Opinions on insulating a crawl space.

[KarTek]

Guys, I'm at a crossroads with regards to what to do with the crawl space. It currently has plastic over about 2/3 of the dirt and R13 insulation under the floor.

I bought another layer of R19 to add to what I have now but have since seen a neighbor have some kind of crawl space "encapsulation" system where they remove the insulation and seal everything with silver panels and tape.

I'm kind of a traditional guy and while intriguing, I'm a little leery of this kind of thing. Should I just insulate with what I have? Should I completely cover the dirt floor with plastic? Should I dump it all and try this new thing?

Thanks for the ideas!

[engatwork]

I'd recommend removing the existing insulation and going with closed cell spray in foam. Stuff works great and seals everything up thoroughly.

[MS Fowler]

Need a bit for information.
What is the use of the crawl space?
Do you access it often?

Usually it is best to insulate between the "conditioned air" ( heat and/or cold) and the "non conditioned air".

[Emmerich]

Ditto on the foam, but it is a LOT more expensive that regular insulation, it might be more cost effective if you increase the coverage. I do not know how they price, but if there is a fixed setup plus cost based on coverage, it would be worth it to cover more.

[t walgamuth]

The plastic is there to keep moisture from the ground from entering the crawl space.

If you insulate the floor really well and don't insulate the foundation walls of the crawl space the walls may get below freezing. I am not inclined to think that is a good thing.

I suggest if you feel the crawl needs more insulation you might want to insulate the block walls and leave the r 13 alone. If the plastic does not cover all the ground I would cover the rest of it.

Having a semi- warm crawl space seems like a good idea to me.

[MS Fowler]

Tom,
That's why we need more info. In my experience, most crawl spaces are below grade and the walls are not exposed to air, except for the top 8" or so. Some insulation for the top 2'-3' might be useful, but below that the soil stays pretty constant temp --depending on location.
Agree completely on the benefit of covering the soil with plastic to reduce moisture.

[Txjake]

You could always use the John Wayne Gacey method.......

[KarTek]

The crawl space is slightly below grade. I access it a couple times a month at the most. It's simply for maintenance access for wiring, plumbing and HVAC.

I definitely don't want the space to get too cold since all the plumbing runs through it.

[MS Fowler]

You're in North Carolina, right? How cold does it get?
Insulation, by itself, does not make an area warmer; it just reduces the flow of heat. The earth, itself, is a source of some relative heat. Some insulation around the top of the crawl space should keep temps above freezing.

[The Clk Man]

You could go around and gather up all of the road kill that you can find and use the fur to line the crawl space with.

[Kuan]

Here in Minnesota they tell us to not insulate the crawl space. I wonder why.

[barry123400]

Originally Posted by Kuan

Here in Minnesota they tell us to not insulate the crawl space. I wonder why.

Preventing frost from heaving the wall I suppose. Insulation on the outside of the wall is okay though.

I am not a concrete expert either. They may not want the concrette or block wall put through too many freeze thaw cycles. Your winters are at least as harsh as ours I think. Take into consideration that when your house was built the chance of the contractor ordering a mix that was better able to cope with the freeze thaw cycles as highly unlikely to non existant.

Cost of energy today though means any improvement is worth the effort usually. Plus it will make the floors on that part of the house warmer.

I have many thoughts about insulating concrete or block walls on the inside. A german bricklayer I once employed told me in northern europe they never insulated on the inside. He also suggested it was not the best ideal to do so in our climate in this part of Canada. . As you get further south in the United States these concerns are not as valid.

[elchivito]

stupid jobless commie cheese-eating MOFO crawlspace!

oh wait. you said insuLATing, never mind.

[t walgamuth]

I have designed and built about a dozen solar and or super or well insulated homes.

In the real peak of it I insulated a number on the outside by putting 1.5" of blue styrofoam outside the concrete. We put metal over the exposed portions of the styrofoam to protect it from ultra violet light.

It is ideal from an energy performance standpoint but one of the homes got termites up under the styrofoam and into that part of the house.

After that I quit insulating on the outside.

[barry123400]

Originally Posted by t walgamuth

I have designed and built about a dozen solar and or super or well insulated homes.

In the real peak of it I insulated a number on the outside by putting 1.5" of blue styrofoam outside the concrete. We put metal over the exposed portions of the styrofoam to protect it from ultra violet light.

It is ideal from an energy performance standpoint but one of the homes got termites up under the styrofoam and into that part of the house.

After that I quit insulating on the outside.

There is always a fly in the ointment it seems. We have no termites here. Possibly the weather would freeze their private parts off.

Actually code here started this year is insulation both inside and outside on basement walls. No other option allowed. Most contractors set up a styrofoam block system that has lots of re rod in it and pour a six inch wall inside it for one and two story houses.

The styrofoam has devices that lock it into the outside and inside of the concrete. It is the concrete form as well. You then screw something on the outside. The styrofoam has screw retaining inserts made of plastic. You can carry this system to the roofline as well. For all practical purposes straight forming for household basement walls is dead here now. Also means that finished basements are pretty well a given as you must put something over the foam to meet fire codes.

Other code changes this year. Two by eight sidewalls mandatory if frame construction and low e argon filled glass on all exposures. Fifteen inches of insulation or r 50 minumin in attics

Actually I am just leaving to buy insulation and get the machine to blow an additional 8 inches of celalose into our own attic space tomorrow.