Butt joints for ceiling/floor joist

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Forum topic by PaulLL posted 11-09-2014 04:37 PM 1859 views 0 times favorited 4 replies Add to Favorites Watch
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160 posts in 1397 days

11-09-2014 04:37 PM

Topic tags/keywords: question tip

Hey Guys! I’ve had a crazy busy summer with a new job so haven’t been able to get on here, now that snow has fallen (why do I live here?) I decided I’d start a home reno! On our main floor we have an alley kitchen with a solid wall separating it from a hallway that leads from front door, past kitchen to dining area and living room. I guess i could have just taken a picture, but I think you get the idea!

SO… I started removing that wall, to open up the kitchen. I was expecting a couple of support posts to extend up, I can see in the finished ceiling where the joists are, one at each end of the kitchen. The problem I found was that a heating duct goes up, they’ve stopped the joist about 12” before and then started again on the other side. I’d like to extend the joist right to the ducts frame so that I can just make one post at the end of the counter. This also affects whether we put a overtherange microwave over the stove or a hanging ceiling vent.

I believe I can extend the joist, then use steel plates to bolt over the joint on secure it without compromising the integrity of the joist. It does extend to support the top of our stairs, but there is a posts on each side of the stairs so that shouldn’t be an issue. I attached a pic with some line drawings so you can get an idea of what I’m looking at, does anyone have any professional opinions on this, my wife wants a structural engineer, but I’m saying we don’t need to spend the money, I build steel buildings, this seems pretty easy!

Thanks in advance guys!

4 replies so far

View molan's profile


120 posts in 1643 days

#1 posted 11-09-2014 05:10 PM

Sorry I am a bit confused. you are talking about extending the Joists (which are the horizontal supports that run under a floor) but your picture is of a wall section.

The plumbing in the wall and the 2×4 wall being cut out to allow the heat duct is perfectly normal. Are you wanting to bridge that section to allow you to support cupboards and a microwave?

View bobkberg's profile


420 posts in 2494 days

#2 posted 11-09-2014 08:38 PM

Hi Paul,

If I understand correctly, you are asking about how to join that top plate that is “broken” by the duct so that it is continuous. As Molan mentions, what you have is normal, but personally, I like the idea of some continuity.

What I would do is what you already suggested: nail long steel straps to the top plate on both sides of the duct.

Hope that helps,

-- Bob - A sideline, not how I earn a living

View bold1's profile


259 posts in 1268 days

#3 posted 11-09-2014 11:50 PM

Let me see if I understand where you’re going. The header that is visible on the top left you wish to extend straight out toward the duct on the right? You want to get rid of the support studs on the left and move them to your white line marks beside your stud at the duct on the right? If that’s right, can you go back twice the length of your add on, or more, to bolt flat plate along the side or c channel (underneath)? If I’m thinking with you, I’d prob. go 4 ’ or more, support the upper joists, knock out the studs that far, then slip a 3/8” c channel up under and around the existing header, and reinstall the studs that you can(cutting them to allow for the channel). The weight on the studs should help cantilever the added 1’ at the butt splice. If you think you need more, add a flat top plate.

View PaulLL's profile


160 posts in 1397 days

#4 posted 11-10-2014 06:36 AM

Thanks guys, yeah bold1 that’s exactly what I was thinking. I just wanted to extend the joist to the duct and stop. I didn’t think of using the c channel, was just going to bolt plates to the sides. Of course the plan has now changed since my wife decided she wanted an over the range microwave for sure, so I’m going to leave that post and box it all in anyways. Good to know for future though!! Thanks guys!

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