I have a very tall crawlspace (approx. 5'-6' clearance) with a concrete floor under part of the back end of my house. I use this area for lawnmowers etc. Next week I have the entire crawlspace being encapsulated and a dehumidifier installed. Over the concrete area, he is putting a 20 mil liner and I want to cover that area with plywood or some modular flooring to protect it and also give me access for the lawnmower etc. Would plywood be the best, or any other ideas to cover this area? It is about 15' X 25,' but I may not cover all this concrete.
crawlspace flooring
- Thread starter joec
- Start date
I put some landscape pavers down in mine. With it being fully encapsulated and 20 mil liner and dehumidifier, plywood would probably work. But even with all that I still wouldn't want wood on the floor in a crawlspace due to termites, even with the encapsulation.
Whatever you use I would insist the edges bordering the walls have some foam pipe insulation (or some such) so abrasion of the plastic isn't a future issue.
I would think with the dehumidifier that plywood would be fine if you aren't going to see any running water near it. I would also have the plywood installed weeks after the encapsulation to make sure the humidity gets down to acceptable levels for plywood (or whatever your end solution is).
I would think with the dehumidifier that plywood would be fine if you aren't going to see any running water near it. I would also have the plywood installed weeks after the encapsulation to make sure the humidity gets down to acceptable levels for plywood (or whatever your end solution is).
I had min encapsulated, but problems. I am working on if it is true or not, but according to some newer data, encapsulating is not a good thing. The theory is the ground will always breath. Moisture will always come up and moisture will always come through the foundation walls. So encapsulating traps a humid zone under the barrier where mold can grow. So the new theory is bare walls, 80 to 90% floor covering and the de-humidifier ducted to circulate air through the entire space. Of course, vents sealed.
There is some logic to this, but I was waiting for it to a a tad warmer before I pulled a bit of the foam down to see if there was any growth and cut open the floor to check. I still have a very musty smell in mine.
I had "Reliable" do mine. Never again. Sani-Dry de-humidifier has failed three times. No pump on the drain so is builds up slime and overflows. No ductwork so air does not circulate to the far end.
Oh, the section where I store, I use "stable mats"
There is some logic to this, but I was waiting for it to a a tad warmer before I pulled a bit of the foam down to see if there was any growth and cut open the floor to check. I still have a very musty smell in mine.
I had "Reliable" do mine. Never again. Sani-Dry de-humidifier has failed three times. No pump on the drain so is builds up slime and overflows. No ductwork so air does not circulate to the far end.
Oh, the section where I store, I use "stable mats"
This doesn't address your flooring question, but we had our crawl space set up just as you said and never had any problem with mold under the barrier. Ours was relatively small (30'x60'x3') and we used 20 mil poly over sand with the joints taped, about 95% coverage, with the walls exposed. We used a SantaFe compact 70 dehumidifier with an 40' long, 8" flex duct on the exhaust so air circulated throughout the space. When we moved 5 years later, it was still running fine though I did have to clean out the condensate drain a couple of times a year.
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No logic to the 80 to 90% floor covering. Code requires 100% of exposed earth be covered. Moisture will be captured by the barrier and yes, you may get fungal growth under the barrier, but thats ok. With proper drainage under the barrier moisture will flow to the lowest point where there should be a drain. Properly installed encapsulation crawl space and you won't have issues.
That is the old concept. That is what we have and we have strong musty off-smells. There is no such thing as a completely encapsulated space. Advertising BS.
Or cheap or incorrect installation is more likely than advertising BS. I've been in encapsulated crawlspaces you could eat off the floor. As you said "I had "Reliable" do mine. Never again. Sani-Dry de-humidifier has failed three times. No pump on the drain so is builds up slime and overflows. No ductwork so air does not circulate to the far end." Your issue is incorrect installation. Large or odd shaped crawlspaces need either multiple dehumidifiers or ducted dehumidifiers to pull air from all of the space, as well as a way for the water to drain out of the crawlspace.
