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  • Insulating Damp basement

    Had a friend ask for advice on adding insulation to an older home (1930's). Specifically mentioned the basement ceiling (unfinished). Basement has concrete floor and poured walls that get pretty wet when rains are very heavy but dry out OK. No signs of mold on the framing of the floor above. My question is, is she asking for trouble insulating the floor. The basement is essentially unheated other than what radiates off the furnace (forced air gas) and is only used for storage and laundry and mechanical. Could the floor (basement ceiling) be insulated with unfaced insulation to improve comfort above (all hardwood) or is this begging for trouble. I am going to go look at the home and see how the yard is pitched and how the downspouts are run, etc. but I suspect after 70 years that any french drains have failed or it has none. Due to the price of homes in the area (low) she is not interested in spending a large sum to have the basement trenched and the moisture problems properly repaired as she would be priced out of the neighborhood when all is said and done. Probably an affordability question as well. I know there is no easy solution, but any advice would be appreciated. She is a young single female who people might take advantage of so she is begging for advice. Thanks in advance.

  • #2
    Re: Insulating Damp basement

    wait for the concrete to dry out a bit and paint the whole thing with drylock or something similar, it should help with the moisture. It might also help to add in an exhaust fan of somekind to turn on when it does get damp. Also, just because their is no sign of mold doesn't mean it isn't there. Anything you do to help keep the area dry is a bonus. Once the bulk of the moisture problem is alleviated, then I doubt insulating will cause any troubles.
    No, it's not rocket science, it's plumbing and unlike rocket science it requires a license.

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    • #3
      Re: Insulating Damp basement

      A dehumidifier with an auto pump out feature might work better than a fan. They can be set to cycle on/off at preset humidity levels and there is no bucket to empty.
      "It's a table saw, do you know where your fingers are?" Bob D. 2006

      https://www.youtube.com/user/PowerToolInstitute

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      • #4
        Re: Insulating Damp basement

        I am going to suggest a dehumidifier. I guess the biggest issue is that she has described it to me as water running across the floor after several days of heavy rain! She has about 1/4 of the basement floor covered with scavenged pallets that she stores stuff on! I really need to do an exterior evaluation to see if runoff needs help or even if there is a bad storm drain somewhere as it is a small corner lot and the side street runs about 8 feet from the house. If there were a clogged or broken storm drain on that side street that might explain some of the issues. The basement walls and floor have been painted at some point in the homes past. We have had a dry year here so I have no opportunity to observe.

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        • #5
          Re: Insulating Damp basement

          Well water running across the floor is not something that a dehumidifier will not handle on its own. That's gonna require some perimeter drainage, or re-evaluating landscaping adjacent to the house, and/or waterproofing the basement walls as previously talked about.

          I wonder what treatment the exterior of the basement walls received? They should have been waterproofed with something such as a sheet membrane product or drainage mat, and perf pipe with crushed stone and proper backfill and compaction.
          "It's a table saw, do you know where your fingers are?" Bob D. 2006

          https://www.youtube.com/user/PowerToolInstitute

          Comment


          • #6
            Re: Insulating Damp basement

            With the house being built in the thirties (Great Depression!) there is no telling what was done as far as exterior on the foundation. The soil around here is usually a very dense clay. I really don't know if typically a french drain is required or not. I am sure one at that age has probably failed. I do know that when I built my deck on my house, the code wanted the posts in 2x2x2 ft of concrete and I had to rent a jackhammer to dig the clay! Anyway, she may have a dry spring under the house or outside the wall that starts running after a good rain, or who knows? I will know more after I find time to get over there and look at it. Thanks to everyone for their responses!

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            • #7
              Re: Insulating Damp basement

              I think the real question here is why she wants to add insulation to the basement ceiling. If she's trying to lower her heating costs, adding fiberglass under her feet is not going to change much. She should be looking at attic/wall insulation and new windows.
              If it's the actual temperature of the floor under her bare feet that she's trying to change, fiberglass won't help much there either.
              The only way to significantly raise the temp of the finished floor would be to add radiant heating on the underside, and that sounds like it wouldn't be an option economically to add a secondary heating system.
              If she has simply watched too many DIY home shows and is convinced that she needs insulation in her floor, unfaced fiberglass bats would be fine. As long as the basement never gets so humid that water begins to condense on the walls and ceiling, the bats will stay dry.

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              • #8
                Re: Insulating Damp basement

                I would look into outside and footer drainage problems. Then I would think hard about a sump (or two) and pump(s). After that I would look into a "Low Temp" good dehumidifier and maybe a furnace condensate pump to pump water from the dehumidifier to a drain or outside through a small hole in the wall where you install copper tubing or such.

                Until that basement stays dry 24/7/365 there's no way to insulate it or want to do so. As others said there may be a serious bio hazard mold & mildew problem that must be addressed.

