I have an addition on the back of my house which has a flat roof. When originally done, they insulated the ceiling with batts pushed up against the flat roof. Last winter I was having a condensation problem from this and removed the insulation and let the roof dry . After remodeling the room, I am getting ready to put up new insulation, but would like to wash down the rafters and underside of the roof with something to make sure I do not have any mold growth. I have read bleach works, but would like your opinion on what product is available for this? Also, by installing baffles against the flat roof before the insulation,would this solve any moisture problems in the future?
Thanks for the question. This is a common problem when proper ventilation and in properly installed insulation is not done correctly, as you found out. So the resulting amount of moisture build up results in mold build up. In your case it has gotten onto the rafters and the wood of the underside of the roof.
Most often you will read about bleach as the most common product to use when cleaning mold and it is used in situations like this as well. Typically you would mix about 3/4 cup of bleach with a gallon of water to apply to the rafters etc. You would want to mix it thoroughly. Then you would also need a second bucket of clean warm water.
You would always want to protect your skin by wearing rubber gloves when using this process. And the process is to scrub the wood with the mixture using a sponge or cleaning brush working small sections at a time. Be sure to visible watch as you remove the mold and or mildew stains. You would then want to follow by using a clean sponge with the warm water to rinse of the small sections as you work the entire area. You will also need to refresh the clean warm water at times as needed.
Even though this is the most common way of removing the mold, working in tight areas like this, you risk the fumes from the bleach filling up the area and causing problems with breathing and possible eye irritation.
My suggestion in working in areas like this would be to use a product that is more environmentally friendly and one that not only will not cause the issue with fumes and eye irritation, but also would be a proven product to take care of the mold just as well as the bleach.
Once such product is Concrobium Mold Control. Concrobium Mold Control® is a revolutionary way to fight mold, with no bleach, ammonia or VOCs.
Unlike traditional “wet kill” products, Concrobium works as it dries –
hardening over the moldy surface to form an invisible film that
physically crushes the mold micro-organism underneath.
And Concrobium stays on surfaces to provide continual resistance against mold regrowth.
Plus this product can be used throughout all areas of the home. Click on the following photo to see a larger drawing of a home showing the areas where it can be used.
This product can be purchased and man local home improvement centers. So, this and other products like it, would be a better option for you, if you are concerned about the build up of fumes that might be harmful to you or others applying this bleach or other toxic type products.
As far as installing the new insulation, you will need to install the baffles prior to the insulation and make sure you have proper ventilation to remove the air and moisture from this area. I am not sure exactly how this was constructed, but hopefully you will have some time of vents installed and or sofits vents. This area needs to be able to breath so that it keeps the area from developing a future similar problem.
I hope this helps. Rick
Rick Maselli is Founder and Editor of Showroom411.com and Ask Rick