Go Back  DoItYourself.com Community Forums > Interior Improvement Center > Basements, Attics and Crawl Spaces
Reload this Page >

Sealing off 'crawlspace' for temp and moisture purposes?

Sealing off 'crawlspace' for temp and moisture purposes?


  #1  
Old 11-19-18, 11:55 AM
N
Member
Thread Starter
Join Date: May 2012
Posts: 611
Received 2 Upvotes on 2 Posts
Sealing off 'crawlspace' for temp and moisture purposes?

Sorry in advance for the long-winded posted, and I've posted a few questions here and there in the past on what to do with my crawlspace/expanded basement (I'll just call it crawl space in this post), but I really need assistance in figuring out how to solve cold/humidity once and for all (so I'm not worrying about one or the other all year long).

Quick background: Prior owners expanded the back of the house out about 4 feet (and about 30' long) which created the 'crawl space'. It's actually more like a long additional basement space than a crawl space (concrete floor, 5 or 6' high), and it has a cement floor and cinder block walls (the rest of the basement is poured concrete walls).

When we moved in 6 years ago, we had attic insulation put in, and the company convinced me to spray foam the rim joist of the entire basement, including the crawl space. They did not cover the 4 vents in the cinder blocks (that even when closed don't seal well).

A year or so later, I noticed that the temps got down to around 40 in the winter (not bad, but got me a bit worried as there are 1 or 2 pipes there), and humidity got high in the summer (80% or so). Unfortunately I don't know what it was like before we sealed the rim joist. I don't believe the prior owner did anything (no humidifier, heater...). If I leave the door open between the basement and crawl space the temps stay above 40 and humidity stays below 60% in the summer (I have a Sante Fe dehumidifier in the main basement space). We don't heat the rest of the basement and it stays around 60 I believe. I don't want to have to leave the door open forever though.

Separately, we also have a cold kitchen floor above the crawl space and a few years ago a contractor convinced me to seal the vents in the crawl space and insulate the ceiling. He cut rectangles out of foam block insulation and put those over the vents, and used regular rolls of insulation in the ceiling.

This did (I think) help the kitchen floor a little but, the temp in the crawl space has actually gotten lower in the winter (approaching freezing) and humidity is still high in summer.

I'm now looking for a permanent approach to fixing both the cold in the winter and the humidity in the summer (and don't care as much about the kitchen floor above). I almost don't care what it costs (within reason), I just need it to be done with.

Thanks for any thoughts/suggestions!
 
Attached Images  
  #2  
Old 11-19-18, 12:25 PM
M
Member
Join Date: Mar 2009
Location: Northern Virginia
Posts: 3,913
Received 27 Upvotes on 21 Posts
You have two options. A ventilated crawlspace or unventilated crawlspace. With a ventilated crawlspace, you'll want to insulate pipes and between the floor joists. With an unventilated crawlspace, you'll want to insulate the foundation walls and can leave the floor joists and pipes uninsulated. If you're having issues with humidity, then I would go with the ventilated option.

How is the drainage around the house? Make sure all your gutters are clear, downspouts are well away from the foundation, and the grade slopes away from the foundation. Do you have a french drain/sump system installed?
 
  #3  
Old 11-19-18, 12:33 PM
N
Member
Thread Starter
Join Date: May 2012
Posts: 611
Received 2 Upvotes on 2 Posts
Thanks for the input. Won't opening the vents make the space colder, even if I insulate the walls (as there will essentially be big openings for cold air to pour in)?

The pipes are (mostly) wrapped with typical foam insulation (like this https://www.homedepot.com/p/Everbilt...1812/204760805).

I now agree/realize that insulating the ceiling of the space was a mistake and would consider ripping it down if that will help with anything.

Will opening the vents be enough to keep humidity down in the summer? Or no way to know until I do it, close the door to the basement, and see what happens?

Right now there is no insulation on any of the walls within the crawlspace, and I believe there is insulation behind the wood paneling that goes around the basement itself, including the wall that abuts the crawl space. the main basement space stays around 60.
 
