Mold removal

christiesternerz · 10-13-20, 06:51 AM

I already confirmed that my attic has a mold. What is the best solution for this?

pinballlooking · 10-14-20, 12:20 AM

Take a picture to show us what you are dealing with.

WillyP · 10-14-20, 08:30 PM

usually when dealing with mold, the first thing you need to do is fix whatever is causing the moisture. In the attic it probably has to do with poor ventilation (or a leak). If you cure that, in something like an attic, the mold will practically fix itself. Of course you still need to remove it, but making it dry will stop it from growing.

mk1st · 10-26-20, 12:29 PM

Any mold growth means you have a water problem.
It will either be a 1)water leak or 2) condensation (in rare cases it could be both)

1) A water leak will usually be pretty easy to determine and the mold will be confined to only that area: is the roof in poor condition?, is there a flashing penetration such as a vent or chimney that's failing. The damage may not show up though right under the leak as water can wick along framing members. Fix the ongoing leak and the mold won't be able to grow. Old mold, once it's inactive, is not harmful to most people and if you don't go in the attic I'd not worry about it. Definitely DON'T try to "kill the mold" with bleach!!

2) If you see mold over a wide area of the underside of the roof and framing members then you have a condensation problem, most likely because you have air leaks from your living space up into the attic. In the winter the warm moist air from below will condense on all of the cold surfaces in the attic (insulation won't stop the air movement) Air sealing the attic floor is the solution. Get an energy audit (mainly that's a blower door test with infra red imaging) and you'll get a good idea as to how much air sealing is needed. Once the air sealing's done then you can insulate with confidence.

I know roofers will beat me up over this but this problem (if it's condensation) is NOT because you don't have enough attic venting. A properly air sealed attic needs very little venting - really just to allow expansion and contraction of the air in there when it changes temperatures. Good attic venting is fine but it's not the fix-all that roofers would have you believe (partly because roofers never go in the attic and want the easy work of adding vents).

Now....off to set up my blower door.

MN Renovator · 10-26-20, 05:59 PM

I agree that you don't need a pile of attic venting, but you need some to allow the incidental moisture in winter to flow out. Moisture flows readily and usually it doesn't take much ventilation to remove the amount of moisture that ends up in an attic through incidental air bypasses. If you have attic mold, you've likely got a larger air bypass than just loose wooden top plates, small holes drilled for wires, or a hole cut for a plumbing vent stack. If there isn't a roof leak, most likely there is something like a broken or missing bathroom vent duct, a grossly oversized hole cut for a plumbing stack(square hole for a round peg or someone likes their sawzall too much), can lights(hate these things, there are insulated versions and gasket retrofits that make this a better situation though), or a soffit chase. ..or perhaps you have a cape cod house and a knee wall is involved which could have all sorts of leaks in tons of places, especially the upstairs floor bypass.

When I talk about ventilation, I'm talking about free flowing vents, not powered vents because those make the problem worse by creating a vacuum and sucking the moist and warm interior air into the attic.

I also noticed you are from Spokane. I assume this is Washington? There is a ton of wet there and I know from my friends in Portland and Seattle that their roofs essentially are caked with algae/moss because they are never dry, I don't know if there are any specific building design or science that should be different for your climate and type of house. In my region, the air is generally far enough away from the dew point to where it doesn't take much to keep the attic moisture down. This isn't a livable attic space, is it? How much mold? any particular spots it's common in, throughout the entire attic? ..or above the attic hatch or a bathroom specifically?

nibs · 01-28-21, 07:15 PM

mk1st says
"Definitely DON'T try to "kill the mold" with bleach!!"

My microbiologist friend says bleach is a very effective anti mold agent, curious why you say not to use it?
Also says be careful with bleach on fabric, may discolor or even dissolve it.

MN Renovator · 01-29-21, 12:34 AM

Quote:

Originally Posted by nibs

mk1st says
"Definitely DON'T try to "kill the mold" with bleach!!"

My microbiologist friend says bleach is a very effective anti mold agent, curious why you say not to use it?
Also says be careful with bleach on fabric, may discolor or even dissolve it.

