Mold Identification on Deck Boards

Kent Adams

Kent Adams
User
Does anyone know what type of mold this is in the pictures? It's attacking the stringers and boards of my deck and rotting them out. I want to find out how I can remediate it. The first picture is of a stringer rotting and the 2nd is a deck board with a close up of this mold. Thanks.
 

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Kent Adams

Kent Adams
User
Jeff, the house is bordering Pisgah National Forest in the Wild Acres/Little Switzerland area. Does Terminix work with mold?
 

Jeff

Jeff
Corporate Member
DQ
Yes, I remember your house over there. Your location still says Greensboro.

I don't know if Terminix treats mold but I'd call them and ask.
 

Phil S

Phil Soper
Corporate Member
DQ
I will take a guess. A form of white rot fungi, Bjerkandera adjusta aka Smoky Bracket fungus. Effect on the wood is white rot. Decay rating is severe. Growth rate is fast. This info is from the reference book Spalted Wood by Dr. Sara Robinson. Unfortunately the book is about where to find and how to grow the many fungus but not how to kill it.
 

Tarhead

Mark
Corporate Member
DQ
How would you remediate that? Cut it out and sister in new joists? Once rot starts it's in the wood and other than treating the surface there's not a lot you can do for a structural member of the deck. I would never trust it.
The decking needs to have an open space between the boards or this will happen. Over the years compost builds up in those openings on top of the joists and the joists never really dry. We had something similar happen with our deck in Asheville under Pine trees. Just sweeping the surface doesn't help. A strong blast from a water hose a few times per year will keep them clean and dry.
 

Skymaster

Jack
Senior User
DQ
too late to remediate, pull the top decking, reframe it all structural strength severely compromised. new deck sorry
 

Kent Adams

Kent Adams
User
Jack, this is a 2000 square foot deck with a total of 20 square feet of this fungus, approximately. I would have to spend $80,000 to reframe the entire thing. I'm going to try anything first before contemplating reframing the entire structure and if I did, it would be composite only. Without a doubt, the infected members have to be removed. However, if I can identify the species of mold, I can apply some sort of defensive measure across the remaining frame.

Mark, one of the remedies I'm looking at is placing copper flashing on the new joists on the top. I pressure washed the deck completely and thoroughly last year and I actually believe that may have caused this. I'll sister in the new joists back to the wood that isn't effected on the old joists and then remove the old infected joist.
 

Oka

New User
Oka
looks like Typical white wood mold. 20% bleach or 30% borate mix will get it killed then make sure the wood is dry, then treat the deck with 2/3linseed oil and 1/3 paint thinner or turpentine) mix. Spray the deck with the Hudson sprayer until it gets a little shiney, but make sure it fully absorbs within 5 secs +/-. Otherwise you will have build up and that looks crappy. If you get too much on just use a roller to remove the excess. This is the standard treatment for this and has been since I was a kid (before electricity)

There are a lot of types of wood mold it could be but, that is hard to tell by looking at it. This type is rarely dangerous to your health, like some of the black varieties can be.
 

Kent Adams

Kent Adams
User
looks like Typical white wood mold. 20% bleach or 30% borate mix will get it killed then make sure the wood is dry, then treat the deck with 2/3linseed oil and 1/3 paint thinner or turpentine) mix. Spray the deck with the Hudson sprayer until it gets a little shiney, but make sure it fully absorbs within 5 secs +/-. Otherwise you will have build up and that looks crappy. If you get too much on just use a roller to remove the excess. This is the standard treatment for this and has been since I was a kid (before electricity)

There are a lot of types of wood mold it could be but, that is hard to tell by looking at it. This type is rarely dangerous to your health, like some of the black varieties can be.
Thanks Oka. I've heard something similar from a friend that did deck repair.
 

Kent Adams

Kent Adams
User
Jeff asked about the temperate rainforest where the deck is located. I took this picture over the weekend from behind the deck to give you guys a look at what it looks like at my elevation. The picture is of the understory of the forest.
 

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