Removing a load-bearing wall: where does the load go?

Installing a portal isn't the work. The work is establishing where load ends up once the wall is gone - and whether the foundation can take it.

A load-bearing wall carries load from the floors above and the roof, and spreads it evenly along its full length down to the foundation. Remove the wall and that distribution disappears.

What replaces it - a steel portal frame - transfers the same load through two points. That's the core of the work, and it's why an opening doesn't end at the steel.

From line load to point load

Before demolition, load runs down as a line load along the full wall length. After demolition, that same load converges on two column bases.

The foundation under those bases was originally sized for a line load. Whether it can take the concentrated point load is a separate question - and the answer isn't always yes.

This is where openings go wrong. Not at the portal, which is usually calculated properly. At what sits beneath it.

Single or double portal

At larger spans or heavier loads a single beam isn't enough. That calls for a double portal: two beams with matching columns, distributing load across two structural lines.

• Single portal - limited span, load from one plane
• Double portal - larger span or load from multiple floors
• L-shaped portal - load from two directions, for example an extension where the rear elevation also comes out

The section follows from the calculation, not from a rule of thumb. HEA and HEB take substantial load at limited construction depth; IPE is slimmer and suits lighter loading. Where the structure stays visible, available depth also feeds the choice.

The sequence is fixed

Prop, then demolish. In that order, always. The structure above is propped before a single brick moves.

Propping isn't the item you cut to save a day. You never get that day back.

Once set, the structure is loaded progressively by releasing the props in stages. Settlement then happens under control rather than all at once.

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