Was just looking for some input on different techniques for ensuring a permanent seal between a block foundation wall, and a 6 mil. poly barrier resting on a dirt crawlspace floor?  If one could referrence specific products that would aide also.  Thanks in advance for your input.

Views: 16721

Reply to This

Replies to This Discussion

I use CCA treated furring strips and mastic in the caulking tubes. Wrap the plastic around the strips, apply mastic, and fasten to the block with a hilti gun. Time consuming but it seems to work.

Tim,

I have used a recommend a product from crawlspacerepair.com called "Foundation Seal Tape".

It is a very strong and tacky double sided tape that is also waterproof.  I apply it continuously around the crawlspace about 3" below the top.  I use 15 mil poly that goes down the wall and then across the floor.

The tape seals and temporally mechanically holds the barrier in place until I ADD mechanical fasteners every 2 feet for  permanent bond.  

I highly recommend this product.

Tripp

I use the same mastic I use for sealing ducts, in my case Air Seal polymer adhesive.  Brush on a thick layer, then attach to the foundation wall as James describes.  I also use it for the laps across the crawlspace floor.  I don't trust the tape that Tim mentions.

I'm of the opinion that mechanically fastening the furring strips is a necessary, time consuming, and therefor costly step merely to insure the vapor barrier stays in place till the mastic dries. Once it dries, your not pulling the VB off without some effort.  If I come up with an easier alternative to temporarily hold the material in place, I'll test that theory and get back to you.

Tim,

I imagine you're using foam on the walls in the crawl space? If so, I have recently switched to foaming over the vapor barrier. It has been a very effective approach, assuming someone doesn't crawl through the space like a bat out of Hell and rip the barrier off the wall.

I run the poly up the walls (about 6 inches) and spray over the poly, and spray especially thick at the interface of the walls and the floor of the crawl.

Just my take on this, given personal experience and a genuine concern for the cost of projects getting out of control for the average HOs.

Don't use poly, use EPDM roofing material. Then you can use sprayfoam to seal.

Pat, about what are you paying per square foot of the EPDM membrane? I assume you use a roughly 60-mil product?

Thanks in advance!

Patrick

The EPDM can be purchased at 40 mils and 60 mils. I use the 40, over the past couple years we have paid between $0.80 and $1/sf for it. We buy black material. The white is much higher cost. It is very unlikely that it will see any sunlight or wear, so i see no reason to go thicker.
We usually spray foam fom the subfloor down on th EPDM and at east 4 ft in long the bottom of the wall and seal all joints. I am in upstate NY, 7000 HDD, so frost penetration under the wall governs how much of the floor we spray. I usually spray the whole floor if the space is less than 16 ft across. That is an arbitrary choice.

I do know of one job where the owners decided to tear down the existing house and put a year round residence in place of it after we did this work. he is a friend of mine, and he called to tell me demolishing the house was easy with an excavator until they got to the crawl space. Apparently the EPDM stretched enough so the excavator could not pull far enough to pull it loose from the block. In the end it pulled the blocks out still attached to the EPDM.

Impressive story Pat.

Thanks for the info on the EPDM!

I think you may have made a convert out of me (from poly vapor barriers to EPMD).

The foam manufacturer's make an extra sticky single part foam - same chemicals as the air sealing foam, different proportions.  We use Convenience Products Foam and they make one called Panel Foam.  This sticks the plastic up quite well, then we use it stick 2" board on the wall overlapping the plastic by a foot or so

i haven't heard of this before.  as far as I know all urethanes are 1:1 ratio, so i would sooner believe the resin/iso mix is 1:1, but the chemical reaction time is slowed a lot. 

have you gone back to one of these a month or further after install to see how the adhesion is? 

generally we get worse results with single component and dual component 'portable' or 'unheated' kits than we do with plural component heated kits.  those electric wraps for the cylinders are well worth the cost and hassle. 

Pat

I have no doubt that the ratio is 1:1, but not all are the identical formula.  We have been doing this for about 10 years and have had occasion to get back in to see up to 3-4 years later - no problem.  The 2 inch board is not extruded styrene but iso board with faces on it.

Any problems w/ VOC in crawl space during application or migration to home through floor?

RSS

Featured Forum Discussions

What's the Most Profitable HVAC Job for Your Company?

Started by Wayne Melancon in HVAC. Last reply by Eric Kjelshus 7 hours ago. 2 Replies

Lighting replacement - 300 watt LED flood light

Started by Mary Sinkler in General Forum. Last reply by Jan E. Graveamker 12 hours ago. 4 Replies

Glass Block Windows

Started by Ken Kalke in Best Practices. Last reply by Sean Lintow Sr on Saturday. 1 Reply

EZ Green Home is Hiring!

Started by Chloe Chapman in General Forum Jan 5. 0 Replies

Videos

  • Add Videos
  • View All

Latest Activity

Eric Kjelshus replied to Wayne Melancon's discussion What's the Most Profitable HVAC Job for Your Company?
"What is your "Key Performance Indicator" dollar per hour? gross dollar per man day? % of…"
7 hours ago
Jan E. Graveamker replied to Mary Sinkler's discussion Lighting replacement - 300 watt LED flood light
"Hi Mary, What is the purpose of lighting the backyard ?  Sense of safety, night time…"
12 hours ago
Chris Laumer-Giddens liked Chris Laumer-Giddens's blog post Rock Wool Insulation for Floor of High Performance Tiny House
13 hours ago
Joe Davis liked Wayne Melancon's discussion What's the Most Profitable HVAC Job for Your Company?
16 hours ago
Joe Davis replied to Mary Sinkler's discussion Lighting replacement - 300 watt LED flood light
"Well said Dennis, try a lighting calculation for the space you need."
16 hours ago
Chris Laumer-Giddens's blog post was featured

Rock Wool Insulation for Floor of High Performance Tiny House

ROCK WOOL INSULATION FOR FLOOR OF HIGH PERFORMANCE TINY HOUSEIn August of 2016, we posted a video…See More
19 hours ago
Horace Douglas Hunt, Jr. joined Tom White's group
Thumbnail

Weatherization

Share your concerns and successes as a weatherization professional, or information for this…See More
22 hours ago
Horace Douglas Hunt, Jr. joined Sean Lintow Sr's group
Thumbnail

Best Practices (Residential)

Best Building, Retrofitting, or even Auditing Practices - what are they, what should change, what…See More
22 hours ago

Home Energy Pros

Welcome to Home Energy Pros – the unique digital community by and for those who work in the home energy performance arena.

Home Energy Pros was founded by the developers of Home Energy Saver Pro (supported by the U.S. Department of Energy) and brought to you in partnership with Home Energy magazine.  Home Energy Pros is sponsored by the Better Buildings Residential Network. Please honor our Guidelines

© 2017   Created by Lawrence Berkeley National Laboratory.   Powered by

Badges  |  Report an Issue  |  Terms of Service