Very clear explanation. I moved into a cedar log cabin that was built in 1990. Very poorly insulated. It's very cold in the winter time. So we started with Caulking between the logs and around the windows and door frames as well as extra insulationing products for the door. I have vents in my crawlspace. It is a very clean and (was tidy until we started using it for storage.. now realizing that wasn't the best idea).(it's not like those scary dark and dirty crawlspaces.) There is a very thick black plastic laid throughout the entire floor of the crawlspace with a good 1/2foot up to 2 feet(in some areas) of pea gravel. The pressure tank and hot water heater are down there.. the floors do not have insulation.. we put in thick foam blocks into the vents during the winter and close them. That's what the previous owner has always done. We take them out in spring . I noticed recently a musty smell that is gradually getting stronger. And then later noticed condensation dripping from around the HVAC system as well as off the PVC water lines. I would like to have the crawlspace completely encapsulated and a dehumidifying system installed in the future but budget won't allow it right now. My question is.... In the mean time, should I keep the outside vents closed and foam blocks in during the spring and summer as well? Or would that make matters worse? Also any feedback is appreciated. Thanks.
If you do not have a dehumidifier installed to control humidity you should not close your vents continuously. If budget allows, you can install the dehumidifier first so it can begin controlling humidity in the closed crawl space until you are able to fully encapsulate with new vapor barrier.
I live in northern Wyoming, not much humidity, my crawl space does not have vents but needs “sealed” for the fact that you can feel how cold the floors are getting with the cold temperatures moving in. Do you recommend sealing everything up tight and putting a vapor barrier down on the ground? What are your thoughts.
Wish I had a crawl space ninja here in Portland, OR. With a cool rainy winter being the norm from November through March, I am thinking to close, using foam board, the foundation vents during the winter and keepimg the open these ret of the year.
I live in Florida (HIGH humidity - rains all summer). When stucco was applied to my wood frame house by the previous owners, they did not add enough vents (3 small ones on a 900 square foot house). Thus, rainwater had collected under the house for a long time in the summer, and termites and wood rot became a problem. Short of spending huge money on an encapsulation or sump pump installation, should I not just be fine with adding more crawlspace vents and/or a crawlspace exhaust vent fan?
Encapsulation with a sump pump is the only sure way to eliminate standing water. Open crawl space vents will just give water more opportunity to penetrate your crawl space. Hope this helps.
I live in Asheville,NC . My Geothermal heat pump and Heating/cooling ducts , are in the crawlspace. It is a huge crawlspace . 12 feet high at the back and 4 feet in the front. How does installing an exhaust vent fan help bring in supply air? My local HVAC company tells me that because the "crawlspace" is so large that I don't have any concerns for the heating and cooling in a completely sealed crawlspace. I am not sure now if I should install a vent fan or not.
I have a 14 by 28 building but there is not any HVAC duct work down there, no pipes at all. It's about 20" off the ground at most. I'm in the process of completely sealing off the underpinning to block airborne noise from the road nearby. I would prefer not to have vents because they will bring in more noise. The underpinning will have mass loaded final, a vapor barrier come on and siding. It's in Asheville North Carolina. Do you think it's OK for this building that is on cinder blocks to not have a favor rarior on the ground and have a completely enclosed underpinning?
Hey I live in Oklahoma with average 54.4% humidity. My crawl space is currently not having any problems with moisture it seem real dry and I have not seen any signs of mold. I currently only have two vents on either side of my house. I am considering encapsulating and insulating with foam board. I am unsure about the need for a dehumidifier as my average humidity is already decent. Was wondering should I bother? Also should I put vent fans in the two sides of the house?
I lived in Southern California, Los Angeles, the average humidity is about 55-60, should I open it or close it. (I guess it is too late, I have 6 vents opened since 1992)
This video I believe refers to a humid weather area. You mention the hot, humid air coming in the house. What about CA weather where air is hot and dry?
