Insulating a crawl space.

acommondisaster

Active Member
So I was up in Pocono Lakes this past week and realized the tile floor in the bathroom was really cold, despite the baseboard heating being maxed. So it turns out (and I guess I'm the last to know) that it's not insulated in any way. Wandering around Lowes, I came across some foil backed bubble wrap insulation and I thought it made a lot more sense than fiberglass batting. So I did a youtube search and the stuff is easy peasy to install (stapler, straight edge, utility knife and some foiled tap) and if I got up the nerve to go all the way in there with a drop light, I could probably do it myself. If I see a mouse, I'll be outta there like a man at a Tupperware party (sorry, that's the best I can think of).

So my questions are: Is it as easy as it looks? Is it really an efficient insulation? I did some searches, but it seems the foam guys say it sucks, the bubble guys say it's great, so don't tell me to google for an answer. If it's not the best (easy to install, good insulation value, other insulation considerations that I don't think of), what is?
 

Ken King

A little rusty but not crusty
PREMO Member
Don't know about efficiency, what is the "claimed" R value? I say "claimed" because most of what I have seen for the foil-faced bubble wrap is an R-1 and is typically used as a vapor barrier. If you are going into the crawl space to install it anyway, get a decent R value fiberglass insulation, installation will be roughly the same process.
 

Chris0nllyn

Well-Known Member
Don't know about efficiency, what is the "claimed" R value? I say "claimed" because most of what I have seen for the foil-faced bubble wrap is an R-1 and is typically used as a vapor barrier. If you are going into the crawl space to install it anyway, get a decent R value fiberglass insulation, installation will be roughly the same process.

^This.

Get it properly insulated with batt or spray foam insulation. Batt is a DIY job and allows you to remove it to get to pipes/wires in the future if need be. Something spray foam doesn't really allow you to do.
 

DoWhat

Deplorable
PREMO Member
^This.

Get it properly insulated with batt or spray foam insulation. Batt is a DIY job and allows you to remove it to get to pipes/wires in the future if need be. Something spray foam doesn't really allow you to do.
Need to avoid installing water lines in a crawl space.
 

PeoplesElbow

Well-Known Member
It is better to insulate the block walls under the house than the floor. 2 Inch thick foam board glued to the block and then a few cans of spray foam to fill any cracks does the job nicely.

The tile floor is always going to feel cold unless you have a heated floor.

The problem with insulating under the floor, moisture retention and mold. You have to provide plenty of airflow and this can lead to frozen pipes.

https://www.houselogic.com/organize-maintain/diy-repair/insulating-crawl-space/
 
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acommondisaster

Active Member
All the plumbing runs in the crawlspace. Winter before last, we had 43 splits in the pipes, so I can definitely rule out putting batt in there. Last year we put in heat tape (I think that's what it's called) and the only thing that froze was the toilets (cracked at the floor). That was definitely our fault; we had an unplanned freeze after we opened up the house for the season. The claimed R value of the foil bubble wrap is R14, but from what I read, that's not necessarily a true claim. Ideally, we'll encapsulate the crawl space, but i would think we still need to insulate the floors.

I'll have a look at the foam board - thanks.
 

Ken King

A little rusty but not crusty
PREMO Member
I would insulate the floors with the batting, easy to install and easy to remove if needed for repairs. The heat tape seems to have solved your underneath freezing issue with the pipes. As you have your electric on (need it for the tape) why not leave your thermostat set at 50 to avoid any internal freezes. Might cost a few bucks but it beats replacing the toilets.

That claimed R-value of R-14 I suspect is based on a developed "air pocket" once the foil backed bubble wrap is installed. Batting will give you a true R-value.
 

PeoplesElbow

Well-Known Member
The foil bubble wrap is very good for insulating against radiant heat (ie putting in windows to block the sun's heat) but as far as conduction goes it isn't that great. I insulated my fiberglass garage door with it because in the summer the sun shined right through the door and heated up my garage to uncomfortable levels and it worked great in the summer, but in the winter didn't do much at all. Fast forward 10 years and I finally got rid of that cheap ass fiberglass door and got an insulated steel door, summer temps are good and winter temps are too.

No matter which way you go, I would be very careful because of condensation in the space. Make sure you have a good vapor barrier on the ground and no water intrusion into the crawl space before you do anything.
 

acommondisaster

Active Member
As of right now, heat source is a wood stove, so aside from the bathroom's baseboard heat, when we're not there, it's unheated. That will change probably this year to a propane in floor furnace.
 

acommondisaster

Active Member
The foil bubble wrap is very good for insulating against radiant heat (ie putting in windows to block the sun's heat) but as far as conduction goes it isn't that great. I insulated my fiberglass garage door with it because in the summer the sun shined right through the door and heated up my garage to uncomfortable levels and it worked great in the summer, but in the winter didn't do much at all. Fast forward 10 years and I finally got rid of that cheap ass fiberglass door and got an insulated steel door, summer temps are good and winter temps are too.

No matter which way you go, I would be very careful because of condensation in the space. Make sure you have a good vapor barrier on the ground and no water intrusion into the crawl space before you do anything.

All good information. We've got the insulated garage doors here at home and they're great! I had hoped the little bit of insulation might be of some help, but I am afraid encapsulation is going to have to be the way to go. Not looking forward to it, not sure how it'll work with the infloor furnace, but will start investigating further.
 
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