I had my crawl space fully encapsulated, also have the Sain-dry dehumidifier which has been running ok for 2 years, it uses hose and gravity to drain into sump. It’s clean and dry under the house. Difficult to find filters for it.
HOWEVER, has a cat pee smell, varies in intensity, so far mostly contained to the crawl space. The company who installed it say it rare, but does happen in a small percentage of homes. Their solution would be to install a radon vent - vented pipe under the plastic with fan exhaust to the outside.
Anyone else out there have the cat pee smell problem?
HOWEVER, has a cat pee smell, varies in intensity, so far mostly contained to the crawl space. The company who installed it say it rare, but does happen in a small percentage of homes. Their solution would be to install a radon vent - vented pipe under the plastic with fan exhaust to the outside.
Anyone else out there have the cat pee smell problem?
pm sent
Every solution seems to have someone contradicting them
One guy claims some of the smells are due to using some reinforced vapor barriers
Other say soil gasses
Others mold, rodents, bugs...
Some say foam the walls, some say never, some say none
Some say water under barrier is normal and fine, Others say not
Some say a drainage membrane to a sump or exit, others say not
One guy says we have no radon in this area, others say so
IF it was truly sealed, then why is it not part of the house environment? If it is sealed, totally stagnant, then smells will build up.
I think by code, if used for dry storage, it can be classified as "livable space" and then part of the total HVAC environment.
I could use a space to store more lumber
I have considered an ERU for the CS, but why not whole house exiting through the CS?
If the CS is living space, why do we have return air ductwork? Why can't the CS be the plenum?
Does moister moving thorough the foundation wall depend more on correct foundation sealing on the outside?
What SOP says, and even what code says may not be correct. We learn things all the time. I know what I have stinks. Figurately and literally.
And of course, ever slick sheet advertisement says only their system works. Think about it, at a maximum, no more than one can be correct.
One guy claims some of the smells are due to using some reinforced vapor barriers
Other say soil gasses
Others mold, rodents, bugs...
Some say foam the walls, some say never, some say none
Some say water under barrier is normal and fine, Others say not
Some say a drainage membrane to a sump or exit, others say not
One guy says we have no radon in this area, others say so
IF it was truly sealed, then why is it not part of the house environment? If it is sealed, totally stagnant, then smells will build up.
I think by code, if used for dry storage, it can be classified as "livable space" and then part of the total HVAC environment.
I could use a space to store more lumber
I have considered an ERU for the CS, but why not whole house exiting through the CS?
If the CS is living space, why do we have return air ductwork? Why can't the CS be the plenum?
Does moister moving thorough the foundation wall depend more on correct foundation sealing on the outside?
What SOP says, and even what code says may not be correct. We learn things all the time. I know what I have stinks. Figurately and literally.
And of course, ever slick sheet advertisement says only their system works. Think about it, at a maximum, no more than one can be correct.
This came up in a class I took on sealed crawl spaces. It was explained as caused by damp soil or soil that had high vegetation content at some point. Solution was to make sure all the seams are fully sealed and overlapped a minimum of 12 inches, or install a vent pipe.
Every solution seems to have someone contradicting them
One guy claims some of the smells are due to using some reinforced vapor barriers
Other say soil gasses
Others mold, rodents, bugs... - It can be hard to identify the causes of smells.
Some say foam the walls, some say never, some say none - for encapsulation, it has to be sealed in some manner, I've seen spray foam and insulation boards used.
Some say water under barrier is normal and fine, Others say not - Well, the barrier is stopping the water, so of course you'll have water under it if it is doing its job.
Some say a drainage membrane to a sump or exit, others say not - I'd want the water to get out instead of building up, so I say yes to sump pump / exit.
One guy says we have no radon in this area, others say so - Radon is everywhere, some areas less, but it's everywhere. I'm in real estate, and we are seeing more and more people do the tests and are finding surprising results of where radon is over the threshold of 4.0 Surprising in that it's in areas people used to say "no radon in this area"
IF it was truly sealed, then why is it not part of the house environment? If it is sealed, totally stagnant, then smells will build up. It should not be totally stagnant, either a dehumidifier that drains to daylight or a sump pump, or air supply from HVAC into the space, or a combination of the two.
