Crawl Space Insulation

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  #1  
Old 01-18-05, 12:55 PM
rric31
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Crawl Space Insulation

I am sure this has been beaten to death, but I am new to the board.

I live in Maine and I have a crawl space. This crawl space has vents in the foundation, is UNheated, R-25 faced insulation in the floor, and the floor of the crawl space has gravel covering a plastic material.

My problem is that the floor inside and the outside walls are cold. Is there anything else I can do to help with the insulation? Heating the crawlspace is out because the foundation walls are really cold and I think a heater would be more of an issue than help. I thought about applying a rigid foam insulation over the already exsiting insulation, but would this help any?

It seems as if I could insulate the foundation walls things might improve, but I think I read you insulate the walls OR the floor, never both. If that is the case, am I stuck with what I have? Is there anything else I can do?

Your thoughts are appreciated.

Rich in cold Southern Maine
 
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  #2  
Old 01-18-05, 01:13 PM
Ed Imeduc's Avatar
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Location: Mountain Williams Missouri
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Go to http://aboutsavingheat.com/crawlspace.html
And read it. its hard to say where to start. We do not vent the crawl. Id check first on the 6 mil poly you say is down there on the ground now. Should overlap 2' and tape all seams up the wall some. A 2 " or 3" polystyrene on the wall up to the joist. A R 19 insulation in each joist space up there on top of the sill plate all around the home. No insulation in the joist at all. Ill bet if you put your hand up there in that insulation you will find its damp are wet like.
We also cut registers in the heat duct if the duct work is down there. This also makes for a warm floor. You could put a small electric heater for down there if you dont have heat duct there now.

ED
 
  #3  
Old 01-18-05, 02:31 PM
rric31
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Thanks for the reply

Ed, Thanks for the quick reply. Good site.

Let me see if I follow you. When you say I should check on the 6 mil poly. Are you saying to make sure that it is a 6 mil poly, or that it covers everything?

If I have floor insulation, can I also cover the foundation walls with insulation as well? I thought if I had the floor insulated, I should not insulate the wall. Is this true. If not, I can bet you my problem can be corrected with insulating the foundation wall, it is really cold.

Thanks again.

Rich in Maine
 
  #4  
Old 01-18-05, 04:14 PM
Ed Imeduc's Avatar
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Its check the poly so it is a good tight job and wont let the humidity up from the ground. did you go to that www and read it?
Is the insulation in the floor damp??????? if so it is no good

For now and as cold as it is. Id put insulation on the wall fast up there maybe 4". seal the vents.Then the whole crawl space works as like a heat sink for you

ED
 
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Old 01-18-05, 05:01 PM
rric31
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Poly tight

Poly is tight and no the floor is not damp.

I did go to the web site and it was good info. I see what you are talking about as far as drape the foil faced insulation on the foundation wall. That sounds like a plan.

My only concern is having both the floor and foundation walls done at the same time. I hope that is ok.

Rich
 
  #6  
Old 01-19-05, 01:50 AM
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We have vents here on the wet coast but they can be closed in the winter months. You need to eliminate all air leaks. Foam board on the walls is good with Hilti CF128-DW spray foam to seal joints.

Keep in mind that heat can also transfer through the studs and joists (also known as thermal bridges). It is also possible to apply thermal controls in these areas.

You may wish to spend some time researching the various insulating materials you have to choose from. Not one insualtion material is suitable for all situations. The three methods of heat transfer are radiation, convection and conduction. The standard and more popular insulations such as fiberglass only addresses conduction. When you take the other two forms of heat transfer the effectiveness can change dramatically.

"Air movement also greatly affects the R-value of fiberglass, as heated air moving through the fiberglass drastically reduces its conductive value. ( see "Attic Insulation Problems In Cold Climates" March 1992, pp. 42-43 Nisson, J.D. Ned, JLC, in the R Value Fairy Tale )"


To better understand these concepts one needs to refer to the basics of "thermal dynamics and insulating" I am providing a link which should help understand how heat behaves and how insulations perform and fall short.

see: THERMAL TUTORIAL

You may wish to consider liquid ceramic insulation on your inside surfaces of your outer walls and ceilings. No need to open wall cavities or attic space. This insulation is the most effective in stopping heat flow whereas the other insulations (which are deteriorating) only slows heat flow.

see the Denver Energy Report: see this Denver Energy Report:
http://www.eaglecoatings.net/content...compressed.wmv
 
  #7  
Old 01-19-05, 08:09 AM
rric31
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Floors and Foundation

Here is a section on this website that says I should not insulate the foundation walls IF the floors are already insulated. My floors are already insulated so according to this, I should not insulate the foundation walls?