  #4  
Old 11-19-18, 12:45 PM
M
Member
Join Date: Mar 2009
Location: Northern Virginia
Posts: 3,913
Received 27 Upvotes on 21 Posts
Thanks for the input. Won't opening the vents make the space colder, even if I insulate the walls (as there will essentially be big openings for cold air to pour in)?
Not enough to make your floor cold. I have a crawlspace in a rental property with no insulation in the joists and all the insulation fell off the walls and the floor doesn't feel cold, even when it's in the teens outside. All but a foot of foundation is above grade though.

The pipes are (mostly) wrapped with typical foam insulation (like this https://www.homedepot.com/p/Everbilt...1812/204760805).
I believe that should be fine.

I now agree/realize that insulating the ceiling of the space was a mistake and would consider ripping it down if that will help with anything.
Not so fast. Lets figure out what the best course of action for your particular application is first.

Will opening the vents be enough to keep humidity down in the summer? Or no way to know until I do it, close the door to the basement, and see what happens?
It should, but we need to determine if the main source of humidity is coming from inside or outside, which is why I asked about drainage. Sealing the slab may help amongst other things.

Right now there is no insulation on any of the walls within the crawlspace, and I believe there is insulation behind the wood paneling that goes around the basement itself, including the wall that abuts the crawl space. the main basement space stays around 60.
If you have high humidity, closing the vents is going to make it worse because you just took away any sort of air circulation.
 
  #5  
Old 11-19-18, 12:56 PM
M
Member
Join Date: Mar 2009
Location: Northern Virginia
Posts: 3,913
Received 27 Upvotes on 21 Posts
Do you have a limited budget, or you want this resolved no matter what the cost (within reason of course)? Are you ever going to convert this space into conditioned living space, or is the ceiling too low for that? If it is always going to be unfinished, then I'd go with the ventilated option. Ideally, you'd want a drain tile around the basement perimeter that drains into a sump, a waterproof membrane on the outside of the foundation wall, seal the slab, insulate the pipes, insulate the floor joists, and open the vents to get some good circulation down there. Install an exterior door to the basement if you don't have one already. The drain tile and waterproofing membrane would be a little pricey, so depends on your budget and whether it makes sense financially. You could start by opening up the vents, sealing the slab, insulating the floor and pipes, and ensuring your drainage outside is in order, then seeing what difference that makes.
 
  #6  
Old 11-19-18, 01:03 PM
N
Member
Thread Starter
Join Date: May 2012
Posts: 611
Received 2 Upvotes on 2 Posts
Thanks again and sorry, I forgot to address your drainage questions.

Drainage is good for the most part. Gutters are clear (and are cleaned each year). Downspouts generally point far away, though two of them go right down into the ground into some sort of 5" diameter (or so) white tubing. From there they either both go to the same spot way in the back of my back yard (I did witness water pouring out of a black tube just coming out of the ground in the back during a heavy rain), or one goes to that spot and the other I have no idea. In either case, the 2 downspouts closest to the crawl space are not these in ground ones, they are traditional ones and I have extensions running them a few feet away from the house.

That being said, one thing I have noticed is that after an extremely heavy rain (well over an inch) there is sometimes some moisture on part of the floor in the crawl space. I can't tell where it's coming in. Also, the deck at the back of my house runs along almost 100% of the exterior wall of the crawl space. Not sure if that might affect the way water falls near the crawl space.

Finally, the lawn does slope away from the foundation (particularly in the back of the house which is where the crawl space is), though I think it's pretty flat under the deck, but I believe may slope away a little.

No french drains or sump pump as, knock on wood, main part of basement is very dry.
 
  #7  
Old 11-19-18, 01:11 PM
N
Member
Thread Starter
Join Date: May 2012
Posts: 611
Received 2 Upvotes on 2 Posts
Do you have a limited budget, or you want this resolved no matter what the cost (within reason of course)? Limited, but willing to spend more than I'd like for a 100% final/effective solution.

