Replacing moisture barrier in crawlspace

[mrblotto]

Today, I got home and saw a piece of paper stuck in my door. I was like 'wha?'

It was from my exterminator company. They came out a few years ago to treat a minor case of termites and come out every year for an inspection.

Anyway, it said something like 'you need to replace the moisture barrier in your crawlspace. Give me a call!' Yes, the exclamation point was there lol

I look more, and there's a sketch on graph paper of the house, with a note saying they'd use 6mil plastic and pin/stake it down.

On another piece of paper attached was an estimate for $550.

Five Hundered and Fifty dollars! I was like 'omgwtfbbqsaucepedobearattack!

Really??? My house is only a mere 1200sq ft. I go to homedepot.com and price out a 12' X 100' fire retardant 6mil sheet and it's like $70.

Am I the only one to think this guy is looney tunes? A person can literally go into the crawlspace under my house and stand with arms fully up and still not touch the 'floor' for about half of the entire space. If I woulda known earlier, I would've gotten an actual door installed instead of a removable metal 3' X 2' cover thingee.

Anyhow, I digest. There's no question I'm gonna do it myself using landscaping stakes/staples/whatever they're called.

But I'm wondering:
-Should I remove the 'old' moisture barrier, or just install over top of it?
-If I should remove the old, is there something I should put down or apply beforehand to eliminate/decrease the present moisture? Maybe something like diamat......diabodacious....diarama earth gah...(I can't spell it)?

TL : DR
-advised to replace moisture barrier in crawlspace/standup space lol
-company is on crack and wants beaucoup bucks
-remove old or leave
-if remove, apply something beforehand?

Danke Shern in advance!

 

[boomerang]

I don't know but maybe you could call the guy that left the estimate and ask him these questions?

 

[Greenman]

Do you actually need a moisture barrier?

 

[SparkyJJO]

Is the old one even bad in the first place? Plastic sheeting doesn't typically just disintegrate.

 

[mrblotto]

I don't know but maybe you could call the guy that left the estimate and ask him these questions?

I figure with his estimate being so out of the ballpark, I could not rely on a logical/sound answer from him

Do you actually need a moisture barrier?

Good question......the paper mentioned 17%. I'm guessing that is the 'wood moisture content'. From googling around a bit, that doesn't seem that high. I did close the vents under there this winter. I need to get under there anyhow to open them back up.......or do I?

From http://contractingbusiness.com/residential/cb_imp_7253

"......As a general rule, if it’s above 75F outside, there’s more moisture in the outside air than in the 70 to 75F crawlspace air; therefore, if you ventilate the crawlspace, you’re bringing more moisture into the crawlspace than you’re removing....."

Is the old one even bad in the first place? Plastic sheeting doesn't typically just disintegrate.

You're right, it doesn't. But it's about 18 years old and I've been down there a few times messing about. Parts of it have become torn and whatnot.

 

[tsiunltdus]

Remove the old and replace with the new. No need to add anything else before placing the new in. You don't even need to stake it if you don't want to. It keeps the moisture at the ground level versus allowing more moisture into the air. It is wise to allow some air flow into your crawl space to prevent moisture buildup which can cause more complications such as mold growth.

 

[mrblotto]

Remove the old and replace with the new. No need to add anything else before placing the new in. You don't even need to stake it if you don't want to. It keeps the moisture at the ground level versus allowing more moisture into the air. It is wise to allow some air flow into your crawl space to prevent moisture buildup which can cause more complications such as mold growth.

Thank you. Hopefully I'll get to it this weekend :thumbsup:

 

[DrPizza]

I don't know if it matters for some other reason, but I'd leave the old there to give it more puncture resistance if you're going to be walking on it. Also, I watched a couple of videos on Youtube of the installation - specifically, I was looking at the installation of a barrier for radon; basically the same thing.

 

[mizzou]

I put a moisture barrier underneath my deck after it was built. I'm honestly not sure if it did anything...the basis of it was to help water runoff feed down the slope and not soak into the dirt against the house. I never had water problems in the basement again, and I also had less bug problems (although that was mainly due to erasing the debris field from the mess under the old deck.

I had it covered with 2-3 inches of pea gravel

 

[mrblotto]

Went out Friday and picked up a sheet of 6mil 10'X100' plastic at the local big box store.

I left the old plastic in place. Took a couple hours to put down - most of it unfolding and adjusting - under the house. I then put some bricks here and there to hold it down.

There wasn't quite enough plastic to lay down, so I'll be picking up a bit more and probably getting under there to finish it up this weekend.

Thanx all for your input

 

[MadScientist]

From http://contractingbusiness.com/residential/cb_imp_7253
"......As a general rule, if it’s above 75F outside, there’s more moisture in the outside air than in the 70 to 75F crawlspace air; therefore, if you ventilate the crawlspace, you’re bringing more moisture into the crawlspace than you’re removing....."

That's a good article. And this one: http://www.crawlspacedepot.com/closed-vs-vented-crawl-spaces/
Code here in TN is to add vents to crawl spaces. In my sub-division the contractor put in auto vents in the crawl spaces that start opening at 40F and are fully open at 70F. Our homes are only 4 years old but almost all of them have mold and mildew in their crawlspaces.
We all have all-in-one heat pumps and I am getting condensation in the summer on my large round insulted return ducts. The humidity of the outside air in TN in the summer can get very high.
So my plan is to encapsulation the crawl space, treat it like a finished basement. The contractor put a thick vapor barrier on the floor, but nothing on the block walls. So I will insulate the walls and close off the vents with pieces of foam blocks. And if needed add a dehumidifier.