Grant Park fireplace puffing smoke on windy days: the new addition stood taller than the chimney

By Jacob Dove, Friendship Chimney Sweep

A fireplace that only misbehaved when the wind blew

The house sits on the edge of Grant Park where the last street gives way to open fields, a story-and-a-half home with a brick chimney on the west gable. The owners had burned wood in it every winter without complaint. Then, the first season after they built a two-story addition off the west side, the fireplace began puffing. On a calm evening it drew fine. On a windy one, every strong gust pushed a breath of smoke out past the lintel and into the living room.

They had already tried the usual things: a hotter fire, drier wood, cracking a window. Cracking the window is the right test for a house that is starved for air, and it made no difference here. That told me the problem was not inside the house. It was at the top of the chimney.

I swept the flue and ran the camera first, because I do not guess. The clay tiles were sound, the smoke chamber was clear and the damper opened fully. Then I went outside, stood in the yard and looked at the roofline. In 29 years in the trade I have learned that a good share of draft complaints can be read from the lawn.

The addition changed the wind, not the chimney

The new addition had a ridge that stood well above the top of the old chimney, and it was only a few feet away from it. That is the whole story. A chimney needs to end in clean, moving air. The rule we work to under the NFPA 211 standard is plain: the chimney must rise at least three feet above the point where it passes through the roof, and at least two feet higher than any part of the building within ten feet of it.

Before the addition, this chimney met that rule easily. After it, the top of the flue sat in the shadow of a taller roof. Around Grant Park there is not much to slow a west wind down. It crosses a mile of flat prairie, hits the wall of the addition, rolls over the ridge and tumbles down the far side. That tumbling air creates a zone of higher pressure right where the old chimney ended, and each gust pressed down on the flue hard enough to reverse the draft for a second or two.

A different cap alone would not solve it. Wind-directional caps help with a chimney that is nearly tall enough. They do not make up for a flue that ends several feet below the nearest ridge. The chimney had to go up.

Raising the chimney the right way

We extended the masonry rather than bolting a metal pipe to the top, because a brick chimney carried higher looks right and lasts.

• Removed the old crown and cap. The crown was cracked anyway, so nothing of value was lost.
• Checked the stack below. New courses are only as good as what they sit on. We repointed two soft bed joints near the top before adding weight.
• Laid new courses and flue tile. We matched the brick as closely as the yard could supply and carried the clay liner up with it, each tile joint sealed with refractory mortar so the flue stays one continuous passage.
• Poured a new crown. A proper crown overhangs the brick with a drip edge and leaves an expansion gap around the tile.
• Fitted a stainless cap. It keeps rain and animals out and takes some of the edge off gusts.

With the top of the flue two feet clear of the addition ridge, we waited for a windy afternoon and lit a test fire. The smoke went up and stayed up. A taller flue also drafts a little stronger in general, so the fireplace starts easier than it did before any of this began.

The owners asked what an extension like this runs. Our pricing is published on the pricing page, and we went over the scope in writing before any brick was laid. Friendship Chimney Sweep is Insured & Bonded, and the phone at (815) 449-4264 is answered 7am to 9pm, seven days a week.

If you are planning an addition, a dormer or a taller garage near a chimney, have the height checked while the plans are still on paper. It is far simpler to include a chimney extension in the project than to discover the problem on the first windy night in November.

If this sounds like your house: we handle chimney repair and masonry extensions across Kankakee County, and our Grant Park page covers what we usually find there. Call (815) 449-4264, 7am to 9pm, any day.

Quick questions