Two days ago we got a
mess of snow here, like 10-15cm, it still hasn't melted away. The hatch insulation was doing fine, couldn't feel cold air dropping like usual in this weather.
Unfortunately, this morning there was a puddle of water on the floor under the hatch
This got me worried, I thought maybe I drilled too deep with the screws? So I unscrew the new internal hatch and I see that the external hatch is dripping wet with condensed water.
So here is my theory: The old hatch is fiberglass and doesn't insulate well, so we were losing lots of heat through it. That heat would melt any snow laying on it. Add that it wasn't sealed well and there was always lots of airflow around the edges (warm air leaving, cold coming in) which took any vapor with it. Now, with the second insulated hatch in place and more seals around the perimeter, the old hatch is much cooler and there is much less airflow. Since it is in the highest point of the house, warm moist air will naturally rise there and since there's not enough draft to suck it out, will condense on the external hatch.
So, what do I do now? If I put the new hatch on the problem will persist. If I don't I'll keep losing heat, eh. Next year we plan on redoing our ventilation into an active system that will suck warm air from the kitchen and bathrooms and run it through a heatpump to warm water. I could add a small duct to suck air from around the hatch, since it's the highest place in the house. If we have enough $$$ I'd also like to add insulation to the roof, and then I'd replace the old hatch with an insulated model. But until next year it looks like I'll be losing heat :verysad: