Hi, I'm new to the group (though an avid reader of TOH for years!). We live in an older home (exact date unsure, but estimated to have been built around 1910-1920). It was originally a one floor cottage with open attic, with an enclosed porch that went across the entire front of the house. Through the years it's had numerous rennovations, including chopping the porch in half, and then expanding a small bedroom into the porch space. The old porch part has had little done to it, and what was done wasn't done well. When they closed in part of the porch for the bedroom, they removed the old windows and framed it in, added insulation, but as you can tell, left the old window sill! (you can see if in the exterior photo) The ceiling remains the old wood slats (though painted over), though there has been an access hatch cut in (which is drafty and not sealed off), and insulation added to the space above (there is perhaps a 2' high crawlspace at the highest point). The added closets run along the exterior wall of the old porch and often smell very..... musty? I'm not sure if that's the right word, it's a different smell than what you would get in a musty basement. There is no ventilation in the space. We've noticed over the last 6 months or so that the smell is getting worse, we never used to notice it at all, and now we're noticing it more often. There's no signs of a water leak, my husband has popped his head up and there's no sign of any animals being up there, though there is LOTS of dust/dirt.
Does anyone have any suggestions of what could be causing the smell, and ways to correct it?
I've attached a link to a photo of the exterior of the house and the interior, so you can see the area I'm talking about.