Fire safety is an essential building regulation design requirement for any completed building. It covers aspects such as fire resistance, means of escape, fire spread and space separation. The latter determines the minimum distance of the completed building from a notional boundary such as a centre line of a road. The notional boundary concept applies to every new building, and in doing so, creates a minimum separation distance between completed buildings. For the purposes of this Notebook, this is called 'space separation in-service'. In a completed building, the timber components are protected from the effects of fire by internal linings and external claddings. During construction however, the temporary exposed timber frame structure may present a risk of fire spread across the site, creating a safety risk to people and property beyond the site boundaries. For buildings under construction there are no codes or standards that provide technical guidance to determine what the safe fire space separation should be to existing buildings outside of the site boundary. Within the site, the contractor has the ability to control works and escape routes for the site labour, for which there are training and guidance available. The UKTFA working with the Fire and Rescue Service, Association of British Insurers (ABI), The Fire Protection Association (FPA), Health and Safety Executive (HSE) and Fire Engineers has developed guidance, together with supporting documents, to address this gap in good practice information. The guidance relates to safe separating distances during construction for timber frame buildings with a total floor area >600m2. The work undertaken by these organisations is the focus of this Timber Engineering Notebook. Methods of achieving the in-service fire resistance of completed timber frame structures will be addressed in a subsequent article.