Are you ever going to convert this space into conditioned living space, or is the ceiling too low for that? Not going to be living space. It's literally 4' wide and basically unusable except for stage. We have the main basement as conditioned/living space.

If it is always going to be unfinished, then I'd go with the ventilated option. I will go ahead and remove the insulation blocks on the vents. Should I also open the vents all the way (I think they slide a little bit) even in the winter? I don't want to open/close them twice a year...

Ideally, you'd want a drain tile around the basement perimeter that drains into a sump, a waterproof membrane on the outside of the foundation wall, seal the slab, insulate the pipes, insulate the floor joists, and open the vents to get some good circulation down there. Is this just for the crawl space or the whole basement? Either way, while I do want a permanent solution, I'm sure the cost of this is way more than I'm willing to spend.

Install an exterior door to the basement if you don't have one already. There's a door leading to a bilco hatch in the main basement

The drain tile and waterproofing membrane would be a little pricey, so depends on your budget and whether it makes sense financially.

You could start by opening up the vents, sealing the slab, insulating the floor and pipes, and ensuring your drainage outside is in order, then seeing what difference that makes. Opening the vents is no problem, and the floor and pipes are already sealed. As for sealing the slab, is that done on the interior or exterior of the house, and how is it done?
 
  #8  
Old 11-19-18, 01:22 PM
N
Member
Thread Starter
Join Date: May 2012
Posts: 611
Received 2 Upvotes on 2 Posts
One more follow-up. When I said:

Thanks for the input. Won't opening the vents make the space colder, even if I insulate the walls (as there will essentially be big openings for cold air to pour in)?

And you said:

Not enough to make your floor cold. I have a crawlspace in a rental property with no insulation in the joists and all the insulation fell off the walls and the floor doesn't feel cold, even when it's in the teens outside. All but a foot of foundation is above grade though.

Will opening the vents make the crawl space itself too cold (even if the pipes are wrapped and I insulate the walls)?

I assume the answer is no, as prior owner probably did just that (no insulation anywhere, vents open) and pipes never burst...

I'm just concerned that even with the vents covered it's just above freezing, what will happen if I open the vents...
 
  #9  
Old 11-19-18, 02:41 PM
M
Member
Join Date: Mar 2009
Location: Northern Virginia
Posts: 3,913
Received 27 Upvotes on 21 Posts
Sorry, I was thinking your entire basement was unfinished and unconditioned. Now I'm confused. If the crawlspace is open to the basement, then I would insulate the walls and close off the vents. Pictures would help.
 
  #10  
Old 11-19-18, 04:21 PM
N
Member
Thread Starter
Join Date: May 2012
Posts: 611
Received 2 Upvotes on 2 Posts
Sorry, to clarify, there was/is an existing, finished, 600 sq ft basement (plus some amount of sq ft in the boiler room but that's separate) which is conditioned in that it has baseboard heat and a sante fe dehumidifer. Adjacent to the 600 sq ft is the 'crawl space'. The finished basement has tile floor, drop ceiling and wood paneling (we want to redo it with sheetrock and start using it a lot more, hence want to keep the door to the crawl space closed going forward).

They are only 'open' to each other in that there's a regular door that I leave open as that keeps the crawl space warmer/less humid. I'd like to keep that door closed, and therefore the crawl space and basement would be completely separate.

There's a quick diagram above, and I'll try to take some real pics tomorrow.

Thanks again.
 
  #11  
Old 11-19-18, 10:14 PM
M
Member
Join Date: Mar 2009
Location: Northern Virginia
Posts: 3,913
Received 27 Upvotes on 21 Posts
I see. In that case, I would insulate the wall between the basement and crawlspace, the floor joists above the crawlspace and any exposed pipes, open the vents, lay 6 mil poly on the floor (if dirt floor), and install an exterior door between crawl and basement. If your basement is still humid, then moisture must be coming through the basement wall and/or slab. You can seal the slab. For the walls, the best solution is to install a waterproofing membrane along the outside of the foundation. Once you have your thermal envelope in order, you should consider adding a couple vents and a return down there to keep fresh air circulating, which will help with the humidity (which should be minimal if you do all the aforementioned things).

