How to fix 25mm+ dip in floor

[MrNoob]

I've read the "how to level a very uneven floor" sticky, but wanted to double check before I order the material:

1) The floor in the upstairs bedroom has a very big dip of arround 25-30mm in over a 1.5m run before going back up again. The area that is suffering the dip covers two-thirds of the middle portion of the room, and was probably caused by the bad removal of a wall downstairs by previous owner.

2) If F-Ball 700 flex still the only product on the market? The sticky is seven years old, so I wonder if there is anything new/better?

3) Could I try packing the joists and re-laying the floorboards?

I've attached some pics to give you an idea of how bad it is.

 

[ree]

You have posted before about removing a wall by yourself - the task gave you some difficulties. Now you say someone else has removed a wall - in the same house?

Your best, and safest, bet would be to post more pics of where the walls have been removed - floor and ceiling. And scan a sketch of the floor plan showing where the walls have been removed.

I hope that you dont mind me saying that your post above appears a little confusing, and there's no mention of a lintel.

 

[MrNoob]

The wall that I had knocked down by a builder and which is currently being signed off by buuilding control was sat in between the kitchen and dining room.

The previous owner had already knocked through a wall between the lounge and the backroom. The floors in the picture are of the bedroom above the through-lounge which was created. When the previous owner got this done, using a wooden beam, they did not pack above the beam as they should have done. This caused the wall to sag - as part of the renovation work, I removed the skirting from all the rooms. When I did this in the bedrooms upstairs I saw a fairly big gap across two third of the bottom of the wall joining the two bedrooms i.e. above the wooden beam. I've made this good by packing it with slate and a 3:1 mixture of sand/cement.

I think this sagging is what has caused the problem. There is a dip that goes 20mm, 25mm, 30mm, 25mm, 20mm over the span of roughly 1.5m.

I'll get some more accurate measurements later - but I hope the bit of background helps. I'm also going to pop down the timber merchants and get some wood cut of the that thickness and see if the easy fix of battening works.

 

[MrNoob]

I've added a couple more pics to show the size of the room. The bigger room has the most visible dip, but both room are effected by what happened.

The effected are in the big room is pretty much 2mx2m - from the wall to the middle of the pain splodge.

As I will be laying down 6mm plywood, instead of ripping the floorboards up and laying the battens onto the joist, can I not just screw the battons onto the floorboard and ply over it?

 

[ree]

The dip in the floor is not caused simply by faulty packing - its caused by whatever has been used as a lintel ("a wood beam") not being sturdy enough.
The beam has begun to "bend" in the middle, and has dropped at its seating.

The joists are presumably fit for purpose - the lintel is at fault.

A floor plan is necessary to see whats been done, esp. as now we seem to be referring to a kitchen floor and two bedroom floors?


It defies building common sense to knock-thro another wall when you already have an issue with an adjacent knock-thro.

And how could a wall have run into the face of a chimney breast, which is the direction your lintel must be running in the new pic number 5? Probably my misunderstanding.

In 2014 very few BCO's will be signing off timber lintels and dropping floors.
By and large, steel has been required for knock-thro lintels for a number of years.

Typically, a dip in a floor or a dropping floor is Acrowed back to level and a steel lintel is inserted. Your proposal for battening above the floor boards is not a solution.