Crawlspace encapsulation

  • Active since 1995, Hearth.com is THE place on the internet for free information and advice about wood stoves, pellet stoves and other energy saving equipment.

    We strive to provide opinions, articles, discussions and history related to Hearth Products and in a more general sense, energy issues.

    We promote the EFFICIENT, RESPONSIBLE, CLEAN and SAFE use of all fuels, whether renewable or fossil.
I did mine myself few years ago. Man it was a lot of work but was definitely worth it. Butyl tape works good for holding liner to concrete wall. I used it then I tap conned every 16 inches to keep it from pulling down when I am in the crawl walking around. I terminated my liner a foot below my sill plate. I put a gravity condensation draining dehumidifier in mine that drains into my hvac condensate pump. It has a washable filter that I check every 6 months but it's always pretty clean. I keep the RH setting at 55% on mine. It raised my electric bill about 15 bucks every month except for the first month it was installed which was about 35 dollars more.
 
Rusty18 said:
View attachment 297119
Looking for opinions/confirmation but is that black mold on the blocks? Though it was just dampness until I got up to it, now I’m leaning towards I need to bleach it...
Click to expand...
It looks like the cinder blocks have weeped water which from all the block foundations I've seen is pretty common. Does it get pretty damp in their during the wet season?
 
Grizzerbear said:
It looks like the cinder blocks have weeped water which from all the block foundations I've seen is pretty common. Does it get pretty damp in their during the wet season?
Click to expand...
Not any more, it used to do to poor landscaping decisions/lack of downspout maintenance by previous owners.
Looking like I might be having some of these decisions made for me though. Just bought a radon detector, I know it needs to run for a few days to get an accurate average but initial numbers are not looking good. I may be opening the vents back up and adding a powered vent to make sure it moves the bad stuff out...
 
  • Sad
  • Like
Reactions: Grizzerbear and begreen
Mellow how big of a crawlspace are sq ft wise is this dehumidifying? I have two main 670 sq ft areas Im going to need to dehumidify at a cabin that we only use during the weekends and most of the summer. There is an old cabin and a new expansion area. Small 3x3 opening between each building area. My indoor humidity during the summer is upwards of 80+%. As you can imagine, wood becomes an issue. I installed T/G paneling in my expansion during the winter/spring, and when summer came all of my boards expanded and pulled away from the walls a tiny bit. For shorter runs like between windows close together, the pieces expanded ALOT and pulled the window casing from the walls! I thought I properly gapped things to accommodate, doing some experiments/research online but apparently not. I still have half the place to do, plus Im plan on putting down hardwood floors.

My plan is to insulate the walls with 2" rigid foamboard cut into pieces of course, spray foam between the joists where they meet the sealplate(spelling?), but I would leave between the joists free of any insulation. In the old cabin, they insulated between the joists then stapled plastic up. Well that all fell, mold everywhere. When I did my research, it was explained to me that I should seal off all the crawlspace vents, vapor barrier, insulate walls not joists, then condition the space. Here's the issue, I really want to get rid of this big old oil burning furnace. Our place is small so Id like to maximize on real estate, so conditioning the crawlspace is going to be a challenge unless I go with another forced air system. I also did not extend the duct work from the old to new area. I am considering going with mini splits in the future. We have no air conditioning other than two window air conditioners, one in the living room one in the bedroom.

I know I have to vapor barrier this entire place, and it's going to be a HUGE pain in the old cabin as it's only 2' space between dirt and floor.

To say that mold is an issue is an understatement. If you get a bright LED flashlight and shine it along the base of the walls, you will see white mold along EVERYTHING. We store ski/snowboard boots on the floor and they get it too. As well as ANYTHING that is stored on the floor like boxes with decorations in them etc.

Wifey wants me to finish the expansion and put a proper kitchen in before she stops making breakfast for me. But once that area is done Im going to tackle the next project which is to put in DIY mini splits. Then put in the insulation/vapor barrier immediately after that. And then if the mini splits cant tackle the humidity as we will likely keep them running on non livable bare minimum settings while we arent there, Im considering a dehumidifier under the crawl space to run as the primary means of dehumidifying.
 
gthomas785 said:
Is it really cycling 152 times a day? That poor compressor..
Click to expand...
Yes. On for about 3 minutes then off for 6 minutes. The dehumidifier has a switch on it to set it to your RH but as I mentioned it looks like it doesn't have a sensor and just affects timing.

