Basements, Attics and Crawl Spaces - Insulating my walls (pics)

I am about to start finishing my basement and wanted pointers specific to my insulation needs before starting. I have no experience in this area but have been reading a lot (including insulation posts on this forum).

My basement:
- 4 years old
- walk-out (about 75% of it is below grade)
- I don't think I have a french drain by foundation, but it is tarred on the outside.
- Regularly run dehumidifier, keeping it no higher than 50%
- Since running dehumid, the regular "sweating" into the walls mostly went away
- Since more recently burying the drains, I'm very hard pressed to ever see actual visible moisture on the walls
- Sump pump only seems to run when dumping out from the dehumidifier (so, rarely)
- Recently put 12X12" tinfoil and packing tape patches on my concrete slab and after three weeks there was zero moisture/condensation under them (granted it's been dry lately)

Here are the pics:

The entire basement is done like this:wall1.jpg picture by Skoorb100 - Photobucket (http://s897.photobucket.com/albums/ac177/Skoorb100/?action=view&current=wall1.jpg)
http://s897.photobucket.com/albums/ac177/Skoorb100/?action=view&current=wall1.jpg

I ripped some back from a section that previously had been moist often:
wall2.jpg picture by Skoorb100 - Photobucket (http://s897.photobucket.com/albums/ac177/Skoorb100/?action=view&current=wall2.jpg)
http://s897.photobucket.com/albums/ac177/Skoorb100/?action=view&current=wall2.jpg

Close-up of that corner:
wall3.jpg picture by Skoorb100 - Photobucket (http://s897.photobucket.com/albums/ac177/Skoorb100/?action=view&current=wall3.jpg)
http://s897.photobucket.com/albums/ac177/Skoorb100/?action=view&current=wall3.jpg

A local contractor said my insulation setup is fine. However, even with pretty dry walls, I wonder if when I finish it (notably I'm drywalling the ceiling), the lack of airflow will exacerbate any possible moisture problems. It appears the best approach is to rip all this down, clean/scrub the walls, then drylok them (although I've heard that can wear out over time?), then put down a plastic sheet against the wall, THEN put my insulation stuff back (or put some other batts or something in place...?). I just don't want to waste a lot of time and money if it's huge overkill.

Finally, this crack showed up shortly after moving in but has not moved since. I think it was from water leaking in the garage (since fixed). It's 1/8" thick. Should I stuff it? Unfortunately it goes behind my circuit box and I am not going to move that!
wall4.jpg picture by Skoorb100 - Photobucket (http://s897.photobucket.com/albums/ac177/Skoorb100/?action=view&current=wall4.jpg)
http://s897.photobucket.com/albums/ac177/Skoorb100/?action=view&current=wall4.jpg

I have the occasional crack like this (this was against garage where there was no insulation). I presume I should fill these, although they are small (and haven't grown that I can tell):
wall5.jpg picture by Skoorb100 - Photobucket (http://s897.photobucket.com/albums/ac177/Skoorb100/?action=view&current=wall5.jpg)
http://s897.photobucket.com/albums/ac177/Skoorb100/?action=view&current=wall5.jpg

Thanks so much everyone :)

The crack may not have grown but I would walk around the house outside. Do you see any similar cracks? That would be how the moisture enters & eventually gets trapped.

The crack may not have grown but I would walk around the house outside. Do you see any similar cracks? That would be how the moisture enters & eventually gets trapped.I've looked around the parts that are above ground and filled in a few cracks here and there...most of it is below grade, though, so i can't see them!

That's the problem. The real way to seal them is to dig down to the footing & cover the wall with a membrane. I've done a lot of them as part of a crew. If you don't, you may not have any problems for years but something could develop at a later date.

Normally, people frame walls inside a couple inches away from the block & use R13 insulation. That way if any moisture does enter, it's not trapped.

The drylock is a good idea but it's usefulness is lessened if the outside isn't sealed.

That's the problem. The real way to seal them is to dig down to the footing & cover the wall with a membrane. I've done a lot of them as part of a crew. If you don't, you may not have any problems for years but something could develop at a later date.

Normally, people frame walls inside a couple inches away from the block & use R13 insulation. That way if any moisture does enter, it's not trapped.

The drylock is a good idea but it's usefulness is lessened if the outside isn't sealed.I do think the outside is decently sealed; they did tar the exterior. Some water, either through cracks or above the seal but still below grade (they are close to each other but not perfect) still can get in but really as far as basements go I do think this one is pretty dry.

Yes, from the pics you posted, it looks fairly dry. Keep in mind, that it's rarely the cracks above grade that lets water enter, when you make your final decision on how to proceed.

I have spent some more hours reading about basement insulation. In the past people have used generally for basements batt insulation with a vapor barrier on the warm-in-winter side (like in my pics). Everything I have found by any kind of an official source today says it is wrong due to moisture issues.

So it appears that best practice now is to use Extruded polystyrene (XPS or XEPS) rigid insulation flush against the concrete blocks, sealed up tightly, then put the stud wall up and fill that with _unfaced_ batt. I am seeing multiple sources specifically say to not use a vapor barrier in basements of any kind. Climate does matter, but this is for a colder climate like I'm in.

