How do I attach EPDM to concrete underground?

We have a 4 ft high concrete block crawlspace finished and ready to start the wooden structure on top of it for our cordwood house. Finished that last summer and this summer we will be backfilling and starting the woodwork. 3/4's of this crawlspace will be fully or partially bermed underground. Trying to figure out the best way to seal and insulate this wall completely. I have 4 rolls of epdm roofing rolls that were given to me. My thought is glue the epdm to the concrete blocks then glue foam board insulation on top of that and backfill. Didn't seem like any need to cover the foam board with anything. Rob Roy didn't cover the foam board before he backfilled in his book Earth Sheltered House. Is there a epdm glue out there that will adhere to both concrete and foam board or else a tar based product that I can imbed the epdm in and foam board. Doesn't seem to be products compatible with both mediums. Would really like to use the epdm as it was free and should work excellent. Any thoughts on this method or better ideas? House site in general has excellent drainage and there will also be a french drain around the exterior. We are planning to do a climate controlled crawl space.

The only reliable means of attaching epdm to concrete I've come across from professionally building ponds, is to mechanically fasten it at a point above the water level... Or wet dirt level in this case with strips of aluminum flat bar sandwiching the liner between aluminum and concrete with small concrete screws.

I googled and the roofing industry calls it termination bar:

http://www.bestmaterials.com/term-bars-518.html

I could probably drape the epdm and not attach to concrete. It would need to overlap itself and I would need to seal at those points. I still would need to attach the foam board insulation to the epdm. Not all of it will be totally bermed so I will need to attach it somehow.

Sounds like you are in over your head. Have you ever seamed epdm? It's no easy task to get it right.

Good luck.

Tracy, I have done a similar task. You definitely want to seal the block since it is not waterproof. I have used a product called xypex, forms waterproof crystalline matrix in surface layer of concrete, as well as brushed on tar like sealers, since you have free epdm, I would try to use it. There are 2 methods of sealing seams, liquid adhesive and tape. You may find online (Google epdm adhesive), but if you can purchase items at roofing supply house, I would do that, they will also be able to answer questions. Make sure the liner is tight everywhere, especially on corners. On my epdm roofing jobs, they were always heat seamed with special irons, adhesive and/or tape is easier and cheaper for the diy'er. You will need some kind of terminal bar as recommended in prev post, it can be as simple as treated 1x2 tapconned to block (you will get better grip if you drill into webs or filled cells).

Look into johns manville, " jm.com", they have a big line of sealers and adhesives, they might have one that will attach the epdm to the concrete, you will need different product to seal the seams thotgh.

So now that you have epdm installed, you have to get the foam on. Be careful, some adhesives will melt the foam, need to check compatibility. I have not have had much success with adhesives. I know a door builder that sandwiches foam in the middle of his doors, he spent years trying different epoxies until he found the right one, compatibility with epdm would probably be an issue. What bothers me most is trying to glue foam to epdm that is really not attached to substrate. I use screws to attach the foam, and when the foam is thick (6-8"), I just stack it, use great stuff from Home Depot to glue it to itself and let the dirt hold it in place. If part of the perimeter foam is to be exposed, you need to attach the foam with mechanical fasteners so you can put a protective surface finish on it. There are sheet goods you can use, or lath and mortar. Need to have well fastened foam to do that.

I saw you are thinking of using no protection on the outside of the foam. I know people do that, I don't like it because foam could get damaged by a variety of things. I use delta drain on top of the foam, it protects the foam, channels the ground water to perimeter drain, and keeps the foam clean and dry, ensuring that it maintains its insulative properties. Make sure the foam you are using won't absorb water, such as xps, or eps geofoam. If you use mechanical fasteners to attach the foam, you have a penetration of the epdm that will be pretty hard to seal. Maybe just 6mil plastic on the exterior of foam if cost is an issue.

You said French drain, to me, that says a hole filled with gravel that works well until you reach its capacity and then can have too much water until it seeps away into the ground. If you can, run a perimeter drain to daylight, much better in long run. If not, I would rethink the epdm material. You won't be able to seal the epdm at the bottom, and if water collects at footer, it will wick up the block and cause moisture issues inside crawl space. Not only is concrete not waterproof by itself, it will wick water up, that's why builders use sill moisture barrier and code requires treated lumber for sill plate. (It did not look like you used a liquid applied capillary break on top of the footer, that helps stop the wicking action). In that case, I would use a brushed or rolled on liquid sealer. Make sure perimeter drain is at bottom of footer, and let epdm go to bottom of footer and even run horizontally a little to direct water away from footer into perimeter drain.

