The key to using a foam plate is to choose the right thickness and seal it properly to create an effective vapor barrier. If you're only going to use foam boards, you'll most likely need 2 to 4 inches thick, depending on local energy code requirements. I recommend sealing all joints with Tyvek adhesive tape (or similar). You can also use “Great Stuff” spray foam in a can to seal all your utensils and also along the bottom of the foam board.
One you should also do is to have your gutters cleaned and check first either by you or by hiring a professional gutter cleaning service such as Gutter Cleaning Tacoma WA. In addition, clogged gutters may not properly drain water, which can lead to water damage to your ceiling, interior walls, and basement. This means that this could also damage the installation and drywall if not fixed or unclogged.
For more information on using foam boards, I recommend that you read How to insulate basement walls with polystyrene insulation. As for framing tips, I could try to minimize the approach mainly because of the limitations of the allowable thickness in which I can make the wall due to existing piping systems (which I am not going to relocate for cost reasons). The bottom line is that I can't go more than 2 inches in total. An important point I didn't mention is that this specific part of the basement wall is only about 12 feet wide.
Other surrounding walls will be framed in front of the foam. Perhaps an alternative would be to place a treated 2x on the floor? The pipes are more than 80 years old, horizontal steam supply networks of programmed steel 80 and condensate return networks suspended on the basement ceiling. They supply the elevators for the entire house, one of which is close to this wall. The pipes have a diameter of 3 and 2 inches.
They are too expensive to relocate for the partially finished basement project. If they were copper hot water pipes, I would consider moving them, but steam is much more complicated. In addition, the ceiling has a 26% lath plaster finish, so I hope to keep it as much as possible. The return pipe is 2 inches away from the basement wall (hence the maximum thickness of the new wall is 2 inches) and the supply pipe is approximately one foot away.
Inconveniently located to create new insulating walls. I think it's OK to insulate your basement, however, I highly recommend that you use a minimum of 2″ of foam board, followed by fiberglass of sufficient thickness to get the desired R value. Isn't the 60mm polyethylene that I glued around the outer walls to help keep moisture out, reducing the need for 1.5- to 2-inch foam panels?. Also, is it OK to fit the 6-inch bats in the header? Thank you.
Yes, Todd, it definitely makes sense. Thanks for the great contribution, Todd. I live in Ohio, so do you still recommend 2″ insulation now that you know where I live? When I place the insulation between the threading strip, do you think I should tape it or seal it so that it is sealed in the space between the insulating plate and the pickling strip? If it were tape, do you think duct tape would work well? Do you think it's necessary to take this step if I install a plastic vapor barrier and clip it to the flush strips?. I also want your opinion on whether I should leave a gap between the insulating plate and the drywall.
I had also thought about putting insulation on the panels that I currently have there. What shape do you think would be the best way to insulate?. Insulate just above the panels or remove the panels and install them between the flush strips? The flush strips extend horizontally, so I'll have to make a lot of cuts. Will the insulation lose much of its R value if I cut it to place it between the flush strips?.
Putting the foam board over the panels would be the easiest thing to do, but is it so well insulated that way? Which method do you think would better isolate between the 2 options I've listed? Thanks again for all your advice. Very interesting site, thanks for all the information. I haven't seen any mention of using DryLock or any other type of waterproofing on the concrete block. Is it a bad idea? Also, has anyone used or has any knowledge about magnesium or MgO boards instead of gypsum boards?.
There are 2 places that advertise its use, one has an all-in-one system with insulation between 2 pieces of magnetic board and the other site sells only a straight sheet of magnetic board that can be installed like plaster. I have websites if I'm interested, but I don't want to advertise them, I just want ideas. Thank you, Kenny, the aluminum face will serve as a radiant barrier. If you can afford 4″, you'll have a very well-insulated room.
Do you think it is necessary to use DryLock before gluing the foam boards to the basement walls? Will the PL300 adhere to it properly? Joe — I really don't think it's necessary, but again it can't hurt. The PL300 is a good adhesive, but it takes a long time to “set” and makes it difficult for the foam to stay in place. Lately we have used the Great Stuff Pro foam adhesive with very good results. I already have xps against the foundation.
My basement is also partially above the ground, as I mentioned earlier in another question. I put 2-inch xps in these studded areas above the base. I wonder if r10 will be sufficient for the Chicago area. The previous owner installed a French system.
But I don't have sipping water and the pumps haven't had to work in almost 12 years. I have lived here. I have read “Basement Insulation Systems”, a research report, (C), 2002 by Building Sciences Corporation. Their diagrams indicate sheet-coated rigid polyisocyanurate foam (or XPS) to insulate the tire beams and the top of the concrete foundation wall, and then XPS rigid foam on the face of the concrete wall.
