Open plan drama

[erikwoolf]

Hi everyone although I am planning to get a second opinion from a structural engineer it will be good to know if I am completely unreasonable in my thinking. As a bit of background we want to join 2 relatively small rooms on the ground floor by opening up one of the walls. Overall the building is 4 storeys split into 2 different properties (build around 1875 on clay soil). Had the structural engineer coming in a few weeks ago and he suggested to replace the existing wall with a steel goal post on top of new concrete pads. After he send the calculations through we discovered that the wall that we want to open is actually not aligned to the rest of the walls on the next 3 stories above (it has a 30cm or so offset). We asked him to come back for a second opinion and also asked him to run calculations that will allow us to keep the existing wall (maybe if we keep 50cm or so on each side of the existing wall and we just make the opening smaller). We were hoping that in this case we wouldn't need a goalpost and the concrete pads and just a lintel will suffice. SE cam back to say that this is not possible now because of the off set and the new support needs to be aligned with the rest of the walls and eliminate the offset that exists for the last 150 years or so...I dont want to go against the science here but what am I missing? Does it make sense to 'correct' in retrospect the original plan of the house?
This kind of secondary consideration but the house is build on clay soil and high risk for subsidence but not entirely sure that adding a steel goalpost and concrete pads will actually make the risk less given that the rest of the foundations will still be on the soil.
The wall we want to open is between the bathroom and the dining room in the image below.

 

[erikwoolf]

For clarification the wall is actually aligned with the rest of the ground floor wall that 'connects' the back and front of the property and only offset with the wall above.

 

[Cubist]

Sorry Erik but it's not clear which rooms you are seeing to connect. i'm assuming the Living and Dining rooms, but is that correct?

 

[Drayton]

Sorry Erik but it's not clear which rooms you are seeing to connect. i'm assuming the Living and Dining rooms, but is that correct?

i read it as bathroom and dining room...

 

[a twig]

It says bathroom and dining room in the OP.

No structural engineer will ever recommend the riskier option if a safer more certain one exists.

You’ll still get the same effect at the end, personally I’d just crack on and do the steel goalposts as the engineer recommended.

Faffing about trying to laterally transfer load for the sake of 30cm seems a bit OTT, just line it all up and happy days.

It will also make the job easier / cheaper as you can put the goalposts in first, make sure they have taken the load and then take the old wall out. No juggling acro props and strong boys

 

[erikwoolf]

Apparently the joists run the whole length of the property (from the edge of the bathroom to the edge of the dining room, 6 meters in total). This effectively means that the joists carry the load so it becomes less 'important' to align the goalpost with the wall above. Lifting the floorboards I can see that the there is another piece of timber underneath the joists (they don't touch the masonry directly). I am now planning to drill a couple of holes to see if there is gap between the masonry and the joists.

 

[erikwoolf]

We lifted he floorboards today to look at the condition of the subfloor before proceeding with the goal post installation. There needs to be a 120x120cm concrete base on each end, flash with the wall. The concrete base needs to extend 50cm past the external wall (and equally where the other end meets the internal wall). This means that it needs to go past the existing masonry foundations. Does anyone has experience on what is considered best practice in this case? Do they need to go underneath the existing foundations or replace them? I am spooked by the various experiences with tradespeople and this is one of the tasks that we really need to get right.
Second photo shows the subfloor next to the external wall and the third next to the internal wall.

 

[Stevers]

I doubt whether this is how this job would have been tackled in the past - it seems an intrusive solution with those girt pads. I have previous - how experienced is your SE, and is this going to be an expensive solution? It's a small thing but retaining parts of the old wall and using that to support a beam would make the history of the building easier to read, it also ought to less work and well within the capabilities of any builder.

Our house from 1879 has a long wall on the ground floor that is not aligned with any basement wall, so has a steel built-in within the floor space, so even then they were using a steel or more likely wrought iron beam. It's a long beam with intermediate support not centred on a shallow stone arch. I doubt that any engineer would be too impressed with that now!

We put an 8' opening through the brick wall that runs along that beam and with the Acrows supporting the ceilings both sides, the remains of the wall above would have hung there without any other support whilst the builder went off to get a 'steel' - that was actually just a lintel. Lacking his faith in ancient brickwork I got him to support it properly before he left the building!

 

[erikwoolf]

I doubt whether this is how this job would have been tackled in the past - it seems an intrusive solution with those girt pads. I have previous - how experienced is your SE, and is this going to be an expensive solution? It's a small thing but retaining parts of the old wall and using that to support a beam would make the history of the building easier to read, it also ought to less work and well within the capabilities of any builder.

Our house from 1879 has a long wall on the ground floor that is not aligned with any basement wall, so has a steel built-in within the floor space, so even then they were using a steel or more likely wrought iron beam. It's a long beam with intermediate support not centred on a shallow stone arch. I doubt that any engineer would be too impressed with that now!

We put an 8' opening through the brick wall that runs along that beam and with the Acrows supporting the ceilings both sides, the remains of the wall above would have hung there without any other support whilst the builder went off to get a 'steel' - that was actually just a lintel. Lacking his faith in ancient brickwork I got him to support it properly before he left the building!

We need to rethink our approach about this whole thing, we will get a second opinion from a structural engineer that has more experience with older properties so they dont try to fit the situation into one of their boxes. I am too spooked to let anyone near the foundations at this point.