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
Draw a scaled elevation showing existing and new windows together. Resolve the roof-edge, wall and window junction before deciding from an atmosphere image alone.
Coordinate finished levels
Compare floor levels, ceilings, thresholds and the garden. Include layers still to be added, not just rough construction dimensions.
Design hidden junctions
Structure, weather protection, insulation and finishing meet at the connection. The trades should use the same detail.
How to review the result
Review the result close up and from the garden. Check junctions and continuous lines; a neat individual joint says little about the coherence of the entire elevation.
Which trade-off matters?
Exact reproduction and a clearly contemporary addition are different design choices. Compare their junctions; an almost matching brick or profile can look less coherent than a carefully chosen contrast.
A situation to test your plan against
A garden room beside a house with distinctive facade details needs a deliberate transition. First record the lines that give the existing building its identity: window heads, roof edges and the scale of its brickwork.
Questions for your own property
- Are finished heights known?
- Who designs the junction?
- How are material differences handled?
Must an addition use the same style as the house?
Not necessarily. Compare scale, rhythm and material transitions. Review two junction details before choosing reproduction or a recognisably new addition.
Illustrative design situations, not evidence of completed work. Assess decisions against the actual property.