Rotten joists under the living room floor

Hi how’s you , Ok first I wouldn’t think your wood worm was caused by the neighbours decking , the wood worm treatment will cure the wood worm but depending how bad the rot was some of the joists likely would of need changed , or the rot cut away and new joists joined along side the old ones . The Most important Thing is that your void below the floor is vented no matter how much room you have outside you still need the vents , this can be done by building in brick vents or if you haven’t the room and the ground outside is to high you need to pipe across some of the other rooms till you find lower outside ground and build the vents in there and the pipe will carry the air across , the min would be to pipes one coming from the outside vent to one side of the room and the other from the far side of the room back to another outside vent to allow the air to flow across the room , if this isn’t vented you will for sure get rot again in this void , it must be vented I do understand that sometimes it’s hard to get somewhere to put the outside vents but no matter they still need to go in Thanks Paul Apex building

You have to have air vents and as many as possible . They can be installed in a stepped manor or through pipes in the wall . If you don’t do that , your floor will rot, again ! It’s unlikely that the next door affected your floor joists .

Replace the suspended timber floor with a solid floor. If you cannot provide adequate sub floor ventilation, a timber floor will be at high risk of fungal decay

Ventilation,ventilation, ventilation!! It’s key to dryness. Don’t rip out and put concrete in. This is bad for the house and your health in the longer term.