1st winter in new shed, getting some mold question

[remagenman]

I built a loft area in shed, which is 12x16, and was starting to put up some insulation I noticed the rafters have a fine black dust/mold on some of them and the top of my plywood sheet (loft) has a subtle gray mold on it, as some leather briefcases I had stored up there.

Is this normal? I googled ideas and some came up as maybe being a "cosmetic mold" and not harmful but really cant say for sure. Best way to treat?

I live in a very wet rainy area and have a gable vent, soffits are open but covered with wire mesh and the ridge is vented. The rain hits my front door and gets wet so some moisture gets inside but nothing alarming.

Is this excess condensation that needs to be dealt with or normal for sheds?

Thanks.

 

[u2slow]

I'm in a very damp climate too.

Concrete or wooden floor? Door has weatherstripping?

The sheds I have that perform the best (stay dryest) have wooden floors above grade, and only minimal top venting (gable or soffit) Air ingress near the floor seems to create a constant convection draw that keeps pulling moist air through.

 

[remagenman]

I'm in a very damp climate too.

Concrete or wooden floor? Door has weatherstripping?

The sheds I have that perform the best (stay dryest) have wooden floors above grade, and only minimal top venting (gable or soffit) Air ingress near the floor seems to create a constant convection draw that keeps pulling moist air through.

Floor is wooden, above grade on cement piers. It's dry inside and no visible water leakage from roof. No seals around doors( 2 barn style front doors that swing out).

 

[Bretny]

If your getting moisture in the building any time it rains your building will not last. Fix that first before you insulate any further.

 

[danfromsyr]

have you been heating it (putting up insulation)? and with what method?

being very wet your regular relative humidity may just be very quite high w/o any additional water leaking in..

condensation from moist air on cold surfaces.. even in normal day to day swings at certain times of year (here in my local).

leather will grow mold easily outside of a interior conditioned space. ie. even in the basement.

 

[Jazz1]

moisture coming up through the floor. Moisture coming up through floor. Vapour barrier would eliminate that

 

[Showkey]

being very wet your regular relative humidity may just be very quite hig

leather will grow mold easily outside of a interior conditioned space. ie. even in the basement.

Prolonged relative humidity levels over 70% will produce mold on all organic surfaces....like leather, fabric, rubber and wood. Grandma’s musty basement.......

 

[u2slow]

Floor is wooden, above grade on cement piers. It's dry inside and no visible water leakage from roof. No seals around doors( 2 barn style front doors that swing out).

I would close off the gable vent and try to seal the doors a little better. You should have adequate venting with the soffits and ridge. All it may need is a perimeter edge/sill of 3/4" for the door to close against.

 

[remagenman]

Thanks, good ideas and will try some. It was friggin water world last night with the rain we got. I am also going to make some DIY Damp Rid buckets with calcium chloride ice melt. It worked great in my very wet inside Audi to control the moisture and should also help with the shed.