I have taken down the ceiling in a downstairs room to expose quite attractive beams.

Unfortunately one is cracked where there is a t-joint at the outer corner of a trap door which is right in the corner of the room. At the crack the joist is 0.5” lower than those which are clear of the trap door. If I do a little jump right on the corner of the hatch hole the joist moves down just a little and the crack visibly opens, but it appears to only go about halfway up to where there is a hole cut by whoever fitted the hatch – it’s a real messy job involving old large headed wrought iron nails (The house is 200 years old though maybe not this bit!)

Thinking of the letter ‘T’ formed by the joists at the corner of the trap door I want to put a flat steel plate across the top of the ‘T’ and bolt it in place with 2” square steel washers on the other side. I have seen advice on your forum (and elsewhere) that  holes for pipes (and cables) in floor joists should always be drilled at the midpoint where the joist is neither in tension nor compression when loaded above but for my case a friendly builder thinks I should drill a zigzag pattern for bolt holes. I have in mind to make the plate as wide as I can fit.

What do you recommend re the holes? Also any guidance on length and thickness of plate, diameter of bolts?

Some further details: joists are 7.5” x 2.5” spaced at 16” spanning 8’ except for 5 which span only 5’6” because they abut the long side of the trap door. The room above is mainly used for storage including lots of heavy books. I intend to use an acroprop when I fit the plate to push up under the crack so that it is slightly too high, say 0.25”, when I fit the plate.

Jason, nice looking job.  What is that kitchen mixer tap?  It looks as though it is adjustable for height?  Am I seeing things?

LOL  

Cheers Jason, shame these taps are high pressure only, hot would run a bit slow with 5m head.