# Insulating underneath my floor



## Windows on Wash (Aug 30, 2011)

I would insulate the ceiling as well and make sure that you have a complete air barrier. No reason you should deal with all the fumes and smells in your apartment.

Spray foam applied at an appropriate thickness would probably be best because it forms a complete air barrier.

Insulating the underside of the floor will be the warm side. Placement of the vapor retarder/barrier depends on your climate location and what is the upstairs floor covering.


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## joecaption (Nov 30, 2011)

There is no way to insulate it unless you remove the sheetrock covering the floor joist. It needed to be in the joist bays.
An old house like that most likly has ballon wall framing. The walls are open from the basement to the attic. There needed to be blocking in every one of those wall stud bays to stop air flow in the attic and the basement.


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## ToxicPaul (Dec 1, 2011)

Thanks. I was actually only considering insulating in the basement, between the sheet rock and floor joists. I guess the best bet would be to pulldown the sheet rock and insulate from the basement. In no way way I planning to rip up my hardwood floor to get insulation in there.

My one concern is working around all the gas lines, plumping and other wires throughout the basement. A lot of them seem to be mounted or held to the ceiling in one form or another. What would be a good way to work around that? Can I punch holes where I can in the ceiling and insulate like that? Or do each one of those lines have to be detached and put back up again?


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## joecaption (Nov 30, 2011)

Punching holes is not going to work and trying to get something in there once you did try it that way would just make a bunch of holes needed to be patched.
No way of knowing what's got to be moved or how unless someone was on site looking at it.
We now do not even bother trying to insulate ourself any more we get a real insulation company to do it. In our area there can do it faster, better and just as cheap once you spend all the time picking up materials and having to deal with a helper.


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## Windows on Wash (Aug 30, 2011)

joecaption said:


> There is no way to insulate it unless you remove the sheetrock covering the floor joist. It needed to be in the joist bays.
> An old house like that most likly has ballon wall framing. The walls are open from the basement to the attic. There needed to be blocking in every one of those wall stud bays to stop air flow in the attic and the basement.


I should have been more clear but thank you for point that out.

I should have detailed that the existing drywall ceiling should be removed and the insulation (whatever choice he makes) should be applied directly to the underfloor. 

Good catch on the balloon framing as well. Blocker those holes and spray foam them.

You will not be able, as joe mentioned, properly insulate that without dropping the ceiling.


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## Perry525 (Jan 10, 2010)

The idea of insulation is to keep you warm, as such you must consider that warm air rises and drags in cold air from the basement. Therefore, block all holes in your ceilings, walls and floors, if the warm air cannot get out, then cold air won't come in.
Its a shame that you have those nice floors, as the best form of insulation is three inch thick polystyrene sheets laid over the existing floor, with a totally floating floor above.
The next best is to remove the existing dry wall from the basement ceiling, fit sheets of polystyrene below the joists and replace the double layer of drywall - that is there to provide one hours delay in fire burning through the floor.
It is important that the insulation is fitted below the joists as otherwise each joist creates a heat bridge, being in contact with the warm air in your home at the top and the cold air in the basement at the bottom.
There is no point in even thinking about insulating the basement brick walls as the amount of heat escaping through your floor will never raise the temperature in the basement and therefore will never pass into the walls.


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