Notches too deep in joists?

[Kate123]

I had a new central heating system fitted about a year ago. In a room which didn't previously have a radiator the plumber installed new pipework, for which he cut holes in joists across the length of the room, about 0.7m away from the wall. The room is 3m wide by 3.7m long. I noticed when putting the floorboards back after they had finished that the notches looked quite deep. The joists are 180mm deep and these notches were 40mm to 45mm deep, for 15mm pipes, and roughly cut. I raised my concerns with the plumber and he got very unpleasant with me so I had to leave it at that and hope there would be no future problems. There was also a lot of pipe banging and I had to put felt between the pipe and joists to stop this.
Once the room was furnished I noticed some evidence of deflection not long after since the two parts of the divan bed didn't fit flush together anymore, there is a slight tilt, the divan sections meet at the bottom and there is a 1cm gap at the top. The floorboards also make popping noises in places, despite having been screwed down.
Is the issue likely to get worse and require some remedial work?

 

[bernardgreen]

You will need to fill the notch with solid hard material as well as a plate or similar along the sides of the joists,

Sistering the joist ( timber bolted to the sides ) is an option. The bolts must be fitted midway between the top and bottom of the joists.

Shaping the sisters or metal plates as shown in green will restore much of the joist's resistance to bending. The bit above the pipe should be a large as possible wthout touching the pipe

The bottom half of a joist is under tension and the top half is under compression as the joist tries to bend under load. A notch in the top side will close as the joist bends. The mid point ( from top to bottom ) is neither under compression or tension hence holes for bolts there will not weaken the joist.

Bernard

edit pope replaced by pipe

 

[tony1851]

If it was done a year ago, it's unlikely to get any worse. There will be some reduction in bending strength of each joist, and an increase in deflection - and it might 'bounce' a little, but it's not going to collapse.
A 45mm notch in a 180 deep joist is not ideal - and if you're worried, try sistering as above. But there are plenty worse examples which remain intact.
Timber-joist floors have a remakable capacity to survive drilling, notching and over-loading without going south.

 

[Lower]

I hope he notched the pipes in a position where there is a floor board bridging each notch, or do you have chipboard boards?

If you've got proper floorboards, screwing the board into the joist either side of each notch will stiffen the joist up.