Author Topic: Crawl space insulation plan - input please  (Read 1292 times)

Sibley

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Crawl space insulation plan - input please
« on: May 27, 2018, 02:24:14 PM »
I need to insulate my crawl space. Specifically, reinsulate it since it has insulation which is all messed from from another project. And I don't want to mess up my house by doing it wrong! Below is specs and the plan, poke holes in it please.

Specs:
1919 house
crawl space, uneven floor, fairly ok to move around in there.
Dirt floor. NOT sealed, and its not going to be sealed. No vapor barrier currently.
Big pits in the corners so you can stand upright
Various plumbing, etc
Ventilation through 4 vents in the foundation + the door to the crawl allows some air movement.
Midwest location - real winter, hot/humid summers.
If it rains a LOT, the crawl can get water, which then drains naturally. This seems to be require unusual weather conditions. Last winter, had 3 feet of snow then it rained for a couple days and between snow melt + rain, the crawl got wet. Otherwise, appears dry.
Also last winter, the first floor was FREEZING. Which prompted the project to do something with the crawl space.

Plan:
Remove all old insulation from between joists (its installed paper side towards the ground, which I think is incorrect), general clean up of the mess
Inspect plumbing, determine if need to replace anything cause it's time before it breaks and makes a mess (1919 house...)
Install new insulation between joists, with the paper side facing the underneath of the 1st floor. This is opposite of current.
Staple up plastic as a vapor barrier on the underside of the joists
Insulate the hot/cold water pipes so maybe it doesn't take 5 minutes to get hot water upstairs in winter :)

I am most concerned with the possibility of water condensation leading to mold/rot, while also making sure that the entire first floor isn't freezing cold all winter. Based on my research, the paper side of the insulation should face the bottom of the floor, since it'll act as vapor barrier, which is the reverse of what it is currently. Would that be sufficient to keep the floor warm? Or do I need to add the plastic vapor barrier too? Would plastic cause water problems?

Also, assuming that the insulation is going to go paper side up, then how do I keep it from falling down?

TheWifeHalf

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Re: Crawl space insulation plan - input please
« Reply #1 on: May 27, 2018, 03:31:41 PM »
I can't address your questions, but in our crawl space (Ohio) the plastic vapor barrier is on the ground

TheHusbandHalf came home, info from him:
The insulation bats stay between the floor joists by friction. It's been there 26 years. Last year a couple were falling down and he said they make wires that hold up the bats. They are not attached to anything, because they are a bit longer than the space between the joists, so curve up and hold the bat up.
« Last Edit: May 27, 2018, 03:52:25 PM by TheWifeHalf »

Sibley

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Re: Crawl space insulation plan - input please
« Reply #2 on: May 27, 2018, 03:51:24 PM »
My understanding is if you put the vapor barrier on the ground, then you're basically closing the system, so you have to provide ventilation. I'm not able to do the ventilation bit, so have to come up with alternative.

TheWifeHalf

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Re: Crawl space insulation plan - input please
« Reply #3 on: May 27, 2018, 03:54:37 PM »
Yes, every spring it's my responsibility to open the vents, and in the fall to close them.

Sibley

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Re: Crawl space insulation plan - input please
« Reply #4 on: May 27, 2018, 09:26:43 PM »
Ok. My vents are fixed, they're just open. Sounds like I'm good up to the vapor barrier bit at least.

Are your bats fluffy side up or down?

bacchi

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Re: Crawl space insulation plan - input please
« Reply #5 on: May 27, 2018, 10:00:32 PM »
Use rigid foil-faced polyiso sealed on the underside of the joists. It'll add insulation and a vapor barrier and also create a thermal break that the poly barrier can't do.

Note that kraft paper batts are a fire hazard.

http://www.greenbuildingadvisor.com/blogs/dept/qa-spotlight/details-closed-crawlspace


Goldielocks

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Re: Crawl space insulation plan - input please
« Reply #6 on: May 27, 2018, 10:34:33 PM »
Vapour barrier on the warm side, in heating conditions...

I recommend spray foam insulation because of the incredible vapor seal you get and resistance to moisture.  Also would reduce any creaks.

yodella

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Re: Crawl space insulation plan - input please
« Reply #7 on: May 29, 2018, 02:29:20 PM »
So, on a related note, my husband and I also live in an old house in the Midwest and this Winter we paid to have our crawl spaces encapsulated. We do almost all other home/reno work ourselves so this was definitely a non-mustachian splurge, but it has turned out amazingly.

It made a HUGE difference in keeping the first floor warmer (floors were no longer freezing), and decreased our heating bill. Now that we are having a crazy hot few days (mid 90s) and we've had the AC on, we are not getting what I call "basementy smell" while its is running, which used to really bother me. The humidity in our basement has also gone waaaay down (our house has a basement in the middle, flanked by two crawl spaces).