I think by code, if used for dry storage, it can be classified as "livable space" and then part of the total HVAC environment.
I could use a space to store more lumber Yes, if it's installed correctly you could store lumber down there.
I have considered an ERU for the CS, but why not whole house exiting through the CS?
If the CS is living space, why do we have return air ductwork? Why can't the CS be the plenum? Code actually says "crawl spaces with moisture vapor control installed in accordance with this section are not to be considered plenums"
Does moister moving thorough the foundation wall depend more on correct foundation sealing on the outside? - To a degree yes, I had to dig out my foundation on the outside and put a much better sealer in, it has cut down on water in my crawlspace by huge amounts.
What SOP says, and even what code says may not be correct. We learn things all the time. I know what I have stinks. Figurately and literally. - You need a vent to pull the air from under the barrier out of the crawlspace.
And of course, ever slick sheet advertisement says only their system works. Think about it, at a maximum, no more than one can be correct. - there are multiple ways to skin a cat. some better than others.
One guy claims some of the smells are due to using some reinforced vapor barriers
Other say soil gasses
Others mold, rodents, bugs... - It can be hard to identify the causes of smells.
Some say foam the walls, some say never, some say none - for encapsulation, it has to be sealed in some manner, I've seen spray foam and insulation boards used.
Some say water under barrier is normal and fine, Others say not - Well, the barrier is stopping the water, so of course you'll have water under it if it is doing its job.
Some say a drainage membrane to a sump or exit, others say not - I'd want the water to get out instead of building up, so I say yes to sump pump / exit.
One guy says we have no radon in this area, others say so - Radon is everywhere, some areas less, but it's everywhere. I'm in real estate, and we are seeing more and more people do the tests and are finding surprising results of where radon is over the threshold of 4.0 Surprising in that it's in areas people used to say "no radon in this area"
IF it was truly sealed, then why is it not part of the house environment? If it is sealed, totally stagnant, then smells will build up. It should not be totally stagnant, either a dehumidifier that drains to daylight or a sump pump, or air supply from HVAC into the space, or a combination of the two.
I think by code, if used for dry storage, it can be classified as "livable space" and then part of the total HVAC environment.
I could use a space to store more lumber
Yes, if it's installed correctly you could store lumber down there.I have considered an ERU for the CS, but why not whole house exiting through the CS?
If the CS is living space, why do we have return air ductwork? Why can't the CS be the plenum? Code actually says "crawl spaces with moisture vapor control installed in accordance with this section are not to be considered plenums"
Does moister moving thorough the foundation wall depend more on correct foundation sealing on the outside? - To a degree yes, I had to dig out my foundation on the outside and put a much better sealer in, it has cut down on water in my crawlspace by huge amounts.
What SOP says, and even what code says may not be correct. We learn things all the time. I know what I have stinks. Figurately and literally. - You need a vent to pull the air from under the barrier out of the crawlspace.
And of course, ever slick sheet advertisement says only their system works. Think about it, at a maximum, no more than one can be correct. - there are multiple ways to skin a cat. some better than others.
As I understand the code, as soon as you put fixed storage in the CS, it can them be considered living space. When I say plenum, I mean the return path, not the strict definition of plenum the code says. So, the return air grills ( not enough anyway) just dump into the CS, and the HVAC sucks from the CS through the grills , added grills, and leakage. I could then add grills in the back of the walk-in closet and each bedroom to improve the overall circulation.
I don't know how to skin a cat, but I do have a guide with 101 used for a dead cat. None of them will vent the crawl space unfortunately.
So: Things that seem certain
Removal and treatment of pre-existing mold on the sub floor.
Vent under the vapor barrier. I gather I should run a few perf pipes the length of it under the VB. If located stragically, they might serve as a ground water drain. Likely have radon as well as any soil gasses or things growing if it got damp. My CS is sloped from 2 to 5 feet so gravity can be my friend. I just need a nice quiet, efficient fan. I think a 4 inch boxer will actually work.