The foam that people want, by the way, is (if you're not spraying) _extruded without a face_. Uncoated means there is no membrane on either side, and extruded is DOW blue foam in Lowes or pink owen cornings in Home Depot (there are other brands too). These are the ones to use, don't go more than 2″ (R). I would like to place the 1.5″ or possibly 2″ foam board as needed (Manchester, NH area) with straps over it.
The problem is that I would like to add electrical outlets to the wall, which would require drilling holes in the foam plate so that the boxes fit inside the wall. Is it possible to seal electrical boxes and still have a properly insulated wall? I want to avoid building a traditional wall with studs in the lower half, as it would make the shelf almost 8″ wide, it looks uncomfortable. Thoughts or suggestions? For me, sealants are a good second line of defense, as are the old “belt” and suspenders. It certainly won't hurt and isn't likely to make much of a difference.
If you have the time and money, I tell you to do it. If you decide to use straps, I would use 1×3 boards. This will require fasteners long enough to penetrate the straps, the foam, and then sufficient inlay in the concrete. We have an old basement in the Midwest (192), there are no signs of current humidity problems there, I glued aluminum foil to the floor and walls and there was no condensation in it after two weeks.
Good news that uneven walls don't make a difference. Should I use Lepage PL 300 or excellent material to stick the foam to walls? I'll use cool stuff on the top and bottom and around any pipes, etc. Basically, small blacks are nailed between the beams (the wall enters the bay). The blocks are usually spaced 16 to 24 inches apart in the center.
They must be flush with the bottom of the adjacent beams. I removed the wood paneling and found that the walls were framed with 2×3 uprights that are offset about 1″ from the base. There is a thick paper, similar to a sheet, against the inside of the base. I think it's Reflectix (?) There is no other isolation.
You seem very knowledgeable about all this. I've talked to a lot of builders and no one seems to have a real answer about a dead airspace, but I think it's a conditioned space and with the 3.5 inches of foam there should be no heat to cold transfer. What do you think about it? The real problem is that the 3.5″ foam WILL PREVENT moisture from the house from entering that dead space. Without the moisture on that side, and if the outside has a decent coating, then it really can't be a problem.
I have a new house with a basement with no exit in South Dakota. On the exit side, the walls are floor to ceiling 2 × 6, on the opposite side they are all concrete, the sides go from full height concrete, to 4-foot concrete, then to a full-height wooden structure (2×. All wooden frames have 6-inch insulation and vapor barrier. The wooden structure sits on the concrete and there is a 2-inch concrete ledge in the basement.
I live near Philadelphia, Pennsylvania, and would like to finish my basement. I don't think there are any moisture problems; however, I've read your article and others who claim that just because I don't see them doesn't mean they don't exist. All the contractors I've spoken to don't use foam, and most don't even know what it is. Everyone recommends a space with respect to the wall and then coating the R13 insulation on the wall.
Contrary to their recommendations, I have obtained a permit from my municipality and would like to do so once and immediately. By code, I have to install a fire blocker behind the new wall and under the floor joist, but also vertically every 10 feet. Would you install 2 x 4 pressure-treated units every 10 feet as a first stop and then 2 inches of rigid foam in the middle? I'm really not sure where this idea of 10 feet horizontally comes from. If that is necessary for your location, I would do as you suggest, install PT 2x or 1x as a firewall.
Todd, do you agree that, from what I've described, my basement shouldn't be considered a damp one? Rather, my problem has more to do with controlling the passage of air between 2 ends (conditioned side versus. Outside) through the concrete? My basement is above a floating slab, around it there are some drain holes about 3″ above the slab. I started hanging foam boards about 2 inches from the slab. Is this correct or should the foam be flush with the tile? I have been using 3″ plastic plates to secure each foam board.
I'm wondering whether to use an adhesive instead. But other than that, I have an unusual situation. I had to install a new well (a long story about a septic system that broke down after 5 years). The original well was in the backyard and the pipe reached the house under the shed basement floor.
The new well is in the front yard and the pipe enters the house about 30 inches above the floor and is attached to the wall of poles, inside the room. It extends along the entire length of the wall. Before I found their website, I had planned to install another wall in front of the pipe, but I was worried that I would sweat because of the summer humidity. Now you may have to remove the walls from the uprights a bit to finish them properly.
There's enough play in the pipe to stop that from being a problem. However, I really don't want to completely dismantle all the pole walls. Do you have any suggestions on what I should do with this pipe? It is 1.5 inches in outer diameter. Is the “extra wall” a silly idea? (It's a big basement and losing 3 inches isn't so bad).
