Should crawl space be warmed space or cold?


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Old 04-08-16, 03:03 PM
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Should crawl space be warmed space or cold?

I bought a cheap house as a practice fixer upper, and I am wondering what to do with the crawl space. I'm in eastern New Brunswick, and like a lot of the houses in the area there's a 5-6 foot crawl space with a dirt/gravel floor, and absolutely no insulation at all. Obviously it has the usual moisture problems, and I need to replace a few posts as a result. So after that is done, I want to seal the vent and close up the outside access and vapor barrier the whole thing. The question is, do I insulate the walls (and floor?) and make the crawl space part of the heated part of the house? It is useless space, so I really don't want to heat it, but I see a lot of people recommending this online. Or should I insulate the ceiling (main level floor) and leave the crawl space cold? I see a few recommendations for this, but a lot of people saying not to do that without saying why not. Ideally I'd like to wall off a corner of the crawl space to use as a root cellar, so at least that part would need to stay cold space.

Also I checked the sticky since it seems like it would tell me all about this, but the links have been broken at some point and now just redirect to a general page. If anyone knows where the updated urls for those links are that would be awesome too.
 
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Old 04-08-16, 03:17 PM
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That's a tough one. Not knowing anything about your climate or building practices... or the quality of the house makes it hard to know if its worth it. If you were going to put 2" styrofoam on the floor and pour cement to use the area as storage, I would say yes, insulate and condition the space. But if you don't intend to use it for anything other than a root cellar I would insulate the floor. Get an estimate on having it professionally spray foamed... that would be best.
 
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Old 04-08-16, 03:57 PM
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Going to get a lot of different opinions on this one.
No one can see what your dealing with without pictures.
People here could be any place on the planet and there's a wold of difference from Alabama to AZ and Canada.
Rule #1 is prevent moisture ever becoming an issue under the house by having proper grading away from the foundation.
Foundation needed to be water proofed before it was ever back filled.
If there's gutters they need to have down spouts leading away from the foundation.
No mulch piled up against the foundation.
No flower beds forming ponds.
Always should be a vapor barrier on the ground in a crawl space, (6 mil. plastic will work)
 
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Old 04-08-16, 04:22 PM
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Hi MT and welcome to the forum.
Eastern New Brunswick may be a bit milder close to the ocean, but fairly similar to central Maine. I'll repeat some of the previous comments, but I would resolve any water issues as mentioned and then install a good vapor barrier and add 2" of rigid foam to the walls. Not familiar with your codes, but 2" should be close. Check to see if they require a thermal ignition barrier over the rigid in a crawlspace.

The advantage of insulating the walls is you can also air seal house to foundation and avoid having to air seal and insulate the floor. You can isolate an area for your cold storage but it will still need the VB on the ground.

Once closed off, then you supply heating and cooling just as the house. Instead of having to exchange air with the outside (the insulated floor approach) you now exchange air with the house and if well insulated it presents a minimal load on the heating system.

Bud
 
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Old 04-08-16, 05:41 PM
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Two options: Seal to the outside and open the space to the conditioned air of the house. In this case, you insulate the walls. Other option is to close the space off to the house air and open it to the outside, in which case you insulate the ceiling. Either way, you need a vapor barrier on the floor. Generally speaking, the first option is more common in norther climates, the latter in southern. Hence, if I were you, I would lay a vapor barrier, close off the vents to the outside, insulate the walls and open the space to the house air. Not necessarily an inexpensive endeavor.
 
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Old 04-12-16, 04:51 PM
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Sorry I should have been more clear about what I am after. Does anyone have any concrete pros and cons to each approach? I want to try to make a good informed decision about which is best for this situation, rather than just rely on whichever one more people vote for as it were.
 
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Old 04-12-16, 04:57 PM
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It is useless space
Well, there is a "concrete con" for you right there. Why spend all the $$$ on this "useless space", unless your intent is to make it usable space.

 
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Old 04-12-16, 05:43 PM
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Living far south of you under the house is just that part of the yard covered by the house that thank goodness doesn't need mowing. We don't do anything with them except occasionally wiggle under on our bellies.
 
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Old 04-12-16, 05:50 PM
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A big "Pro" is that a warm basement will result in warm floors, everywhere in the house.
Leaving the crawlspace cold does not address the moisture issues down there. Once you ventilate it, the relative humidity in the summer will he higher than the outside RH, because it is a cooler space and that damp cool air will just sit there.

By bringing that space inside the conditioned space of the house, regardless of it' use or not, you have it under your control. Left to mother nature it will be an ongoing problem if vented.

IMO,
Bud
 
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Old 04-13-16, 08:55 AM
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It has to be sealed either way, the way these crawlspaces were designed creates moisture problems from bringing outside humid air into a cool space to condense.

As for "Why spend all the $$$ on this "useless space", unless your intent is to make it usable space.", I don't understand the question. An uninsulated crawlspace means I am paying to heat the outdoors. It will cost more in the long run to leave it the way it is than to insulate it. The question is not "insulate or no?" it is "insulate the ceiling or the walls?". The con of it being useless space will still apply to either method.
 
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Old 04-13-16, 08:59 AM
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My 2 is to seal this off from the outside, put a vapor barrier on the floor, insulate the walls and open this space to the house air.
 
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Old 04-13-16, 09:46 AM
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I already said insulate the floor... that should be a given... as is the poly on the floor. My comment about the extra $$$ is the cost of insulating walls and conditioning the space, or finishing the floor.
 
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Old 04-13-16, 10:02 AM
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Brant - when you say floor, are you talking about the ceiling of the crawlspace/floor of the space above or the floor of the crawlspace?

Personally, I would not insulate the ceiling of the crawlspace if the walls were going to be insulated and the air in the space conditioned; I would insulate the ceiling only if the space was being left open to the outside air.
 
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Old 04-13-16, 10:06 AM
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Yeah sorry... that was confusing. Insulate crawlspace ceiling (floor of finished area) and poly on dirt floor in crawlspace.

I agree with your last paragraph... I just cant see how its the best most cost effective option in this case.
 
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Old 04-13-16, 10:13 AM
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Yeah, not the more cost-effective option but the warmer floors above are worth it, IMO.
 
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Old 04-13-16, 03:06 PM
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I would not be a big fan of pulling return air out of a crawlspace with a dirt floor. You would need to be sure that vapor barrier is completely sealed and taped or you will spread that moldy earthy smell all through the house. Mastic is a good way to glue it to the side walls. Adding a heat register may not give you the best circulation without return air so its kind of a catch 22. So best advice is to make sure the poly is sealed well if you're going to condition it.
 
 

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