It would depend on relative humidity, you can keep an eye out with a humidity reader and determine how to proceed from there. diy.crawlspaceninja.com/product/thermopro-tp65/
Good explanation Mr Church.... 1st thing I did today.....I opened up the bsmt windows ..put a fan to circulate air....n tomorrow will get rid of all dirty insulation n clean up...so it will be easier to work in an open Crawlspace. Question 1....b/4 U do the job....do U ck on Beams or Girders that the wood it's good...??? Question 2.... in a beams 24 inches center.. I plan 1st to put 6 mil plastic...then R-19 insul. ...n close ...with a thin sheet of pink foam boards to cover the job. Is that sound to U ... ok ???
As a previous poster briefly mentioned - radon is a concern. If you leave the vents open radon will escape and your house radon levels will be lower. Close them off and radon levels increase in the house. It is a Radon vs. Humidity issue. I have bought a digital radon detector and it is a significant difference between leaving the vents open and blocking the vents. And I live in supposedly a low radon area. Obviously, the best choice and the most expensive choice is to address both. However, if I have to pick one give me humidity over radon.
When encapsulating we still recommend installing one ventilation fan blowing outward to help expell some of the soil gases. Obviously, if your levels are still high you will need a radon mitigation system like you already mentioned. Here is a video talking about the ventilation fans we recommend if you're interested: ua-cam.com/video/-8Q_jWuRMqw/v-deo.html
Hello crawl space Ninja I live in Chicago Illinois does the same rules apply in the cold climate which we have about 60% of the year should I close my crawl space vents we do have parts of the year that is humid thank you and truly appreciate your videos
Hi Jack, I do exactly that. I close all my crawl space foundation vents during the winter only to offset the potential of freezing pipes. I have all vents open from spring tru the first low temp / freeze of the winter. hope this helps.
Thank you for your videos. I live in the Chicagoland area and just moved into a home on a lake with a vented crawlspace. We are on a high water table but not a flood zone. We do not want to encapsulate because there is no drain tile and no sump pump (luckily the home is 20 years old and has not needed either). The space has cement walls and a cement floor with open vents and one HVAC vent pumping into the crawl space. What would you recommend in order to control temp extremes and humidity? There is no code saying we can't close the vents, but we do not know, other than professionally sealing off the vents and joists, if we need to spray foam the ceiling and/or insulate the walls. Also would we need a dehumidifier? With all vents open the highest the humidity has been in the summer is 70%.
Building code does require insulation. If you seal the vents, that gives you the opportunity to insulate the walls instead of the subfloor. That should be efficient enough to handle the temperatures. For controlling humidity and keeping it around 50%, we recommend installing a dehumidifier.
Even if the crawl space is not encapsulated, sealing the vents will help better regulate the humidity by keeping the humid outside air from entering. Installing a dehumidifier, in addition to sealing the vents, is recommended. If you do seal the vents, you will need to install a vent fan to push out any soil gasses that may build up in the crawl space.
Actually the walls will sweat creating a hostile environment under the home even though you have a dehu. You have to cover your walls and piers with a 8-10 mil poly. Sealing the vents completely air tight along with a dehumidifier. Do a preventative Wood treatment to the sub floor, joists and the the band sill. If your crawl takes on water even though it’s encapsulated you need to install sump pumps to evacuate the water. For vents that sit on the grade you will need vent wells. Do your homework before you do anything to your crawl. You could make it worse if you do not know what your doing. Again cover the floor, walls and piers with Polly. It’s very important if your doing a encapsulated crawl.
I have a ground water issue . With vents open I got humidity. With the vents closed I got mycotoxins coming out of the ground and trenching up into the house . Older houses don’t have ventilation tubes in foundation slab:/ In my case you may want to address ground water when sealing the vents. With vents open humidity got in and cold in winter. Summer the floor in crawl space was cold from Ac causing condensation and mold. Heating the floor inside was cold causing condensation inside but less because of the lower winter humidity also a mold condition .. I agree sealing them if your not getting gases from the ground coming in.
Not fully sure about your question, I will guess its regarding the vents.... It would be the same approach as any other home encapsulating and closing vents you improve your indoor air quality.
You can have vapor barrier and closed vent but leave a few 3-4 vent fans. Also install dehumidifier for when the vans are not keeping it low enough...... I’m really disappointed you don’t mention THE COST OF ELECTRICITY TO RUN A DEHUMIDIFIER. FAN PULLING AIR OUT OF A SEAL CRAWLSPACE will lower humidity.... but depends on case by case some need both system dehumidifier and vent fans pulls air out..... please inform people about increased power bill.
