Another crawlspace insulation question

[rocky1]

I am in Indiana. The house was built in 1980 and has fiberglass batts paper side toward the dirt stapled to the floor joists. Space is vented. I am considering taking it down, turning it over and putting in back up. There is plastic down on the dirt. Is this a good plan or should I pull it out and install fresh. I could also cut it into strips and hang it paper side in along the block foundation. Of course, I could get it sprayed.

I do not know if it is moldy. Just looking for ideas before I climb under.

Thanks
I have seen moisture under the plastic at times. There is a sump, but have never heard it run. It may have been installed as an afterthought. 5 gallon bucket with pump plumbed to outside. Evidence of frozen(burst) pipe outside faucet in the past

 

[MagKarl]

What is your goal?

 

[rocky1]

Good question. I guess mold avoidance. We have allergies, so if the mold candy is growing and being carried into the house, I would like to reduce or eliminate it
I guess the correct answer is to get a mold kit for inside the house and test it.

Thanks for the reply

 

[GRN96WS6]

Mine is paper towards my floor, and space is vented.

 

[DNK]

Id get it encapsulated

 

[kd3pc]

there should be no air flow between the crawl space and the house "air"....except a few particles when the doors or windows are open.

In this part of TN they actually don't insulate between the floor joists at all...as all that does is trap moisture against the bottom of the subfloor. And they have seen a LOT of rot in 2-3 year old homes from doing so.

Most homes are on a crawl space, and the water heater and HVAC ducts and pipes all live in that space, so that even with vents on the crawl space walls a lot of moisture is trapped, and condenses.

There is an industry that has convinced us that the space has to be spotless and sealed and .....for only $xxxxx.00 or more.

My crawl space has plastic on the dirt floor, and no insulation. I put up a test piece of R30 between the joist last summer for about 3 weeks and it was soaked, no matter which way it was installed. And the subfloor and joist both grew slime/mold in that time as well, where the insulation was placed.

I can only assume that the only way to prevent the moisture from being trapped is to "condition" the air in the crawl space by completely sealing/encapsulating it and providing an air exchange system of it's own. That will cost, according to one local outfit that "seals" them for about twice what the sealing process cost.

I have left mine vacant of insulation, and go down twice a year with a clorox sprayer to do the joist and floor above the HVAC duct/mainline where things condense the worst. And that is where that is.

Others will chime in, but no way am I tying my crawl space to my house air, nor am about to spend 10% of the value of the house to merely pretty things up.

 

[purplezr2]

Remove it and go with spray foam?

 

[gregtwojeeps]

there should be no air flow between the crawl space and the house "air"....except a few particles when the doors or windows are open.

In this part of TN they actually don't insulate between the floor joists at all...as all that does is trap moisture against the bottom of the subfloor. And they have seen a LOT of rot in 2-3 year old homes from doing so.

Most homes are on a crawl space, and the water heater and HVAC ducts and pipes all live in that space, so that even with vents on the crawl space walls a lot of moisture is trapped, and condenses.

There is an industry that has convinced us that the space has to be spotless and sealed and .....for only $xxxxx.00 or more.

My crawl space has plastic on the dirt floor, and no insulation. I put up a test piece of R30 between the joist last summer for about 3 weeks and it was soaked, no matter which way it was installed. And the subfloor and joist both grew slime/mold in that time as well, where the insulation was placed.

I can only assume that the only way to prevent the moisture from being trapped is to "condition" the air in the crawl space by completely sealing/encapsulating it and providing an air exchange system of it's own. That will cost, according to one local outfit that "seals" them for about twice what the sealing process cost.

I have left mine vacant of insulation, and go down twice a year with a clorox sprayer to do the joist and floor above the HVAC duct/mainline where things condense the worst. And that is where that is.

Others will chime in, but no way am I tying my crawl space to my house air, nor am about to spend 10% of the value of the house to merely pretty things up.

Interesting read and your viewpoint above has me thinking now, with concerns... .

We are moving and the house we are buying has a horizontal flow gas furnace in the crawlspace. Before we made an offer, I went under the house to check out the framing, plumbing,wiring, heat system....

The owners in their good intentions I am sure, has put open faced fiberglass batts in between the floor joists. The house has all hardwood floors mixed with porcelain floors. The 3 ft. tall cinder clock crawlspace does have good 6 mil poly for vapor barrier on top of the dirt and foundation vents that are operative. ..

I am sure the owners did this to hold the heat in the room spaces. I have been taught that heat movement transfer in a room space will go upwards first, then if met with resistance( ceiling insulation) it will go outwards and then lastly downwards... which in my opinion would be the least method of heat loss ...

So I as you, have always been an advocate of leaving crawlspace floors uninsulated whenever the furnace in in the crawlspace. I like the warmer floors on bare feet, and the fact that moisture could not get trapped against the sub floors by the insulation as you have stated makes sense, which could possibly creating havoc with the our new home's original real hardwood floors. ...

Now that I have read your reply, I am torn now. Should I remove the insulation from our new home's ( it is actually 45 years old) floor joists or just wait and see what pans out and keep an eye on the crawlspace moisture ? Thanks Greg

 

[Jackfre]

You could check out the Tjernlund Under Aire. It is a crawl space ventilator with a built in humidistat. they are a good outfit.

 

[PT Doc]

Crawl spaces under basement floors here in Volorado all have a humidistat with a ducting system on one end to pull in fresh air and another on the opposite side connected to fantech in line fans to keep a steady flow of air across the vapor barrier that is mechanically fastened to the foundation.

 

[rocky1]

If I pull down the insulation to see if I have mold growth, then the question is what to do next. I guess if no mold, I can leave it as is. The AC ducts do drip water in the summer.
Thought about installing a fan too.

 

[finn]

Insulate the crawl space walls and rim joist with 2"foam board and spray foam. Seal the air vents and install a dehumidifier. Don't forget the vapor barrier on the floor.

Latest thinking is that venting the crawl allows warm, humid ambient air to condense when it hits the lower temperature crawl.

The problem I see is that the dehumidifiers that work in crawl spaces without freezing up the voilà are quite expensive.

 

[NUTTSGT]

I insulated the walls of our crawlspace on the back of the house. I also cut the plenum for the hot air of the furnace and put a register in it. Every time the furnace runs, it puts a little heat in the basement. Then I hung a box fan from the floor joist and it blows that wamer basement air into the crawlspace. Haven't had an issue with frozen pipes since.