Good luck with the project, what you are doing is great for insulating the crawl space, and keeping it dry, but has some complicated parts that, if not done correctly could cause you head aches in the future.

Thanks Kevin for your imformative reply. The 4 rolls epdm I have are 35' - 40' long and 8' - 9' wide. The exterior diameter of our house is 32'x40' with a 4 ft opening/future door into crawl space located on a 40 ft side and opens to ground height on that wall so will not be bermed at all in that particular corner. If I started one 40' piece at door opening then it will wrap around corner, overlap with next piece and continue around until door opening. That would then only make 3 seams to seal. If the tape is proven to be a good sealer then that would be my preference unless I can buy a small can of adhesive. I had also thought I could start the epdm on the top side of the block poking holes through it where it would need to slip over the bolts for the sill plate, then put down the sill plate gasket and then the sill plate. That should certainly hold the epdm from slipping down and moisture coming up through the block into the sill plate. Is there any contradictions to having the rubber under the sill plate like that, we would put the regular foam gasket on top of the rubber as well? I have enough width to work with on the epdm the I could drape it down over the foundation and angle towards the drain pipe. Also the drain pipe will wrap the house and drain towards daylight with a couple access points where we can flush it out if need be. Sorry for the misunderstanding, I thought that was a french drain. Honestly don't think setting water or saturated soil for long will be much of an issue as we are on a mountain top and water quickly drains away. But certainly would rather overseal instead of under seal. On the part of the wall where I would like to cover the foam board with a rock veneer it wouldn't be a problem to screw the foam board to the concrete blocks on the top half as that won't be bermed anyway. I do realize we would have to puncture the epdm, just have to seal it good at those points and they will never be below grade. Also the 40ft side of the crawlspace that will be completely below grade will have a 10 ft porch/ overhang going the whole length of the house so all water will be directed away from the foundation on that side. Will also be using foam board that doesn't absorb moisture. Now to just figure out how to glue foam board to epdm. At least temporarily on side of house where it will be completely backfilled so as to make it easier to keep it in place.

Tracy,

Tracy Lee wrote: I had also thought I could start the epdm on the top side of the block poking holes through it where it would need to slip over the bolts for the sill plate, then put down the sill plate gasket and then the sill plate. That should certainly hold the epdm from slipping down and moisture coming up through the block into the sill plate. Is there any contradictions to having the rubber under the sill plate like that, we would put the regular foam gasket on top of the rubber as well?

Using the bolts to hold the epdm should work well, may be tough to stretch and get the holes just right, but I would try it. this will also prevent moisture from moving up by capillary action (seal around bolts with a sealant that will stick to epdm). I would still use the sill gasket, it will fill any level imperfections in the top of the stem wall, caulk on the outside of the sill plate at joint with epdm.

post a pic if you could, as you proceed

kevin

I’d rethink this. Sounds like plenty of food for fungi and bacteria in this design at the EPDM interface to foam and/or concrete with no way to vapor or liquid dry when it accumulates and it will. New reports are showing carpenter and subterranean ants are eating away at the foams, most are moving to mineral wool as in Roxul IS or Drain board….their board has 70+ times more compression strength @ 2.5 % more deflection to handle the ground pressures, back-filling, and building movements that will fail foam/plastics at installation or in a short time.

Pour some test concrete spray some silioxane or silane (natural silicone/sand) products with 40% solids and watch how water resistant but 100%+ permeable remains ( lime wash would also do the same), along with the high perm mineral wool when (not if) that crawl space reaches high humidity levels(sealed or vented) the only direction drying can occur is out, not the case with EPDM/Foam barriers.

To aide in capillary breaking that mineral wool provides due gravity drainage due to it's high capillary desorption rate, do not add high clay content soils up against wool or the foundation. Follow their website for flashing and concrete protection boards , and/or use drainage pea gravel or a lime or MGO mortar to help manage liquid and vapor pressures. Ants don’t like the stuff either.

http://www.roxul.com/files/RX-NA_EN/pdf/Technical%20Bulletins_Guides/Residential/13A76%20ROXUL%20COMFORTBOARD%20IS%20Installation%20Guide%20FINAL.pdf Pg 22-23.

