. The problem was a combination worn out mortar and a poor initial design when it comes to flashing. Chimney flashing is thin sheets of metal, usually aluminum, copper, lead or tin, that are inserted under the uphill roof covering, such as shingles, and then run up the exterior of the chimney beyond the height that water might accumulate. Flashing is heavily sealed with roofing tar or modern sealing compounds, which make up the seal between the metal and the rough surface of the brick and mortar.

When you have a chimney with a nice architectural feature, like a curved shoulder which juts out in a graceful sweep, you also have the problem with water running down that curve and trying to penetrate the house behind the siding. The particular repair I was working on yesterday was for a house with vinyl siding that jutted out a good inch from the old siding, leaving a gap that size along the chimney for water to course down. Over time, the water began to penetrate along that interface, stain the walls and drip into the cellar. It would have been nice if they'd flashed along the chimney when they installed the siding, but there was no simple way to do it after the fact. So I sealed the whole run along the vinyl siding with a couple tubes of grey cement repair caulk. When it dries out it should match decently:



I also tried an unorthodox flashing repair on the shoulder of the chimney where several bricks were half gone and the mortar was worn away. Rather than trying to rebuild that section of the chimney, which intersected with several large decorative sandstones, making refitting a pain, I tried flashing right over the bad area with a few six inch by 18 inch sheets of aluminum, heavily tarred on the uphill side and caulked along the edges. My gut feel is that it will hold out for a couple years, but not much longer. The choice was based on available materials, not best practices. I thought I'd throw in a link to a guy who runs a top homeowner repair site doing a temporary tar patch on his own garage roof to defend myself:-)