As long as the dehumidifier is sized and ducted properly, you should be able to accomplish that. We'd recommend continuing to monitor humidity in both areas to make sure its working correctly and adjusting as needed.
i have a very specific question im seeking an answer for, but I plan on homesteading this summer here in MN . I plan to build my own home myself and although I may get my brothers help with some things im mostly on my own and the foundation I had initially thought I would do an open crawl space so I could create a drain for a bathtub right away, but im realizing with our weather here that isn't a good idea. Im looking for an easy affordable DIY foundation for my home that im planning to do straw bale and cob and need a high foundation to reduce moisture as well. I guess my question is with a closed crawl space how do I do an easy drain that will seep out not under my house as I probably also know I need concrete blocks to uphold my foundation, but can I seel it closed with wood so I can drill a hole through it for pipes and make it more affordable and DIY more friendly?
I live in GA where it’s very humid and would like to close my crawl space vents but I have a gas furnace. What would you recommend as the safest option?
+William Turk Great question. I just got off the phone with a gentleman that is installing the whisper fan (goo.gl/aRxPgP) to satisfy his code requirements of 1 cfm for every 50 square feet. Check local codes to see if this is sufficient for you. Thanks for watching. 😀
Crawl Space Ninja I’m confused how that fan would allow fresh air In needed for hvac combustion? From your fan video explanation doesn’t the fan exhaust air Out of crawl space?
I'm not totally sold on this stuff. I have a house that was a mobile home added on to. It has a dirt crawlspace and is only two ft off the ground. There are no vents in the crawl space. When it rains heavily, there is a slightly earthly smell. The house gets extremely hot in the summer. The other day, I pulled open the one access point and I could feel the air pushing out. There's no way anyone is going to get under there and lay a barrier down. That said, I have a hard time believing that increased airflow is going to trap moisture. That's why roofs vent though the sofit and peak. The outside air pulls through the attic and circulates, helping dissipate some heat. There's no way that adding vents in my crawlspace and increasing air flow is going to increase mold. It's just another big sell. It might work for a lot of people but airflow always reduces moisture opposed to trapped Air. I'm going to add an automatic vent on one side and possibly a fan/humidifier.
I live in Texas and since I've lived in this 95 year old house, I've been sick to death with allergies. I have a basement that is 1/2 finished and 1/2 dirt crawlspace. I also have 4 crawlspace vents. My furnace and all ductwork is also in the basement next to the dirt crawlspace. Do you think I could be suffering because of these factors? Does a vapor barrier for the crawlspace floor and maybe closing off those open vents make sense? Thank you!
We do find that dirty/humid crawl spaces can contribute to allergies in some situations, so it may be possible. While we do recommend vapor barrier and closing off vents, we recommend also installing a dehumidifier to control humidity and install a ventilation fan blowing out of the crawl space to help mitigate soil gases.
What kind of system do you recommend to ventilate a home in the south where there is high humidity (Huntsville/Madison Alabama region)? I'm looking to DIY install a Aprilaire 1850 and close up my vents in a home with ~2700 sqft crawlspace that is b/w 2 and 3 feet in height (probably averages about 2.5). Radon is (if my Airthings Wave it to be believed) low (averaging around 0.5) but I don't want to go from no Radon to too much Radon after closing the vents. At the same time I don't want to have a never ending issue with bringing in more air to have to dehumidify (i.e. a vent fan). Is there a better way? Aprilaire 8126X in the crawlspace?
The AprilAire 1850 will work great for the humidity control and the Lomanco vent fans will work well. You will need 2-3 installed. Just need a 110 plug for both the dehu and vent fans, closing all the other vents off. You are more than welcome to call 865-659-0390 if you need any assistance with your DIY.
I'm on a job where the small Dri-ez DeHu won't fit into the opening of the crawl space. We we were thinking about running plastic ducting from the unit to the area. Have u ever been in a space where u could not fit a dehumidifier?
Yes, although usually we avoid any crawl space that our guys would not fit in... working conditions would be less than beneficial for them and moving under the house would be very limited.
