My dad's shed had a roof wasn't take care of for a while and now appears to have rotted in several regions.


What is the best way to approach a problem like this, and what would be the best solution to it? Also, what is the likely extent of the damage so far, and is this a risk to the roof failing?

Left Side: Left Side

Right Side:

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1 Answer 1


The black is bad. Get a screwdriver and see if the plywood is compromised. Push on the screwdriver and if it goes into the wood 1/8" or further the wood needs to be replaced. If it is still solid I would use a very strong solution of hydrogen peroxide and water 5-8% and saturate all the fungus areas a second treatment may be needed but this will kill the surface fungus that will break down the plywood.

Note that 8% hydrogen peroxide will bleach just about anything including your hair, so use PPE. It can be applied with a paint roller or sponge, at this strength I would not spray it as I do with 3-4%.

Always add acid to water (and not vice-versa) to reduce the exothermic reaction when diluting concentrated hydrogen peroxide with water.

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