--76.125.xxx.xxx

No way to verify if the tenant is telling the truth. In the house there is fiberglass insulation in the walls where when remove the fiberglass insulation is filled with mold where chalk all the seems then spray foam the cavities where there is no air transfer then there is no mold. Check the house where all exhaust fans are working in the bathroom and kitchen along with checking the dryer vents for leakage. The basement may need a sump pump to clear out water around the foundation. Sometimes the walls around the basement may need to be waterproofed by installing a barrier below the grade then drainage to remove the water. Hot water heat does not dry out like forced air where it is going to be expensive to install a furnace. Had a tenant complain about mold in the bathroom where she was doing laundry in the bathtub where the walls were insulated along with exhaust fan was in the bathroom. She called the building inspector where she was causing the problem. Sometime tenants dry laundry in the house where that causes humidity to build up. View some videos on You tube about installing a waterproof barrier around basement walls on the outside. Insulation board does not absorb water where insulating the basement walls will prevent heat transfer along with no mold on the walls. Fiberglass is the worst insulation out there where they sell as it is cheap. Solid board or Roxul is much better. --147.194.xxx.xx

Interested in this topic myself. Got a rental with a crawl space that has insulation falling down in it, monster crickets and a dehumdifier that I'm not sure is doing it's job well enough. Is there a home tester that people have used that can detect if the air quality shows the presence of mold in the air or poor air quality? I fear the exchange of crawl space air and living area air. --167.102.xx.xx

Check the attic to be sure no leakage in the roof or structure. A lot of tenants are reluctant to use a exhaust fan in the bathroom where can buy a humidity switch that will run exhaust when humidity builds up. Installing a low flow shower head minimizes humidity build up in bathroom. If the tenant is drying clothes in the house then a outside clothes line. A lot of tenants are simply lazy where they do not care about the problems they create. Radiant heat does not stir up dust like forced air along with a indirect hot water can be used where the boiler heats the hot water tank. In the kitchen a exhaust fan above the stove will put humidity outside. Some older houses use a window where there is no exhaust fan where the tenant is too lazy to open window after a shower or bath. More then likely if the tenant has bad habits the humidity build up will be the same where they move. --147.194.xxx.xx

42 years ago, I moved into a cute little 1944 build stucco Craftsman Bungalow house in San Diego. I was a renter. There was mold growing up the bedroom walls, lots of mold in the tiny bathroom, musty smell all over. I tore out all the yukky carpeting, cleaned everything with bleach, and I opened the casement windows, screwed them in place with a 4 inch gap and have NEVER closed then again. Lots of fresh air, no more mold, nothing musty. Would not recommended this for Landlords to advise their renters, but in our climate and being only 1 mile from the ocean, it works for me. Sometimes you just can't get all the mold out. I have one closet (front bedroom) which I put those Damp Rid, hanging moisture remover bag in every few months. That closet still builds up mildew/mold no matter what I do. Lots of mold on clothes and shoes before I found the Damp Rid and now I don't store any cloth items in that closet. Unless there is massive air flow, you will never get rid of mold no matter how hard you try. Comes free with the rental? A selling point for the scientific minded tenants? When I did my first and only eviction and the Tenant cried...mold...the judge told her to 'prove it'. Ha. She couldn't, case closed. --72.199.xx.xxx

BRAD --73.102.xxx.xxx

My tenant herself had allergies but they were caused by the hay for her rabbits stored in the apartment so that's why the windows were open. Your tenant's habits probably have something to do with it also. You did the best you could with the dehumidifiers and letting her out of the lease. My living room just started smelling like mold. I have some antique furniture in there. Cooking smells will stick on the surface and feed the mold. --71.104.xx.xxx

Our church has a basement that wasn't used for the summer a few years ago. They shut off the air conditioning down there and when they went back down, everything had mold on it, the chairs, the desks, etc. It wasn't the normal black mold. They had to clean everything up and they learned a valuable lesson - you have to keep the air fresh and circulating in the basement. Since they have done that, we haven't had any more issues. --99.165.xx.xxx

Wait, you let the tenant store stuff in the basement? Lock the door. If it hasn't happened to you yet eventually you'll wind up with a basement full of empty boxes and old junk. And she has kids who will go horse around in the basement and cause damage Maybe. At my cabin when it's very wet things can get mildew that is not mold and if you refer to old posts on this site you can't differentiate between bad mold and mold. So there's no reason to test for mold because mold is in the air everywhere. I servings the use of Damp rid. It also comes in a container w a resivoir they you can put in a corner or under a sink. I have a garden level unit and it is damp during the summer. Dries out in the winter. If you are not able then you need someone to check out what looks damp in the basement (or attic) see if the tenant has windows wide open. Good time to go is after a heavy rain. BTW what has been the experience of prior tenants? --99.203.x.xx