I don't have an AC unit and my crawl space is open. It's very dry in crawl space. Will closing the space cause it to be to dry or poor ventilation? Thanks!
Depending on the region you live in, you might want to have the vents open to avoid gasses. I know around my area, radon is a definitely a common thing.
@@CrawlSpaceNinja ok say it's probably better to just not seal it and keep it vented. But to make sure the home itself is sealed as far as penetrations?
A window AC would be significantly less efficient at removing moisture from the air. One of our employees recently was utilizing a window AC while waiting on their HVAC to be fixed. They still had to use a portable dehumidifier in addition to the window AC because the it was not removing enough moisture from the air and the home felt sticky and uncomfortable.
Mr M5 - It is impossible to dehumidify all the air within and outside the crawl space with a dehumidifier if you do not seal the crawl space vents. We appreciate you watching and hope you have a happy & blessed weekend.
+Kevin Cody If you know you have radon (it was tested and found to be high) you may need to install a sub-membrane depressurization system. Radon restrictions vary state tot state so this is one you should ask your state about to make sure.
@@21gonza21 It will depend on how high the humidity in your crawl space is, if it's sealed and encapsulated, etc. It's likely to run periodically throughout the day depending on your humidity settings.
@@seidweidner89 @ vent fans that pull air out of the crawl space, none that pull air inside. There will be enough air coming up through the ground, naturally
@@seidweidner89We've got a video that goes into detail about closed crawl spaces and makeup air that will answer your questions, watch it here: ua-cam.com/video/ySTgO4PQT7M/v-deo.html
How much does it cost to run the dehumidifiers? Yearly or monthly... I see that the unit itself is about $1000. Curious to know if I can get away with doing ventilation in my crawl space for cheaper initially and over time, opposed to running a dehumidifier.
The only time to open them is if you have some standing water inside and an underbelly, that way the water can evaporate outside as the humidity will be higher on the inside then outside.
That is, if you don't have a dehumidifier getting rid of the moisture for you! You'd definitely want to address the standing water by installing a perimeter drain and sump pump to make sure that does not keep happening though.
Yeah close them and trap all that humidity under your house and see what happens. By leaving them open you are allowing air to flow under your house to keep things dry. By closing them you trap moisture under your house. Simple as that. You should only close wet in middle of winter when temps drop below 20 degrees to prevent pipes from freezing.
I know why they are still building them open, conventional wisdom left over from days before AC. It's hard to teach an old dog new tricks. I prefer the idea of vents that you can close in the winter and open in the summer.
That's a great idea if your outside humidity is low year round, but humidity in the summer where we are in East Tennessee can be extremely high! We find it more beneficial to seal the vents and install a dehumidifier. Thanks for commenting!
Very clear explanation. I moved into a cedar log cabin that was built in 1990. Very poorly insulated. It's very cold in the winter time. So we started with Caulking between the logs and around the windows and door frames as well as extra insulationing products for the door.
I have vents in my crawlspace. It is a very clean and (was tidy until we started using it for storage.. now realizing that wasn't the best idea).(it's not like those scary dark and dirty crawlspaces.) There is a very thick black plastic laid throughout the entire floor of the crawlspace with a good 1/2foot up to 2 feet(in some areas) of pea gravel. The pressure tank and hot water heater are down there.. the floors do not have insulation.. we put in thick foam blocks into the vents during the winter and close them. That's what the previous owner has always done. We take them out in spring . I noticed recently a musty smell that is gradually getting stronger. And then later noticed condensation dripping from around the HVAC system as well as off the PVC water lines.
I would like to have the crawlspace completely encapsulated and a dehumidifying system installed in the future but budget won't allow it right now. My question is.... In the mean time, should I keep the outside vents closed and foam blocks in during the spring and summer as well? Or would that make matters worse? Also any feedback is appreciated. Thanks.
If you do not have a dehumidifier installed to control humidity you should not close your vents continuously. If budget allows, you can install the dehumidifier first so it can begin controlling humidity in the closed crawl space until you are able to fully encapsulate with new vapor barrier.
