Can you insulate behind kitchen cabinets without removing the kitchen?

I've dealt with this situation in two ways in the past on different jobs which have the same issue as yours. In one, we removed all the units, cleaned off the mould, applied a breathable damp seal (Thompson Damp Seal or other good quality breathable damp seal), then refitted the units. In this instance, we found that the cause of the damp was two-fold: firstly, there was no ventilation in the kitchen due to there being double glazing and no mechanical extractors or passive vents; secondly, the owner had built up the outside patio above the dpc level around the kitchen extension. Once we had lowered the outside level to below the dpc, and installed mechanical ventilation (over-hob extractor and trickle vents on the uPVC patio doors), there was no more damp. In the other scenario, we simply cleaned away the mould, installed proper ventilation (again, the house was under ventilated because of double glazing and a lack of ventilation), and monitored the issue. Checked after a couple of months, and there was no more mould. In any event, I would suggest you double check that there is no reason on the outside of the house for damp penetrating the walls (dpc level, water ingress from failed guttering, etc).

It is difficult to judge this case without pictures or site visit but I am sure only insulation behind cupboards does not helps. The problem probably is missing dump proof course in the room by it self or no insulation in cavity wall. This simply needs bigger investigation and help of professional builder to figure out what is the reason of mould coming back

Hi, u have couple options to do, firstly check outside home, if your wall is not damage and damp, water is not penetrate to cavity( doesnt need to be on same level, water can be run down from 1st floor or roof to cavity and find way., another option is build small stud wall and insulate wall, or Cavity walls can be insulated by injecting insulation into the cavity from the outside through drill holes. Regards

Hi, your damp course would have failed, you will need a new one, insulating the wall won’t help, all it will do is make it worse because the damp will Penetrate the insulation and spread,

Most likley condensation caused by lack of airflow behind your kitchen cupboards no amount of insulation will solve this.

As you may have read all the above comments, the possibilities are endless. So, best to get someone to check physically, and possibly the cavity wall insulation (if any) with an inspection camera or otherwise. First thing that springs to mind is cavity wall insulation So as you mentioned, this is an external wall, yes this can be sorted by approved trades that can "pump" in cavity wall insulation.. If anything at least you have insulated your home. Ventilation is a requirement nowadays, so can easily add trickle vents on your windows, without having to replace them. Hope you get it sorted asap.