Preparing for an airtight fireplace chimney
I am in the middle of building a house. I’m looking at installing a Stuv fireplace, but it might have to wait a year or two. At the moment, we have no ceiling cover, tongue/groove pine to come. My thinking is to install a chimney support box now. Are they all about equal, or are there any designs out there a bit more sealed/insulated than others? Our air barrier is Intello on the underside of the roof. Then, 24″ deep parallel chord trusses, R80 timberfill, and an air gap. My thinking is to tape the intello to the chimney box. Then the joints of the (future) stove pipe are the only weakness.
Unfortunately, I thought of this plan after insulation and after roofing are done. Oh well.
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Replies
Hi Tim,
I don't know of anyone who has tested a chimney support box for air tightness. If you have a concern, caulk the seams inside the box before you install. If the sealant ends up close to the chimney pipe, you might want to use an RTV high temp sealant. Here's an article I wrote a while back related to the topic:
https://www.greenbuildingadvisor.com/article/air-sealing-a-chimney-chase
Randy
Thanks Randy, looks like I can do all the sealing to the cathedral ceiling support with high temp RTV, and it sounds like there are some products that are good for up to 2000*F that could be used for the stove pipe joints potentially.