You should know that I'm no expert on the subject, but these are things I've picked up through personal research. The basic idea is to create a thermal envelope around your living space and keep moisture from entering the home. I'm sure others with more experience will chime in soon.
 
  #12  
Old 11-20-18, 05:47 AM
N
Member
Thread Starter
Join Date: May 2012
Posts: 611
Received 2 Upvotes on 2 Posts
Thanks mossman.

Just to further clarify, I'm not overly concerned with the humidity in the main basement, as I have the Santa Fe dehumidifier. While of course it would be nice to not have the santa fe, I don't think it's worth it for me to install a waterproof membrane along the outside of the foundation, as I'm sure that's very expensive.

I'm only concerned with the humidity in the crawl space (and the winter temps). The floor joists above the crawl space are insulated, and the pipes are wrapped. The floor is concrete so no need for poly. I will look into insulating the wall between basement and crawl space (do you recommend doing so within the crawl space or on the basement side, or both)? And I'll open the vents. I'll then see what happens next summer with the humidity in the crawl space.
 
  #13  
Old 11-20-18, 06:30 AM
M
Member
Join Date: Mar 2009
Location: Northern Virginia
Posts: 3,913
Received 27 Upvotes on 21 Posts
Not sure what you mean about insulating on the basement side or crawlspace side. Assuming there is drywall, you'll need to do it from the crawlspace side. You do not need to insulate the crawlspace foundation wall. I would seal the crawlspace floor as well. Your crawlspace will be an unconditioned space, and the vents should provide adequate ventilation to prevent humidity from causing issues (e.g. mold). If you're using fiberglass insulation, I'm thinking you'll want to protect it on the crawlspace side (perhaps sheath the underside of the floor and adjacent wall). I'll let someone else address that.

BTW, what state are you in?
 
  #14  
Old 11-20-18, 06:33 AM
N
Member
Thread Starter
Join Date: May 2012
Posts: 611
Received 2 Upvotes on 2 Posts
Thanks for confirming.

I'm in CT. So it's hot/humid in summer and cold in winter.
 
  #15  
Old 11-20-18, 07:45 AM
M
Member
Join Date: Mar 2009
Location: Northern Virginia
Posts: 3,913
Received 27 Upvotes on 21 Posts
Did you say your deck is adjacent to the new crawlspace? Is it very close to the ground? I'm wondering if that could be contributing to your issues because rainwater that makes its way under the deck is going to saturate the ground and not dry out as quickly as it would if it were exposed to the sun and wind. That and cinder block is more porous than concrete block or poured concrete, so it is going to absorb moisture from the ground.
 
  #16  
Old 11-20-18, 07:47 AM
N
Member
Thread Starter
Join Date: May 2012
Posts: 611
Received 2 Upvotes on 2 Posts
That is correct concerning the deck. Aside from possibly grading the dirt underneath the deck even further (to slope away), anything else I can do to help keep the water away?
 
  #17  
Old 11-20-18, 07:53 AM
M
Member
Join Date: Mar 2009
Location: Northern Virginia
Posts: 3,913
Received 27 Upvotes on 21 Posts
How tall is the deck? Can you get underneath? Maybe something can be secured to the underside of the joists to divert rainwater away from the foundation.
 
  #18  
Old 11-20-18, 07:56 AM
N
Member
Thread Starter
Join Date: May 2012
Posts: 611
Received 2 Upvotes on 2 Posts
It's about 3-4' feet off the ground so it's possible for someone to get under there and do something. Not super easy/comfortable, but doable.
 
  #19  
Old 11-20-18, 07:56 AM
M
Member
Join Date: Mar 2009
Location: Northern Virginia
Posts: 3,913
Received 27 Upvotes on 21 Posts
Can you post some pictures of the crawlspace so we can see what you're dealing with?