I live in northern Wyoming, not much humidity, my crawl space does not have vents but needs “sealed” for the fact that you can feel how cold the floors are getting with the cold temperatures moving in. Do you recommend sealing everything up tight and putting a vapor barrier down on the ground? What are your thoughts.
Wish I had a crawl space ninja here in Portland, OR. With a cool rainy winter being the norm from November through March, I am thinking to close, using foam board, the foundation vents during the winter and keepimg the open these ret of the year.
I live in Florida (HIGH humidity - rains all summer). When stucco was applied to my wood frame house by the previous owners, they did not add enough vents (3 small ones on a 900 square foot house). Thus, rainwater had collected under the house for a long time in the summer, and termites and wood rot became a problem.
Short of spending huge money on an encapsulation or sump pump installation, should I not just be fine with adding more crawlspace vents and/or a crawlspace exhaust vent fan?
Encapsulation with a sump pump is the only sure way to eliminate standing water. Open crawl space vents will just give water more opportunity to penetrate your crawl space. Hope this helps.
This video explains alot. I asked this question on your other video. Answered it here. Thank you for explaining it.
Glad we can help!
I live in Asheville,NC . My Geothermal heat pump and Heating/cooling ducts , are in the crawlspace. It is a huge crawlspace . 12 feet high at the back and 4 feet in the front. How does installing an exhaust vent fan help bring in supply air? My local HVAC company tells me that because the "crawlspace" is so large that I don't have any concerns for the heating and cooling in a completely sealed crawlspace. I am not sure now if I should install a vent fan or not.
I have a 14 by 28 building but there is not any HVAC duct work down there, no pipes at all. It's about 20" off the ground at most. I'm in the process of completely sealing off the underpinning to block airborne noise from the road nearby. I would prefer not to have vents because they will bring in more noise. The underpinning will have mass loaded final, a vapor barrier come on and siding. It's in Asheville North Carolina. Do you think it's OK for this building that is on cinder blocks to not have a favor rarior on the ground and have a completely enclosed underpinning?
Hey I live in Oklahoma with average 54.4% humidity. My crawl space is currently not having any problems with moisture it seem real dry and I have not seen any signs of mold. I currently only have two vents on either side of my house. I am considering encapsulating and insulating with foam board. I am unsure about the need for a dehumidifier as my average humidity is already decent. Was wondering should I bother? Also should I put vent fans in the two sides of the house?
I lived in Southern California, Los Angeles, the average humidity is about 55-60, should I open it or close it.
(I guess it is too late, I have 6 vents opened since 1992)
This video I believe refers to a humid weather area. You mention the hot, humid air coming in the house. What about CA weather where air is hot and dry?
It would depend on relative humidity, you can keep an eye out with a humidity reader and determine how to proceed from there. diy.crawlspaceninja.com/product/thermopro-tp65/
Good explanation Mr Church....
1st thing I did today.....I opened up the bsmt windows ..put a fan to circulate air....n tomorrow will get rid of all dirty insulation n clean up...so it will be easier to work in an open Crawlspace.
Question 1....b/4 U do the job....do U ck on Beams or Girders that the wood it's good...???
Question 2.... in a beams 24 inches center..
I plan 1st to put 6 mil plastic...then R-19 insul.
...n close ...with a thin sheet of pink foam boards to cover the job.
Is that sound to U ... ok ???
As a previous poster briefly mentioned - radon is a concern. If you leave the vents open radon will escape and your house radon levels will be lower. Close them off and radon levels increase in the house. It is a Radon vs. Humidity issue. I have bought a digital radon detector and it is a significant difference between leaving the vents open and blocking the vents. And I live in supposedly a low radon area. Obviously, the best choice and the most expensive choice is to address both. However, if I have to pick one give me humidity over radon.
When encapsulating we still recommend installing one ventilation fan blowing outward to help expell some of the soil gases. Obviously, if your levels are still high you will need a radon mitigation system like you already mentioned. Here is a video talking about the ventilation fans we recommend if you're interested: ua-cam.com/video/-8Q_jWuRMqw/v-deo.html
Hello crawl space Ninja I live in Chicago Illinois does the same rules apply in the cold climate which we have about 60% of the year should I close my crawl space vents we do have parts of the year that is humid thank you and truly appreciate your videos
Hi Jack, I do exactly that. I close all my crawl space foundation vents during the winter only to offset the potential of freezing pipes. I have all vents open from spring tru the first low temp / freeze of the winter. hope this helps.
