I need some professional input on how to create a storage space in my attic
First of all I am not even sure I am in the right forum to ask my question. Please excuse me if I am not and maybe some one here can point me in the right direction.
I live in Myrtle beach SC. My house was just built. It is a cape cod style with an attic, accessed by drop down ladder in the garage. It has ridge vents and soffits and no gable vents. All up to current SC code.
I would like to store some post WW2 Lionel trains and various Christmas decorations in the attic. My questions are:
Is it feasible to create a storage area/room of about 8′ x 8′ and be able to control the humidity inside it?
If it is feasible what would be the most cost effective construction? I was thinking 2″ x 4″s – 24″ oc.
I was thinking 7/16″ OSB for the walls and ceilings, as the flooring is already OSB.
Would I need insulation or would a vapor barrier be sufficient? How should I install the insulation and or vapor barrier?
I am guessing a dehumidifier of some sort would be needed to keep the humidity at around 50%.
I would love to have any advice that can be offered.
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
First of all, you need to consult an engineer or an experienced builder to find out whether the floor joists (the ceiling joists of the room below) or the roof trusses (if that's what you have) are strong enough to allow the construction of a storage room.
Assuming that an engineer gives a green light to your plan, the next step would be to build insulated, airtight walls and an insulated, airtight ceiling. (I don't think that you want to attempt to control the humidity of the space without also trying to control the temperature, for a variety of reasons. So the room needs insulation. Remember, too, that installing a dehumidifier in the attic only makes sense if you monitor it -- to make sure that it doesn't stop operating, and to empty the condensate bucket or check its drain line. That's a thankless task.)
The walls need to built like insulated exterior walls (except that they don't need siding). If there is room for a flat ceiling, it needs to be built like an insulated low-slope roof, only without the roofing. If there is no room for a flat ceiling, you will need to insulate the sloped roof assembly as if it were an insulated cathedral ceiling. Pay attention to air sealing when you build this room. It should be as airtight as possible.
Once this room is built, you will need to connect the room to your home's forced-air HVAC system. (I'm assuming that your home has a forced-air distribution system to provide heating and air conditioning.) The room will need a supply air register and a return air grille. If you do that, the room won't need a dehumidifier.