Leaks at, for example, sockets, telephone sockets, antenna sockets can increase the house’s heating needs by 2–5 kWh/year per item It may therefore be worthwhile to seal with a suitable sealant, so you avoid unnecessary heat loss and reduce costs.

You seal leaking sockets by disconnecting the power and opening the box itself. Here you grout with a suitable sealant in the penetrations, and grout along the outer edge of the box towards the wall mounting. When the sealant has hardened, the box can be put back together and the power connected.

You can read more good advice about improving the house’s density plan here: