Extra Floor Joist Framing And Support Needed Under Kitchen Island? - Building & Construction - DIY Chatroom Home Improvement Forum

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Old 09-27-2012, 11:01 AM   #1
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Extra Floor Joist framing and support needed under kitchen island?

As part of a kitchen remodel in our mid-50's rambler (2x8 floor joists), we're putting in an island that will be a primary work space and also an eating area. The total footprint of the island is 20.5 sq ft.

As we're looking at different countertop options, we're talking over granite, silestone, and butcherblock. The countertop will be about 26 sq ft (extra because of overhang for eating area). One of the questions that has come up is overall weight and potential long-term issues. As we think about countertop, cabinet, and contents, the total weight will be between 700lbs (butcherblock) and 1000 lbs.

The closest points where the floor joists rest on something (can't think of proper term) is 2 feet from one edge of the island (steel I-beam) and 6 feet from the other (block foundation in great condition).

Given the size of the island and the location of load-bearing supports, how much concern is there about the weight and any long-term sagging/movement? The previous layout of the kitchen had the fridge in the place where the island will be located...I know, not as heavy, but smaller footprint as well. There is currently no noticeable sagging.

I recognize that this is best answered by a structural engineer on site, but I wanted to just get some quick responses first from those with more experience to see if we're being overly concerned.


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Old 09-27-2012, 11:41 AM   #2
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At about 50 lbs./sq. ft. for the island I think I would sister some 2x8s to the joists if it is not too difficult.



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Old 09-27-2012, 11:48 AM   #3
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Andygump is correct about sistering joists. If the floor sags in the middle raise the joists that are there now up to level and then sister the new joists next to them. Wires, pipes, ducts, and insulation are one of the first steps to deal with...
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Old 09-27-2012, 01:45 PM   #4
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how about at 35 lbs/sq ft? That's more so what we would get with a butcher block top. Opinions on that?
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Old 09-27-2012, 02:38 PM   #5
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I would sister joists even with the butcher block top. you'll only talking about 3 or 4 joists. most older rambler homes have bouncy floors to start with

just my thoughts ....

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