I know this is totally not what you are asking about, just throwing it out there in case anyone else is thinking about it.

Sibley

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Re: Crawl space insulation plan - input please
« Reply #8 on: July 07, 2018, 06:58:24 AM »
Update on the plan. Ish. Help with the fiddly details? Or direct me to a source I can trust? I don't want to screw up my house.

I've had 2 companies in to do estimates on insulating the crawl space, and and what they're recommending is slightly different.

Company 1: Will put 2 inch rigid foam board on the walls (glued, from ground to sill plate and inside the joist cavity). 6 mil plastic as a vapor barrier stuff on the dirt floors. Will cover up the existing vents. They will not put insulation between the joists. This will create a semi-closed system, with air exchange happening naturally through the 1st floor, etc. Old house, not air tight, there will be air exchange.

Company 2: will put an insulation "blanket" with vinyl backing on the walls, will have to use pins and glue to secure it, so there will be drilling into the block. They will NOT block the vents, but will leave them open. Will put vapor barrier on the dirt floor, and new batt insulation between the joists.

Concerns: Moisture, moisture, moisture. What's the right materials? Should the vents be open/closed? There WILL be water under the plastic, it gets wet in heavy rains. Moisture can destroy the house, so I need to make sure I do this right, and I just don't know enough.

@yodella - what did you do in your crawl? 

gwhunter

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Re: Crawl space insulation plan - input please
« Reply #9 on: July 07, 2018, 07:17:25 AM »
I want to 2nd the encapsulation idea.  We just moved into a house in the midwest built in the 1860's.  Over the winter the floors were FREEZING even with a woodstove keeping the air temp around 80f.  We had a company come out an encapsulate the crawl (we also have a partial "michigan" basement attached to the crawl that was spray foamed as well).  They put down the vapor barrier on the dirt and left about 6" of the plastic to also be on the wall.  Then they sprayed the foam insulation from the floor to the sill (thereby attaching the plastic to the wall).  This made the crawl a closed system and with 1 diffuser/register the air in this space is now conditioned.  We didn't have the issues with the moisture like you do, but the spray foam would have corrected this too since it is water resistant/proofish (from what we were told). 

Sibley

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Re: Crawl space insulation plan - input please
« Reply #10 on: July 07, 2018, 07:24:13 AM »
Are there any moisture concerns with putting the spray foam up to the sill? I'm good with the encapsulation plan overall, just need to make sure the details are right. And since the companies want to make money.... independent research.

Rcc

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Re: Crawl space insulation plan - input please
« Reply #11 on: July 07, 2018, 07:28:48 AM »
Update on the plan. Ish. Help with the fiddly details? Or direct me to a source I can trust? I don't want to screw up my house.

I've had 2 companies in to do estimates on insulating the crawl space, and and what they're recommending is slightly different.

Company 1: Will put 2 inch rigid foam board on the walls (glued, from ground to sill plate and inside the joist cavity). 6 mil plastic as a vapor barrier stuff on the dirt floors. Will cover up the existing vents. They will not put insulation between the joists. This will create a semi-closed system, with air exchange happening naturally through the 1st floor, etc. Old house, not air tight, there will be air exchange.

Company 2: will put an insulation "blanket" with vinyl backing on the walls, will have to use pins and glue to secure it, so there will be drilling into the block. They will NOT block the vents, but will leave them open. Will put vapor barrier on the dirt floor, and new batt insulation between the joists.

Concerns: Moisture, moisture, moisture. What's the right materials? Should the vents be open/closed? There WILL be water under the plastic, it gets wet in heavy rains. Moisture can destroy the house, so I need to make sure I do this right, and I just don't know enough.

@yodella - what did you do in your crawl?

Option 1 is exactly what we did. (We have 20 mil plastic) We had 3 other things done with the price. 1- a vent from the HVAC was added to blow into the crawlspace to regulate the temp/humidity, 2- a drain to daylight through foundation required by code, and 3- they also scrubbed the joists of all traces of mold. Water under the plastic isnít a concern to me -especially if it has somewhere to go when then dry out (that isnít your crawlspace).

I had posted in another crawlspace thread some studies done on this in NC in another thread. Iíll repost here to help your thinking.

Rcc

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Re: Crawl space insulation plan - input please
« Reply #12 on: July 07, 2018, 07:32:07 AM »
As discussed, plenty of good info here.

https://www.advancedenergy.org/portal/crawl_spaces/

Iím happy with our results (your option 1) since doing this last October.

