Insulating Attic Before Installing New Water Tank

Bateman

Any reason why one wouldn't do this?
That is, is there any important reason why if you wouldn't want to insulate the attic before installing a new pvc water tank (to replace an existing galvanised one)?

jack of all

Others here will advise better, especially where current building regulations stand, but it would be better to install the tank first and carry out all associated plumbing before insulation. Then if using quilt insulation (mineral fibre or glass fibre) this should be ommited under the tank but brought up over to totally envelope the tank (thus including the tank in the insulated and heated building envelope). A prefabricated tank jacket would make this job easier and allow for easier access for routine maintenance and inspection. Pipework (including all fittings, valves and overflows) need to be carefully insulated to a high standard to prevent freezing. As with any insulation work it is important to understand the processes involved so that problems with condensation and mould are avoided- proper ventilation and vapour controls are essential otherwise upgrading insulation can cause more harm than good in the long term. Make sure your existing tank base is adequate in terms of strength, is properly located, adequately braced and is boarded out with solid wood or plywood to prevent catastrophe should there be any leaks! Downlighters, cable and pipe penetrations, draughty loft hatches etc will all require attention and careful detailing to minimise air leakage and maximise any benefits from insulation.