Crawlspace Insulation


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Old 12-07-11, 09:46 AM
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Question Crawlspace Insulation

Hi folks looking for some additional advice on my crawlspace insulation project. Living space above my crawlspace is very cold & drafty in some spots. After doing a few recon missions, I can see why. Fiberglass batts are installed backwards & also the rim joists are not insulated properly. I can feel the air flowing in at an alarming rate. I currently have no issues with moisture nor do I want to. That is where I need your advice on what products and tactics to use so I can achieve the goal of making the living space above warmer and not creating any moisture issues going forward.

Some background information. Area is approx 550Sq ft. I would classify as a unconditioned crawlspace however the vents are blocked w/ FG and there is insulation on the foundation wall. The floor above looks to be plank flooring with carpet above that except in the kitchen where ceramic tile floor is installed over top of vinyl flooring.

For the rim joists my plan is to seal off the rim joists w/ some caulk (see pic#2. Cut to fit Rigid foam board and seal the edges with Great stuff (see pic#1). Finally back-filling the cavity w/ Roxul insulation. For the rest of the crawlspace I planned on sealing up any gaps around duct-work or vents with fire rated GS and then use faced FG insulation. Please feel free to chime in on any advice. Thanks much in advance!



 
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Old 12-07-11, 01:05 PM
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Crawlspaces either need to be vented to the outside or conidtioned with the rest of the house.
 
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Old 12-07-11, 01:10 PM
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Yep, agreed! What would be the definition of a conditioned crawl space? From what I am reading insulating the walls and sealing off the vents can be considered a conditioned. In saying that and thinking about my setup I'd guess I'd have to say my is conditioned. However the room above it does not feel as thought its conditioned.



 

Last edited by CBAUR88; 12-07-11 at 01:33 PM.
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Old 12-07-11, 02:03 PM
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So, what else is down there, HVAC, water lines, ducts, furnace?

If the space is not heated, then it will get cold despite the insulation. Air sealing is important because the cold air pushes into the lower portions of a home and forces and warm air up and eventually out the upper portions. Lacking a heat source, that space just plain gets cold and the floors above it as well.

You currently have a mixed approach with perimeter insulation and floor insulation. I would recommend sealing the rim to the foundation, then sealing and insulating each cavity. You do have termites down there so you might consider just sealing each joist cavity and then carefully packing it with the Roxul, so rigid foam board. That makes inspection much easier and the Roxul will do a good job. The insulation on the walls looks like open fg insulation, not worth a lot. That is where you could add some rigid foam board. Once the perimeter is super insulated and sealed, then add some heat down there and enjoy some warm floors. Be sure your plastic on the ground is in good shape and your net heat loss will be minimal.

Bud
 
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Old 12-07-11, 02:53 PM
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Originally Posted by Bud9051 View Post
So, what else is down there, HVAC, water lines, ducts, furnace?
If the space is not heated, then it will get cold despite the insulation. Air sealing is important because the cold air pushes into the lower portions of a home and forces and warm air up and eventually out the upper portions. Lacking a heat source, that space just plain gets cold and the floors above it as well.

You currently have a mixed approach with perimeter insulation and floor insulation. I would recommend sealing the rim to the foundation, then sealing and insulating each cavity. You do have termites down (I DO?) there so you might consider just sealing each joist cavity and then carefully packing it with the Roxul, so rigid foam board. That makes inspection much easier and the Roxul will do a good job. The insulation on the walls looks like open fg insulation, not worth a lot. That is where you could add some rigid foam board. Once the perimeter is super insulated and sealed, then add some heat down there and enjoy some warm floors. Be sure your plastic on the ground is in good shape and your net heat loss will be minimal.

Bud
Thanks for the reply Bud, much appreciated. There are only ducts and water lines down there no HVAC or furnace. Yeah I am not sure what the previous owner had in mind but it's definitely a hybrid approach and what I am afraid of. It's not done any harm so far as it's clean and dry down there for the most part. But I don't want to seal things up and create a problem. I am really not sure which direction to go. Should I insulate the walls better? But if I do that should I insulate between the joist as well? Isn't it one or the other? Should I keep the vents opened or closed? I am really torn on the approach I should take. However I know where I can start and I feel needs to be done regardless of which direction I go and that's the rim joists. They are a problem and letting air so I'll start there which will buy me more time to make up my mind and do more research.
 
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Old 12-07-11, 04:51 PM
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Here's some reading if you haven't seen it yet.BSI-009: New Light In Crawlspaces — Building Science Information

Bud
 
 

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