[austin]

I was looking for the source of a cold air draft coming from under the kitchen sink. There were pipes going down through the floor into the furnace room and I stuffed the hole with insulation. There was still a draft. I took out the false floor under the sink and discovered water pipes going horizontally through to the dining room. I removed the bottom 16" of drywall along the entire length of the dining room wall and found that the pipes extended across the room behind this wall, then vertically to the bathroom above. This wall is parallel to an exterior wall and there is 6" of space between the two walls. There is no vapour barrier covering the insulation on the exterior wall (other exterior walls in the house do have a vapour barrier). There is an unheated garage under the dining room and kitchen. I also discovered a heating outlet (forced air heating system) between the two walls where the pipes are. The cold draft appears to have come from the space around where the drain coming down from the upstairs bathroom goes through the dining room floor (between the two walls) to the garage ceiling below, and from two other rather large holes in the floor between the kitchen and the dining room. The wood there is rotten, apparently due to water damage some time ago. Everything is dry now. I stuffed all the holes with insulation. Here are my questions: 1) What should I do about the lack of a vapour barrier over the insulation? (2) Should there be a hot air register there behind the wall; is this standard practice? (3) Could I divert the hot air duct (that currently opens into the space between the two walls) into the garage and wrap the pipes between the two walls with heating wires instead?