Replies

1. 
   Knightdiamond | Mar 04, 2009 05:44am | #1

   Kungur,

   Is the crawl space "ceiling" your living space floor? What R rating insulation did you use?  Is your intent to make your crawl space sealed? Just a coupla questions to start. A sealed crawl space will require some significant work but should pay dividends over time. I am thinkin you got a little more due diligence to do. But if you have questions query me through breaktime. I have lots of reference material on sealed crawl spaces. Oh and BTW there is a significant energy savings depending on your region and your techniques.

   Good luck.

                          KD6

1. 
   agewon | Mar 05, 2009 12:10am | #2

   I too have a crawlspace issue of the same sort.  I live in New  Jersey, and the space is 300 square feet, and is attached to my basement by a four ftsq opening.  The floor joists from the living space above are insulated but poorly. 

   I have beenoing lots of research on "tightening" my house and came across the article that suggests making the crawlspace part of the house. http://www.taunton.com/finehomebuilding/how-to/articles/built-wrong-from-start.aspx?LangType=1033&ac=fp.

   I have since removed the panel that covered the the opening to the baement, and am planning on sealing and insulating the walls and floor as per the article "Sealing a Crawlspace" http://www.taunton.com/finehomebuilding/how-to/articles/sealing-damp-crawlspaces.aspx?LangType=1033&ac=fp

   My only issue is that the two articles dont cover insulation AND sealing togeather.  Any ideas?  Does the sealing take place first or the insulation?  I plan on using rigid foam and cant imaging putting that before the barrier and if putting it after, how do you make a tight seal to the wall?

1. 
   MSA1 | Mar 05, 2009 01:42am | #4

   We generally seal the crawl before we insulate. 

   Family.....They're always there when they need you.

2. 
   MSA1 | Mar 05, 2009 01:41am | #3

   Get the insulation out of the the joists. Install 6 mil plastic on the dirt, seal any vents or gaps, install 2" rigid ins on the walls at least to grade, then cover the rigid with drywall (you need a fire stop) then drop a heat run into the crawl.

   This will make you crawl more like a basement, and you'll have warm floors, fluid in your pipes, and peace of mind.

    

   Family.....They're always there when they need you.

1. 
   agewon | Mar 05, 2009 02:10am | #5

   In my case, i have a full slab in the crawlspace.  Do seal everything then cover it all with rigid, floors too?

1. 
   MSA1 | Mar 05, 2009 04:18am | #8

   Good question on the slab. Shooting from the hip i'd say that it may not help much. But It probably woudnt hurt either. Just remember you'd have to cover it for firestopping.

   You could do that with osb and make a pretty cool storage area.

   Sorry I dont have a definitive answer on the floor. I'd assume someone will be along soon though to help. 

   Family.....They're always there when they need you.

1. 
   Clewless1 | Mar 05, 2009 04:10pm | #10

   Most construction never insulates the slab in a crawl based on what I've seen over the years. We could debate that to some degree though. You either decide to couple with the ground at ~50 deg or you diconnect yourself by insulating.

   If you do as the one poster suggested ... dump a heat duct into it ... I'd certainly consider it, then. But I'm not convinced that doing that would be the best approach.

   I do recall a 'system' about 20 years ago ... don't recall the name of it. It provided all the heated supply air to the crawlspace and then to supply registers in the floor. But this system had a lot of specific requirements to work ... you essentially pressurized the crawlspace ... leaving you with a much warmer floor. It wasn't used to much, mostly because of the construction logistics, I suppose.

1. 
   MSA1 | Mar 05, 2009 07:39pm | #13

   I suggested the heat duct and its not an option. You need to treat the crawl as a basement for this system to work. 

   Family.....They're always there when they need you.