I used to think this way too until I talked to a storm damage contractor casually who told me that on a non-porous surface, mold can be removed with bleach. On surfaces like wood and drywall, the mold apparently has a membrane that lives deep and the chlorine in the bleach evaporates but the water that suspends the chlorine in the bleach takes longer to dry. Basically you might kill and wipe away the mold on the surface, but you'd be giving the underlying mold water to immediately restart growth. Granted if you can keep things dry enough the mold might not spread enough to be visible or to be able to smell it and you might get away with it, but if there is any moisture it encounters in the future, it will come out of dormancy.

His suggestion to me if I ever encounter mold is to spray it down with undiluted white vinegar out of a spray bottle, keep it wet with vinegar for 1 hour, scrub away the mold with towels you are willing to throw away, then spray it down and keep it wet for another hour.

I've read other stuff online that apparently hydrogen peroxide works better than bleach too. ..but I don't think you want to mix any of these chemicals, so do research on mold removal, decide on one thing and stick with it. If it's drywall, I'd opt to spray it down with vinegar to prevent living surface spores from spreading while I remove it and seal it immediately into a trash bag and get it outside as quickly as possible.

WillyP · 01-29-21, 05:40 PM

Quote:

Originally Posted by MN Renovator

I used to think this way too until I talked to a storm damage contractor casually who told me that on a non-porous surface, mold can be removed with bleach. On surfaces like wood and drywall, the mold apparently has a membrane that lives deep and the chlorine in the bleach evaporates but the water that suspends the chlorine in the bleach takes longer to dry. Basically you might kill and wipe away the mold on the surface, but you'd be giving the underlying mold water to immediately restart growth. Granted if you can keep things dry enough the mold might not spread enough to be visible or to be able to smell it and you might get away with it, but if there is any moisture it encounters in the future, it will come out of dormancy.

His suggestion to me if I ever encounter mold is to spray it down with undiluted white vinegar out of a spray bottle, keep it wet with vinegar for 1 hour, scrub away the mold with towels you are willing to throw away, then spray it down and keep it wet for another hour.

I've read other stuff online that apparently hydrogen peroxide works better than bleach too. ..but I don't think you want to mix any of these chemicals, so do research on mold removal, decide on one thing and stick with it. If it's drywall, I'd opt to spray it down with vinegar to prevent living surface spores from spreading while I remove it and seal it immediately into a trash bag and get it outside as quickly as possible.

Bleach doesn't evaporate (like water) But it does break down. It leaves behind salts that do in fact help prevent mold from growing. I've never heard of chlorine based bleach adding to mold growth long term. That sounds like an old wives tale. However there are much better things to use. Many products use enzymes to break down mold. These enzymes literally eat the mold.
No matter what you use, you should clean the surface first with soap and water. Of course something like the rafters in an attic are going to be very difficult to clean.

nibs · 01-29-21, 05:51 PM

My microbiologist friend tells me that bleach kills mold, and does not believe that vinegar kills it, but she does say that it may set up a condition in which mold does not like to grow in, but does not kill it.

WillyP · 01-29-21, 06:12 PM

Quote:

Originally Posted by nibs

My microbiologist friend tells me that bleach kills mold, and does not believe that vinegar kills it, but she does say that it may set up a condition in which mold does not like to grow in, but does not kill it.

That makes sense. Vinegar changes the ph and will make the mold sick.

10-13-20, 06:51 AM	#1
christiesternerz Lurking Renovator Join Date: Apr 2020 Location: Spokane Posts: 2 Thanks: 0 Thanked 0 Times in 0 Posts	Mold removal I already confirmed that my attic has a mold. What is the best solution for this?

10-14-20, 12:20 AM	#2
pinballlooking Super Moderator Join Date: Jun 2013 Location: SC Posts: 2,923 Thanks: 172 Thanked 564 Times in 463 Posts	Take a picture to show us what you are dealing with. __________________ Current project Aquaponics system , Passive Solar Greenhouse build To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. Solar Install 12.5 Kwh- To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. Mini Split installs - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. EV Chevy Volt - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

10-14-20, 08:30 PM	#3
WillyP Helper EcoRenovator Join Date: Jul 2020 Location: Virginia Posts: 30 Thanks: 8 Thanked 3 Times in 3 Posts	usually when dealing with mold, the first thing you need to do is fix whatever is causing the moisture. In the attic it probably has to do with poor ventilation (or a leak). If you cure that, in something like an attic, the mold will practically fix itself. Of course you still need to remove it, but making it dry will stop it from growing.

