Eliminate mold from ceiling

[kiotick25]

It has been a while since I have been on this forum. I have run into a problem with my workshop. I'm developing mold on the ceiling at the interior eaves of the bldg. This workshop is a basically a non-insulation sealed box. The condensation between the exterior and interior of the bldg is causing moisture to stand on the interior of the metal roofing allowing mold to develop. I definitely seem to have more mold growing on the south facing side of the interior of the building than the north.

Specs on the building are below along with a picture may be reviewed before I get into what I think may resolve the issue. However, that is why I'm posting the question here before committing to a solution.

see attached picture

30x36 metal building 14' eave, 19' at top of A-frame.
2x8's (doubled) purlins used to support the metal/snow load spaced 2' apart.

1. I do-not or would not prefer to insulate the building, there is no need based on my limited use. The building works fine for my use as it stands right now, simply need to eliminate the mold from a minimal cost perspective.

2a. I believe using a gable fan whether it be a signal or multiple gable mounts to flush moisture out would work, but...
i. problem I see with this is since I have channels of depth between the 2x8's.... is the draw of a gable vent fans going to pull the moisture away from between those sections? I think if my interior roof was flat and not partitioned in such a way I would likely agree this is the way to go.

2b. Or using 4 industrial ceiling fans equally spaced in the 30x36 building to pull air to the ceiling drying the condensation equally a better plan?

3. Looking for other options....ie... I don't know what I don't know for example.


Thanks

 

[kiotick25]

Here are some simplistic drawings of the two examples.

 

[Shawn S]

Mold is a living organism. It needs food, water and air to survive. From what you have typed I see the water and air, but where is the food coming from? Sheetrock paper is a good food source now that standard sheetrock paper isn't treated. Wood can be a source. But painted metal?? Have you tried cleaning it? Maybe there is something there from day 1 that is providing the food, and a simple cleaning will eliminate the mold and its food source.

 

[kiotick25]

Shawn,

The mold does wipe away after spraying the metal with a mix of bleach/water using a garden sprayer. Which is good, just not something as an annual project I want to look forward to.

I painted (sprayed) the entire interior of the building with white roof paint mixed in with a radiant barrier powder. This was done several years ago. The reason I painted the interior was after about 2 years from completion of the workshop I started to see badly stained 2x8's from the condensation buildup on the sheet metal. It would run down to the 2x8's then drip onto the floor. The roof 2x8's are not treated lumber so I wanted a way to protect them from rot. Painting them and the building seemed the best course of action.

Since painting the 2x8's this has eliminated 98% of the condensation dripping onto the floor. But it appears there is still some condensation just not enough to accumulate and then drip onto the floor.

However, this year has been exceptionally wet with several maintained days of high humidity on the east coast. Which I believe is due to seeing mold this year and not in years past.

 

[matt_i]

Ceiling fan is your best bet. Keep air moving and it will not be able to nucleate the life forms...too dry...

 

[walta]

If you have no plan for heating or cooling, I would ventilate it.

1 square inch net free ventilation at the ridge for every 600 square foot of roof area, plus 1.25 square inches of net free ventilation as low as possible for every 600 square foot of roof area.

This should keep indoor and outdoor temps very close to the same. What I think is happening is your building is full of warm moist air when a cold front passes by the sheet metal cools below the dew point if the indoor air water condenses on the metal dust stick to water now the mold has everything it needs to grow.

Walt

 

[Firebrick43]

Don't use bleach on metal! Notice deicing chemicals are sodium chloride, magnesium chloride and such? It the chloride that's is corrosive.

Sodium hypochlorite(aka bleach) is corrosive even to stainless steels.

 

[BillK]

How hard would it be to retrofit a ridge vent ? I would think that would be the easiest way to get ventilation across the entire underside of the roof.

 

[NUTTSGT]

I'd get some ventilation and a fan moving some air. I'd imagine the air gets quite stale when you first go inside after having it closed up.

 

[kiotick25]

Thanks for the responses. I'll start off spacing equally 4 ceiling fans on a switched timer to come on in the AM for 3 hours when the condensate has a chance to occur.

If that doesn't take care of it then I'll transition to phase two and install two 16" gable exhaust fans.