Where they first company drilled a 4 inch hole in my foundation, with some work could be close to the lowest spot. Ground slopes away steeply on that side, so gravity drain is possible. But I need a way to prevent critters from getting in. Especially baby copperheads.
Airflow through the CS. If not house air, then an ERV unit. My thought was outside air, through the exchanger and into the house, then from the house, through the CS and out the exchanger to the outside. So one unit moves air through both. If I have it sealed well enough, then I don't see why using house air to circulate would be a problem as it would be now.
Duct the dehumidifier to the far end. A big box and 3 12 inchers shoudl not be too much drop.
Seal the seams correctly. I found some thin duct tape that seems to be stickier than the vinyl tape they used. Flex caulk and tape combo.
Seal correctly around posts
Seal the foam-board, top to the wall, bottom to the VB. Any actual water seepage should then go under the VB. Any mold would be excluded from the CS.
Thinking about an enclosure with 4 inches of OC 407 around the dehumidifier as I can hear it in my HT.
I can swap the vinyl drain hose for copper. I could install a dedicated pump, or drain directly below to the AC condensate pump. I was first worried about freezing, but with the heat on, it is too dry in the house so that would to be a problem. ( 42% right now, 49 in the CS)
I would like to find a hygrometer that can send an alarm to my phone. I just use a remote sensor, but have to remember to look at it. This is to tell me WHEN the Sani-Dry fails again. I would also like to sense standing water. Either form ground water pushing up, plumbing fault, or condensate overflow. I have PB plumbing ( copper connectors) so I intend to replumb.
I would rather not spend all summer doing this myself, so if anyone knows a trustworthy contractor, let me know.
I don't know how to skin a cat, but I do have a guide with 101 used for a dead cat. None of them will vent the crawl space unfortunately.
So: Things that seem certain
Removal and treatment of pre-existing mold on the sub floor.
Vent under the vapor barrier. I gather I should run a few perf pipes the length of it under the VB. If located stragically, they might serve as a ground water drain. Likely have radon as well as any soil gasses or things growing if it got damp. My CS is sloped from 2 to 5 feet so gravity can be my friend. I just need a nice quiet, efficient fan. I think a 4 inch boxer will actually work.
Where they first company drilled a 4 inch hole in my foundation, with some work could be close to the lowest spot. Ground slopes away steeply on that side, so gravity drain is possible. But I need a way to prevent critters from getting in. Especially baby copperheads.
Airflow through the CS. If not house air, then an ERV unit. My thought was outside air, through the exchanger and into the house, then from the house, through the CS and out the exchanger to the outside. So one unit moves air through both. If I have it sealed well enough, then I don't see why using house air to circulate would be a problem as it would be now.
Duct the dehumidifier to the far end. A big box and 3 12 inchers shoudl not be too much drop.
Seal the seams correctly. I found some thin duct tape that seems to be stickier than the vinyl tape they used. Flex caulk and tape combo.
Seal correctly around posts
Seal the foam-board, top to the wall, bottom to the VB. Any actual water seepage should then go under the VB. Any mold would be excluded from the CS.
Thinking about an enclosure with 4 inches of OC 407 around the dehumidifier as I can hear it in my HT.
I can swap the vinyl drain hose for copper. I could install a dedicated pump, or drain directly below to the AC condensate pump. I was first worried about freezing, but with the heat on, it is too dry in the house so that would to be a problem. ( 42% right now, 49 in the CS)
I would like to find a hygrometer that can send an alarm to my phone. I just use a remote sensor, but have to remember to look at it. This is to tell me WHEN the Sani-Dry fails again. I would also like to sense standing water. Either form ground water pushing up, plumbing fault, or condensate overflow. I have PB plumbing ( copper connectors) so I intend to replumb.
I would rather not spend all summer doing this myself, so if anyone knows a trustworthy contractor, let me know.
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