10-26-20, 12:29 PM	#4
mk1st Friend of Entropy Join Date: Feb 2010 Location: Fort Atkinson Wi Posts: 17 Thanks: 1 Thanked 5 Times in 2 Posts	Any mold growth means you have a water problem. It will either be a 1)water leak or 2) condensation (in rare cases it could be both) 1) A water leak will usually be pretty easy to determine and the mold will be confined to only that area: is the roof in poor condition?, is there a flashing penetration such as a vent or chimney that's failing. The damage may not show up though right under the leak as water can wick along framing members. Fix the ongoing leak and the mold won't be able to grow. Old mold, once it's inactive, is not harmful to most people and if you don't go in the attic I'd not worry about it. Definitely DON'T try to "kill the mold" with bleach!! 2) If you see mold over a wide area of the underside of the roof and framing members then you have a condensation problem, most likely because you have air leaks from your living space up into the attic. In the winter the warm moist air from below will condense on all of the cold surfaces in the attic (insulation won't stop the air movement) Air sealing the attic floor is the solution. Get an energy audit (mainly that's a blower door test with infra red imaging) and you'll get a good idea as to how much air sealing is needed. Once the air sealing's done then you can insulate with confidence. I know roofers will beat me up over this but this problem (if it's condensation) is NOT because you don't have enough attic venting. A properly air sealed attic needs very little venting - really just to allow expansion and contraction of the air in there when it changes temperatures. Good attic venting is fine but it's not the fix-all that roofers would have you believe (partly because roofers never go in the attic and want the easy work of adding vents). Now....off to set up my blower door.

10-26-20, 05:59 PM	#5
MN Renovator Less usage=Cheaper bills Join Date: Nov 2010 Location: Minneapolis, MN Posts: 940 Thanks: 41 Thanked 117 Times in 91 Posts	I agree that you don't need a pile of attic venting, but you need some to allow the incidental moisture in winter to flow out. Moisture flows readily and usually it doesn't take much ventilation to remove the amount of moisture that ends up in an attic through incidental air bypasses. If you have attic mold, you've likely got a larger air bypass than just loose wooden top plates, small holes drilled for wires, or a hole cut for a plumbing vent stack. If there isn't a roof leak, most likely there is something like a broken or missing bathroom vent duct, a grossly oversized hole cut for a plumbing stack(square hole for a round peg or someone likes their sawzall too much), can lights(hate these things, there are insulated versions and gasket retrofits that make this a better situation though), or a soffit chase. ..or perhaps you have a cape cod house and a knee wall is involved which could have all sorts of leaks in tons of places, especially the upstairs floor bypass. When I talk about ventilation, I'm talking about free flowing vents, not powered vents because those make the problem worse by creating a vacuum and sucking the moist and warm interior air into the attic. I also noticed you are from Spokane. I assume this is Washington? There is a ton of wet there and I know from my friends in Portland and Seattle that their roofs essentially are caked with algae/moss because they are never dry, I don't know if there are any specific building design or science that should be different for your climate and type of house. In my region, the air is generally far enough away from the dew point to where it doesn't take much to keep the attic moisture down. This isn't a livable attic space, is it? How much mold? any particular spots it's common in, throughout the entire attic? ..or above the attic hatch or a bathroom specifically?

01-28-21, 07:15 PM	#6
nibs Apprentice EcoRenovator Join Date: Jun 2010 Posts: 206 Thanks: 1 Thanked 18 Times in 17 Posts	mk1st says "Definitely DON'T try to "kill the mold" with bleach!!" My microbiologist friend says bleach is a very effective anti mold agent, curious why you say not to use it? Also says be careful with bleach on fabric, may discolor or even dissolve it.

01-29-21, 05:51 PM	#9
nibs Apprentice EcoRenovator Join Date: Jun 2010 Posts: 206 Thanks: 1 Thanked 18 Times in 17 Posts	My microbiologist friend tells me that bleach kills mold, and does not believe that vinegar kills it, but she does say that it may set up a condition in which mold does not like to grow in, but does not kill it.