@@malsx2 thanks so much for response that makes sense truly appreciated
Thank you for your videos. I live in the Chicagoland area and just moved into a home on a lake with a vented crawlspace. We are on a high water table but not a flood zone. We do not want to encapsulate because there is no drain tile and no sump pump (luckily the home is 20 years old and has not needed either). The space has cement walls and a cement floor with open vents and one HVAC vent pumping into the crawl space. What would you recommend in order to control temp extremes and humidity? There is no code saying we can't close the vents, but we do not know, other than professionally sealing off the vents and joists, if we need to spray foam the ceiling and/or insulate the walls. Also would we need a dehumidifier? With all vents open the highest the humidity has been in the summer is 70%.
Building code does require insulation. If you seal the vents, that gives you the opportunity to insulate the walls instead of the subfloor. That should be efficient enough to handle the temperatures. For controlling humidity and keeping it around 50%, we recommend installing a dehumidifier.
I live in sc.
My ac is in the attic. And my crawl space has open vents. Can we close the vents. What should we do
So it would be better to close all vents even if space is not encapsulated? Or would you need a fan afterward?
Even if the crawl space is not encapsulated, sealing the vents will help better regulate the humidity by keeping the humid outside air from entering. Installing a dehumidifier, in addition to sealing the vents, is recommended. If you do seal the vents, you will need to install a vent fan to push out any soil gasses that may build up in the crawl space.
Actually the walls will sweat creating a hostile environment under the home even though you have a dehu. You have to cover your walls and piers with a 8-10 mil poly. Sealing the vents completely air tight along with a dehumidifier. Do a preventative Wood treatment to the sub floor, joists and the the band sill. If your crawl takes on water even though it’s encapsulated you need to install sump pumps to evacuate the water. For vents that sit on the grade you will need vent wells. Do your homework before you do anything to your crawl. You could make it worse if you do not know what your doing. Again cover the floor, walls and piers with Polly. It’s very important if your doing a encapsulated crawl.
I have a ground water issue . With vents open I got humidity. With the vents closed I got mycotoxins coming out of the ground and trenching up into the house . Older houses don’t have ventilation tubes in foundation slab:/ In my case you may want to address ground water when sealing the vents. With vents open humidity got in and cold in winter. Summer the floor in crawl space was cold from Ac causing condensation and mold. Heating the floor inside was cold causing condensation inside but less because of the lower winter humidity also a mold condition ..
I agree sealing them if your not getting gases from the ground coming in.
We normally add a vet fan when we close vents and use a dehumidifier to prevent any humidity.
What do you recommend for a non-central air unit home?
Not fully sure about your question, I will guess its regarding the vents.... It would be the same approach as any other home encapsulating and closing vents you improve your indoor air quality.
You can have vapor barrier and closed vent but leave a few 3-4 vent fans. Also install dehumidifier for when the vans are not keeping it low enough...... I’m really disappointed you don’t mention THE COST OF ELECTRICITY TO RUN A DEHUMIDIFIER. FAN PULLING AIR OUT OF A SEAL CRAWLSPACE will lower humidity.... but depends on case by case some need both system dehumidifier and vent fans pulls air out..... please inform people about increased power bill.
In a split level home Can a Dehumidifier unit be set up to handle a crawl space and basement space together?
As long as the dehumidifier is sized and ducted properly, you should be able to accomplish that. We'd recommend continuing to monitor humidity in both areas to make sure its working correctly and adjusting as needed.
i have a very specific question im seeking an answer for, but I plan on homesteading this summer here in MN . I plan to build my own home myself and although I may get my brothers help with some things im mostly on my own and the foundation I had initially thought I would do an open crawl space so I could create a drain for a bathtub right away, but im realizing with our weather here that isn't a good idea. Im looking for an easy affordable DIY foundation for my home that im planning to do straw bale and cob and need a high foundation to reduce moisture as well. I guess my question is with a closed crawl space how do I do an easy drain that will seep out not under my house as I probably also know I need concrete blocks to uphold my foundation, but can I seel it closed with wood so I can drill a hole through it for pipes and make it more affordable and DIY more friendly?
