I read Larry Janesky’s article about Sealing a Crawlspace with great interest. I have a very similar project that I have been wanting to do something about for some time. Larry’s article may motivate me to complete it. Following a description of my project I have indicated my questions and concerns.
1. My crawlspace is approximately 20 x 15 x 3. The space is under a one room addition (my bedroom) to my house and is accessed through a former basement window. As far as I can tell, there are no vents in the crawlspace. The outside roof of the bedroom is a flat and has a sealed rubber surface.
The foundation wall is concrete block. Inside of the crawlspace, the foundation walls are covered with approximately 4 inches thickness of styrofoam board. The styrofoam extends vertically from the dirt floor approximately 3 to 4 feet to the base of the overlying joists.
I realize that Larry describes in his article to fasten and seal the poly liner directly to the foundation wall, below the floor joists. My question is this: Should I remove any of the styrofoam board to get to the foundation wall? It seems the obvious thing to do, but, I hesitate to remove the styrofoam board because the room above the crawlspace is cold during winter (and I live in Wisconsin) and I have the impression the styrofoam board must have some much needed insulating properties.
2. The cieling of the crawlspace (between the joists) is insulated with fiberglass insulation that has a black paper-lile backing (in my opinion, the area is poorly insulated because I can see gaps between the insulation and joists, some pieces are falling away from the joists, and the room is cold during winter).
I don’t really want to remove the existing insulation and replace it with new insulation because it would be messy, labor intensive and expensive to replace. I would, however like to insulate it better than it is right now. I have a few ideas, but my question is this: What are my options for insulating this crawl space better to keep the overlying room warmer? I estimate the age of this added room to be circa early 1970s, and I dont know how well the walls are insulated.
Two of my ideas include installing a poly barrier to the joists using staples, and installing an insulation blanket to the joists. Is either of these a good idea?
I have enclosed pictures of my project area.
Thank you.
Jim
Replies
With four inches of foam on the wall perimeter, you shouldn't need more insulation there. It is probably in the walls or ceiling that you are loosing heat to make th room cold. The underfloor insulation is sloppy but you realy shouldn't need that much there, IMO.
The floor - crawl - is it a mudslab or dirt? It looks very smooth for jusr a dirt floor. If there is something down already and no signs of water, then you need no vapour bar on the floor as in that article. If it is a dirt floor, maybe you do but you don't need it up the walls because the existing foam is already doing the job there. You could just tape the edges of the plastic to the foam wall board.
Another option that I would consider for here is to buy some Astro-foil or Reflectix. This is similar to the bubbles in plastic for wrapping and shipping items but it is a double bubble layer and is coated with a foild surface. You can staple it up to the bottoms of the joists, leaving all else as is. Seal at edges with duct tape. I will combine the functions of additional insulation, vapor bar, and a fun afternoon all in one activity.
Excellence is its own reward!
Piffin:
The floor of my crawl space is dirt, but there is cardboard covering most of the dirt surface. The cardboard has been there since I bought the house 4 years ago. I have not ventured into the crawl space since I move in, but I have never noticed the cardboard to be visually wet.
I like your idea about placing the barrier on the floor and leaving the styrofoam in place.
Thanks.
Jim
If you have cardboard laying on a dirt floor for over 4 years and it is not mush then you do have a very dry space.