Crawl space floor Insulation?

[Jeremy]

Hello.....I have a cape cod that was built in 1948 i believe.

It has 2 rooms upstairs that I am renovating. The back of the house has been dormered.

The front of the rooms has a knee wall. Behind the knee wall, obviously one of the previous owners did not know what to insulate. He had the knee walls insulated with 3-1/2" insulating, but had the vapor barrier on the unfinished side (crawlspace side). He also had the angle walls inside the crawl space insulated with i believe 3-1/2" insulation, luckily there is a air space behind that insulation since the angle walls are out of 2 x 6's.

Now for the floor......it is not insulated as far as i believe. It is made out of those 2-1/2" wide tongue and groove boards, and I do not want to pull them up to install insulation or blow new insulation under them......

So can I lay unfaced fiberglass insulation on top of the floor throughout the whole crawl space......the only bad thing about laying it on top i believe is i wont be able to use it for storage.

Will laying it on top help with heating or not?

I have more questions to come, I just cant think of them right now.....thanks for any advice......

Big J.

[Unregistered]

Laying on top is a waste of time. I often see celulose blown in to these cavities. Some people will also pry up a few of the center tongue and groove pieces to add batting. If you do this be sure to screw them back down, NOT nail, as the jarring will potentially cause cracks in the plaster below, giving you another repair. The vapor barrier on the knee wall is wrong. The barrier should be towards the living space.
NOTE: Be sure you know what the situation is with your electrical wiring before filling these cavities. I do recommend filling them, but be sure for instance, if you have recess lights in these areas, that you leave 3" around them unless they are IC. (iNSULATED CANS) Nor do you want to loosen any other wire connections. The good news in that there usually is little if any of either in these areas of the attic floor/1st floor ceiling.

Good luck.

[Unregistered]

thanks for the advice.
I pryed up one of the boards on the one front side of my cape and there was no insulation below it.
Now this side of the cape has a peak in the front about 10-12' infront of the knee wall......

would it make more sense to take all the boards off and unroll fiberglass insulation in there and then put new flooring on (plywood).?
If cellolose is blown into these floor areas, what is the chance of getting it in every spot in the floor, obviously you dont want to miss areas.

Once you pry these boards off, they are basically impossible to get back togethere since they are tongue and groove.

[Unregistered]

Cellulose works well for this area. The next thing is do you want to have to pay someone or be able to do it yourself? If you want to do it yourself, you might want to go with the batts. You don't have to remove them all, just a few in the center. You'll be able to re-use them by chiseling off the "tongue". Use a chisel and tap it from end to end with a hammer. The tongue will come off easily and allow for easier reconstructing. As far as installing the batting, you can use some type of push stink to get it from the point where you removed the T and Groove in the center, to the ends under the ones you didn't remove. Just be sure to check for wiring first. (A flashlight and mirror can help) AND SCREW THE T AND G BOARDS BACK DOWN, DON'T NAIL. (To prevent cracking the plaster from the jarring)
Good luck.

[Unregistered]

i am glad to hear that the batts will work also. Now the tongue and groove baords run perpendicular to the joists, so if i remove 3 or 4 of them opening up roughly a 10" hole........what is a push stink? I am guessing you mean stick to push it against the soffits, but not covering them?

I believe my joists are 2 x 6's.....so what type of insulation will i want?
R-19 6-1/4" thick, 15" wide...... which will compress slightly?

now should i put the vapor barrier down or no vapor barrier at all?

[Unregistered]

Use the R-19 Kraft faced, (x15) Paper down. (Towards living space)
Correct on the push stick. You are better off using 2 pieces per cavity than 1. You can meet in the middle where the T and G was removed. It will be easier to work with. Cut them slightly long. (3"-4") If you need to trim them after the fact so be it.
Good luck.

Don't forget to make sure your not creating a fire hazard with any wires or recess lights.

[Unregistered]

now if i decide to blow cellulose in those cavities.......do i still have to worry about electrical wires, or can i just blow that crap in?

thanks.

[Unregistered]

all in all, which would be better, fiberglass rolls or cellulose?

[Unregistered]

ok, sorry to keep on posting....but i pryed up a couple boards tonight and put my head under to look in the cavities.

over the dining area only has 1 junction looking box where the chandalier hangs, and the wiring from that goes half way through the 2x6's across the room.....now will i install the rolls directly up to that wiring or not.....i believe the previous owner of the house left some metal piping in the basement which will cover the junction box.

there is also a peak as i mentioned before on the one side of the front of the cape....i believe the bottom on the slopes have suffit vents because i felt some air while i was near them so baffles must be used there and then insulation up against the baffles, right?

more questions to come....thanks.

[Unregistered]

The J-boxes are alright. Your mainly concerned with not jamming the fiberglass in to the point that you loosen the wire connections. Your bigger concern electrically, would be if you had recess lighting. If that was the case, you'd be sure to allow 3" between the insulation and the light can. If you have recess lighting and it is a I.C., (Insulated can) you can go right up to it. You can determine I.C. or not, by removing the bulb and reading the inside of the can. If its origional, it won't be I.C. If it is there but added after the fact, it may or may not be.

Regarding the peak, you can either baffle it or leave it away from the soffit an inch or 2. I assume that other than those few soffit vents, the only other means of venting is gable venting....

[Unregistered]

ok guys, im almost done laying fiberglass roll insulation in the floor of my crawl space.........took alittle over 4 rolls of r-19 15" insulation......now I still have the floor in place, would there be any point of laying extra insulation on top of the wooden floor....maybe 4-5" thick batts??

I am asking because i will use some of the previous insulation that was in the crawl space.....not the old deteriorated stuff, this is pink stuff that is still usable.

thanks......this was not as hard as i thought it would be, i did break a few boards, but they are replacable.

[Unregistered]

If your going to use the attic for storage, i wouldn't. This is not the first place your going to loose heat so whats the point other than finding a home for the left over stuff. Maybe you should consider using any excess fiberglass in the band joists. This would be in the rectangular cavities between the floor joists in the basement. Cut a bunch of rectangles to fit and put them in with the vapor barrier towards the living space.

[Unregistered]

where is the most heat lost from a house?
ceiling?

[Wgoodrich]

A heating envolope is just that totally surrounding the house with proper materials to envelope that home totally. Picture no heat in your house on a cold night in bed with lots of blankets. crack that envelope surrounding your body by those blankets and bed and that area gets cold right fast. Anywhere you have a gap in that heating insulation envelope will loose heat you can not afford concerning money or comfort.

Heat wants to rise but heat seeks cold. However if it is cold outside your ground is also cold the heat will seek any opening to cold any direction.

Good Luck

Wg