Insulating old coal shed that has been converted into a utility room.

Evening, You could use external insulation board and then render over the top. You'll need to check that you have space under the eaves. Steve

There are three main approaches depending on your property type: Cavity Wall Insulation If your home has a cavity (a gap between the inner and outer walls), this can be filled with insulating material such as mineral wool, beads, or foam. It’s quick and effective, but only suitable if the cavity is clean, dry, and in good condition. Internal Wall Insulation Insulation boards (such as PIR/Kingspan) or insulated plasterboard are fitted to the inside of external walls. This keeps heat in, but reduces the room size slightly. Boards must be fitted tightly and joints sealed to avoid cold spots. External Wall Insulation Insulation is fixed to the outside of your walls, then rendered or cladded over. This is the most effective method for older solid-wall homes and also helps protect the building from the weather. 🚫 How to Prevent Damp When Insulating Before any insulation goes in, the key is moisture control. Here’s what needs to be done: Check for Existing Damp: Rising damp, penetrating damp, or condensation must be resolved before insulating. Good Ventilation: Ensure there’s airflow in the property (trickle vents, extractor fans, etc.) to avoid trapped moisture. Moisture Barriers: Use vapour control layers or breathable membranes where required (especially with internal wall insulation). Proper Sealing: Joints between insulation boards should be taped/sealed to prevent warm moist air leaking behind the boards. Quality Materials: Use insulation designed for your wall type — for example, breathable materials for older solid-wall homes. 🌡 The Bottom Line Insulation improves warmth and reduces energy bills, but it must be installed alongside proper damp prevention measures. At Green Energy Houses, we always carry out a survey first to check for any damp issues, then recommend the safest and most effective insulation method for your walls.