The aim is controlled ventilation, not accidental gaps. As unwanted draughts are reduced, check that kitchens, bathrooms and living spaces still have suitable ventilation. Existing damp or condensation is a reason to assess the whole situation rather than seal more openings. Ask the installer how the proposed work will maintain fresh air and moisture removal.
Join the discussion: What ventilation is fitted now, and do you already see condensation?
Suggested next step: Include ventilation in the scope of any insulation or draught-proofing work.
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