How to insert pictures.
 
  #20  
Old 11-20-18, 12:06 PM
N
Member
Thread Starter
Join Date: May 2012
Posts: 611
Received 2 Upvotes on 2 Posts
Here are some pics taken from the doorway of the basement to the crawl space (looking left, left/straight, straight, and then right.

Just for reference, the first pic (looking left) you can see where there's an existing window that used to be the window from the basement to the outside, but is now a window from the basement to the crawl space.
 
Attached Images     
  #21  
Old 11-20-18, 12:41 PM
M
Member
Join Date: Mar 2009
Location: Northern Virginia
Posts: 3,913
Received 27 Upvotes on 21 Posts
Thanks for the pics. Looks like you have some water getting in (I believe you mentioned that). You need to tackle that issue if there's any hope of decreasing humidity in that space. I would block off the old basement window. Another thing I noticed is your floor joist insulation is upside down. You want the paper/vapor retarder facing upwards, directly against the subfloor.

Is the basement wall on the conditioned side exposed concrete, or is it already finished with a stud wall and gypsum board? If it's exposed, the proper way to insulate is 2" rigid foam board against the concrete (sealed around the perimeter), 2x4 wall against the foam board, then fill the stud cavities with unfaced fiberglass batts.
 
  #22  
Old 11-20-18, 12:49 PM
N
Member
Thread Starter
Join Date: May 2012
Posts: 611
Received 2 Upvotes on 2 Posts
Thanks for the quick follow up. Just curious, where are you seeing water/signs of water in the pics? You are correct that once in a while I see some, but am wondering where it is in the pics.

I thought the insulation was upside down as well, but the guy who did it said (after the fact) that it was done this way to stop any moisture in the crawl space from rising up to the kitchen (due to air flow in the house), or something along those lines if I recall correctly. He said if he did it the other way, then the humidity in the crawl space would be directly touching the pink insulation itself.

What sheathing on the wall are you referring to?
 
  #23  
Old 11-20-18, 01:01 PM
M
Member
Join Date: Mar 2009
Location: Northern Virginia
Posts: 3,913
Received 27 Upvotes on 21 Posts
Thanks for the quick follow up. Just curious, where are you seeing water/signs of water in the pics? You are correct that once in a while I see some, but am wondering where it is in the pics.
On the left of the fourth picture you posted (the wall with the plywood leaning up against it).

I thought the insulation was upside down as well, but the guy who did it said (after the fact) that it was done this way to stop any moisture in the crawl space from rising up to the kitchen (due to air flow in the house), or something along those lines if I recall correctly. He said if he did it the other way, then the humidity in the crawl space would be directly touching the pink insulation itself.
You want to crawlspace to dry to the inside, meaning any moisture that makes it's way into the insulation needs to be able to dry to the crawlspace area, facilitated by the air flow provided by the foundation vents. With the vapor retarder facing down, you are trapping moisture inside the joist cavities.

What sheathing on the wall are you referring to?
I edited my post. It looked like some sort of sheathing, but it was concrete.
 
  #24  
Old 11-20-18, 01:07 PM
N
Member
Thread Starter
Join Date: May 2012
Posts: 611
Received 2 Upvotes on 2 Posts
[Is the basement wall on the conditioned side exposed concrete, or is it already finished with a stud wall and gypsum board? If it's exposed, the proper way to insulate is 2" rigid foam board against the concrete (sealed around the perimeter), 2x4 wall against the foam board, then fill the stud cavities with unfaced fiberglass batts.]

it's already finished, but may get refinished in the near future.
 
  #25  
Old 11-20-18, 01:13 PM
M
Member
Join Date: Mar 2009
Location: Northern Virginia
Posts: 3,913
Received 27 Upvotes on 21 Posts
it's already finished, but may get refinished in the near future.
Okay. When the time comes, you'll know the proper way.
 