I cant say I fully understand your question, but congrats on you building a new home!!
Can I glue my foundation vents in with silicone?Block under pinning actually, they keep falling out, thank you much
I have seen silicone used to secure foundation vents.
@@CrawlSpaceNinja thank you
I live in GA where it’s very humid and would like to close my crawl space vents but I have a gas furnace. What would you recommend as the safest option?
+William Turk Great question. I just got off the phone with a gentleman that is installing the whisper fan (goo.gl/aRxPgP) to satisfy his code requirements of 1 cfm for every 50 square feet. Check local codes to see if this is sufficient for you. Thanks for watching. 😀
Crawl Space Ninja I’m confused how that fan would allow fresh air In needed for hvac combustion? From your fan video explanation doesn’t the fan exhaust air Out of crawl space?
I'm not totally sold on this stuff. I have a house that was a mobile home added on to. It has a dirt crawlspace and is only two ft off the ground. There are no vents in the crawl space. When it rains heavily, there is a slightly earthly smell. The house gets extremely hot in the summer. The other day, I pulled open the one access point and I could feel the air pushing out.
There's no way anyone is going to get under there and lay a barrier down. That said, I have a hard time believing that increased airflow is going to trap moisture. That's why roofs vent though the sofit and peak. The outside air pulls through the attic and circulates, helping dissipate some heat.
There's no way that adding vents in my crawlspace and increasing air flow is going to increase mold. It's just another big sell. It might work for a lot of people but airflow always reduces moisture opposed to trapped Air. I'm going to add an automatic vent on one side and possibly a fan/humidifier.
I live in southern Indiana by Columbus. Should I close it all the time ?
It depends on your humidity levels. If you want to control humidity and install a dehumidifier, we would recommend it. Thanks for commenting!
I live in Texas and since I've lived in this 95 year old house, I've been sick to death with allergies. I have a basement that is 1/2 finished and 1/2 dirt crawlspace. I also have 4 crawlspace vents. My furnace and all ductwork is also in the basement next to the dirt crawlspace. Do you think I could be suffering because of these factors? Does a vapor barrier for the crawlspace floor and maybe closing off those open vents make sense? Thank you!
We do find that dirty/humid crawl spaces can contribute to allergies in some situations, so it may be possible. While we do recommend vapor barrier and closing off vents, we recommend also installing a dehumidifier to control humidity and install a ventilation fan blowing out of the crawl space to help mitigate soil gases.
What kind of system do you recommend to ventilate a home in the south where there is high humidity (Huntsville/Madison Alabama region)?
I'm looking to DIY install a Aprilaire 1850 and close up my vents in a home with ~2700 sqft crawlspace that is b/w 2 and 3 feet in height (probably averages about 2.5).
Radon is (if my Airthings Wave it to be believed) low (averaging around 0.5) but I don't want to go from no Radon to too much Radon after closing the vents. At the same time I don't want to have a never ending issue with bringing in more air to have to dehumidify (i.e. a vent fan). Is there a better way? Aprilaire 8126X in the crawlspace?
The AprilAire 1850 will work great for the humidity control and the Lomanco vent fans will work well. You will need 2-3 installed. Just need a 110 plug for both the dehu and vent fans, closing all the other vents off. You are more than welcome to call 865-659-0390 if you need any assistance with your DIY.
Woohoo I'm in Huntsville also
I'm on a job where the small Dri-ez DeHu won't fit into the opening of the crawl space. We we were thinking about running plastic ducting from the unit to the area. Have u ever been in a space where u could not fit a dehumidifier?
Yes, although usually we avoid any crawl space that our guys would not fit in... working conditions would be less than beneficial for them and moving under the house would be very limited.
I don't have an AC unit and my crawl space is open. It's very dry in crawl space. Will closing the space cause it to be to dry or poor ventilation? Thanks!
You would want some sort of active ventilation to avoid any soil gas buildup.
Depending on the region you live in, you might want to have the vents open to avoid gasses. I know around my area, radon is a definitely a common thing.
Interesting!
What about a mobile home on a dirt pad, with a brick skirting? Should I try to seal that skirting and not install vents?
Normally we find it hard to seal skirts.. i would proceed cautiously
@@CrawlSpaceNinja ok say it's probably better to just not seal it and keep it vented. But to make sure the home itself is sealed as far as penetrations?
Why can't I use a window ac as dehumidifier in crawl space drain water out with drain pan to outside?
A window AC would be significantly less efficient at removing moisture from the air. One of our employees recently was utilizing a window AC while waiting on their HVAC to be fixed. They still had to use a portable dehumidifier in addition to the window AC because the it was not removing enough moisture from the air and the home felt sticky and uncomfortable.
Are you struggling to keep your crawl space humidity under control? Check this out!
Can you block off the vents without doing a full incapsulation and just do a dehumidifier
Mr M5 - It is impossible to dehumidify all the air within and outside the crawl space with a dehumidifier if you do not seal the crawl space vents. We appreciate you watching and hope you have a happy & blessed weekend.
@@CrawlSpaceNinja so does that mean yes?
@@MRM5J There is a lot of humidity coming out of the ground (ground water), your dehumidifier will be suffocating working too much. You can try though
If I close my crawlspace, no how do I address radon?
+Kevin Cody If you know you have radon (it was tested and found to be high) you may need to install a sub-membrane depressurization system. Radon restrictions vary state tot state so this is one you should ask your state about to make sure.
What do you mean by “ventilating”?
allowing air flow.
Crawl Space Ninja so a dehumidifier won’t be enough? Fans will be necessary?
the fan helps to remove any type of soil gas that might build up.
Crawl Space Ninja I see, do you know how often the dehumidifier runs for? Does it run every day ?
@@21gonza21 It will depend on how high the humidity in your crawl space is, if it's sealed and encapsulated, etc. It's likely to run periodically throughout the day depending on your humidity settings.
So if I install a crawlspace dehu I should close of my vents?
Great question! You will need to install 1 vent fan per 1,000 sf and close all the other vents.
@@CrawlSpaceNinja Thank you....so 1 fan pulling air in and 1 pulling air out?
@@seidweidner89 @ vent fans that pull air out of the crawl space, none that pull air inside. There will be enough air coming up through the ground, naturally
@@CrawlSpaceNinja Thank you. So even if the ground is encapsulated the fans will still pull air from the ground?
@@seidweidner89We've got a video that goes into detail about closed crawl spaces and makeup air that will answer your questions, watch it here: ua-cam.com/video/ySTgO4PQT7M/v-deo.html
How bad is it to have a drier venting into a crawl space?
You are pumping in more humidity causing it to create a perfect environment for mold. Also might be a fire hazard
Your attic is an open system, and people don't have issues with that?
How much does it cost to run the dehumidifiers? Yearly or monthly...
I see that the unit itself is about $1000.
Curious to know if I can get away with doing ventilation in my crawl space for cheaper initially and over time, opposed to running a dehumidifier.
Here is a video we did answering this question: ua-cam.com/video/KJyCaScMktk/v-deo.html
The only time to open them is if you have some standing water inside and an underbelly, that way the water can evaporate outside as the humidity will be higher on the inside then outside.
That is, if you don't have a dehumidifier getting rid of the moisture for you! You'd definitely want to address the standing water by installing a perimeter drain and sump pump to make sure that does not keep happening though.
Dude is like the Jasse Robertson of Crawl space insulation...
exactly what i was thinking.
Yeah close them and trap all that humidity under your house and see what happens. By leaving them open you are allowing air to flow under your house to keep things dry. By closing them you trap moisture under your house. Simple as that. You should only close wet in middle of winter when temps drop below 20 degrees to prevent pipes from freezing.
we do close the vents, and also add a dehumidifier to control the humidity!
I know why they are still building them open, conventional wisdom left over from days before AC. It's hard to teach an old dog new tricks.
I prefer the idea of vents that you can close in the winter and open in the summer.
That's a great idea if your outside humidity is low year round, but humidity in the summer where we are in East Tennessee can be extremely high! We find it more beneficial to seal the vents and install a dehumidifier. Thanks for commenting!
Terrible idea... Slab on grade only way to go