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                • #9
                  Re: Insulating Damp basement

                  Originally posted by jtroanoke View Post
                  had a friend ask for advice on adding insulation to an older home (1930's). Specifically mentioned the basement ceiling (unfinished). Basement has concrete floor and poured walls that get pretty wet when rains are very heavy but dry out ok. No signs of mold on the framing of the floor above. My question is, is she asking for trouble insulating the floor. The basement is essentially unheated other than what radiates off the furnace (forced air gas) and is only used for storage and laundry and mechanical. Could the floor (basement ceiling) be insulated with unfaced insulation to improve comfort above (all hardwood) or is this begging for trouble. I am going to go look at the home and see how the yard is pitched and how the downspouts are run, etc. But i suspect after 70 years that any french drains have failed or it has none. Due to the price of homes in the area (low) she is not interested in spending a large sum to have the basement trenched and the moisture problems properly repaired as she would be priced out of the neighborhood when all is said and done. Probably an affordability question as well. I know there is no easy solution, but any advice would be appreciated. She is a young single female who people might take advantage of so she is begging for advice. Thanks in advance.
                  i wouldnt insulaye the ffloor.it wont keep the floors that much warmer and besides it will hold the moisture.dehumidifier and maybe think of sprayfoam on the floor??

                  Comment


                  • #10
                    Re: Insulating Damp basement

                    Well I went over to the home and did an evaluation. The basement problems are definitely due to landscaping. She has water pooling at the back door (upstairs) during rain (which is where the water starts) and the ground is pitched toward the house. Her future father in law is a landscape architect so I told her to ask his guidance for a solution. I think fixing the landscape will fix the moisture problem in the basement. I also climbed into the attic to see what was there, and found a previous owner or owners had added insulation upside down with the vapor barrier up and not toward the living space! Underneath it was some dirty white loose insulation (not much). What are the chances of this containing asbestos? I think I am going to take a sample of this and have it checked. If it is not asbestos, I will flip what is there over and then blow some cellulose over it to fill the voids. If it is asbestos, to minimize disturbance, the only idea I have is to just roll another layer of unfaced batts the other direction to the joists to add some insulating value without kicking up the old. Any other ideas, suggestions? I want to cover the exposed paper on the insulation (fire hazard), but do not want to get into a round of asbestos mitigation, as it would cost more than the home is worth (100k). I think the inspector that inspected the house before she bought it should be shot - he never mentioned the improperly installed insulation, and I suspect he never went into the attic. The only access from inside the house is tiny, and I went in thru a cosmetic window in a dormer. If he checked the roof, he checked it from the ground, or he could have gone in the same way I did. Anyway, thoughts, ideas, suggestions?

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                    • #11
                      Re: Insulating Damp basement

                      if the insulation does contain asbestos, you might roll another vapor barrier over the top of it before you add insulation, not neccesarily plastic, but possibly tyvek.
                      No, it's not rocket science, it's plumbing and unlike rocket science it requires a license.

                      Comment


                      • #12
                        Re: Insulating Damp basement

                        If the batts are currently on top of loose fill insulation, I'd just pull the vapor barrier off the batts (should come off real easy).
                        Then add unfaced batts perpendicular to the existing, or blow in some cellulose. If you blow cellulose, make sure to leave an air channel connecting the soffits to the gable space.

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                        • #13
                          Re: Insulating Damp basement

                          Originally posted by MoJourneyman View Post
                          if the insulation does contain asbestos, you might roll another vapor barrier over the top of it before you add insulation, not neccesarily plastic, but possibly tyvek.
                          This will cause moist air from the house to rise into the attic and condense on the vapor barrier, slowly soaking the insulation.
                          In a heated environment, the only place for a vapor barrier is on the back of the finished wall/ceiling.

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                          • #14
                            Re: Insulating Damp basement

                            A damp basement brings all these plagues into your house, and more. The excess moisture can damage tools and furnishings, make prime workshop or rec room space unusable, and even endanger your health.

                            Fortunately, it's easy to handle many of the things that cause damp basements. The two most common causes are condensation inside and poor drainage outside.

                            1. Tape a 24-inch-long piece of aluminum foil to the wall in an area where you think dampness may be accumulating or coming into your basement. Run duct tape around all four sides, sealing the foil against the wall.

                            2.
                            Leave the foil in place for at least 48 hours.

                            3.
                            Remove the foil and see which side is wet.
                            Value Dry Expert

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                            • #15
                              Re: Insulating Damp basement

                              jt, no the inspector shouldn't be shot, not yet anyway. all the contractors on this site have insurance. this is what it's for. when we screw up. take pictures get somebody knowledgeable is field. monday morning would be a good day to do it. get a copy of inspection or the lawyer can get it for you. breid

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