Insulating a crawl space in termite country

[anwalt]

My house a partial basement - partial crawl space, poured concrete. I want to insulate the crawl space. Central Indiana is termite country. I do not now have termites. Nor I do not want to create a hospitable environment as a part of the insulation project.

The blogs, particularly green building blogs, say insulate ones’ crawl space. They also say “[T]he plastic should be continuous, taped at any seams, and mechanically attached and sealed at the perimeter.” http://www.greenbuildingadvisor.com/gree...awl-spaces

‘Mechanically attaching and sealing’ pe to concrete walls is a challenge I have not conquered.

I am considering spraying closed cell polyurethane insulation.

I am seeking opinions on two questions and any further wisdom or experience – good or bad.
1. Will termites tunnel in closed cell pu?

2. Any suggestions on ‘mechanically attaching and sealing’ pe to a concrete wall?

Thank you for your time and suggestions.

Tom

[K. L. McReynolds]

We used an adhesive (in a caulk tube) when installing 6 mil plastic sheeting in crawl spaces oh HfH houses to seal the ground for the passive radon abatement system. The adhesive glued the plastic to poured concrete and also sealed overlapping sheets together.

We applied the adhesive to the wall and pressed the plastic to the bead of adhesive. That was also used to seal around water/waste/etc lines buried in the crawl spaces.

Was so long ago, I cannot remember what it was, but it passed inspections and we did more than 80 houses that way.

[David G]

We used tough crosslinked 6 mil plastic for a ground cover. Special tape at the joints. It doesn't have to be perfect to be a great improvement. Used spray foam insulation in a can to attach the plastic to the concrete walls. Run a bead and slap it up. Stuff sticks to everything. It has lasted over ten years. Leave 6" between the plastic and the wood. Check yearly for termites "tubes" from the ground.

I would suggest treating for termites before laying the plastic. Either a professional treatment or spray Timber on the ground and underside of the wood. Or both.

[gamma]

anwalt said:

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‘Mechanically attaching and sealing’ pe to concrete walls is a challenge I have not conquered.

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Two options, though a bit pricey...

Tescon
Extoseal

Their website is also a pretty good source of info. Of course, they're selling, take with a grain of salt. I'd also look at Building Science for lots of research based building advice.

[frule]

I'm in E.Tennessee (termite country here, too). We put down 6 mil poly vapor barrier on the ground and 18-24" up all side walls and piers. Taped ALL seams with vinyl (tarp) tape.

Then put up blue (1") foam board on all walls leaving a few inches at the top for termite inspection. You can use adhesive or nail the foamboard using those large plastic washers with the nails. Pushed the foamboard tightly down against the poly at the ground. Worked great.

We completely sealed all penetrations through the floor and to the outside (exterior vents, gas lines, etc.).

Added a good commercial grade dehumidifier. Temps never get below 65* in the crawlspace (usually 70*+) and it has no musty small like before. The dehumidifier will pevent any mold issues. It's a huge improvement over an open vented crawlspace! NO insulation between the crawlspace and floors of the heated space.....it's not needed and allows better inspection of the underside of the floors.

Just google "crawlspace encapsulation" for the supplies needed.

[meackerman]

pretty sure closed cell insulation offers no food source to bugs of any type. and according to the insulation contractor that came out to look at my place the stuff once cured is very hard, and hard to remove if it ever needed to be.

open cell is much easier to remove.

[Robert Adams]

All good info. I leave a 2" gap at the top of the wall. If you can find them anymore there are steel termite shields that attach to the foundation wall and the termites can't build tube around the sharp edge.

Unfortunately there are good methods to crawlspace sealing on gba and building science but they neglect to tell people what products to use and how to actually get the stuff stuck to the wall.

You can use long tapcons to attach the foam to the wall or long nails with plastic washers using a concrete nail gun. Hilt I makes a nice one specifically for this that you may find for rent somewhere.

For the plastic construction adhesive usually works well. And tuck or other tape for plastic for the seams. Very expensive tape as well...

Depending on how it's done and how well there is no need for a dehumidifier but it is cheap insurance as is an exterior temp/humidity sensor with the sender in the crawlspace. After the initial dry down in there humidity should be stable and lower.

The house will heat and cool better with a sealed crawlspace and be more comfortable.

Also don't forget to insulate the entire rim joost. Spray foam is perfect for this but 2" foam can be cut to fit and foamed into place. That is if you can get 2" foam. It's special order most places.

As for tunneling they will tunnel in most anything hence the 2" inspection gap at the top of the wall but the plastic may keep them from heading that way. We hope anyway...

[Axehandle]

If you do a proper termite treatment with Termidor on the exterior of the crawlspace wall you will not have to do a treatment inside the crawlspace. It is still a good idea to leave the inspection gap in the plastic.

It is probably better to use a fiber reinforced 10-20 mil plastic as well. It is more durable if you plan to do any work under there such as when the HVAC guys come to do maintenance.