A modular sofa encourages rearrangement, but its name is not a promise that every section and connector offered under a familiar search term will work together. Before adding a module or replacing missing hardware, identify the parts you actually have. The useful drawing shows product identities and approved connections, rather than only the sofa shape you hope to create.

Read the connection as part of the named instructions

IKEA's SÖDERHAMN corner-section frame instructions, document AA-570543-5, depict a corner section joining adjacent seating in steps 9 and 10 on printed page 22. The drawing includes connection hardware beneath the seating. That is a documented arrangement in a particular instruction set. It does not demonstrate that another module, a later revision or a similarly shaped clamp is interchangeable.

Use the applicable manual to locate the connection question before shopping for parts. A photograph of a metal component may help the maker identify it, but appearance alone should not become a compatibility decision. This article has not assembled a sofa or tested a replacement connector.

Make a module and connection map

For a hypothetical extension to an existing sofa, list each module's exact product identification and any available instruction reference. Sketch the intended arrangement and mark the proposed joins. Where an identity is missing, leave a visible question mark. A tidy plan with an unknown module is still an enquiry, rather than a ready-to-order bill of materials.

Ask the manufacturer or responsible supplier to confirm whether that exact combination is supported and which hardware belongs to it. Include revision or purchase information if available. Do not assume an accessory listing describing the range name resolves every variation. A documented answer may identify the right original part, require more information or rule out the arrangement you first drew.

Separate a room-layout change from a parts substitution

Once compatibility is confirmed, use the relevant complete assembly instructions or an appropriate provider for the work. This article does not reproduce the connection procedure, prescribe a tightening value or recommend hardware from another system. A visual room plan can explain your intention; it cannot authorize a mechanical substitution.

Keep the final module identities, connection answer and applicable instructions together. If buying secondhand, make unresolved hardware part of the purchase decision before assuming a cheap section completes the sofa. The best outcome may be a confirmed addition, a different approved arrangement or no extra module. Modularity is useful when the actual connections, as well as the room proportions, have an answer.

Sources & further reading

Published sources for the details and examples discussed in this story.