I need to know how big a problem this is...

[LoveGigi]

We are doing up our bathroom. We live in a Victorian terrace and the plan was to knock the separate toilet into the bathroom to make one room. It's been such a long saga, going back to May, I don't have the energy to go through it all! However we had employed a firm to do the entire job but that didn't wrk out so we decided to do some ourselves and employ the professionals where they were needed.

Plumber comes and moves the toilet waste 1 meter away from its original location and it has since transpired that he has drilled directly through the header plate to get to the outside. The bathroom overlooks the side return and this section of the house is often referred to as the rear addition if this info helps to describe what I'm taking about. So I'm not a structural engineer but to me this can't be good. Does anyone know just how bad it is and what I should do now.

Do I need to speak to a structural engineer? Will we need to bolster up the joist, add a steel? Help!

What's a header plate? Photos would help.

I probably haven't got the correct term. The header plate is the length of wood that runs along the exterior wall that the ends of the joists run into for support. It is attached to the exterior wall. The floor is screwed down now but I'll attach a photo taken at the time and if you zoom in you will see the hole at the top of the image.

Well, if it's attached all the way along the wall it's probably just a convenient way to attach the joists rather than building them into the wall, to avoid damp. So maybe it's fine.

It might be what I call a wall-plate, or possibly a ledger, though the joists would be standing on it, which as far as I can see, they aren't

I don't recognise the method of construction.

The joists and the plate look as if they are standing on the ground, although there is so much rubbish it's hard to know.

Is, or was, this a timber-frame house?

see also en.wikipedia.org/wiki/Wall_plate

Thanks for your replies, I can't actually recall how the joists meet the wall plate/header plate. The piece of wood stops prior to reaching the corner of that room to allow for the old toilet waste pipe to exit the wall. This is a room on the first floor of the house, and below this room is the kitchen which has a wire/lath/plaster ceiling. It is hard to see what is going on in that photo as the piece of wood in question is in the shadow of the old bath waste pipe.

We have got so far now as to be putting self levelling compound over a new marine ply floor to level and embed the underfloor heating. This was yesterday and it was halted due to the fact that it was going to need 10 bags to properly level the floor as at its worst place, the floor needed raising 50mm. So I suppose I'm unsure about loading a first floor bathroom with 200kg plus water weight of screed. We also have a cast iron bath which is extremely heavy, perhaps around 140kg.

Is there a way of calculating the weight that will be happily carried? Is it regular practice to use this much screed on a first floor?

20/20 hindsight would have had me lifting the floor again and levelling it properly. 4 bags of compound have already gone down, but I'm on the cusp of rippping it back up again.

Hard to advise without seeing it and being an SE, but I don't feel like 200kg is a lot spread evenly over the whole room.
Normally you would need extra joists under a bath because it's a large load over a small area, but baths do get moved and joists notched all the time, and you rarely hear of collapses.
Our bathroom and toilet joists are notched about half way through the wood for a waste pipe, and it's been up like that for probably 40+ years!

Thanks Johnd2, that's reassuring. Pigletjohn, it's not a timber framed house just a brick built construction dating to 1890. Thanks for the link.