Mostly a housekeeping disorder, not picking up wet towels from the bathroom, opening the window after taking a shower, air flow needs to improve to -mix the moisture- so it can disperse easier, dryer vent? slightly open a screened basement window so that area can dry out, finished basements are very hard to keep mildew free until you cut away the bottom 8-12 inches of wall so the air can flow again. --76.188.xxx.xxx

Mold can grow only in the presence of excess moisture. Basement moisture problems are sometimes nothing more than poor gutter/downspout maintenance. Clean the gutters. Put an extension on the downspout to divert water at least 4' away from the foundation. This may or may not solve your problem, but it's something you should before looking at expensive alternatives. --107.141.xx.xxx

Thanks to all of you with great ideas. Brad I think you might be correct as I have an old boiler in there and it is on its last leg. I think when the tenant moves and before winter comes, I will replace the boiler with a forced air furnace so it moves air and filters it too. I learned yesterday that a HEPA filter air purifier works better to trap mold and bacteria that a de-humidifier alone. There is no movement of air in a house with hot water or steam heat. I tried to Google if hot water heated houses get more mold than forced air furnace houses but I did not find anything to make that claim. --76.125.xxx.xxx

Changing out a boiler can be done is less then a day along with a indirect hot water tank. It is more cost effective to keep the heating system that was installed in the house. As most houses were better insulated then high heat was no longer required. High efficiency furnaces the temperature coming out the registers is lower as the secondary heat exchanger extracts heat that would go up chimney. Find forced air furnace there more dust and noise compared to boiler system. Installing a furnace it going to involve tearing out walls for piping for the system. It is going to create a considerable amount of mess as well. Would not recommend if anyone is living in the house. Pick up some humidity meters to check the humidity in the house. --147.194.xxx.xx

Robert, I agree with you. You are a qualified person to ask these things. The furnace conversion can only be done while the house is vacant. I am not fond of cutting walls and adding ductwork, but airflow from the furnace and filtration should keep mold at bay. Replacing the boiler would be about $3500 and adding new forced air system might be more with the house alterations, but this way I could add central air later on too. This summer season was hot as hell here with temperatures in the high 90s and keeping that way for weeks on end. It was humid too. I was looking at humidity meters/guages on Amazon, not sure which one would be more accurate. I read somewhere if the humidity level in your home is higher than 50% you should use a dehumidifier. What do you say. --76.125.xxx.xxx

--70.161.xxx.xxx

If the house is well insulated with spray foam then demand for heating and cooling is reduced. A metal roof does not get as hot as shingle roof where the vent is on top of the roof. For air conditioning then can install a split heat pump which can be used all year round for heating and cooling. In the event the heating system fails then use can use the split heat pump. A high efficiency split heat pump is more efficient then coil installed in the furnace as there is no duct work. So often people on adding a heating or cooling without thinking about how to reduce the amount of energy use. The most important issue when renting out a house or rental unit is having low energy costs which makes it stand out from other rentals. So far in the house there is a metal roof which is much cooler then shingle roof where at night it always cools off. Having exhaust fans in all the bathrooms and kitchen will exhaust all the humidity. View some videos on You tube about split heat pumps and spray foam insulation. Unlike fiberglass there is no air movement where no mold. Was in northern Germany two years ago where fiberglass insulation is not used, shingle roofs are not used along houses do not use furnaces where no air conditioning. It started to get dark around 10.30 at night as much further north then here. Houses use metal or clay tile for roofs along concrete block or poured concrete with stucco installed over insulation. To find a house with bricks is rare as most houses have stucco, insulation over brick. Heating is by boilers with panel radiators or radiant floor heating. In the house slowly adding more insulation where taking out the moldy fiberglass then installing spray foam which has no air movement. Can see the different with a thermal camera. Have ceiling fans in all the bedrooms. During the day close windows then at night open windows. Here most houses use furnaces if built in the fifties to now where boilers are only used in expensive luxury houses where there is a snow melt system installed in the driveway. --147.194.xxx.xx

My tenant complained about "water, running down the wall." It was on a wall which had no plumbing or water source and California was experiencing a drought. I explained this. She dropped it without further complaint. A year or so later she complained about mildew in a different room. I explained she needed to clean it and open the windows. One day we were there working outside during a heatwave. We noted she did not have a single window open. Turns out she had never opened a window in several years and didn't know how. Not even when showering or cooking. She had dirty clothes all over the floor and closed drapes. In short, the tenant was creating her own problems by refusing to open the windows or clean. She literally never cleaned anything. (apparently mold can grow on dust). So start with a simple solution like cleaning and regular air circulation. My husband used to call her the Dirty Millennial. --23.125.xxx.xxx