In the detail above I feel more comfortable mating EPDM to an inert permeable mineral wool.

Otherwise, too many unknowns mating chemically active concrete, glue, rubber EMPD, holes, fasteners, sealants, foam blowing agents and fire retardants, etc….for me. Use of simalr materials to cut down on dissimilar materials galvanic reactions that can rot risk…less is more approach.

XYPEX:

Blend of portland cement, fine treated silica sand and active proprietary chemicals. When mixed with water and applied as a cementitious coating, the active chemicals cause a catalytic reaction which generates
a non-soluble crystalline formation of dendritic fibers within the pores and capillary tracts of concrete. This process causes concrete to become permanently sealed against the penetration of liquids from any direction.

If you add enough Portland cement and sand to a low Portland cement mix like 2000 PSI you should be able to water seal the surface or get close enough. The need will go down with higher compression rating's. The "active proprietary chemicals" are probably cost reduction fillers or synthetic silicone or lime (MGO), fly ash or other pozzolan. I could not find a perm rating guessing zero. As it states this is an "active compound" knowing what it reacts to is critical to sustain it's seal.

I have the epdm which is why I wanted to use it but it is not a must use. The xypex looks interesting but I would still need to insulate the walls somehow. The roxul looks like a good product as well, however with all the steps and materials recommended I would make a good guess that the price would be out of range. Maybe I just have to do like Rob Roy did and put on a tar based product and imbedded 6 mil plastic in it, and then put foam board over that. Simple, inexpensive, but messy. These days he uses bituthene adhesive sheets and adheres them directly to the concrete. A good option to, very similar to the epdm I already have though. Honestly don't know which route to go. Have researched so many different options my head is spinning. Like most people on here building the houses we are budget is a big concern. If it wasn't i would just hire someone and be done with it. We do plan to put a dehumidifier in the crawl space to use as needed, but hope do minimize use by controlling moisture other ways.

We ended up going with a product called platon to seal the wall. It is only attached at the top and drapes down like a curtain. It has little channels in it that direct any moisture that comes from the walls down to the footer. Easy to install, not off the charts expensive. We are going to insulate on the interior due to the amount of ants and bugs in our area and their propensity to channel in the foam.

I notice in this second post aboveand in one in another post on another thread that the builders plan on utilizing a dehumidifier.   There is a characteristic of dehumidifers that is not widely known but ought to be taken into consideration.  

Most room or basement dehumidifiers draw about as much electricity as an electric space heater.   As the unit stays generally within an enclosed or semi enclosed space all that electrical energy ends up as heat in that enclosed space.  However, it need to be realized that when a certain amount of water becomes water vapor, energy is required to accomplish the vaporization.  That energy is known as the heat of vaporization.  To return the water vapor back to liquid state that amount of heat must be removed from the vapor.  

The way dehumidifiers work is that they are basically a small air conditioner, but rather than have the cooling coils indoors and the heat rejection coils outdoors both sets of coils are inside the dehumidifier.   Moist air is drawn in through the cooling coils and as the air is cooled it loses the ability to hold the vapor and it condenses into droplets and drips into a catch bucked or are carried away to a floor drain or the like.   After the air has passed through the cooling coils it is directed across the heat rejection coils warming the air back up and making the unit more efficient by helping the refrigerant inside return to a liquid state for re-use in the cooling coils.   The problem is that the heat of vaporization is also returned to the air in the enclosed space.   As a result the dehumidifier acts to put all the electrical energy into the space as heat and also put all the heat of vaporization into the space as well.  Typically this makes the dehumidifier a better heater that a space heater.  On the ones I analyzed they put about 125% as much heat energy into the air as the electricity they drew from the outlet.  E.G. run a 1200 watt dehumidifier and you get as much heat as a 1500 watt space heater.  But it does take the moisture out of the air, and that is satisfactory so long as all that heat is not a problem.   An air conditioner does not do this because its heat rejection coils are outdoors and the water is usually routed to a drain or drips out doors as is common on window mount units.  A central air unit may have a sump and small pump to pump the water away.  It is also worth noting that the condensed water from dehumidifiers and air conditioners is essentially distilled water, so it is useful for where soft water is desired, Its only shortcoming is that this water will have a bit of dust or mold spore etc. in it but not usually enough to bother and the water is also useful for watering plants that are sensitive to choline or flouridea or whatever else is found in your tap water.