With this type of installation, youll be able to remove a section of rigid foam without destroying the foam or making a huge mess. What about the rest? Thanks in advance for you help! How would I add insulation to the finished basement itself? wikiHow, Inc. is the copyright holder of this image under U.S. and international copyright laws. Karl: If I use the rigid foam insulation for the basement and CS stud walls, which type should I use, and I need to use a vapor barrier over it? The cooler surfaces of a crawlspace or What is best fix for sagging, falling fiberglass anything that can simply be rolled or stuffed in between joists without removing all fiberglass? This image is not<\/b> licensed under the Creative Commons license applied to text content and some other images posted to the wikiHow website. You can buy waterproof tape from a hardware or home improvement store. Unlike fiberglass crawl space insulation that can degrade into a pink pile on the crawl space floor, rigid foam insulation cant absorb moisture or be damaged by it, and will never fall out of place. The crawl space is vented and not insulated.
House is heated with hot water and there are no pipes or ducts in the CS. The mold that thrives in a damp crawl space wont just damage wood and other organic materials in the crawl space. Our house is on an island in SE NC and has a vented crawlspace (18 @ 8x16 vents) with a sand floor covered with plastic. I am pretty sure were going to do a little mold remediation down there before buttoning it back up tight, so well definitely take your advice and let the dehumidifier to its thing. above grade, and then its wood studs and sheathing on up. There is no way to add heat to the crawl space via the forced air system as all the ducts originate in the attic (that is where the air handler is located). The rim joist area is sure to be very leaky, so seal and insulate this perimeter zone as described elsewhere in these comments. Make repairs if necessary, and contact a mold abatement specialist if theres widespread mold.
Tim, I have a weird situationpartial basement with crawl space adjoining it. This image may not be used by other entities without the express written consent of wikiHow, Inc.
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\u00a9 2022 wikiHow, Inc. All rights reserved. Chlorine is a powerful whitener and disinfectant, but All suggestions welcome. Youll end up with a classic moldy crawl space one that represents a significant source of moisture for the house above.. Could i throw down some 44s and screw decking boards to them force platform for staorage? There are certain to be energy-wasting leaks in this thermal & air boundary like where plumbing, electrical and ductwork extend up through the first floor. Seal this to the wall insulation. Should the foam against the walls rest on top of the foam placed on the floor? This image is not<\/b> licensed under the Creative Commons license applied to text content and some other images posted to the wikiHow website. Because of the termite issue in the past, I suggest having a termite inspection done again. I think it may be from the heavy rains we had in August (13 in 24 hrs.)
This is not recommended. Cut rigid foam to friction-fit between crawl space joists, then seal along the edges with spray foam.
If its the latter, Im guessing that your contractor will recommend installing a radiant barrier beneath the tubing, to help reflect heat up toward your living space.
I am conditioning the 2 crawl spaces. Good luck. They are proposing fiberglass batts with the paper facing upward toward the subflooring.
What is the distance between the fasteners used to hold the vapor barrier? I have a cottage on piers which had a incorrectly insulated crawl space. Installed against crawl space walls, rigid foam insulation wont degrade or fall out of place. Make sure to close all vents in the CS walls and to make the CS access door as airtight as possible. Only the blue (Dow) or pink (Owens-Corning) rigid foam insulation are fire-rated. Finish up by installing rigid foam insulation against the bottom edges of the joists, taking care to seal all joints between panels. Gregory: 2. Good luck. I share your concerns about moisture & mold. As a follow-up, do you typically fasten the vapor barrier directly to the foam board, to the foundation wall above the foam board, or somewhere else? Thanks again. Once the crawl space is dry, you can stop running the dehumidifier. What are your thoughts about DIY spray foam for the rim joist bays? Spread a water-based mastic or other adhesive approved for use with foam insulation across the area where the first sheet of insulation belongs. It doesnt seem like anyone else does them. About Michael Church Also would you remove the sand floor before adding the vapor barrier to the floor? These vents stay sealed shut until rising flood waters trigger them open, allowing flood waters to flow through the foundation rather than beating against it. Hi Chris, A dehumidifier has been installed in the room where mold was found, and it seems to have taken care of that problem. The fasteners are mainly to hold the panels in place until the adhesive cures. Lastly, the house is in a flood zone but has only experience a few inches of water once in 28 years and that was during Hurricaine Sandy. Masonry foundation walls and wood framing & sheathing can store a great deal of moisture.
This is not recommended. What has been proposed to us is closed-cell insulation in the floot joists above both the basement and the crawlspaces. Does cold basement make such a huge impact on main floor? If you air-seal the crawl space and air-seal the attic/living space pressure boundary, you can short-circuit the stack effect and score good savings during heating season. Thank you. after I encapsulate the crawl space, will it still be ok to have just an interior door closing off the crawl space from the downstaris? Uninsulated crawl spaces can allow moisture and cool air inside, making your floors feel colder and your heating system less efficient. In the meantime, I think that it would be smart to contact an experienced HVAC contractor and see if he can supply combustion air to your furnace by installing a PVC pipe that extends through the rim joist. John:
Just 2 or three fasteners per panel should be sufficient. I could have contractor #1 install the vapor barrier and have contractor #2 do the insulation but I really wanted to use 1 contractor. We have enough to use 3 layers, providing R-18 or so. Air-seal and insulate the rim joist. Heat pump has been installed, with all the ductwork in the attic. CRAWL SPACE? The Essential Guide to Crawl Space Encapsulation is a free guide to help you in choosing the best crawl space encapsulation contractor and methods. Well address this issue in more detail in a future blog, but for now heres the short answer. Make sure to seal these openings completely. 2-in.-thick or 4-in.-thick rigid foam insulation for crawl space walls: Id opt for the thicker insulation if I were planning to stay in the house for more than two years. Screened vents 36 X 3 at gable ends, plus 24 X 32 door at middle of front. Resolve these issues and youll be on your way. The furnace ducts and water pipes run through the crawlspace below the floor joists. Sewer pipes go through the slab and connect in the crawlspace to a common pipe which travels under all the units to a common exit. Fernando: The house construction youre describing is very unconventional masonry walls and even concrete floors. Tim, The crawl space is vented to the outside without mechanical assists.
Since the house is in a flood zone you arent recommending spraying closed cell foam insulation between the joists but as an alternative screw rigid foam insulation to the bottom of the joists taping at the seams. What is the Best Way to Insulate My Crawl Space, Essential Guide to Crawl Space Encapsulation, Watch this video to discover 3 critical areas you should air seal in your crawl space, https://diy.crawlspaceninja.com/wall-insulation/, https://diy.crawlspaceninja.com/foam-board-insulation/, https://diy.crawlspaceninja.com/contact-us/, Do I Need Weep Holes for Crawl Space Waterproofing, 7 Soil Contaminants That Can Show Up in Crawl Spaces. I recently bought a beach house in northwest Washington state. His vapor barrier was a standard vapor barrier 6mil thick with seams to be overlapped by 12 inches but not taped. Thank you.
An associated issue: how you will you empty the dehumidifier if its installed in the crawl space? Learn aboutCrawl Space Ninja Franchiseopportunities.
Hold an end of the plastic sheeting against the far end of the first crawl space wall.
Many foam boards are not designed to touch the ground and are not approved for crawl spaces. Insulating the crawl space walls will help reduce your heating bill, but in your case the air sealing may be even more important. Since adhesives can fail over time, we recommend screws or nails. Address your water issues first, then address the encapsulation. Hi Roy,
Are you looking to air seal or create a thermal break or both? Dirt bottom with the septic pipes exiting through the same space.
We are experiencing real cold temperatures in the main level only in the portion that sits on the finished basement.
2. Today a basement repair company said that I needed to put the plastic on the sides of the crawl space and then to seal it off from the basement. Im trying not to spend $12,000. Very low 18-24 inches below the joists. If I encapsulate the crawl spaces, what do I do about the fact that they open up directly to the uninsulated basement? Its mainly for keeping the house cooler. Its MUCH cheaper to do this now than as a retrofit. Multiply the results for each wall to determine the square footage. I have a question, hopeful to get some feed back. Unfortunately, leaving the crawl space as it is will lead to problems with mold and wood rot, not to mention poor energy performance. Youll also need a dehumidifier running in the encapsulated crawl space to dry out the air and the moisture-saturated wood and create a dry environment thats hostile to mold. The 3rd contractor utilizes a vapor barrier called Silver Glo which would have taped seams and was around 9mil thick.
of closed-cell spray foam. Thank you for your response. The dimpled plastic sheet material mentioned (and shown) in the blog works well. Thanks Timso the plan is..3 rigid foam sheeting between the floor joists..1 foil backed rigid foam for the foundation walls.and 6 mil plastic sheeting on the floor.
Good luck. This image may not be used by other entities without the express written consent of wikiHow, Inc.
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\u00a9 2022 wikiHow, Inc. All rights reserved. Install rigid foam insulation against crawl space walls, so that were insulating the crawl space instead of the first floor. Rigid foam is inert and permanent; it wont degrade, lose R-value, compress or displace like fibrous insulation can. Installing the rigid insulation and air-sealing involve techniques that DIYers can accomplish. Yes, youll need to cover the block supports with rigid foam to get the full benefit of perimeter insulation.
I really appreciate it. Last year, I had a dehumidifier installed in the crawl space to combat high moisture. Create a continuous air & moisture barrier on the floor by taping the poly floor cover to the rigid foam wall insulation. It would also be good to know whether you have masonry or wood-frame walls, and what kind of heating system you have. Similar to mudding drywall in order to prevent moisture from escaping from between the panels. I really dont want to do concrete on the floor due to time, know how and money restraints. Lower drains wont capture water that seeps through foundation walls. (My understanding is that if the crawl space was opened up to a condition space, i.e the removed the basement window to open it up to the inside there really was no need for vents.) Can I obtain an R-19 with 2-3 of rigid foam and 12 air space? Place a poly moisture barrier over the floor, lap the poly onto the foam wall insulation, and tape the joints with compatible tape. But I was more than surprised to hear that they did not plan on putting any insulation along the wall. My question is can I simply insulate the walls with 2 inch foam board all around the outside walls and not do the Cement Ceiling? Craig. Then spray foam closed cell over walls and granite ground to create encapsulated space. My situation is a combination of many others discussed earlier. Karie Fay earned a Bachelor of Science in psychology with a minor in law from the University of Arkansas at Monticello.
GA 6 inch minimum gap. This way the sub-floor becomes the thermal break to help keep the cold crawl space air from transferring to the living space.
Four open vents, two on each side of the crawlspace. The big caveat here is that if you live in a flood zone, youll be better off installing the foam insulation against the underside of crawl space joists. Make sure to seal all seams between foam boards with compatible tape to maintain the air barrier. No heat, no insulation and no laundry room! If your crawl space isnt properly drained and fixed by professionals, you risk moisture reappearing and reducing the lifespan of your insulation. My problem now is that I am at risk for a frozen pipe in the crawl space because the 2 fin tubes are no longer functioning because I dismantled the base board heating system. there is a regular interior door that accesses a closet that is open to the crawl space. Good advice, Chris. Waterproof & dehumidify the basement first. And caulk the edges of the rigid to the joists, where the rigid fits in between joists at the rim joist. Then, a specially trained and licensed remediation expert will remove the Hi Karl, If you cant use these fasteners, Id go for Tapcon screws with fender washers. One option is to dig a trench around the outside of the foundation and insulate the exterior walls with 2-in.-thick extruded polystyrene. She enjoys "green" or innovative solutions and unusual construction. Just about at ground level. Once you get the CS dry, you shouldnt need to supply it with conditioned air. If the crawl space was damp for a long time before encapsulation began, dry out the space with a dehumidifier to create a mold-hostile environment. After that, you can insulate the crawl space walls so cold air is less likely to come in. ( meaning we are in a beach town) The crawl seems to stay relatively dry unless its a major storm, but we are afraid it it takes on a little water all will be ruined with the encapsulation method. 4. covers for vents The pressure (air) barrier in a vented crawl space is also the floor sheathing, even though its got plenty of holes in it to bring wiring, plumbing and ductwork up through the crawl space. Its adobe and one of the oldest homes out here.
If I remove the window and create an open access point the the crawl space, would you recommend installing some sort of vented door hatch or a sealable one? Couple of questions/clarifications. In a coastal flood zone, crawl space encapsulation takes a back seat to flood protection measures. This also includes gaps between any joists on the ceiling or the subfloor. Maybe 6 of it is above grade. Spray Foam is very expensive in NY and the installer is telling me I have to do 3 inches to have a vapor barrier (is this true?). What should we do? Now one company told me that in order to encapsulate I would need to brick in the lattice frames, another company told me that I would be able to encapsulate without bricking in the lattice openings. of foil-faced polyiso board (youll probably have to buy thinner polyiso board and install a couple of layers.). I also bought one of those $15 foundation vents that open when temps are above 70 degrees and close below 50 degrees. Will our plan (which seems to be required by the building code) work, or are there downsides to it? This is a question that was somewhat asked a few times, but I never saw a direct answer to. We recently sprayed the entire perimeter of the house with an industrial poison after noticing a number of runs from the ground to the sill plate. Above all, dont apply closed-cell foam between the floor joists before drying out the basement, because this can actually trap moisture in your framing and make the mold invasion more severe. Hi Tim, Your description leads me to believe that whoever built the addition used shoddy construction techniques. What do you think of this approach? Once this insulation step is complete, screw 1/2-in.-thick exterior plywood to the bottom edges of the joists to keep critters & insects out.
Always wear safety glasses, a dust mask, and gloves while working with foam insulation to prevent any irritation. As for sealing the vents, its possible to make vent covers from 3/4-in. See the comment above for details on how its done. Hi Tim, thanks for the great website and advice. About sealing & insulating the rim joist: Do this task first, when the rim joist area is most accessible. mold infected portions of your home, or contents, and take them to a Applying an appropriate pesticide to the crawl space is certainly one such strategy. The type of foundation wall insulation you choose depends on the type of wall, budget, and if you will hire a crawl space contractor or do it yourself. Either closed-cell SPF or rigid foam will work to insulate your crawl space walls. Tip: If you plan on storing items in your crawl space, get 12-mil polyethylene sheets so they dont rip or tear when you walk on them. 2) What would be a good material to mount on frame that can be at/under ground, keep critters out, and serve as a backing for an aesthetic finish (faux face brick)? Brick or stone crawl space walls are insulated differently than block or concrete. Both crawl spaces are 3 or 4 feet above the rest of the basement floor with small doors to climb in so they have never had moisture problems at all. Id frame & finish an access door with beefy stop molding that would accept equally beefy weatherstripping for maintaining a good airseal.
Im guessing building a cinder block wall to separate the areas would be the best option. What do you suggest for the rest of the foundation? I would suggest having a spray foam specialist coat your rim joist and crawl space walls with 2 in.
Gerry: Roxul is more expensive, as you probably know. Brick or stone crawl space walls are insulated differently than block or concrete. I dont have much money to spend, so I wont be able to install spay or rigid foam underneath. I like your suggestions and will be doing just that. Having 2-part, closed-cell spray foam applied to the underside of the concrete crawl space ceiling is one option. Claire: You have several options for improving comfort and cutting your heating costs. These are also separate HVAC zones and I am concerned about thermal loss. Hi Tim, I have a house with an addition and its own crawl space and HVAC. Good luck. A few months back my husband and I had several companies give us estimates on encapsulation of our crawlspace. Its difficult to make a helpful recommendation without knowing where your house is located. Your aim is to meet or exceed the minimum recommended level of R-19 for floor insulation in your climate zone. This week a contractor is jacking and leveling the addition and adding proper footings under the piers but my son and I need to address the following issues afterward. But the contractor seems to think that its unsafe and unhealthy to have this nasty crawl space open to the basement.
Might even double them up to get the extra r value if they are ok. Hi Gary,
also have put vapour barrier on floor. Which option you choose will probably depend on price. Please advise. Hot, moist air enters through CS vents and condenses on cooler surfaces.
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\n<\/p><\/div>"}, https://www1.eere.energy.gov/buildings/publications/pdfs/building_america/29238.pdf, https://www.bobvila.com/articles/insulating-crawl-space/, https://todayshomeowner.com/how-to-insulate-a-crawl-space-under-your-home/, https://insulationinstitute.org/about-naima/health-and-safety/, https://todayshomeowner.com/video/how-to-insulate-under-floors-in-a-basement-or-crawlspace/. Now to my question. My pipes never freeze. as moisture is a problem what is your advice to insulate ceiling of CS, floor in bathroom very very cold, oh is open on east end, will be purring cinder block wall up when finishing up bathroom project.
Radon mitigation is already in place. I live in Portland Oregon. Vapor barrier to the floor and walls. Tim I have a complicated problem. First of all, crawl space foundation walls are rarely sufficiently clean and dry. I dont believe termites will be an issue. Pay attention to vents, crawl space access doors and the rim joist.
Instead, youre erecting short walls to get the first floor framing up off the ground. Hi Charles, Install 2 in. If I understand your advice correctlyyou are saying first use a 1 part spray foam Great Stuff (is this specifically called 1 part?) Windows have been replaced with new double panes windows. You can get polyethylene sheets from your local home improvement or hardware store. Floor joists are 40 above CS floor. Good luck. Thanks again! Spray foam just to the top of the masonary and use ridig fowam bord on the joist so you can still gain acces to inspect? 