http://doityourself.com/insulate/diyinsulate.htm

Here is a copy and paste from that section in question:

The homeowner can often insulate basement or crawlspace walls, or floors over unheated areas, using rigid insulation or batt insulation. Sprayed-on insulation products are also available for these locations, but would require a qualified contractor. If you insulate a floor above a crawl space, all ducts and water lines running below the insulation should be insulated as well. Insulate crawl space walls only if the crawl space is dry all year, the floor above is not insulated, all ventilation to the crawl space is blocked, and a vapor retarder (e.g., heavy-weight polyethylene film) is installed on the ground to reduce moisture migration into the crawl space. The Builder's Foundation Handbook published by the US Department of Energy is a complete guide to foundation insulation, including basement, crawl space, and slab insulation.



This is what makes me think I am stuck with what I have. I hope not.

Rich
 
  #8  
Old 01-19-05, 04:34 PM
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Office of Energy Efficiency in Canada

The information below is a link to the Office of Energy Efficiency in Canada (hey who else should know about cold climates and insulation methods) This part discusses a "partially heated crawl space" however this may be referring to those crawl spaces with ducting and water pipes h/c which would provide some heat to this area but not as much if the floor were left uninsulated.
http://www.oee.rncan.gc.ca/keep_heat...tView=N&Text=N


It is possible to insulate between the joists and create an unheated crawl space. However, this can lead to problems of freezing pipes, frozen ground and possible rot at the joist ends. For these reasons, floor insulation is recommended only when combined with foundation-wall insulation to create a partially heated crawl space.

A few points of general importance should be summarized:

The air and vapour barrier must be applied on the warm (top) side of the insulation. If the floor above the crawl space is already covered with an impermeable material (e.g., linoleum or plywood), you already have a vapour barrier where you want it. The solid materials of the floor can serve as the air barrier, but be sure to locate and seal any air leaks. The airtightness at the perimeter joist spaces is critical. This area can be sealed with polyurethane foam.


Batt insulation may be held in place with heavy-duty permeable building paper stapled to the joists, or by chicken wire, sheets of polystyrene bead board or a commercially available insulation-support system.


Place the insulation firmly against the floor above. It should be installed so that it fills the space between the sub-floor and the support system (usually the depth of the joists).


Tape the seams in any heating ducts and insulate all ducts and water pipes in the crawl space. Remember, even insulated water pipes may freeze if the temperature of the crawl space is allowed to fall below freezing.


Make sure that the crawl space is adequately ventilated in the spring. Vents should be installed at a ratio of 1 to 500 (vent area to floor area). Do not ventilate in winter: the vents should be plugged and insulated.


There must be a moisture barrier on the crawl-space floor.


If your basement has both a full basement and a section of crawl space where the floor has been insulated, remember to insulate the wall separating the basement from the crawl space.


If the ground level inside the crawl space is lower than the ground level outside, there is a slight danger that frost heave can damage the walls by pushing them inward. Make every effort to keep water away from the foundation walls slope the ground away from the house and install eavestroughing where necessary.


There is an added safety precaution: if freezing becomes a problem, you may want to install a thermostat attached to a small heater in the crawl space. This unit can turn on and heat the walls when the crawl- space temperature approaches freezing.


I would suggest reading the complete section on insulating the crawl space as it attempts to address different scenarios dependent upon structural details unique to your situation.
 
  #9  
Old 01-20-05, 10:54 AM
rric31
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Thanks for the info. Wolfclan.

According to this, I can insulate both the foundation walls AND floor. My crawlspace is under the full length and width of my house. I have no basement, just a crawlspace. I do have pipes under my house and freezing was a bit of a problem, but I did correct that with some heat tape and pipe insulation.

It is a dry space under the house, with the 6 mil poly in place. Moisture is not a problem. I need to figure out which type of insulation I need to cover the foundation walls.

Rich
 
  #10  
Old 01-21-05, 05:13 AM
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Unconditioned Vented Crawlspace

For vented, unconditioned crawlspaces such as yours, the only place you can insulate is in the ceiling of the crawlspace/floor joists of the main story.

R-25 for Maine is not enough as the ceiling of a crawl space needs to be treated as the attic for the location.

This means you need at least an R-48 or more for your crawlspace ceiling to be efficient and warm.

Depending on the depth of your floor joists, you can achieve an R-48 by using combinations of fiberglass batts and rigid foam insulation.

Since you already have R-25, you can reach R-50 by placing 4 inches of rigid foam by fastening it to the bottom of the existing joists.

Unless you plan to condition the crawlspace and eliminate the vents, placing insulation on the crawlspace walls and floors is useless.
 
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