[Hearth.com] Crawlspace encapsulation
 
That dehumidifier definitely has a sensor. I have the same one. Suspect it's just way oversized for your space and it's short cycling in the compressor timeout. Either that or you have poor air circulation down there.
 
gthomas785 said:
That dehumidifier definitely has a sensor. I have the same one. Suspect it's just way oversized for your space and it's short cycling in the compressor timeout. Either that or you have poor air circulation down there.
Click to expand...
But you mentioned you are not monitoring the electrical usage, how do you know what it is doing?
 
Well, I have a humidity monitor in my crawlspace and it has been holding rock solid at 50% despite weather fluctuations, so it must have some kind of sensor. Also I can hear when mine kicks on

Edit: by the way do you have the fan set to continuous? It works better if you do
 
I would think creating a microclimate by sealing up the crawlspace is a good thing, no? Venting it will just bring in more moisture and add work for the dehumidifier. It's maintaining RH fine, just that it's cycling frequently.

Personally I have a feeling that the rapid cycling could be a side effect of the fan setting. I've seen this too with window ACs on the "economy" setting. When the fan shuts off, water in the pan starts evaporating, gets to the sensor and makes it think the RH is higher than it really is so it kicks back on. Then once the fan is running it gets some fresh air from the room and sees the real humidity again, so it kicks off. Still averages out to the right humidity but cycles more than needed. Again, just a hunch.
 
  • Like
Reactions: stoveliker
gthomas785 said:
I would think creating a microclimate by sealing up the crawlspace is a good thing, no? Venting it will just bring in more moisture and add work for the dehumidifier. It's maintaining RH fine, just that it's cycling frequently.

Personally I have a feeling that the rapid cycling could be a side effect of the fan setting. I've seen this too with window ACs on the "economy" setting. When the fan shuts off, water in the pan starts evaporating, gets to the sensor and makes it think the RH is higher than it really is so it kicks back on. Then once the fan is running it gets some fresh air from the room and sees the real humidity again, so it kicks off. Still averages out to the right humidity but cycles more than needed. Again, just a hunch.
Click to expand...
That is my feeling too.
 
mellow said:
Called Santa Fe and they think my crawlspace is "too sealed up" and it is creating a microclimate?!? in my crawlspace, they want me to add venting to the exhaust and see what that does. It apparently does have a RH sensor right by the knob according to the tech I spoke to.
Click to expand...
Can you put the unit on a light timer or smart plug. Set it to minimum rh and let it run in a schedule?
 
  • Like
Reactions: stoveliker
EbS-P said:
Can you put the unit on a light timer or smart plug. Set it to minimum rh and let it run in a schedule?
Click to expand...
It is already on a smart plug, I had thought about doing it this way if I can't get the switch to act right, just not sure what kind of schedule to put it on.
 
mellow said:
It is already on a smart plug, I had thought about doing it this way if I can't get the switch to act right, just not sure what kind of schedule to put it on.
Click to expand...
With a humidity monitor down there it just might take a few tries to get it right. Calculate your total run time and then have it run once every hour or two to get that total run time per day. It will shut it self off so you don’t have to get it perfect just close.

Honestly I think some is wrong with the unit it should have a delta range of at least 5% RH if not 10. But it could be just fine. the other thing to try is to add a piece of flex duct to the exhaust and carry it as far away from the unit as you can and point it in a direction that help circulate the air best.
 
mellow said:
Been playing with schedules and I am currently at 2 hours OFF, 1 hour ON to keep the humidity at around 53%.

I think the dang unit's meter is messed up, still does the same thing, just now it gets turned off:
View attachment 299621


It still runs the same pattern of off and on after a 2 hour break:
View attachment 299622
Click to expand...
SO how many times does it cycle on/off during the on period? 48 times in a day seems like alot. If you only have it running 1/3 of the day for an hour each time. Have you asked the manufacturer?
 
Seriously I think it's the fan setting. Try putting the fan on continuous.
 
Have you contacted Santa Fe and asked about cycle times?
 
You must log in or register to reply here.

Similar threads

BigJ273
Crawlspace dehumidification
Replies
22
Views
5K
DIY and General non-hearth advice
EbS-P
EbS-P
J
Replace Jotul 3CB with used Hearthstone Heritage (non cat)?
Replies
12
Views
5K
The Hearth Room - Wood Stoves and Fireplaces
Manly
Manly
R
What can be done with a crawl space on an old house?
Replies
32
Views
19K
DIY and General non-hearth advice
EbS-P
EbS-P
A
Wood Stove lack of comparison / operational demos
Replies
9
Views
2K
The Hearth Room - Wood Stoves and Fireplaces
EbS-P
EbS-P
N
Hearthstone Manchester issues
Replies
54
Views
12K
HearthStone
Bill S
Bill S
Top Bottom