Basement Ceiling / Floor Joist Insulation?? Yes or No

[NWOhioChevyGuy]

OK I have an 1880's brick farm house with an old fuel oil furnace (yes I know someday she will get replaced) and had a quick question. The basement is unheated and unfinished.

Here is the question; Would it be worth the money to insulate the basement ceiling with fiberglass batts?

I know in new construction they do not insulate the ceiling but in an older house would it be worth it? I have seen crawl spaces insulated before but not basements, Why?

I did blow 20+ inches of cellulose into the attics this fall, and all walls are insulated to their max with either fiberglass or cellulose. Windows are new replacements of good quality. I'm trying to make this old house as effiecient as possible with the fuel bills what they are.

 

[timgr]

I was warned not to go overboard in insulating the floor. I'm told it's possible to make the basement so cold that your pipes will freeze. Certainly it makes sense not to waste money heating the basement if you aren't living there, however...

 

[Dragster Racer]

I was wondering..Where does the vapor barrier go? Heated area is upstairs, but plenty of moisture as a rule downstairs.

 

[hidollartoys]

If the basement is "closed up" in the winter then the space should remain close to 50 degrees. This is based on a tight area with little or no air exchanges. You can seal air pathways with the spray foam and you should insulate the space between the joists in the mud sill area above the basement wall and below the house floor the all along the parameter of the house. I use 3.5" batts folded in half to form 7" thick plugs. This will help a bunch.


If you choose to insulate the floor the vapor barrier should be installed facing the bottom of the floor. What type of walls and floor is there? If the basement is not conditioned space then it might be advisable to treat it as a crawl space. That said I have seen more that one unconditioned basement (with concrete floor/walls) where nothing was done including house floor insulation. You should make sure in winter that there is very little or no outside air entering the basement and in summer you should vent the area. I was raised in a house like yours.

My personal recommendation would be to insulate the floor and properly vent the basement. There is a great body of info out there on this topic. I would google and read as much as you can. Several schools of thought on insulation subject.

 

[chaingang]

When I built 6 years ago we insulated between the basement and first floor. However mine is a walkout basement and it is a conditioned space. I have two heat pumps and treat them as seperate areas. It was also done for noise since the upstairs has all hardwood and tile floors and it would have been rather noisy downstairs otherwise. There is a bedroom and bath downstairs also.