  #26  
Old 11-23-18, 05:38 AM
N
Member
Thread Starter
Join Date: May 2012
Posts: 611
Received 2 Upvotes on 2 Posts
I hope everyone had a nice Thanksgiving. Quick follow-up; a contractor (who was here looking at other stuff for me, so I showed him the crawl space while he was here) said that his HVAC guy would recommend:

"...taking out the foam board that is blocking 2 of the vents. Both of the vents would get backdraft dampers on them, and then one of them would also get a fan with a humidistat. That would turn on when the humidity hits a certain level and circulate air through the crawl space though the vents. The fan is very energy efficient. The vents would only be open when the fan is running, and they will be shut when the fan is off. So that during the colder months when it is dry and not humid, cold air won't be blowing through the vents into the crawlspace. He would also have to get power from the light and install an outlet for the fan. "

Thoughts on that? Seems like a decent idea and was under $1,000.

I'm just concerned that the dampers, etc. only last x # of years and then I'm checking them constantly to make sure they are working, need to replace them every 5 years or whatever... Or maybe they really just keep on going?
 
  #27  
Old 11-23-18, 07:51 AM
B
Member
Join Date: Oct 2008
Location: New England
Posts: 9,460
Received 47 Upvotes on 43 Posts
Long thread and short attention span (comes with age) but wanted to add a couple of links.
One
Two Your crawlspace actually looks more like a small basement space.

I'm a fan of closing off basements and crawlspaces, insulating the walls with rigid foam board (rims look done), and then conditioning those spaces with heat and ac. It is a onetime solution that will last a long time. Only concern is your current moisture issue which should be resolved before adding the rigid foam board.

Using rigid foam board solves two problems. One is it ensured that the inside surface will be above the dew point so no condensation from interior humidity. And two, allows a small amount of drying to the inside, so small that moisture is easily handled by the conditioning. No plastic vapor barriers.

Bud
 
  #28  
Old 11-26-18, 07:53 AM
N
Member
Thread Starter
Join Date: May 2012
Posts: 611
Received 2 Upvotes on 2 Posts
Thanks. How do you recommend I condition the crawl space (yes, it's really like a small basement, but I'll continue to call it a crawl space in this trail to avoid confusion with the regular basement).

I could add a Santa Fe (which I was hoping to avoid), but that would just be for humidity, not for cooling/heating (if that's what you mean by conditioning it.

I don't know how I would heat/cool. Existing basement has electric baseboard heaters which don't get used, as basement only drops to the 60s in the winter and not too hot in summer (I don't recall exact temps), and we don't use the space right much now anyway so the heaters are never on. If we do refinish it the heat wouldn't be on too much anyway.

Thanks again.
 
  #29  
Old 11-26-18, 08:03 AM
N
Member
Thread Starter
Join Date: May 2012
Posts: 611
Received 2 Upvotes on 2 Posts
Separately, just a quick update on current status:

Right now, it's 48 outside with near 100% humidity (as it's going to rain soon, but hasn't yet, though it did rain a couple of days ago so ground may still be wet).

Main part of house (2 story colonial) is 68 upstairs with 38% humidity (according to nest and verified at 70/39% with a thermometer/hygrometer), and downstairs is 65/37% (via nest only).

Main basement is 60 / 51% via wireless sensor portion of the thermo/hygro that I have upstairs.

Crawl space is 52 degrees / 75% via wireless sensor...

If I were to open the door between main basement and crawl space the humidity would drop to probably 60%, and temp may or may not go up a little (I know this from prior experience).

Also, a few days ago when it was in the teens overnight and 20s during the day, it was well over 40 in the crawl space.

After it rains today, next rain won't be until Friday, so I'm curious what the humidity in crawl space will be Thursday (after several dry days outside).

Given all of this, is there really any chance that I'm going to keep the humidity in the crawl space low by following some/all of the suggestions above (unless I take the costly undertaking of digging around my foundation and waterproofing from outside, then fully sealing/encapsulating the space, and then figuring out how to condition it)?

I feel like the best/easiest option might just be a Sante Fe... Of course it may have to run way too much if a lot of moisture is coming in causing the humidity to constantly be high...

