The fire authority is the enforcement agency for rrfso therefore why think you need do more? I doubt if the smoke seals (not in tumescent strips) would fit the doors as there would not be the necessary grooves to take the seals in doors that old. Just make sure the doors close positively into the frames and are not wedged open by the occupiers.

Hello Ivor; try the Fire.org website for Fire Authority advice on fitting intumescent strips to Fire Doors. It is correct that there is no Legal requirement to fit them retrospectively IF the Fire Inspectorate (FI) are happy that the current door fit/seal is adequate in preventing the passage of cold smoke. This assessment would be carried out within the Fire Risk Assessment element of you work, subsequently sighted by the FI and coupled with their inspection and confirmation of your assessment. Regional FI are happy to drop in and offer advice on Fire Safety and guidance etc. Older style doors are nout routed to accept intumescent fire and smoke seals, therefore if the FI disagree with your assessment and find the current fit not adequate, you would need to hire a joiner to remove the door, carry out routing, fit the smoke/heat strip and re-hang the door; unless of course your DIY skills are up to grade, which in finality would of course be the decision of the FI carrying a post works inspection. I am currently having 22 older style doors removed, routed, fitted and re-hung but that is because we are a Hospital with vulnerable patients and increased risk accordingly.

There are joiners with third party competence do do such work, you need to ensure your joiner is competent?