Basement Insulation
Basement Insulation – Walls
I’ve started insulating the basement walls in our new basement storage room. I’m attaching 1-1/2″ extruded polystyrene foam insulation board by DOW. I used a special Styrofoam adhesive to adhere the foam board to the concrete (you can also use “Great Stuff Pro” foam in a can). The foam board I am using comes with a tongue and grove so installation is pretty easy. Just cut the boards to length, apply some adhesive and press it against the wall.
You’ll notice that I installed the boards horizontally. Since doing this project we’ve been installing them vertically at work and it’s much easier to do! Placing them vertically makes it much easier to keep them from falling down while the adhesive cures.
Seal Insulation Joints
After I installed all of the polystyrene foam insulation I sealed all of the joints with Tyvek tape. Tyvek tape is a really strong tape that will stay adhered to the foam board and it keeps out moisture. Concrete holds a tremendous amount of moisture so creating a moisture barrier is essential.
Frame Basement Walls
Once all the insulation was in place I started framing up 2×4 walls. I’m going to place the walls directly in front of the foam insulation and then insulate the wall cavities with fiberglass insulation. You’ll need to nail the pressure treated plate of the wall to the concrete with a Trigger Tool Kit, 22 Caliber. By doing the combination of insulation materials I can achieve approximately a R values of 16.
After I finish framing and insulating the walls I will i
nstall luan paneling over the framing. I plan to install 2′ deep shelves all around the room for our storage.
Check out my previous post, Finished Basement Step 1 – Insulation where I explain the methods of insulating in detail. Also check out How To Insulate Basement Walls. There is also some really great information at the Building Science Corporation.
Insulated Concrete Floors
For this project we’re not insulating the concrete floors because we have radiant heated slabs. However, if your home doesn’t have radiant heat and you’re looking for information on that topic then we recommend you read How To Insulate A Concrete Floor.
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A additional layer of foam? What if i used R13 faced insulation?I dont think i have enough space for exra foam
@ Pete – The trouble is having a vapor barrier at the concrete surface. There is a TON of moisture that comes from the concrete. If you don’t have room then put another layer of foam between the studs.
there is a lot of water it flooded my house
Todd,
Mike again. Another question.
What is your recommendation for insulating rim joists and the joist area against the outside wall? Do you also recommend XPS (2″) sealed around the edges with Great Stuff? Is there a code issue with unprotected XPS? I have unfaced fiberglass now-that is the way the house was built.
Thanks in advance for your answer. Again, great website and we all appreciate your help for us DIY’s!
@ Mike – I like to use 2″ thick foil faced polyiso foam board. I’m in the process of replacing my fiberglass rim joist insulation with it and I’ll be writing an article on it at some point.
Thanks for the quick response again, Todd. Looking forward to the new article about it. Will the article be located at this site or somewhere else? Please keep us posted where it is. I’ll wait for your article before doing anything.
@ Mike – It will be here. Subscribe to the email feed on the home page and you’ll get each article emailed to you. We’re just waiting to hear from some project sponsors before we begin.
Thanks
Todd,
Mike again.Have you had a chance to complete the rim joist article and if so how can I get to it?
Thanks.
@ Mike – Not yet. It’s quite easy though. I recommend you buy 2″ thick foam, cut it so that it fits between the joists, then use a can of Great Stuff foam to seal around all the edges.
Long story short – I live in a split-level and the downstairs is half-way under ground on the front side and above ground in the back. Due to a previous flood, I have found that I now have black mold under my sheetrock – even though “clean up” was performed. I began by removing 5′ of sheetrock from the ground up. I now have new problems. The walls are concrete block construction. No sealant – furring strips nailed to block (flat side against block) – and sheetrock nailed to furring strips. The strips are 1 X 2′s. NO INSULATION. Also, there is a furring strip laid flat against the floor (concrete) around the perimeter of the room. I am a single Mom and ripping everything out and beginning over again is out of the question. Outside of start over, what is the best way for me to insulate this area? By the way, the furring strips are not 16″ on center. I keep researching various sites – but just have no idea what to do. Well, other than lighting a match ; > I appreciate any suggestions you may have.
@ Tami – Unfortunately I really don’t think there is any other option. First off you need to get all the contaminated materials out of there as soon as possible. You should be very cautious removing it yourself as mold spores can easily get airborne and cause a serious health issue. There are lots of online government resources about proper mold removal. Once the mold is removed the best option is insulating the walls with some sort of foam board or spray foam.
Thank you Todd for your quick response. Yes, I have researched the mold removal and am in that process now. Once I have everything out (sheetrock and mold), would it be sufficient to glue the blue board between the furring strips and then sheetrock on top of that?
@ Tami – I would glue the foam board directly over the furring strips, marking the location of the furring strips, then securing the sheetrock over all that.
Thank you, Todd. Your website is priceless – and so are you!
Todd:
I have poured concrete walls in my basement. I used a combination of UGL Latext Dry-Lock paint and Super Thoroseal to seal out the moisture. I am now planning on gluing foam insulation boards to the painted walls. After that, I plan to build a framed wall leaving a 1-inch space between the insulation and the framed wall. Does this sound OK to you?
@ Dan – Sounds good, just remember to seal the foam well.
We just added more foam between our studs which brings us to a 1 ½ of sheathing. By adding this extra foam we only have 3 inches of space in some spots to put our R13 faced batts. Will it hurt if we stuff the R13 into a space that’s only 3 inches deep?
@ Rob – Fiberglass isn’t very effective when it’s compressed. You’re better off peeling it apart to make it thinner.
Does it matter if the fiber glass touches the foam or do i leave a gap?
Thanks for all your help!!
It can touch so long as you’ve sealed the foam well.
Really like your comments about basement insulation which I’m doing now: Foam board then stud walls and fiberglass.
My question is do you put tape at the bottom of the foam board where it contacts the basement floor? How about the top? I have already done the joints but there is air space at the top and bottom of the foam board. Thanks
Dennis – We typically fill those spaces with spray foam (Great Stuff).
Would Dow Super-Tuff polyisocyanurate foam core be acceptable to use in place of extruded polystyrene? Locally I can get it in 1-3/8 thickness with an R value of 8.3. I was looking for 4×8 sheets of extruded polystyrene but have only found 2×8 sheets. The 4×8 sheets will be a little more difficult to work with but I felt the trade-off was worth fewer joints to tape and seal. The price of the SuperTuff is almost the same as extruded polystyrene.
@ Jim – It’s a great product as well!
Thanks Todd. The front walls of my basement are completely below grade and the ground slopes towards the back of the house and the back walls are completely above ground. You recommend 1-1/2″ XPS with an R 7.5. I was thinking about using 1″ thick Super Tuff (with R 6.5) on the below grade walls and 2″ on the exposed walls. Will this be sufficient for the walls below grade? In addition to the foam there will be a 2×4 stud wall with R13 unfaced fiberglass.
Jim – The big problem is creating a good vapor barrier. 1″ just isn’t sufficient in my opinion.
Thanks again. One thing I forgot to ask earlier is whether there are any advantages to using XPS over Super Tuff. From an R value perspective it seems Super Tuff is the way to go. But you use XPS in all of your articles.
Jim – Polyiso has traditionally been found more often in commercial applications and it is usually more money. However, today it’s starting to show up more and more on residential projects. You can read more about the differences here: http://www.homeconstructionimprovement.com/foam-board-insulation-values/
I say both are good.
Above Dan asked about using “…a combination of UGL Latext Dry-Lock paint and Super Thoroseal to seal out the moisture.” before putting up foam board insulation. Is it worth sealing the concrete like this before installing the foam board? Also you earlier mentioned using polysio in the rim joist area. Is foil-faced polysio acceptable to have there uncovered?
Jim – I’m really not sure sealing the concrete will make much difference if you’re using foam. Not sure what you mean? Do you mean uncovered as if it’s a fire problem? All foam should be protected by some type of fire break like drywall.
I want to add insulation between the ends of the floor joists. In the area between the top of stud wall and the plywood for the flooring on the first floor. My basement has Kraft faced 3-1/2″ fiberglass insulation stuffed in there now. There was a hole in the garage where mice were able to get in the basement and they made nests in most of the fiberglass insulation. I plugged the hole about two years ago and have had no mice since. I want to replace all the fiberglass and thought about doing it with rectangles of foil faced Polyiso cut to fit between the floor joists and pressed up against the rim joist. I was wondering if the foil faced Polysio does not require a fire block like drywall if I use it in this area. You mentioned writing an article about doing this above, but don’t say if you are covering the 2″ thick foil faced polyiso foam board:
Mike says:
January 29, 2010 at 2:15 am
Todd,
Mike again. Another question.
What is your recommendation for insulating rim joists and the joist area against the outside wall? Do you also recommend XPS (2″) sealed around the edges with Great Stuff? Is there a code issue with unprotected XPS? I have unfaced fiberglass now-that is the way the house was built.
Thanks in advance for your answer. Again, great website and we all appreciate your help for us DIY’s!
Reply to this comment »
Todd says:
January 29, 2010 at 6:20 am
@ Mike – I like to use 2″ thick foil faced polyiso foam board. I’m in the process of replacing my fiberglass rim joist insulation with it and I’ll be writing an article on it at some point.
Jim – I haven’t written that article yet as I haven’t finished that project yet. I will at some point drywall my ceiling so the foam will be “covered”.
Thanks again. I was wondering because in another article on basement ceilings you seemed like you were going with a drop ceiling.
Also, I have two hairling cracks in the poured concrete walls. When we get a good rain a little moisture seeps in. On the one crack the concrete just gets a little darker due to the moisture. On the other a little water will run down the wall. Never more than just a drip here and there. Is polyurethane injection the best way to fix these? From what I read they seem like shrinkage cracks as they are close to the center of the wall and I can see them on both the inside and outside. My house was built in 1987.
Jim – the best way to fix cracks is with pressure injected epoxy. You could try the other but I’m not sure how effective it will be.
I have a basement that used to be prone to water. I just spent a lot of money with basement systems to put an interior french drain. The lip extends out of the floor-wall joint to catch any additional water coming down from the walls. The back wall is full height concrete, the front wall is half-height that extends a few inches out of the ground. The front-wall has standard framing, windows and batt insulation above the concrete.
How should I finish the basement? I was thinking of building interior walls 4 inches off the exterior concrete walls so they can “breath” and to allow me to see behind the walls.
I want to use metal studs with mold resistant building products. What do you recommend?
Mike – For starters I’m glad to hear you’ve addressed the water problem. Was all the work limited to the inside of the basement or did you make changes outside the house as well? I ask this because it’s important to know whether you’ve stopped water from coming in the basement or merely helped direct it into a drain. Do you still get signs of water? If you still have water I would be quite cautious about finishing the basement due to the extreme moisture that you will continue to have even if there is no standing water.
Having said that I would stick to ONLY foam based insulation products and preferably closed-cell foam. I would attach foam to the basement walls and seal the joints well. Then your idea of framing with metal studs out 4″ from that sounds like a good option. I would recommend you install the metal stud walls on top of a piece of composite decking to get the metal up off the concrete floor.
We did do some work outside with grading and extended downspouts. However, the water table is high here so water will always find my sump pits eventually. With a humidifier running in the summer I have no problem keeping the humidity level below 50%.
I would love to find an inorganic wall panel attached to closed-cell insulation that I could remove as necessary. However, they don’t appear available for DIYers. If I decided to just use closed-cell between the metal studs how would I secure it. Thanks for all the great advice!
Mike – You can secure it with spray foam from a can.
Todd,
Mike again – another question.
I have a bathroom in the basement (located against the outside wall). Is there anything special to insulating a bathroom? By this, I mean do I use unfaced insulation in the stud cavities with a poly moisture barrier all around the bathroom or just go with the standard kraft paper insulation in the stud cavities? The basement is conditioned and I plan to insulated the entire bathroom for heat and sound.
Thanks again in advance for your advise. Also, great to see your rim joist article in my email! Do you use glue to glue the poly to the rim joist the same as XPS against basement walls? I don’t remember reading what you recommended to glue the material to the joist.
Mike – Sounds like your bathroom has one wall to the exterior (concrete or framed?) and three interior walls. The interior walls you can use either method. The exterior wall should be foam if it’s against the concrete.
Rim Joist – I actually don’t glue it to the rim joist, the Great Stuff spray foam holds it all in place nicely.
Todd,
I live in southern NH and plan to glue 1 7/8″ foil faced polyiso(R-12.2) to my poured concrete foundation, leave a 1/2″ gap and build a 2×3 wall in front of that. I find, however, when I put a straight edge to the wall that many sections bow slightly in the center leaving gaps where the seems are. Are these gaps going to be a problem? Polyiso doesn’t bend, so they’ll be slight gaps behind the insulation.
Bob – I suggest you fill the voids with spray foam like Great Stuff.
Todd,
Unfortunately, my basement framing went up before I read this and one of your other posts. So, I’d love suggestions on how to make the best of the situation. There is 3/8 foam insulation on the foundation walls (not enough space to add a whole lot more) over dry-lock. The house is about 2 years old, so the foundation prep is good (water-proofed and insulated outside, foundation drain, slab prep), and the soil drains incredibly well (sandy) and allows little hydrostatic pressure. We’ve never had an ounce of water, even as others around have flooded.
Again, based on where I’m at in the project, what would you suggest? I was planning on adding batt insulation before sheet rocking, but your thoughts are appreciated. Oh, and off-topic, any thoughts on QuietRock?
Thanks so much.
-Kurt-
Kurt – At this point I think I’d install 1-1/2 inch or 2 inch foam between stud bays and be done with it. If you do it this way be sure to seal the edges with spray foam from a can. Good luck.
Todd,
I have read several of your articles’ They are very helpful and I am about to start my basement project. I have a couple of questions I was wondering if you can help me with.
What type of adhesive do you attached the foam board with? and do you have to do anything special to hold it in place while it cures?
I looked into PL300 Foam Board Blue Construction Adhesive at Lowes, but it says
apply it to the foam board
Press foam board against wall
Remove and let it sit for 2-3 minutes
Press foam board against wall again and mechanicaly fasten to wall until the adhesive cures
I hope there is a better product that you are using that I do not have to mechanicaly fasten to the wall while is cures. If this is the only way, how do you hold it against the wall until it cures? (I do not like the idea of shooting more holes into the basement wall to hold the foam in place)
Thanks for your help.
Tom – That is how we used to do it. Now we use http://building.dow.com/na/en/products/sealants/gspwallfloor.htm which works very well and fast! Give that stuff a shot….you’ll be glad you did.
If you can’t find it at your lumber store you can buy it here
Wow, thanks for your help, that will make it a lot easier.
By the way is there a difference between the Dow extruded polystyrene (blue board) and the Owens corning (F150). For some reason the Pink stuff is alot cheaper in the stores by me.
Tom – No real difference between the big blue and the pink panther. Just be sure it’s also a closed cell polystyrene.
I plan to follow your procedures on insulating my masonry walled basement. I will be using DOW Super Tuff polysio foam board adhered to the wall, taping joints etc. I will then build conventional 2×4 walls and insulate with fiberglass and cover with wallboard. Two questions. Which side of the polysio should be adhered to the wall blue face or bright face? Also should I use faced or non faced fiberglass for the finish?
Jack – put the blue side towards the concrete. The other side works well as a radiant barrier. Depending on the thickness of the DOW board you may not need either…..or you may only need unfaced.
Thanks Todd, I already have a few pieces up with the blue face toward the air space. Since I will definately have room for and plan to install fiberglass in the 2×4 cavities and then 1/2″ wallboard do you think it is worth the trouble and expense to tear out the DOW and install it as you recommend? I was following DOWs instructions on their web site and they did not specify which side to adhere to the wall. I was reading about radiant barriers and thought I was probably doing it incorrectly.
Jack – It won’t really matter much. Typically you try to keep in warmth (in cold climates that is) so the radiant barrier will slightly improve keeping in warmth. No big deal.
Great article! Super helpful. My question is as follows. I live in Pittsburgh and will soon start a basement remodel (unfinished basement). My problem is that my basement (like many Pittsburgh basements) has Sandstone walls that are highly wavy, bumpy, etc…
I don’t think pressing them against the walls as shown above is an option as there is no flat part. What would you suggest? Finding a straight line outside the most protruding point and start from there? Would the cavities created in the wall void all benefits?
All answers and help are greatly appreciated!
Thanks
Dave
Dave – Voids behind are NOT a problem. The key is to seal all the joints. So, if you can get the adhesive to stick, and then tape and foam joints, holes, etc really well it will work just fine. Good luck.
Much appreciated. I’ll keep you posted.
Do you see any problems using Owens Corning Pink Foamular 150 XPS? Owens Corning offers 150 and 250 with the only difference I see is the crush resistance. The 150 has 15 psi crush resistance while the 250 has 25 psi. The DOW Styrofoam brand has 25 psi resistance. The Foamular 150 costs substantially less than the DOW or 250. I wouldn’t think going with the 150 would cause any problems. The 150 is more easily damaged but once installed it shouldn’t make any difference. As a comparison I was quoted $18.85 for a 4′ x 8′ sheet of 1-1/2″ thick foamular 150 vs $26.36 for the same sheet in DOW blue board. Does this sound like a reasonable quote? Thanks.
Jim – What is the difference in R value? The 15 psi vs 25 psi may not be different in R value but it may be different in how well it acts as a vapor barrier. I’d be curious if they have any vapor transmission values published.
On a document I looked at on the Owens Corning web site titled:
“ASTM C578, Types and Physical Properties for Foamular® Extruded Polystyrene”
They list the “Water vapor permeance of 1.00-in. (25.4-mm) thickness, max, perm (ng/Pa·s·m2)” as 1.5 for the 150 and 1.1 for the 250.
But if you go to the data sheets for the individual products (Foamular 150 and 250) the “Water Vapor Permeance (perm max)7 ASTM E 96″ is given as 1.1 for both 150 and 250. I’m not sure of the 1.5 on the ASTM document is a typo or not. I just sent a message to Owens Corning on their “Contact Us” page. I’ll let you know where the error is if they reply.
On the ASTM document the value given for Foamular 400, 600 and 1000 are all 1.1. Given this I’m inclined to believe the 1.5 is an error since the permeance doesn’t change with density for the 250 through 1000 Foamular products. Why would it change with the 150?
From the ASTM document they also give:
The “Density, min, lb/ft3 (kg/m3)” for 150 is 1.3 and for the 250 is 1.55.
The “Water absorption by total immersion, max, volume” is the same for both at 0.3. In fact, it’s the same for all products from 150 through 1000.
I hope I was able to convey this in words that makes sense this late at night. Is the “Water vapor permeance” what you were asking about when you asked about vapor transmission values?
I forgot to add that the R value for the Foamular 150 and 250 are the same at 5 per inch of thickness.
Jim – Looks like you should be good then!
So, are you saying as long as the water vapor permeance is the same the 150 is as good as the 250 in terms of acting as a vapor barrier?
Jim – Yeah…that was my only concern. If you were using it for insulating a floor then you’d want the higher compressive strength. Since you’re using it for walls it’s a non issue.
i made my own interior water drain system and have a 1\2 to 1″ gap around the floor to the wall so would i just sit the xps right on top of the gap.also the great stuff is that the expanding foam your talking about. thanks
charles – Yes and yes. Good luck.
I’m building a cabin in the woods and want to insulate the floor prior to putting down the sub-floor. My cabin sits on piers, the lowest height from the ground id 14″ and highest is 32″. I have 12″ beams and 10″ joist for a total of 21″ above the piers. I have an oppertunity buy some Polyiso board at a very good price. do you see any issue with moisture ??? or should I go with blueboard?
addtionally, I plan on spraying insulation to have a complete seal within a year or two.
Thanks,
Karl
Karl – Polyiso will perform well in that situation. We often times use foil faced polyiso on the bottom of elevated walk ways, building cantilevers, etc. Just be sure to seal the seems well.
Hi Guys,
I’m going to start a basement project. I have block walls. I’m thinking about using 1 1/2″ foam board and then put either metal or wood stud walls in front of that. Do you need to put insulation in the wall as well or only if you want a higher R-factor? Also do you put any sealant on the bottom where the foam will make contact with the floor? Thanks for your help. Dave
Dave – Additional insulation depends on the energy code where you live and what R factor you need. I prefer leaving the bottom loose so that water can drain if you get any behind the foam. Some folks choose to seal it and that’s ok unless you know that water gets back there.
Thanks Todd. Would the extra insulation be unfaced or would more foam be better. Also, when putting insulation on the basement ceiling would you just put unfaced fiberglass insulation? Thanks, Dave.
Dave – You can do either. If you can afford the foam then use it, otherwise you can use fiberglass. Just be VERY sure to seal all the joints in the foam very well.
Unfaced in the ceiling is fine.
Todd – A few people mentioned putting up foam board and leaving a gap between the foam board and the metal stud wall. Is this needed? And would it be any different with wood? Plus, have you ever used 2×3 metal studs? Space saver but is it as strong? Thanks, Dave
Dave – The gap is more important if you’re installing fiberglass in my opinion. If you’re not then I’d frame up tight against the foam. 2×3 studs could work but I’d be sure to get a heavier gauge if it’s available.
Thanks Todd, If I would use foam between the studs, would you glue it and try to stager the seams? And would you use the thin pink sill foam under your wall? Where the metal or wood make contact with the concrete floor? Thanks again for all your help.
Dave
Dave – You really want to get a good layer behind the framing and tape the seams. Once that layer is installed I’d cut pieces to fit between the studs, another 3/4″ to 1″ thick. Use spray foam from a can (Great Stuff or Great Stuff Pro) and seal the foam to the studs.
Todd, I am finishing half of a walkout basement in Alaska where about half of the walls are cement and the other half are 2X6 stud walls being the outside of the house. I just poured a concrete floor where there was sand and rock for the last 7 years. When I moved in the walls had fiberglass insulation hanging in strips and after pouring the floor I framed the walls with 2X6 studs and put the fiberglass strips in between the studs. I now see I should have put some kind of foam board behind the studs, but it is too late for that. Can I pull out the fiberglass insulation, cut 16″ strips of the foam board and add it against the cement walls, put the fiberglass back in, then put a plastic sheet over the whole thing and be good? I plan to put log slabs on these interior walls to make it look like the interior of a log cabin over that.
George
George – You can do that but it’s not likely to stop moisture problems. Basements are very difficult because moisture wants to travel in two directions depending on the time of year. In the winter warm moist air will move towards the cold walls, him them and condensate. In the summer the cool damp air along the concrete will want to move into the finished room, hit plastic and possibly condensate.
I say all this because the foam board serves two purposes, insulation and vapor barrier. By cutting it in strips and installing it between studs you end up with a broken barrier and broken thermal break. Hard to say what will result but it’s a good bet moisture will get through it.
Todd,
Ouch, thanks for the quick and candid response. would I be better off not putting the plastic on the inside then and possibly allowing the insulation to have access to the warm air from the room?
George
George – May sound like a lot of work but could you simply move the new walls? Many times walls are pretty easy to “cut loose”, cut the nails/bolts in the bottom plate, cut the nails up through the top, then move it out, install foam, put the wall back?
Short of that I’d stay with JUST foam and take your chances, seal it well.
OK, thanks very much Todd. We used a sledge hammer to get two of the walls to fit under the floor beams, so it is not coming out short of sawing it apart. I’ll “seal it well.” Once I put the foam in between the studs is there a compound you would recommend to seal up the cracks between the foam and the studs in order to get the good seal? Do you recommend glueing the foam to the concrete?
George
George – We love using Great Stuff Pro. It seals, adheres and works beautifully. Best of luck.
Have a quick question…. we are insulating our basement walls with foam sheet insulation. I think we are going to use the technique pictured above and tape the seems before we apply the studding. My question is, the walls were previously drywalled over paneling. We have stripped everything off and the studs were just cheap 1/2 boards that were mildewed. We pulled those off two. We have bleached down the walls and am wondering if we should paint on a layer of water sealant before we put on the foam insulation? Thanks much..
Sarah – It’s really not 100% necessary. If you install at least 1-1/2″ thickness of foam it will retard water vapor from coming through.
Todd, I love the site and your wiliness to answer our questions. Much much appreciated.
I am in the process of redoing my basement and had the pleasure of finding furring strips nailed into the walls. I really don’t want to start over so I think board is the way to go. My question is really two parts. First, should I add 1 1/2 inch board in-between the furring strips, or do I cover them up completely and start with a full seal? What about putting 1 1/2 in-between then another inch or so over the entire area? Never read about stacking the boards and if that is actually practical. Looking to get a good vapor barrier, good R-value, yet working around the furring strips as is. Much appreciated!
David – Thanks for stopping by and thanks for the nice words.
I would install a layer right over the furring strips. At a minimum I’d use 1-1/2 but preferably 2 inches. If you use 2 inch long screws with large fender washers that should do the trick. I’d be sure to use galvanized or stainless steel. Then when you’re finished I’d seal over those with tape as well. Then you can install drywall directly over the foam.
Good luck.
That sounds like a plan, just to follow up with few more questions. How would you handle the electrical – do they makes boxes that will come out 2 1/2 (foam and drywall)? and would I great stuff the tops where the gaps would be? Lastly how far off the floor would I go? Going to add a sub floor if that makes a difference.
David – You’ll have to get creative on the electrical. You might be able to find extension boxes that deep but I’m really not sure. I’d speak with an electrician for ideas that would meet code.
I’d cut strips for the top and foam them in place.
I’d drop the foam down to the floor.
Thanks Todd!! Now I just need to pick a product to use.
Super Tuff-R looks good, but I see you did not pick that product in the above pictures – any reason why? Any favorite? Tuff-R is a poly versus a XPS is what I gather from your article and research, but does it matter? Has a better R value…
At the big box stores today and the see adjustable electircal boxes – amazing what they have now a days.
Super Tuff-R is a great product as well. Any of those will work just fine.
just read the comments again, I see you like both.
As the others have said before, thank you for sharing your experience. I noticed the xps used to fill cavities between the floor joists is faced. Couldn’t un-faced be used as well if the lower walls and ceiling will be finished with gypsum board? Also, is insulating this area necessary with a continuous rim board (I no longer recall the thickness) and a brick structure?
Larry – Faced vs unfaced for xps depends on a couple things. First, foil faced works very good as a radiant barrier as well as insulating. Also, foil faced has a lower flame spread rating which is nice when it’s left exposed. So, you’re correct, in an application behind drywall the foil faced may be overkill.
As far as the rim board, this is an area that lots of folks don’t insulate and they pay the price. Insulating the rim board is one of the most effective solutions for cold floors. I wouldn’t skip it EVER!
Good luck.
Thank you and I plan heed the advice of experience.
We are going to close these comments because they have gotten so long. We would like everyone to move on over to the forums section and post their questions there.
http://www.homeconstructionimprovement.com/forum/insulation/basement-insulation/
Thanks in advance!