A plastic vapour barrier and fg are the worst choices for insulating basement walls. But if that's what you have, at least keep the humidity below 50% RH. I suspect the odour is taking the easiest route to your nose. Not all mould is visible. And not knowing your construction, details, it 's possible that the mould is growing under the base plates for your walls. Are you sure it's not sewer gas from a dry trap or unvented appliance? The bathroom in a rental house I owned always had a dank smell. I attributed the aroma to the hygienically challenged university students who lived there. But when they moved and I renoed, I found the appliances were vented into the wall, not into a stack. Here is a link that might be useful: Building Science Corp. on Basement Insulation

I think you should STOP drying your laundry by hanging it inside your loft at once. (Not that I am a foe of clotheslines, I live not far from you and I dry almost all my laundry on a line year-round, but only outdoors.) Indoor laundry drying puts a tremendous amount of water vapor in the air of your loft and then you go away and shut it in. It's not surprising to me at all that you have developed a moldy/musty smell problem. I hope that it can still be cured by simply lowering the ambient humidity and cleaning the existing problems. First of all you should get some dehus running whenever you are at the loft. If you can set one up to dump into a drain, you could run it when you are in NY. It is likely that when the loft was converted it was tightened-up in a big way. That saves energy, but leaves any excess humidity trapped inside making the problem much worse if you are adding moisture. If you must line dry then do so only on an outdoor line. I have one of those non-venting condenser-type dryers which evaporate the water out of the exhuast stream. I can easily "harvest" more than a couple of gallons per week. That's the same amount of water you're evaporating out of your laundry and leaving inside your closed loft while you're away. I also use Miele washing machines (and Askos) so my stuff which produces this amount of water is being washed in high rpm Euro machines, like yours. Now to cure the problem of the smell, I would first make sure you haven't acquired a smell problem inside your Miele. Do you leave it open when you are away? That's a very good idea. I would run a rigorous clean-up cycle in the washer first thing when you return. Also consider running at slightly hotter temps on a routine basis. (And with a Miele, I know you can, ::smile::). Then make sure you are using the highest spin possible to extract more water inside the machine. Now about clothes drying, doing so in front of open windows might make a difference but that's probably out for the season. I do dry outside even at this time of year, but often have to leave my stuff outside for a day or so to sublimate all the moisture out. That probably isn't possible in a semi-public area like a loft conversion. Have you considered getting one of the conenser type dryers? I have mixed feelings about them. My model is an older Asko, and I think it isn't as moisture-tight as the current models from either Miele or Asko. It does add a perceptible amount of moisture vapor when I run it. But in a situation where you can't run a dryer exhaust pipe, condensers do work pretty well, though. And they are far better than drying indoors, especially in a modern tight structure. Have you noticed any subtle moisture problems on books, paper or art work? To remediate the current smell problem I would plan on doing a serious cleaning of most surfaces, including thorough washing of all bedding; steam cleaning mattresses, rugs and upholstery; washing walls and floors and vaccuuming everything else. All that should take place after a period of running dehus to get any existing moisture under control. That should take care of it, though it will be a big job. Basically you have to clean off all the surfaces that might have acquired a thin layer of fungal growth. I would use hot water and Dirtex powdered cleaner on washable surfaces. (Dirtex sometimes is hard to find, once source I know of that may be close to you is the Benjamin Moore dealer in Bennington.) You might also want to consider getting a vaccuum cleaner with a true HEPA filter so you inhibit spreading of spores when cleaning. Finally, if you have breathing or other health problems you might wish to delegate this cleaning to someone else. Or at least wear one of those tight-fitting 3M filter masks (cost about $15 at HD or Lowes). (Not just the small dust masks). When dealing with a fungal problem (mildew and its musty-smelling cohorts are fungal not bacterial issues), keep in mind that most environmental fungi need several conditions to thrive: Free moisture in the air, certain temp parameters (basically what we like, ranging to a little colder), lack of light, and still, unmoving, air. Many of them also need a certain amount of their preferred food, which can range from paper, to waxes and grease (like from not using an exhaust fan when you cook), to just plain old household grime and dust. These are exactly the conditions you may create in a space like your loft when you are away. Changing several of these factors will help enormously in discouraging the problem from reoccurring. Changing what you can will help, even if it seems like small changes. Don't think you have to sterilize or eliminate all of the mold spores. You couldn't do that effectively anyway, and the space would be recontaminated as soon as you opened windows or doors. You just have to lower the overall load and change the environment enough, and it will make a difference. I once livid in a very humid area in the tropics, without reliable electrical service to run A/C or dehus. That required unceasing daily attention to modifying the environment to lower the fungal issues. And every now and then, I'll open a book, or long-closed carton, and poof, out blows a little wiff of the jungle. (I'm not terribly worried about reinfestation from that as those fungal beasties require torrid conditions to thrive; they'd expire of the cold up here in upstate NY. Tee-hee!) I think if you make a big effort you can resolve this. Good luck! Molly

If smell mold, there is probably mold. Mold can hide in walls. I suggest getting a company that specializes in mold inspection/ removal. Mold can make some people sick. I have seen walls painted over to hide mold in re-sells. Once I had a garage, the room smelled like mold. When I went to fix it, I open the drywall & there was nasty mold.The previous owner just primed over it! Ugh. Tore down the wall to studs,treated the studs, aired out, re-drywall. Smell gone. I highly suggest a Pro for removal. There are many types of mold. Some can be quite toxic & don't want to be exposed to it.

The fact you have dust in vent openings eventhough the ducts were cleaned one year ago prove's that duct cleaning is a waste of money(except in rare cases). Since your place is a little over 1k miles from me and I don't have many facts to weigh,I'm going to suggest (A) Use pleated filters (Merv 8 or higher) and be sure filter fit's so that no air can bypass. Some systems have more than 1 filter that are in different parts of home. If you can't buy filters that fit,either special order them or have filter rack changed to the largest commonly avaliable size filter possible. (B) Have evaporator coil cleaned and tell them to clean the catch pan and drain line while in there. Don't worry with cleaning ducts again(other than what's done if filter rack is changed). Not only will that help with musty odor,your system will operate more efficient and you lungs will thank you.