My guess is that the odor is very slight and there all the time. The heat and a/c move the air around, probably filter some air so you don't notice it when they are on.

Running the house fan every so often during the in-between season will probably make it not noticeable.

That said, you still want to hunt down the cause of the mold smell before it becomes a big problem.

I suspect the sub flooring may have absorbed some of the odor from the joists and now the laminate flooring particle board will absorb some also. You can do as prettyphysicslady suggested to disperse the odor. You can also use odor absorbers in the areas where you smell the odor.

However, as mentioned, you need to find the source of the mildew. If the carpet was replaced because of mildew, then there's a problem. It may be as simple as adding a vapor barrier on the basement ceiling. You can also use crushed lava rocks which will absorb the odor. After a few months, hang the rocks outside in the sun for a few hours. They are now as good as new. You can purchase these in a home center. They come in a mesh bag (similar to those onions would come in.)

How old is the house? If it's relatively new - less than 20-25 years old, then there's a very, very good chance that the original builder installed the windows and doors incorrectly. If flashing is left out (or not installed properly) water will find it's way to the wall cavities where mold and rot develop. It is impossible to see this mold and rot until it finally eats it's way through the drywall. As you can imagine, there is a lot of material inside the wall cavity for mold to eat before it needs to eat the drywall. If I were in your shoes, I would hire a structural engineer who has an infrared camera (which can "see" the slight temperature differences caused by mold and/or moisture). Other options would be cameras that can be inserted into the wall to see what is behind the drywall. If you have moldy, rotting walls all of the siding/brick/stucco/whatever will have to be removed, the windows probably will need to be removed and reinstalled correctly, drywall may need to be replaced, etc. If the previous owners needed to replace subflooring that's a very serious warning sign. Subflooring doesn't suddenly get moldy because carpet has been installed on top of it. However, faulty flashing can direct water to the bottom plates of the wall and the subfloor beneath it.

Can musty smell be scientifically measured to prove that it exists in an apartment?

Thanks

I beleive its in the carpet,furniture or in the wood in the flooring or attic.Wood will hold the smell and not be visible.

Suziesnowflake is spot on -- if the PO's had to replace subflooring, something's wrong. The problems with window flashing are espeically bad in stucco houses because the stucco traps the moisture inside.

Our house was 6 years old when we started noticing a pretty strong musty smell in several of the bedrooms and in the laundry room. We had noticed the smell on and off for the past couple springs but it would always go away before we'd get worried enough to do anything about it. That year, the smell stayed and got stronger. We had no signs of water intrusion anywhere and no previous mold problems. We took the electrical outlet plate covers off the wall and noticed that the smell seemed to be coming from inside the walls. Also, the screws inside the outlet boxes were rusty. We had several contractors out and none of them could find any sign of a problem - a few of them even said I was crazy (not so bluntly but that was the implication) becuase they couldn't smell or see anything. Finally, one day, we pulled a piece of slightly punky wooden trim off the outside (the contractors all said that that's just a normal thing that happens to wood trim and we should just plan on replacing it once in a while). While we were removing it, the crowbar went through the house. All of the sheathing was completely moldy and rotten - you could put your finger through it.

We ended up spending over $100K (none of it covered by insurance) to replace the entire outside of the house - we stripped it down completely to studs and drywall. Some of the studs had to be replaced. We had to replace all the insulation - it wasn't wet, but was holding the musty smell. We washed the worst of the mold off the studs with bleach. We reinstalled insulation, new sheathing, and new siding (while PROPERLY flashing the windows). It was a nightmare and we're still recovering financially and emotionally (I'm a stress eater and I packed on a good 40 lbs in less than a year from the ordeal).

I hope that your problem isn't this serious, but if your home is recently built (last 15 yrs or so), there's a good chance that it is. After my hard-earned lessons on flashing and homebuilding techniques, I can even today drive around to new developments and watch new million-dollar houses being built with improper window flashing. This is going to become a big problem over the next 10-15 years as all of this hidden moisture starts to manifest itself.

I'd definitely do some investigating since the sooner you catch it, the less there will be to fix (and maybe you can go after the previous owners for some of it if you can prove they knew there was a problem). Start by taking the outlet plate covers off in the rooms with the smell and sniff -- is the smell stronger in the outlet boxes? Are the screws inside the outlet boxes rusty? If so, you've got moisture in your walls and that's not good.

I'll link to my website if you want to look at the gory details of our house....but it's not for the faint-hearted, LOL! And if you do look, remember that even with all that damage and rot, we never had ANY signs of moisture or leaking inside -- all we had was the smell which, like you said, was worst in the change of seasons (spring especially).

Here is a link that might be useful: Worst case scenario....

Doh - just realized this post is 3 years old and was recently resurrected. Hope the OP has it all figured out by now.

I'm glad you posted...I'm having a similar issue...and I'm freaked...anyone have any good news???? please???

Hello
I would really like to know if you ever resolved your mold problem which you posted about in 06. I have the same problem and can't find the source. Please email me at Ltw@hotmail.com.
Thanks, Liza

ME AND MY SISTER WHERE DISCUUSSING IF WATER GETS MILDEW AND SHE SAID IT DOES AND I SAID IT DOSENT WE TOOK A TRIP TO A SCIENTEST ASTRONMY SCHOOL AND HE SAID IT DOSENT AND ME AND MY SISTER HAD MADE A bet so she had to give me $20

I am having a similar problem...I keep smelling this musty smell in my daughters room which is at the back of our 1000 sq ft home. I read about window flashing in the above posts and windows were installed a few years ago, about 5 before we purchased the home which was built in the mid 1960's...also I am noticing in my living room window sill small (picture window) black dots. I'm guessing this is mold. Helllllp, I'm stumped and definitely cannot afford rebuilding of any kind. Although both my husband and I work, our earnings aren't enough to redo anything to this house. Minor repairs we can do, but if we have to do major work, we'd have to do major, we'd be selling the house :o(.

Did you ever discover what this problem was. We might be having the same issue.

I also have this problem. The musty, mold like odor originates from the electrical box in my daughters closet. It cause the entire room to smell. A handy man once place something like flex tape around the base where the meter meets the brick exterior wall. That helped for several years now the odor has returned.