# Borax/Borate for Crawlspace



## PAbugman (Jun 29, 2010)

Not a bad idea, but to go a step further consider spraying the sill plate and band joist and ends of floor joists with *bora-care* which will penetrate into the wood with a boric acid type material. Will last for years. If you don't want to spray it on, just apply *tim-bor* powder onto the same wood. The ambient moisture will slowly take it into the wood to some degree. I used the powder on the sill plates in our garage. Will also kill/repel crawling insects.

Google Boracare and Timbor. There are generic versions of both now, and they would work fine, and should be cheaper. Just cross-check the active ingredients to make sure.


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## Earnie (Jan 24, 2008)

Thanks Bugman. 

There will still be a few inches of block visible at the sill plate as an inspection area. Just thought since the block to dirt area will be covered, adding the borax/borate might be a good idea.

I'll take a look at those products.

Have you ever read any data that indicates how fast termites can build a mud tunnel? How long would it that to build five inches of mud tunnel?


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## PAbugman (Jun 29, 2010)

I like your idea of treating the soil next to the foundation.

Many factors would affect how fast termites can build mud tubes. Exploratory tubes (smaller ones) would be built slower than the main branches that they build after they find wood thru using the exploratory tunnels.

Warmth, dampness would increase the rate. Distance from soil would be a factor. Your location in the south would be conducive. 5 inches a day would not surprise me here in northeast. When we find a live, active tube we get a kick out of destroying about one inch and seeing how fast they rebuild it, usually in 2 to 4 hours.


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## tbeaulieu (Apr 6, 2009)

I'm no expert, but figured I'd chime in with my experience.

I bought bora care online (half the price!) and a stainless pump sprayer this summer.

Sprayed my barn foundation post/beam structure for powder post beetles.

I'll be monitoring it next year, but I was very pleased at being able to do this myself. It was much easier than I guessed it would be.


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## Earnie (Jan 24, 2008)

Sorry guys. I forgot about my questions here. Thanks for the replies.

I think I will initially try a different approach. I'll still apply the Borax. But instead of installing the plastic up the block walls, I going to apply Zinsser WaterTite. The concrete blocks are above grade with no visible water issues. If that doesn't seal for air and moisture I'll re-look at installing the plastic.

Not knowing what is going on with bugs behind the plastic has me concerned with that approach.


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## PAbugman (Jun 29, 2010)

Sounds good Earnie. Thanks for the update.


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## ConcreteTreat (Dec 5, 2010)

Earnie said:


> Sorry guys. I forgot about my questions here. Thanks for the replies.
> 
> I think I will initially try a different approach. I'll still apply the Borax. But instead of installing the plastic up the block walls, I going to apply Zinsser WaterTite. The concrete blocks are above grade with no visible water issues. If that doesn't seal for air and moisture I'll re-look at installing the plastic.
> 
> Not knowing what is going on with bugs behind the plastic has me concerned with that approach.


Borate works really well -- an added benefit of Boric Acid is that it'll help keep out mold issues.

Installing the sealant on the walls is a good idea. If you haven't done it yet, I'd also recommend installing a thick plastic liner along the floor -- at least 10+mil -- and running it about a foot up the wall. This will seal the floor but still keep the space accessible for you. 


-----------------
Concrete Treat

Concrete Sealer


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## ConcreteTreat (Dec 5, 2010)

Earnie said:


> Sorry guys. I forgot about my questions here. Thanks for the replies.
> 
> I think I will initially try a different approach. I'll still apply the Borax. But instead of installing the plastic up the block walls, I going to apply Zinsser WaterTite. The concrete blocks are above grade with no visible water issues. If that doesn't seal for air and moisture I'll re-look at installing the plastic.
> 
> Not knowing what is going on with bugs behind the plastic has me concerned with that approach.


Earnie, where I work, we add a clear plastic strip along the tip of the installation. This allows for termite inspection, etc. while still having the benefit of the plastic vapor barrier. Companies like Terminex install clear plastic everywhere, but I've seem limited success with that approach. Remember -- you're just looking for mud tubes.


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## Earnie (Jan 24, 2008)

The more I study this project, the more it changes.

Now I'm not sure I want to install vapor barrier material or a water sealer to the block walls. From what I read, you want the block walls to evaporate any moisture in them instead of directing it elsewhere. The plastic vapor barrier will trap moisture between the blocks and the plastic. The painted water sealer will trap moisture in the blocks.

