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Architecture/Structural integrity when cutting out holes


Hi Richard,

I am placing in three high efficiency furnaces in the basement of my three family structure, which require exhaust and intake pvc piping of 3" and 4" out of the side of the house.  So in all, there will be 6 holes through the side of the house in those sizes.  I am concerned about the structural integrity of the house when cutting all these holes.  The holes will be cut out of the the header joist (as I believe it's called as the joists connect to it).  Please let me know if my concerns should exist, what I should ensure, and if there is any other things you think would be good to recommend or share.


Basement Rim Board
Basement Rim Board  

Although I do not have the IRC residential code right in front of me, I believe that you are limited to cutting away one third of the exterior rim board or floor joist.
But I believe that if you begin by cutting 2 x 4 blocking to lengths that can be friction fit adjacent to the new holes, then that should allow us a little leeway knowing that the vertical compression is now distributed around the sides of the hole.
These new holes should not be located above a window or door opening and the holes should be limited to one hole between each joist space.

See attached illustration.

Good luck

Richard Burton, AIA

I am not a licensed architect or structural engineer in the State of Michigan.  It is the responsibility of the home owner to adhere to all State and local building codes.


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Richard Burton AIA


A combined total of 25 years experience with construction, architecture, and building code enforcement. Ask me about residential and commercial design. Ask me about design aesthetics, structural methods, and building something that will withstand severe weather conditions. Ask me my opinion about YOUR design ideas and I will tell you the merits of good design and challenge your thinking about practical issues. Ask me how to best find and work with your local architect and approach general contractors to get the most value for the least amount of headaches. You can ask me about improving your energy efficiency and things that are both green and practical. But don't ask me about solar panels and wind turbines unless you are currently paying your utility company 35 cents per Kilowatt. Otherwise the math does not justify the initial cost and return on investment. Ask me any building code question and how to get a building permit from the most difficult enforcement agencies.


Here in the midwest, we design and build "green" in ways that make sense. My construction methods prioritize weather resistance, ease of maintenance and durability. While a graduate student in San Diego, I taught drafting and history of architecture. After working ten years for other architecture firms, I have started my firm Arrow Architecture in 2008. More than half of my work involves commercial office buildings. But my portfolio of work also includes custom homes, residential additions, home remodels, and second story additions.

President-Elect of American Institute of Architects - Lincoln, NE

B.S. Architecture - (Interior Design) University of Nebraska Lincoln 1997 Master of Architecture - (Urban Design and Professional Practice) NewSchool of Architecture - San Diego 2004 Graduated Summa Cum Laude ICC Certified Building Plans Examiner

Awards and Honors
AIA Henry Adams Medal and Certificate

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