2. 
   jonblakemore | Mar 05, 2009 10:02pm | #14

   "I do recall a 'system' about 20 years ago ... don't recall the name of it. It provided all the heated supply air to the crawlspace and then to supply registers in the floor. But this system had a lot of specific requirements to work ... you essentially pressurized the crawlspace ... leaving you with a much warmer floor. It wasn't used to much, mostly because of the construction logistics, I suppose."

   That sounds like a mess. If we can't effectively use joist or stud bays as returns, how in the world could an entire crawlspace be sealed enough to act as a plenum? I would think that is asking for trouble. 

   Jon Blakemore RappahannockINC.com Fredericksburg, VA

3. 
   agewon | Mar 06, 2009 03:45am | #15

   I agree with MSA1, and have heard of making the crawl part of the living space as a viable option.  I think i will seal up the exterior vents, install a vaporbarrior to the walls and floor, and rigid the whole crawl, slab and all.  My heating is forced gas, and the two runs that enter the crawl to feed the room above are not insulated, so every time the heat runs, the first few minutes, cold air blows out.  Fixed that by running flexible insulated but figure if I control the climate in that crawl close to the basment or better, that room may not be the coldest anymore.  Thanks guys!

4. 
   Clewless1 | Mar 06, 2009 10:15am | #16

   Yeah it was a PITA ...  It wasn't a return, though, it was the supply. That's why it didn't survive as a popular option. Way too much work. But everything has a time and place. But ... you end up w/ warmer floors.

2. 
   Kungur | Mar 05, 2009 03:44am | #6

   Not sure how removing the iulation will help keep the space above warmer.

1. 
   MSA1 | Mar 05, 2009 04:16am | #7

   Because you're now making the crawl part of the conditioned area. You remove the ins from the joists, then insulate the walls. Then you droop a heat run in there. 

   Family.....They're always there when they need you.

3. 
   Clewless1 | Mar 05, 2009 03:54pm | #9

   Good idea ... but you make it sound so simple ... rigid insulation ... then just cover it with drywall. In my experience crawlspaces aren't exactly the easiest places to work in. How did you intend he would attach the drywall? Also ... drywall to the ground could easily wick up moisture, I think so not sure if that would actually be a good solution. While your fire barrier issues is understood, I'm not sure how it is to come together practically.

   The fire protection may not be required in that application ... but it could be. Best check with a building official to ensure that whatever you do, you meet local codes for this detail ... and that you do no more work than is necessary.

   I'm trying to recall details I've seen in the past for this. It seems like rigid on the walls, operable foundation vents (for the summer) ... and nothing else ... I may be wrong, here. Another option is fiberglass batts (faced).

1. 
   MSA1 | Mar 05, 2009 07:38pm | #12

   Yes its a PITA to work in a crawl. We glue the rigid to the walls and usually will glue or cleat the drywall in place. Where I work, they want the rigid covered. As far as moisture you put the plastic down first.   

   Family.....They're always there when they need you.

3. 
   Clewless1 | Mar 05, 2009 04:11pm | #11

   Is the crawl vented to the outside (i.e. foundation vents)? What type of heating do you have? Ducted under floor? Baseboard?

   
   

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   Edited 3/5/2009 8:15 am ET by Clewless1

4. 
   EricGunnerson | Mar 10, 2009 07:07am | #17

   I suggest going to the buildingscience.com website and searching for "crawlspace". You will find some great stuff that details the different options for crawlspaces.

1. 
   gotfoam | Mar 10, 2009 06:07pm | #18

   Put a vapor barrier on the floor. Run the barrier up the walls a foot or two and then install three inches of closed cell spray foam from the top of the box sill down over the vapor barrier to the floor. Cover up all vents to the outside. In one of the vent holes install an energy efficient continuous duty fan pulling air to the outside. Install a vent in the floor so that when the fan depressurizes the crawl space. This pulls air from the conditioned space to the crawl space which in turn makes the crawl space a conditioned space. Also take the fiberglass out. Very important to make the vapor barrier completely air tight so no vapor gets up from below.hope this helps