From what I've read, it's best to install a semi-permeable material, like foam board, which will allow moisture to move out of the blocks.



http://www.buildingscience.com/docum...archterm=floor 

http://www.buildingscience.com/docum...d%20in%20walls


http://www.buildingscience.com/docum...ance-and-codes


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## ConcreteTreat (Dec 5, 2010)

Earnie, what is the disadvantage of trapping the moisture between the plastic and the concrete blocks? As long as it's not affecting the wood in your crawl space, or other organic materials in the crawl space, I fail to see the issue.




Earnie said:


> The more I study this project, the more it changes.
> 
> Now I'm not sure I want to install vapor barrier material or a water sealer to the block walls. From what I read, you want the block walls to evaporate any moisture in them instead of directing it elsewhere. The plastic vapor barrier will trap moisture between the blocks and the plastic. The painted water sealer will trap moisture in the blocks.
> 
> ...


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## PAbugman (Jun 29, 2010)

Be careful about foam board. Termites like to tunnel in it; they feel safe between the board and masonry; they are insulated from temp extremes there as well. We can't see thru the board for inspection. If you go with it, try to at least leave several inches at top for inspection. The termites could also get into the block wall at a lower point and you won't see them anyway.


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## Earnie (Jan 24, 2008)

ConcreteTreat said:


> Earnie, what is the disadvantage of trapping the moisture between the plastic and the concrete blocks? As long as it's not affecting the wood in your crawl space, or other organic materials in the crawl space, I fail to see the issue.


 
I'm not completely sure. I just know that whoever wrote those articles knows a lot more about moisture movement science than I do.


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## Earnie (Jan 24, 2008)

PAbugman said:


> Be careful about foam board. Termites like to tunnel in it; they feel safe between the board and masonry; they are insulated from temp extremes there as well. We can't see thru the board for inspection. If you go with it, try to at least leave several inches at top for inspection. The termites could also get into the block wall at a lower point and you won't see them anyway.


 
The inspection gaps are required in the N.C. residential building code section R409.8.1.1. Three inches at the top rim joist area and three inches at ground level.

No final decison yet. There are so many opinions on the issue I'm still reading and studying. What's a homeowner to do!


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## ConcreteTreat (Dec 5, 2010)

Earnie, we have contractors that install crawl space vapor barriers in north carolina -- the clear plastic covering should also suffice.


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## PAbugman (Jun 29, 2010)

Earnie:
Is your top course of block solid, or filled with concrete? If so, I feel safer about using foamboard, especially since an inspection gap will be present.


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## Earnie (Jan 24, 2008)

ConcreteTreat said:


> Earnie, we have contractors that install crawl space vapor barriers in north carolina -- the clear plastic covering should also suffice.


 
Not sure if you are referring to CleanSpace. I did get a qoute from them last year.


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## Earnie (Jan 24, 2008)

PAbugman said:


> Earnie:
> Is your top course of block solid, or filled with concrete? If so, I feel safer about using foamboard, especially since an inspection gap will be present.


 
From what I can see, the top two courses of brick are mortar filled. Brick is the exterior facade from ground level up to about 30 inches. In the crawlspace is concrete block topped with two courses of the mortar filled brick.

What happend to metal termite shield between the foundation and rim joist? Maybe not a perfect solution but to me it sure beats nothing but straight wall for the bugs to climb up!


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## Jim Gorman (Jul 20, 2011)

*You may want to consider...*

The reason Bora-Care is more effective than borax or Tim-bor is that the glycol formulation in the product will allow Bora-Care to re-liquify when termites start building mud tubes on the wall. The top of the mud tube is always moist, the Bora-Care re-liquifies and the termites building the tube start to die. The termites then abandon the tube.

The best solution is to spray Bora-Care in a 1:1 solution (1 part water: 1 part BC) 2 foot up from the ground on to the concrete block all the way around the crawlspace to create a continous barrier. Then spray all the wood two foot out from the foundation wall and two foot our from all the piers. Applay a secont application 20 minutes later to all beams and married joist.

The manufacturer of Bora-Care also makes a termite resistant foam board for this purpose called Bora-Foam - it can be purchased at www.crawlspacedepot.com 

So Best solution is 
1. Spray the wall with Bora-Care
2. Install the foam board (which is R-10 and has 3 mil poly on both sides) with 3" gap at the top for inspection.
3. Apply a clear 8 mil, nylon reinforced vapor barrier and attach 1 foot up the Bora-Foam


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