Transitions between old and new affect whether an extension feels coherent. Differences in height, material and structure should be visible early.
What the drawing needs to explain
Combine the design plan with logistics for storage, deliveries and protected zones. Identify who approves each interface before the next stage begins.
Coordinate finished levels
Compare floor levels, ceilings, thresholds and the garden. Include layers still to be added, not just rough construction dimensions.
How to review the result
Review each building section and then the whole home. Check transitions, operation and documentation; supplier completion lists do not automatically cover every shared interface.
Which trade-off matters?
Running many trades simultaneously can appear to save time but increases pressure on access and working space. Compare parallel work with a deliberate sequence by building section.
Questions for your own property
- Are finished heights known?
- Who designs the junction?
- How are material differences handled?
Who coordinates work between different trades?
Assign that responsibility explicitly. Use an interface register covering design, execution, inspection and making good so work between two quotations does not remain unassigned.
Illustrative design situations, not evidence of completed work. Assess decisions against the actual property.