Sibley

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Re: Crawl space insulation plan - input please
« Reply #13 on: July 07, 2018, 07:50:39 AM »
Thanks @Rcc. I will read through everything. Of course, option 1 is 2x the cost!

gwhunter

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Re: Crawl space insulation plan - input please
« Reply #14 on: July 07, 2018, 08:34:28 AM »
Are there any moisture concerns with putting the spray foam up to the sill? I'm good with the encapsulation plan overall, just need to make sure the details are right. And since the companies want to make money.... independent research.

Not that I'm aware.  But like I said before, we really didn't have a moisture problem like you do.  The primary reason to use the plastic and completely encapsulate was more for the insulating characteristics and to make the space a conditioned space.  We were trying to prevent any way for outside air to get into the crawl. 

gwhunter

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Re: Crawl space insulation plan - input please
« Reply #15 on: July 07, 2018, 08:42:15 AM »
Something else to look at would be why is there water/moisture getting into your crawlspace?  Is the grade correct around the entire foundation?  Are the gutters and downspouts operating effectively?  Are there any other environmental factors contributing to the water/moisture accumulation in the crawl? (Trees, shrubs, etc.) 

A lot of times we want to 'keep it as it is' because of how we like the look of the yard or the 100 year old tree that is causing water to accumulate in the crawl.  But ultimately you have to decide if you can rip off that bandaid to make it work.  It was a hard decision for us to do to our old house, but i feel much better now with a dry basement (the crawl never had moisture issues, just the basement) and an airtight crawlspace. 

TheWifeHalf

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Re: Crawl space insulation plan - input please
« Reply #16 on: July 07, 2018, 01:40:55 PM »
Ok. My vents are fixed, they're just open. Sounds like I'm good up to the vapor barrier bit at least.

Are your bats fluffy side up or down?

I think we must have a different 'system', TheHusbandHalf said both sides are fluffy

Something that happened a month or so ago:

Under the old section of our 1915 house, there is a full basement. It's where our furnaces, and other things like that ,are.
We started getting water in a typically dry basement, and after a lot of checking, researching, remembering, we solved that problem.

When the house was built, it had an antiquated septic system that was basically two tiles the the ground, that got stuff from the toilet, and then sent it to the creek. Behind our lot is about 200' field, and then to the creek.  It was about 7' underground. One of the first things we did was put in a new septic tank and leach field. The plastic tile were all about 4' underground and in about 2/3 back in our lot, it ties into the old 7' under tile.

We were dry since 1980.

What ended up being the problem - 
At the same time my dad and TheHusbandHalf put in the septic system, they also put drainage tile in the yard. (We live in Ohio, in what is called The Black Swamp), so this insured there weren't water pools anywhere above the ground when it rained. Where the new 4' under tile (drains the yard and the leach field) meets the old glazed tile that goes back to the creek we were okay, but somewhere between the creek and where the new tied to the old, it was clogged.

So we figure, since it's really not being used for anything anymore, cut off  the old 7'under glazed tile, before the tie to the new, so the water from the yard that was getting to our basement could not get backed to the house.  It was making the water table really high when it rained and where our old foundation and floor of the basement met, leaked in it. A lot. There were a couple of times there was 4" of water.

The way we found where the new, 4' under, plastic tile tied into the 7' under glazed to the creek tile, was because my Dad (who has been dead about 20 years),  left a 6" piece of notebook paper with dimensions of where the tie was, in reference to the lot lines. It was written in pencil.

We ended up hiring a guy, about 75 or so, who knew of my Dad, and we told him the vicinity of where we thought the connection was.
Did he use some fancy machine to tell him exactly where the tie was? NO He did it the way my Dad used to, he used a dousing rod (a straightened wire coat hanger). THH saw him!

He had rented a small backhoe, because he didn't have one that would fit through our garage door (we have a front and back garage door for just such reasons). He ended up being within 11" of the tie.

We think we may have solved the problem, and we've had a lot of rain.

I'm going to write all this down, with maps of where tile is around our house and in the yard, so the next person knows what they're dealing with. I've always been thankful that this house, that we bought from the original owner in 1980, had very little changed from it's original condition. I don't know what we would have done, even the crude drawing from my Dad was a stroke of luck.
« Last Edit: July 09, 2018, 12:02:45 PM by TheWifeHalf »

Sibley

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Re: Crawl space insulation plan - input please
« Reply #17 on: July 07, 2018, 02:36:05 PM »
Something else to look at would be why is there water/moisture getting into your crawlspace?  Is the grade correct around the entire foundation?  Are the gutters and downspouts operating effectively?  Are there any other environmental factors contributing to the water/moisture accumulation in the crawl? (Trees, shrubs, etc.) 

