When heritage timber repairs, shaped/arched panes, true muntins, tricky access/scaffolding, or consent add lots of labour and materials.

Both improve comfort a lot. New thermally-broken aluminium usually wins on whole-window warmth. Timber retrofits feel warmer at the frame than older aluminium.

Possibly. The glass is warmer, but older non-thermal aluminium frames can still show edge condensation on cold mornings, depending on your home’s humidity levels.

Often you don’t for simple retrofits but check locally. Full replacement is more likely to need consent, especially with reclads/layout changes.

Retrofit installations are typically faster and carried out room by room, minimising disruption and keeping the site tidy

Replacement requires more site work and finishing, but it delivers a full new window system.