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Is this the arrangement?

UC posts! OMG NOOOOOO!! OK, lets get to basics. Your beam will be carrying approx 16 m2 of flat roof over a span of 5.7m, right? Live load will be 0.75 kN/m2, so tot 16 x 0,75 = 12kN - x 1.6 for the partial s/factor = 19.2kN dead load (assuming joists + chip deck + finish) will be approx...

Far too big for a roof of that span - that's not engineering, just guesswork. IMO and with a back-of-fag-packet calc, a 203 x 133 x 25 would be the optimum in bending and deflection. And you don't need a pier - waste of time and money.

Why do you need a pier? The beam won't be carrying a particularly high load if its just a flat roof? You could sit the new steel beam direct on the 1/2 brick wall on either a concrete padstone or a suitable steel spreader plate. Presumably the end of the steel beam would be covered by a fascia...

Yes the lintel has failed, caused by expansion rusting of the steel reinforcement. Water has obviously been getting in somewhere. In the 1960s, they generally didn't bother too much about cavity trays above lintels. Ultimately it would need to be replaced by a couple of steel beams running...

If the existing beams are in line on opposite sides of the wall, there's no reason you couldn't put the new beam(s) directly underneath. (if the space on the left was an original kitchen its quite possible there are timber beams across that part, particularly if its a pre-War house).

The fact that there's a pier on the right-hand side of the wall suggests that the beam is in two lengths (there may be one or two beams to each span). If they are separate, its unlikely you'll be able to join them effectively, and the elongated beam would be highly unlikely to span the full...

As long as you're only going to be storing light stuff up there (kids old toys, suitcases, decorations etc) you could notch the ends up to nearly half the depth of the joists - it won't affect the deflection or the bending strength; all it affects is the shear stress at the bearing, which is not...

A typical padstone of high-strength concrete might be 140-215 mm deep. A steel bearing plate could be as thin as 12.5mm (depending on load and beam flange size).

One of the factors affecting pad size is ground bearing capacity which can vary widely. In the absence of soil testing, most SEs assume a ground-bearing capacity of around 100 kN/m2 for unfactored loads. So a 1m x 1m pad would be assumed to support an unfactored load of 100kN. In a domestic...

Instead of concrete padstones, steel bearing plates can be just as effective if the right thickness.

Some builders are now using studwork for the inner skin, maintaining the 50 cavity, and filling the space between the studs with 90 PIR, but it needs 32.5 mm insulated plasterboard internally. The relentless increase in U-values is becoming ridiculous and using up valuable space, critical where...

I'm sure we could all debate the thicknesses of insulation 'til the cows come home, but it seems to me that even many inspectors now don't appear to know what type and thickness of different insulation products will give the required U-value. They keep increasing the standards every 2 or 3 years...

For the rafters themselves, structurally it isn't a problem. Assuming its a loft conversion, its probably easier to use deeper rafters to accommodate the ridiculous thicknesses of PIR now required for insulation, without having to put too much more under the rafter. As above, the stud wall will...

There might be a trimmer across the hallway at the top of the stairs?

The white stuff on the corbel is efflorescence ie salt coming out of the brickwork. Not usually an issue, though can sometimes be due to water penetration. The crack is not subsidence but most likely thermal expansion of the wall.

1. Yes 2. Yes 3. Yes, but as per 23vc a bit over the top. A continuous beam is generally better than two separate beams.

In that case, I'll probably have at least 300 bifold beams from over the last few years due to fail. Remind me to check my insurance is up to date.

Many builders are now finding it cheaper to use a standard I-beam with a projecting plate welded underneath to support the outer skin. The manufactured lintels like Catnic and IG are becoming very expensive. For a span of 2.6m, the "extreme" lintel is overkill; I think they use something like...