Ugh... head spinning...
 
  #30  
Old 11-26-18, 08:05 AM
M
Member
Join Date: Mar 2009
Location: Northern Virginia
Posts: 3,913
Received 27 Upvotes on 21 Posts
Just noticed your comment about the deck height. You could install some plastic sheathing material (e.g., corrugated roofing panels) to the underside of the deck joists from ledger to several feet outward to channel rainwater away from the home.
 
  #31  
Old 11-26-18, 11:37 AM
N
Member
Thread Starter
Join Date: May 2012
Posts: 611
Received 2 Upvotes on 2 Posts
Thanks. Am definitely thinking of doing that with the deck.
 
  #32  
Old 11-27-18, 01:49 PM
N
Member
Thread Starter
Join Date: May 2012
Posts: 611
Received 2 Upvotes on 2 Posts
Is something like this a decent option for insulating the walls in the crawl space: Install 2" Demilec Heatlok Soy closed cell spray foam on walls of foundation.

Or is rigid foam board better?

The spray is $4.50 psf and $1,700 total (at least that's what the estimate was from 5 years ago that I just dug up). I'll obviously get it updated and get another estimate or two as I don't know what spray foam should cost.
 
  #33  
Old 11-27-18, 03:32 PM
B
Member
Join Date: Oct 2008
Location: New England
Posts: 9,460
Received 47 Upvotes on 43 Posts
I usually figure rigid foam board at $0.50 a board ft. That's 12" x 12' x 1" thick. From your post a 2" layer of that spray foam comes out to $9 per board ft. Do I need to say more. Even if your local costs for rigid are more, that is a huge difference.

The only advantage of the spray application is in the rim joist where it requires a lot of piece work. But some advance measuring and some can foam to fill the gaps the rim area isn't all that difficult.

Bud
 
  #34  
Old 11-29-18, 06:42 AM
N
Member
Thread Starter
Join Date: May 2012
Posts: 611
Received 2 Upvotes on 2 Posts
Originally Posted by mossman
Is the basement wall on the conditioned side exposed concrete, or is it already finished with a stud wall and gypsum board? If it's exposed, the proper way to insulate is 2" rigid foam board against the concrete (sealed around the perimeter), 2x4 wall against the foam board, then fill the stud cavities with unfaced fiberglass batts.
I have a follow-up question as I'm probably going to be redoing the main portion of the basement at some point.

There is definitely fiberglass batting in between studs which are against the concrete. I don't think there is anything behind the batting or any kind of foam board. I think it's just studs against the concrete and batting in between the studs.

Assuming I'm correct, and assuming I'm not removing/redoing the studs, how should I proceed to insulate the walls?

Again, this is referring to the main part of the basement, not the crawl space/secondary basement.

Thank you.
 
  #35  
Old 11-29-18, 06:51 AM
N
Member
Thread Starter
Join Date: May 2012
Posts: 611
Received 2 Upvotes on 2 Posts
Originally Posted by newbie0101
Thanks. How do you recommend I condition the crawl space (yes, it's really like a small basement, but I'll continue to call it a crawl space in this trail to avoid confusion with the regular basement).

I could add a Santa Fe (which I was hoping to avoid), but that would just be for humidity, not for cooling/heating (if that's what you mean by conditioning it.

I don't know how I would heat/cool. Existing basement has electric baseboard heaters which don't get used, as basement only drops to the 60s in the winter and not too hot in summer (I don't recall exact temps), and we don't use the space right much now anyway so the heaters are never on. If we do refinish it the heat wouldn't be on too much anyway.

Thanks again.
Sorry, another question... this one on the crawl space again.

Currently I have the santa fe in the boiler room, and it's vented with ducts into the main basement, so it sucks out the humid air and returns dry air.

I was thinking that I could move the santa fe into the crawl space, add vents to the door between the crawl space and main basement, and then the santa fe would hopefully cover both areas.

