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Thursday, January 13, 2011

The New Dear Abby of Roofing

Just call me Abby

Mr. Wright,

I came across your blog on my search for a solution on a chimney issue.

My husband and I are building a house in Houston and the installation of the chimney is one of the issues we are dealing with right now. It is a bit complicated.

For technical reasons, we had to change our concept from a wood-burning fireplace with an 8 inches high quality, stainless steel flue to a gas-burning fireplace.

For the gas-burning fireplace we chose a B-vent Isokern fireplace because we wanted to keep the appearance of an open fire.

The issue now is the flue. B-vent fireplace flue pipes only come as galvanized metal on the outside and aluminum on the inside, and the pipe for the Isokern is 10 inches in diameter. From a design standpoint that is of course not very attractive yet, most homes in our neighborhood have very attractive chimneys. Therefore, resale value is a concern.

What makes this issue complicated is the fact that we have a metal roof. The original plan called for an 8 inch, stainless steel pipe flushed with roof material.

During construction, I came to realize that I would prefer a chimney that is ‘boxed in’ and finished with stucco. According to the builder, that would have been actually less expensive than the stainless pipe.

During installation of the roof I continued to ask if the chimney would not need to be installed first but everybody assured me that would not be the case. Well, they considered the metal flue only and did not distinguish between different types of installation methods for different types of chimneys.

Well, now the story is suddenly different. The pipe for the new fireplace is not at all decorative but rather dull looking. A boxed-in chimney would be the better solution.

Now, I am learning a boxed in chimney proportioned to the size of our roof would have to be rectangular shape and would require for the roofers to cut into more than one standing seam. The roof company - who has done really good work - is reluctant to do that and tells us they would require to take off 75 % of the installed metal roof to install the box.

They have to guarantee their work of course and they are cautious to prevent future leakage. I understand their point although I don't quite understand the explanation about the installation technique.

I wonder, though, is it not possible? They have done such good work, I cannot see why they should not be able with their skills to cut, install and seal a chimney box. There has to be something that can be done.

I wonder what your opinion is. I am just asking for an honest opinion and only if your time would allow that - no guarantee of course.

What would you do if you as an experienced roofer would be in our situation and your wife would love to have a chimney made from stucco on her roof. Would you think there is a way?

I wonder if you would be willing to share your opinion.

Best regards

Christine (last name redacted), Houston.

Here's my reponse:

Hello Christine,

Sorry for the delay in response to your question but with the holidays and other issues I haven’t been able to get back with you until now. I am flattered you read my blog.

It seems you have three questions, the first having to do with the roofer needed to know what type of chimney structure he would be flashing, that is integrating the roof with the chimney penetration. With all but standing seam roofs the answer is no but with standing seam the answer is definitely yes. Because the system is locked together the difficulty of installing a rectangular box after the fact is very hard but can be done. The roofers might have to hand fabricate some panels and have some seams where they might not normally have them.

The roofers are concerned that the box would be wider than the ribs causing a dam effect I believe. Hand fabricating would solve this problem with some soldering where the seams would be left out. If my wife wanted a box around the chimney I would try to convince her to turn the chimney at a 45 degree angle to the flow of the water. That way the two lower sides could have traditional pans shaped in an “L” fashion and placed on top of the standing seam and out onto the roof. On the back side two more pans could be made to go up underneath the standing seam and divert the water around the chimney.

The problem is that standing seam is difficult to seal. Metal expands and contracts and the longer the panel the more movement you have. The method I have tried to describe would allow for movement. A traditionally positioned chimney with the water hitting directly behind the chimney, even with a cricket (a sort of inverted pyramid causing two valleys) is difficult enough to do without having to go back later and do it. Besides, the workmen might scar your beautiful new roof.

The cost of changing this could be in the thousands for the roof work plus the carpentry. A fake blind could be made that sat directly on the roof but getting it up there would be difficult too. Plus the wind can really blow in Houston and it might sail away.

Good luck with the project. This sounds like your dream home and I know you want it the way you want it.

Thanks for reading.

Hello Jon!

Thank you so much for answering my e-mail. I read some articles on your blog and especially liked the article about'non tolerance chimneys'. - Well, after reading that article I already suspected that it would be difficult to install a framed structure at this point in construction since the roof is already installed and we don't have a supporting structurein place. My husband as well as the architect have said that all along, only builder and masonry guy said that such a structure is not necessary and they have kept my hopes alive. That resonates exactly with the experience that you are describing in your article.

Reading your comments about the challenges of cutting and sealing a standing seam roof only further confirms, it is too late for us to change course. - If nothing else, the cost will be the decisive factor.
I truly appreciate though that you went into detail of how it could be accomplished if done by hand. Tomorrow, we have our final meeting with architect and roofer, and I will be armed with additional knowledge. I am very grateful to you for taking your time and explaining that to me.

Thank you very much for your help.

Kind regards
Christine (redacted)

Jon Alan Wright

Jon Wright Roofing, Siding, and Windows

1915 Peters Rd., Suite 310

Irving, TX 75061

972.251.1818 Office

214.718.3748 Cell

972.554.8090 Fax

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