Partially Finish Attic For Storage


Old 02-22-16, 08:34 AM
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Partially Finish Attic For Storage

Good Morning,
I live in a twin row home, with a 2-3:12, essentially mono pitch roof, raising from the rear to the front. A foot or two before the front of the house it takes a steep turn to the front wall, similarly to a single saw-tooth roof section. Since space is a premium, I want to finish half of it for non - living, storage space. Drywall, floor, lighting, etc. Right now its simply bare joists with old nasty insulation between them and a single vent on the side that faces outward. The rafters are also bare, and uninsulated. The vent is in the wall below the apex of the space, around 4 feet high. So finishing this space would essentially seal off half of the attic with no means for ventilation.
Couple questions
I plan on replacing the joist insulation with regular bat insulation then putting a sub floor over it. Do I need a vapor barrier between the two? I want to also frame the space out with steel studs, and do some closed cell spray foam between the steel studs and brick/cinder block as well as spray foam between the rafters. Should those be vapor barrier-ed? Do I leave the unfinished space sealed off, or install a roof vent? Attached a picture for reference.
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Old 02-22-16, 09:13 AM
Join Date: May 2015
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Welcome to the forums!

There are several questions and red flags raised with your proposal.

First, do you know that the joists and supporting structure are sufficient to convert the space to storage space? Determining that is crucial and should be the first step.

What is the access into the area in question? With all you are proposing, this seems to walk a fine line between storage space and living area. For example, putting drywall in a storage area like this would be unusual.

Is such a conversion allowed in your area by building codes?

Insulating between the rafters will convert the area to a hot roof (unventilated roof) even if you leave the existing vent. What is the roofing material? Many roofing materials cannot be used over hot roofs without voiding their warranty and experiencing early failure.

Vapor barrier always goes on the warm side of insulation, so it goes between the living area and the insulation and you never put two vapor barriers on opposite sides of insulation.

Are the outside walls block or brick?

You shouldn't seal off the small area of the roof without ventilation. It seems the existing ventilation is very poor to begin with since you really need both low and high vents and they need to be of correct placement and size to provide sufficient ventilation to the whole roof. Are there ridge or soffit vents of any kind now? Just adding a couple of roof vents over the small section would not be adequate.

This kind of thing can be done, but there are a lot of important details to doing it so it won't compromise the building.
Old 02-23-16, 08:15 AM
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Thanks for the warm welcome and feedback!

I understand your concerns, as there are many variables that go into a project like this. The joists are of the same thickness, spacing and mounting specifications as the floor joists I can see looking at the ceiling in the basement so they are definitely up to snuff. The house if very sturdily built

Access is through a wooden, fixed ladder type stairwell from the side of the master bedroom closet. The walls are cinder block on the inside, but brick on the outside. There isn't enough headroom to legally be considered living space in PA as its 4' high at the most. I have not found anything prohibiting such a conversion in my local building codes, nor in PA building codes.
I have no intentions of making similar to actual living space with paint, recessed lighting, multiple electrical outlets, etc. I just want to be able to walk around up there without worrying about putting my foot through the ceiling, have adequate lighting (as there is none), not feel like I'm in a sauna when I'm doing it... and make it look somewhat nice.

The roof is tarred with no discernible separation of sheets or tiles. It's also extremely thick, as I recently discovered drilling through it when installing a drain -waste- vent that previously vented into the lower area of the attic. I also have re-coated the surface of it from black to metallic to reduce heat.

You are all too correct in your poor ventilation assumption. It is ungodly hot up there in the summer time. I was literally soaked in sweat when I went up there to fit the DWV pipe through the roof after 10 minutes. The only vent is that very small hole on the side of the outside wall no bigger than an 8.5x11 sheet of paper. There are no other vents or soffits of any kind. When the weather breaks I do plan on installing several ventilation ducts towards the back for an inlet and If I go through with the conversion several right before the storage space wall.
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