Structural repair/strengthening of notched floor joists

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Structural repair/strengthening of notched floor joistsDuring renovation I have lifted the floorboards and discovered that previous plumbing work has involved cutting large notches across a number of first-floor timber joists to run two copper pipes.
The joists are approximately 170mm deep and around 70mm has been notched from the top, leaving roughly 100mm of timber. The joists span approximately 4.6m and the notches are around 1.85m from one end.
The work appears to be old and the floor has been in use for many years with no obvious sagging or movement.
Ideally I'd like a local reinforcement solution such as structural steel plates or sistering around the damaged area, rather than replacing/full-length sistering every joist if this can be avoided.
There may be approximately 6–12 affected joists depending on whether the pipework continues through the adjoining room. Floorboards are currently being lifted so access is available. Appreciate any advice on this
 
You could follow this.
4.30 in. Kirk sisters joists to repair strengthen


 

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