enter image description hereWhile using my circular to cut away rotted subfloor sheathing, I accidentally cut a thin kerf notch into the flat 2x4 top of my engineered floor truss joists. The cut is about 1/2 inch and very thin. How much risk am I assuming if I ignore this? There will be concrete and tile over this subfloor. See attached photo. That edge was made by my circular saw which I assume was set to incorrect depth.enter image description here


Well, it doesn't matter how thick it is, but it does matter how deep it is. If you've only cut one or two trusses, and it's no more than 1/2" deep, I don't think you have a problem. It's extremely unlikely that it'll cause failure of the floor system in any substantial way.

However, since you have fairly easy access, I'd attach a repair member to the underside of that board, fastening it with construction adhesive and 3" gold screws (through the subfloor where necessary). Make it as long as can comfortably be fit in the space available.

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    Those boards look like 2x s laying flat. If so, 1/2" is one third of their thickness. I think a sistering is really important in this case. – bib Jan 19 '17 at 20:32
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    Yes, but it's very near a supporting stiffback and vertical member. You'd be unlikely to see much flex there even with those cuts. – isherwood Feb 20 '17 at 14:59

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