Unheated storage room in basement

Old 02-11-14, 07:39 PM
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Unheated storage room in basement

Hi, I've asked a few questions on here before and I've received some awesome assistance, so I'm hoping to get some additional advice! I searched and didn't really find anything that applied to me.

I have an approximately 30 year old split level / split entry with a finished basement. There is a coat closet in the basement under the stairs leading from the foyer to the upper level, and the closet continues back under the foyer (you have to crouch at this point), around the corner and under the stairs leading from the foyer to the basement. I don't use this as a coat closet as I have one upstairs, and I don't really use it much for storage either. The water meter is in here, and the room is unheated - the house has electric baseboards and a ductless mini-split upstairs but nothing in the storage room. Winter temperatures here are around -10 C (14 F)

The exterior wall in this storage room (under the front door) is insulated with fibreglass and poly vapour barrier.

In winter I find the floor of the foyer and the stairs leading down to the basement to be very cold under foot. On either side of the storage room in the basement is my family room and a bedroom, and the walls adjacent to the storage space are usually ice cold - if you move your hand up the wall to where the foyer starts, the wall is much warmer.

My question is, would I gain any benefit from insulating (but no vapour barrier) the interior walls adjacent to the bedroom and family room, as well as the ceiling / foyer floor and underneath the stair treads?
Old 02-11-14, 08:13 PM
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hfx, even though the exterior wall in the storage space is insulated with fiberglass I think my first approach might be to remove that material and review the rim joist and sill in that area for air leakage . You would probably be wise to cut foam blocks to fit the rim and foam those in place. I would also look at the foundation itself, if it is block then I would make sure the top course is either a solid block or filled hollow cores or sealed in some way with a piece of rigid foam caulked or foamed in place.

I would also replace the fiberglass from the wall with a foam insulation board, preferably one that has a fire rated foil facing or other code approved facing. Seal all edges where there may be irregularities with a flexible sealant or can foam.

Putting fiberglass insulation in the walls will make the walls feel warmer only if there is a major difference in temperature between the storage closet and the basement area adjacent to it. I believe you will get the same benefit by moving the focus of insulation to doing a top quality job of air sealing and insulating the exterior wall and rim in the storage room itself.
Old 02-11-14, 08:54 PM
Join Date: Mar 2005
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That sure sounds like my home in a colder winter climate.

I used expanding foam around each space between the joists and then immediately pushed in a slightly undersized pieces of 2" XPS as an adhesive that were really just cut up scraps. This eliminated any air leakage problems. Then, I put in Roxol (also scraps) between the joists. Then I covered everything with 2" XSP and 1/2" drywall. That eliminated or minimized the heat loss.

In order to protect the water meter and piping, I did not insulate the wall between that area and the rest of the lower level. that provided a nice cooler area under the steps for storage of jackets, boots, onions and potatoes.

In other words, I tried to turn the localized lower level area into a semi-conditioned space between the outer world and the completely conditioned space.

It is like a uncontrolled space like my tuck under garage that may get below freezing if the door was open too long and no hot cars are pulled in. Since the bedroom over the garage in insulated, it is warm. The nice thing was that the tiled floor and stairs at the split level entry are much warmer.

Not perfect and the anal examiners of construction to the 1/100th or fractional difference of measuring the undefined thing like the variable properties of a "vapor barrier", but it has worked for years and feels great even at -35F wind chill (which does not affect anything below grade).


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