And when it comes to sweating, is it as simple as wrapping it with a foam or rubber tube? Eric — It certainly seems like you have a difficult situation. Too humid? I'm not sure, have you ever had standing water? If not, then you can probably make this work. I would recommend that you remove what you have, install 2 inches of XPS foam board, seal it well and then frame it. I would be careful with fiberglass if you have so much humidity.
Add more foam between the studs or choose something like Roxul. Todd, thank you for providing this site. I also visited his Facebook site and “liked” him. I live in the suburbs of Chicago.
I installed 2-inch thick XPS Foamular 150 rigid foam directly on the concrete wall. I glued the seams with Tyvek tape and then added a 2×4 frame. I then used Great Stuff spray foam to seal the stiff foam to the uprights and plates. I plan to insert an uncoated R13 insulation between the uprights.
My question is about drywall. Should I use regular drywall or green moisture-resistant boards? Thanks again. Jonathan: If you can install a short 2-foot piece along the base before the slab, that would be great. Then you can add on top of that later.
That would be the easiest way to deal with tall walls. One guy suggests that I use the same 3″ roxul (R1 AFB) and fix it against the concrete, then my contractor frames the wall against the roxul (don't back up the areas between the frames because I'm doing R15 against the wall, then just drywall and a primer that will act as a vapor barrier). Are there any benefits or harms in using a layered approach to achieve an R-20 score?. I have a 3″ XPS and was thinking of making an additional 1″ layer by staggering the seams and using JointSealr Owen's corning tape on both layers.
My concern is that if the top 1″ layer isn't a water vapor barrier, could it trap water between the 3″ and 1″ layers? The alternative would be to simply make 2 2″ layers (both have permanents low enough to be sufficient as a vapor barrier). With so much insulation, I plan to leave the stem cavity open. For me, the best approach is to insulate the interior with a minimum of 2″ foam board. For the outside, I like to seal the foundations and install a drain plan to help carry water to the perimeter drain.
Where the basement walls are concrete, there is currently no insulation. The outer walls that frame (as the lot tilts down and the walls are above the floor), the 2 × 6 frame has blocks covered with R-19 Kraft paper. The challenge I have is that floating walls and the movement of the slab are required (the code requires a minimum of 1.5″ space to float, up to 3″). Would the DOW Foamular 250 work if I placed it directly against the wall and then sealed it with canned foam and then placed drywall next to it?.
There would be no wadding insulation at all. I've read that the Foamular 250 is closed-cell, so I think it should prevent mold. Would you recommend removing those bottom plates so that the 2″ foam boards are installed on the floor or would it be OK to install them on top of the 2×4 plates? I would install another 2×4 bottom plate in front of that and build it up from there. In addition, I work for a great builder (Lennar) who uses the thermax with aluminum backing in the foundations of walls poured underground without finishing.
They use. I probably don't have that outer insulation and I was planning to use DOW's 2″ dual-layer Thermax plates so I don't have to frame and balance right away. Rigid foam sheets are best for DIYers who insulate basements before framing walls. Rigid foam also works well when concrete or block walls are smooth and flat.
Rigid foam insulation is easy to use. In addition to marking, it can be cut with an ordinary wood saw. One question I had was the scenario where 2″ of rigid insulation with 1×3 straps are used to hold it in place and it gives you something to attach your drywall to. While builders have traditionally used block insulation directly against the concrete base and covered it with drywall, this is risky if foundation walls have not been carefully installed and waterproofed.
The other day, I came home and noticed that the drywall was raised, but there was no insulation on the walls. In winter, water vapor passed through the insulation and condensed against the cold concrete wall, moistening the insulation. From the base plate to the ceiling; and (Build in place) additional elements to channel water that occasionally seeps away from insulated foundation walls. I have a 2-year-old basement in Minnesota with an outer vapor barrier and rigid insulation panels up to the wooden walls that have spray foam and a standard plastic vapor barrier and insulation.
For example, a wall with a wooden frame, insulated with fiberglass blocks and finished with drywall will only work effectively if a vapor barrier has been applied to the outside of the foundation wall. The key is to use foam insulation effectively to separate wet concrete or block from framing and insulation products that promote mold growth. Aerosol foam insulation is a polyurethane foam that is injected into the cavities between the uprights of the basement wall with a hose and a gun. Some of them are based on the entire house as a whole, so if you have good insulation and windows, you might be able to get away with a lower value in the basement.
Insulation can be added to the outside, but the required excavation must be done by a professional and that is often expensive and complicated. . .