If I did this, I would of course need to fully close off the crawl space to the outside world, which I would probably just do by having an insulation company spray foam the entire outside wall (they told me this would also act as a moisture barrier and therefore kill 2 birds with 1 stone).

I don't think I would need to heat the space as the foam insulation on the outside walls should raise the temp a bit, correct?

Does this seem like a viable solution?

I will hoping to avoid putting a santa fe in the crawl space, but at least with this solution i'm still just using 1 santa fe rather than 2...
 
  #36  
Old 11-29-18, 07:18 AM
M
Member
Join Date: Mar 2009
Location: Northern Virginia
Posts: 3,913
Received 27 Upvotes on 21 Posts
I think you should solve the source of your excessive humidity first, then decide on whether you want to go with a conditioned or unconditioned crawlspace.
 
  #37  
Old 11-29-18, 10:39 AM
N
Member
Thread Starter
Join Date: May 2012
Posts: 611
Received 2 Upvotes on 2 Posts
Originally Posted by mossman
I think you should solve the source of your excessive humidity first, then decide on whether you want to go with a conditioned or unconditioned crawlspace.
I guess what I don't really understand is that anyone who has ever looked at my basement or the crawl space (original home inspector, several insulation companies, several waterproof companies, several contractors that do a lot of basements, etc...) has said that it's dry. Nobody has said there are signs of flooding, water intrusions, leaks, etc... They all say it's a good looking space and there don't seem to be many issues.

They act as if the humidity is just normal, and there's really nothing to be done about it/no need to worry about it, just use the santa fe and all is good.

They've made a point of commenting that I don't need a sump pump, french drains...

This is why I'm so confused as to what to do. None of these people has ever suggested any method to permanently stop the humidity, or offered up a suggestion on what the source is. They all just think that it is what it is...

I guess this is why I keep going in circles and get nowhere It doesn't seem like there is an obvious source (at least according to anyone who has seen the space), so I'm pretty much stuck working with what I know, and that's simply that the humidity is too high, I have vents which are closed, and that's about it...
 
  #38  
Old 12-06-18, 01:45 PM
N
Member
Thread Starter
Join Date: May 2012
Posts: 611
Received 2 Upvotes on 2 Posts
I had an insulation company come out and he suggested installing a 20 mil vapor barrier along the floor and going up a few feet on the walls, and then spraying the walls with 3" of spray foam. Price of $1,500.

I also had one of the big Connecticut basement system companies come out, and while I thought they would be expensive and would try to sell me drainage, etc... they weren't and didn't. Price was actually a notch less than the guy above, but rather than use spray foam they have their own system consisting of various layers of 'stuff' (CleanSpace, drainage matting, terrablock, silverglo insulation board...). Price of $1,200.

Again, neither company saw the need to investigate the source of the humidity, though the first guy did say he believes it was coming in through the walls and up through the floor, so the 20 mil should really help reduce humidity.

The 2nd guy said one of their layers of stuff (I forget which) acts as a moisture barrier, but I'm not sure it sounded as good as simply using 20 mil from the 1st guy. 2nd guy also wanted to include an expensive dehumidifier, but I opted to take that out of the estimate and see how it went w/o it.

Aside from price in general (I know I can do much better on my own with foam board) any thoughts on these 2 companies/proposals? I really thought the big CT basement company was going to be much more expensive, and say that i needed drains or whatnot installed, but they didn't. They said the space looked pretty good and would be an easy fix...
 
  #39  
Old 06-26-19, 10:31 AM
N
Member
Thread Starter
Join Date: May 2012
Posts: 611
Received 2 Upvotes on 2 Posts
Hi all. I wanted to follow-up concerning the idea of diverting water away from the deck.

is this what you guys are suggesting: https://bit.ly/31V4xsN

looks like Lowes even sells a product for this purpose:

https://www.lowes.com/pd/Tuftex-Actu...-Panel/3043409

On a related note though, I'm slightly hesitant to install something like the above, as I'm afraid it could become a haven for insects...

Any thoughts on that being an issue?

Thanks!
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: