I Don't Know The Answer To This One

[@davemeiser521]

What is the current ambient humidity and does it increase during periods of rain or snow melt? this should give an indication of how much water vapor that space will generate if you are going to insulate the biggest factor is to stop air movement through the rim and floor. I would start sealing the rim joist first and insulating with the XPS then foaming around the xps to seal up any gaps. Same thing with the floor joists. Also, ensure the bottom plate is sealed to the foundation. For humidity control, several passive and active measures can be taken such as a dehumidifier, or a Crawlspace Ventilation with a humidistat. and like you said keeping the door open for increased ventilation. I just spent some time sealing all my rim joists for my 100-year-old basement using a 2 part spray foam insulation kit (but I don't recommend home-owners do that themselves as the chemicals can cause severe health issues if you do not have all the proper PPE and use lots of ventilation) Good luck

[@towpathguitars]

20 year building performance contractor here. You want to seal the poly to the basement wall. I would actually consider pea gravel down and EPDM rubber roof right on the floor. Seal the edges. Then use the polystyrene on the walls and the rim joist. Leave the floor to breathe. Insulation on the perimeter and a vapor barrier on the bottom will work correctly, warm the space and the area above. Moisture will be locked out as the foam is a vapor barrier. I would recommend venting it to the rest of the basement. More air dilutes the moisture, heat reduces relative humidity and low relative humidity reduces the chances of mold. Thanks for the one sheet plywood boat video. Built one with my daughter a few years ago.

[@PecosNM]

My guess is if you make that an airtight space, the moisture coming up through the ground is going to have nowhere to go and will create mold. I think you were going to have to vent that air out of that space or dehumidify the air.

[@gardenfork]

I already have a dehumidifier in the main basement, my hope was to be able to keep the door between the two open, so that would allow the moisture to be reduced. thx!

[@SweetChicagoGator]

​@@gardenfork Keep the door open between the two rooms with the dehumidifier, but whatever you do, don't leave it airtight !

[@riverbrewer04]

Add a dehumidifier if you want to keep the door closed. Or keep the door open all the time and let your main basement dehumidifier do the work.

[@gardenfork]

Yes, that what I was thinking . the square footage isn't that much to add. :)

[@DawnieRotten]

Nooooo! In a root cellar, you WANT humidity, up to a certain point.

[@dianeconway293]

In the UK some years ago lining house roofs with spray foam was all the rage but it caused problems and now banks won’t let you have a mortgage on such properties so I think there must be a problem with mold

[@meurigf]

Not an expert, but if those floorboards are not vapour tight already then you’ve nothing to trap moisture up against, so that’s not an issue. For the root cellar itself, my concern with leaving the door open is warm air coming in from the basement and condensation against the coldest part of the room - the cinder blocks perhaps? If you have warm moist air indoors it will want to condense on the coldest surface. If the basement is dehumidified and pretty dry, this is unlikely to be a problem. Go for it, don’t seal anything, and “see what happens” :) A vent, or a dedicated small dehumidifier are easy to add if there are any problems. And worst case you can remove a bit of the polystyrene to let things breathe. Thanks for the videos, please keep them coming.

[@lisamorris4232]

Remember if you use a dehumidifier, it gives off heat too.With the door closed, your room will get warm.

[@dnhman]

The poly on the floor helps, but some moisture will come through. Is the porch heated above?

[@gardenfork]

The porch is not heated, it is a summer room. thx!

[@2andrea]

I think if the floor gets covered it would mold due to humidity. The ceiling would be fine to do is what I think. I saw one recently in a video and she said they were told by a home inspector if the covered it up it would mold since it's designed to breathe. They just fixed the rock on the walls they had and left the rest.

[@DawnieRotten]

I bet that space was, INDEED, built to be a root cellar. My suggestion would be to head over to Shawn James/My Self Reliance channels and look at his root cellar, that is in the basement of his self-built cabin in the (Canadian) woods. I'm pretty sure that you'll want to KEEP the floor DIRT/SAND, for humidity purposes. Shawn's root cellar IS insulated.....but I just don't remember 'how', exactly. But he DOES have vents, in several places, for air flow.

[@stevelitteral]

Maybe seal the top and get a dehumidifier into the space?Just guessing.😎👍

[@shervin6711]

You wil definitely trap moisture.. especially if there is no wall to concrete...and vapor barriers. Maybe look into root cellar principles? Usually you still see some sort of air movement. How much moisture? Some might actually be ok, depending on what you store, especially if areas " breathe"

[@SweetChicagoGator]

U will def get mold on your floor if not flush against the cinder blocks ! Don't worry about the floor joists cuz the spray foam, Etc will seal well from mold. Good luck ! (Nice Labs ya got ! 🤗)

[@gardenfork]

Good to know! thanks for that.

[@Monica409TX]

😂I don’t know it your gonna create Mold..But your videos crack me up🤣Your so funny and Intelligent..I Love your Babies🐾🐾Woof

[@gardenfork]

Thanks! Eric.

[@robgig8821]

Will keep up with this to see what you do with this? I think a floor moisture barrier wood be a good thing!

[@gardenfork]

i will check on that, had not thought of that. :) eric.

[@jamesferris3129]

Before,winter is it to late to insulate the loft with foam the retain the heat in our houses, and is this there a cheaper option.

[@gardenfork]

if by loft you mean attic, i would use shredded cellulose. you can rent a machine at home depot or hire a company. lots of video on YT about how to do it. Key is to spray foam all electric holes etc. that go from the house walls up into the attic.

[@UniqueMoniker]

The “red flag” cracked me up 😂

[@gardenfork]

yeah!

[@briankubik5041]

No moisture no problem if you have moisture get a dehumidifier or circulation of air to dry the moisture they have a wifi measure for humidity that you put part of it down there and other part you keep up where you can watch it also some have alarms on them to say either it's to hot or to much moisture.

[@gardenfork]

excellent Brian, did not know about those wireless rigs. thx!

[@vahshi9876]

Use cold polyurea DIY, if it is used on all surfaces, you will have a completely insulated room, hundred years warranty

[@robertwayman7974]

FREE IS GOOD. If the foam has formaldehyde in it, I would say no to the gap filling. Just my thoughts.

[@gardenfork]

i'll check on that, thx Robert. - Eric

[@robertwayman7974]

I also read that airtight is not good. Got to breath.

[@susankilpatrick2918]

Get a professional to come out and do a quote listen to what they are suggesting and then do it yourself!

[@ernestkooistra1559]

That is a good question.

[@gardenfork]

Yes. :)

[@Ray-r5j9u]

My opinion and $8 will get you a cup of coffee :-). Do your homework on ventilation. Airtight and moist is bad. 🖖

[@gardenfork]

exactly! thx, eric.

[@mr1pearl]

Srayfoam Fan Boy's that's a group from the 80's ain't it 😆 I just don't know either sure look foward to see if you get an answer !