We have an old brick Victorian in Chicago. The basement apartment is directly over a 3' crawlspace with just soil below. I want to insulate it and wonder what I should be concerned about if I do. In the loft we needed to put in webbing between the roofing and the padding, do we need to do that in the basement as well. Thanks in advance.
Who told you to do that, and why? If it was for airflow from soffit vents to roof vents then it would be logical. However, that requirement does not exist for the basement. Any well applied insulation should be just fine there. HTH
Joe
I would think that you would want to put a vapor barrier in place when you insulate as well. The vapor barrier typically goes closest to the "hot" side of the insulated space. i.e. down next to the ceiling in an attic or up closest to the floor in your application.
Paul B
We have an old brick Victorian in Chicago. The basement apartment is directly over a 3' crawlspace with just soil below. I want to insulate it and wonder what I should be concerned about if I do. In the loft we needed to put in webbing between the roofing and the padding, do we need to do that in the basement as well. Thanks in advance.
About that "webbing" What exactly is it? Is there insulation right up to the roof deck? What is under the insulation (drywall over a finished room or non-finished attic area)? Is the attic area ventilated?
I am not sure what you want to do with the craw space. Are you thinking of insulating the floor that is over the craw space or insulating and closing off ventilation of the craw space?
What is it that you want to insulate--the crawl space or the floor? In any case, or whether you do any insulating, the first step is to place 4-6 mill plastic over all of the dirt floor of the crawl space. It should run up the wall about a foot and should not go over any wood members (supports in the center) and should be laid loose with overlaps so that any water infiltration (e.g., from a mishap upstairs) can drain into the dirt. The purpose of the plastic is to reduce the loss of moisture from the soil and provide a dry space below the flooring. If the crawl space is tight and you have vents to this space, you may want to simply insulate the crawl space walls, bringing the insulation from the floor down the wall and a foot inward on the plastic. In the winter you would simply close the crawl space vents. This is efficient, uses less insulating material, but is not a good idea if the crawlspace ocassionally floods. Otherwise you should just insulate the floor with insulation between the joists held in place against the bottom of the floor by various methods (see an insulation dealer or contractor).
I know Vics and Chgo, but you say the basement is over he crawlwspace , by 3" .YOU MAKE NO SENCE on your measurements.,
Go have a beer and re- measure
I'd suggest looking at the crawl space discussion in the Building Science Corporation web site. You may be sealing a space with potential moisture problems. TB
OP wrote: "We have an old brick Victorian in Chicago. The basement apartment is directly over a 3' crawlspace with just soil below."
Three foot crawlspace makes sense to me. What kind of beer are YOU drinking?
Bob
Thanks Bob :-)
great explanation George thanks a lot.
the webbing was for the attic. We are insulating the crawlspace. I have my answers thanks to other posters but thanks Joseph for taking an interest.
Harry
Thanks for the advice Paul we are going to do this.
Harry
Hey Joe, no we put the rigid webbing into the cathedral attic for the soffet venting. Thanks for answering the question it will save me alot of time.
Harry
Thanks to everyone for help me out. I will insulate the wall for now and see how that goes. I will also lay down 4mm plastic to act as a moisture barrier. I thank you all again for you help and comments, they are all useful.
Harry
And thanks for coming back and letting us know you read the responses.
You did not say one way or another, but I strongly suggest that you don't reduce ventilation if that is part of your plan.
This thread has been quite helpful for me, too, because I have a dirt crawl space ranging from one foot to 4 feet in depth, and I'd like to get it insulated before winter. Due to dampness I keep it very well ventilated so zero degrees outside equals a zero degree floor. Regarding the following post,
Since there is access only from below the floor (unless I tear up the floor) how do you get the vapor barrier on the top of the insulation? Do they make an insulation such as this that can be stapled in place with the top being a vapor barrier and the bottom tabs not being a vapor barrier? Or is something like plastic put in place first and then the insulation stapled in place afterward? I had a trailer home about 10 years ago and there was no vapor barrier in the floor. There was insulation and then beneath that a breatheable fabric so moisture wouldn't accumulate.
Bob
if you have a lot of dampness I would not put down plastic on the floor as then the moisture would all be trapped under there.
Wayne
Isn't that where you want it trapped?
no you want air circulation to remove it. Slime and other things will just grow under the plastic. he said he had major problems with moisture that would make plastic not the best choice
A vapor barrier for the floor would make more sense if he didn't mention the major problem with moisture. To me never seeing the crawlspace or knowing where he lives etc.. is that it makes more sense to work on moving air in the crawlspace and insulating the underside of the floor. If he did not have much of a problem then Plastic on the floor and insulating the walls would make more sense as it is supposed to work about at well and is much easier to do as well as costing less!
Wayne
One thing seems clear. We all need to be more specific with terms like "Floor" If I understand correctly we (all those responding, including myself) have referred to two different "floors." There is the floor of the room above the crawlspace and there is the surface of the bottom of the crawlspace.
Given that and assuming there is no problem with flowing water, I suggest plastic covering on the dirt/gravel of the crawlspace and a vapor barrier under the floor of the room above. All this assumes that the crawlspace will be ventilated at or above the local standards.
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