A lot of times we want to 'keep it as it is' because of how we like the look of the yard or the 100 year old tree that is causing water to accumulate in the crawl.  But ultimately you have to decide if you can rip off that bandaid to make it work.  It was a hard decision for us to do to our old house, but i feel much better now with a dry basement (the crawl never had moisture issues, just the basement) and an airtight crawlspace.

Oh, I know why it's getting wet, at least partially. I've got some concrete on the side of the house that is messed up and allowing water to pool. I've got gutters, etc that move the water away in most circumstances, but if it's raining REALLY hard, the rainfall just overwhelms the system and I get a lake. It drains down and at least partially into the crawl. I'm going to get some spray foam stuff and see if I can work on sealing that join, but realistically I need to fix the concrete so it slopes away from the house.

Edit: I had a massive rainstorm on the 4th, and I was out in it. (Got soaking wet and killed an umbrella.) But I saw water gushing from the downspouts and also pouring over the edge of the gutter. So, on the south side of the house, there's a lake. North side - different ground stuff going on, and there isn't standing water next to the house.
« Last Edit: July 07, 2018, 02:43:08 PM by Sibley »

zolotiyeruki

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Re: Crawl space insulation plan - input please
« Reply #18 on: July 09, 2018, 08:12:36 AM »
Something else to look at would be why is there water/moisture getting into your crawlspace?  Is the grade correct around the entire foundation?  Are the gutters and downspouts operating effectively?  Are there any other environmental factors contributing to the water/moisture accumulation in the crawl? (Trees, shrubs, etc.) 

A lot of times we want to 'keep it as it is' because of how we like the look of the yard or the 100 year old tree that is causing water to accumulate in the crawl.  But ultimately you have to decide if you can rip off that bandaid to make it work.  It was a hard decision for us to do to our old house, but i feel much better now with a dry basement (the crawl never had moisture issues, just the basement) and an airtight crawlspace.

Oh, I know why it's getting wet, at least partially. I've got some concrete on the side of the house that is messed up and allowing water to pool. I've got gutters, etc that move the water away in most circumstances, but if it's raining REALLY hard, the rainfall just overwhelms the system and I get a lake. It drains down and at least partially into the crawl. I'm going to get some spray foam stuff and see if I can work on sealing that join, but realistically I need to fix the concrete so it slopes away from the house.

Edit: I had a massive rainstorm on the 4th, and I was out in it. (Got soaking wet and killed an umbrella.) But I saw water gushing from the downspouts and also pouring over the edge of the gutter. So, on the south side of the house, there's a lake. North side - different ground stuff going on, and there isn't standing water next to the house.
In that case, you need to take care of the drainage problem first.  Ounce of prevention and all that.

My understanding is that condensation under a vapor barrier on the floor of your crawlspace isn't something to worry about.  That's where you want the water to be--away from your house.

Sibley

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Re: Crawl space insulation plan - input please
« Reply #19 on: July 09, 2018, 08:21:42 PM »
Update. Finally had time to read through the site that Rcc had posted before, thank you! Based on that (and common sense, once life settles for 5 minutes to think), I'm postponing the crawl space work until I can get the sidewalk fixed that is dumping water into the crawl.

Got a list of contractors who do concrete stuff, going to get quotes. Not sure if they'll need to remove and replace the sidewalk or if they can realign it to direct water away from the house. Once that's taken care of, I will revisit the crawl.

coffeefueled

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Re: Crawl space insulation plan - input please
« Reply #20 on: July 16, 2018, 10:06:47 AM »
We just got quote for a similar crawlspace encapsulation which came to about $17k. We're in a circa 1930's cottage with an addition. The crawlspace opens to the partially sunken utility room in the center of the house meaning everything in the crawl space is basically in our home. $17k is beyond what we can spend at the moment (particularly since we're turning part of our attic into conditioned space). We decided to do some of the work ourselves based on designs from some of the links above and similar research.

I crawled under the house this weekend to close the 4 vents in the foundation and seal them with XPS and canned foam. The fiance and I were pretty proud of ourselves over that small success. next we're going to wrap vapor barrier from what's already on the floor to near the top of the foundation wall and seal the seams with mastic. That should give us a mostly sealed space and I think significantly reduce humidity in the crawl space (we don't have any standing moisture). The vapor barrier won't be as thick as the 20mil the contractor included and we won't have the plastic drainage board or foam insulation for a thermal break underneath, but I don't think the lack will significantly reduce the effectiveness. We already have batt insulation in the floor cavity that is still clean/dry/in great shape. I'm guessing it will be the 80% solution, but worth saving the $17k.

Has anyone else done this type of work themselves? How were your results?

bacchi

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Re: Crawl space insulation plan - input please
« Reply #21 on: July 16, 2018, 12:04:48 PM »
I'm about to start this project myself.

I plan to use 12 mil for the crawl space floor with the walls at 6 mil because it's easier to handle.