My questions then are:

1) If I use 2 inch rigid foam (R10), do I need to bother with the additional batt insulation? This indicates I wouldn't save that much doing so: Energy Savers: Basement Insulation (http://www.energysavers.gov/your_home/insulation_airsealing/index.cfm/mytopic=11470). I could do one inch of rigid foam, but then I'd need a lot more batt insulation, as it is less "R-dense" with thickness. BTW, the XPS foam does allow some moisture through over time, enough to let the walls breath to either side (both inner and outer).

2) How do I install this stuff? Glue it against the concrete? For the tongue/groove do I put glue in there or just attach and tape over? What about the top and bottom for sealing...?

3) I have read a little but not much about a thermal barrier between the pressured-treated bottome plate in the framing--like special foam for this. Do I really need it? I haven't come upon much about it.

4) Last, is it worth tape-insulating ALL my cold water copper pipes in the basement before putting the sealing up?

I should say I've read nothing today in these many sources about painting/dryloking the basement wall so I intend not to bother. I think it serves the same purpose as a vapor barrier, which per the above I do not want, so it could be deleterious.

I haven't read to entire thread so may be duplicating someone, apologies in advance. I usually recommend the 2" insulation above grade plus one foot below. That avoids most of the moisture issues as 2" has half the permeability as 1 inch. Link attached to discuss permeability:
Energy Savers: Vapor Barriers or Vapor Diffusion Retarders (http://www.energysavers.gov/your_home/insulation_airsealing/index.cfm/mytopic=11810)
To attach the rigid to the concrete, I like to have a flat surface. A diamond blade in a grinder, a flat diamond cup, or a hammer and a chisel. The later is a lot of work. Then any adhesive rated for the foam you are using, liquid nails, can foam, or other, but you may have to rig something to hold them in place until secure.

I'm not sure about the thermal barrier you mention, but I would avoid anything that holds water or slows down the drying process.

One of the primary reasons for insulating cold water pipes is to avoid condensation and dripping in the summer. Hot water should obviously be insulated as well.

And yes avoid the painting and sealing of the concrete so it can dry. Address and known moisture issues from outside with drainage or sealing. Patch any known cracks inside and out.

Bud

Skoorb - I to have been doing a ton of reading on this and still haven't decided how best to proceed. I have been thinking about a 1" thick layer XPS flush against the block, then my stud wall flat against that XPS and I was then thinking about another layer of maybe 1" foam w/ radiant barrier on it cut to fit tight within the framing cavities. As long as I keep at least 3/4" air gap between second layer of radiant covered foam and drywall I should get maximum R-value out of the foam. Using the Perma"R" website (http://www.permarproducts.com/onlineforms%5Cpolypro.pdf) -as the product is readily available at Lowe's- I figure I can get 6.75 R out of the second layer of foam and a R-5 out of the first layer giving me about an R-12 with drywall finish. This doesn't even take into account the additional R-value achieved from additional 1" of dead air space in cavity between foil-faced foam drywall finish not used in the Perma-"R" product requirements. Seems best to me since no fiberglass to wick moisture, a large air gap makes it easy to install wiring and fiberglass itchies.

While my labor time will increase having to cut the foil-faced sheets into 14.5" sections and there will be a bit of waste from a 8' x 4' sheet, I still think this makes the most sense to me.

All feedback is VERY welcomed as there just doesn't seem to be a "perfect" solution to basement insulation.

Something bothers me about having something directly against the block. The block is made to breathe as far as I know. I don't have any links to support my claim. It's just a gut feeling, for what it's worth.

Something bothers me about having something directly against the block. The block is made to breathe as far as I know. I don't have any links to support my claim. It's just a gut feeling, for what it's worth.

Well if the finished section of my basement was going to be huge I may entertain the idea of leaving a 16" gap between the block wall and the framing to at least inspect for moisture issues. The problem is that unless you keep air moving through that gap and condition that air you will still have moisture problems. If you are gonna circulate conditioned air through that "inspection hallway" between the insulated framed wall and the block then what was the point of insulating to begin with as the block wall will still eat up so much heat.

I believe the rigid foam can still move water. It's perm rating is 1.4 or something like that, so technically water can still move through it so ultimately it can still dry. It's just it doesn't move it in the same way wet fiberglass batt does.

I was going to make a new thread with this question but won't:Can anybody explain the disconnect between every basement book I've read and the journals? I have gone through 3-4 basement books, including stanley and B&D's recent one, plus a couple of very recent home-maintenance books and they ALL say fiberglass batt in the studs and a vapor barrier. However, everything I read on buildingscience.com and most of the stuff on finehomebuilding says unequivocally this is wrong. I absolutely believe that fiberglass batt against a concrete wall and in the studs is a terrible thing to do. It WILL get wet, there is no doubt about it.

Why the disconnect? Many of these journal articles are several years old now--why are the general fix-it-up books completely ignoring what these sources say about rigid insulation?

I agree moving air in front of the basement wall would be very expensive and unless it was in some separate air circulation system would completely negate the point of insulating, since it would ultimately be air connected to the rest of the conditioned house.

Hi Skoorb, consider, you are dealing with just your own understanding. Try being an energy auditor that has to explain why things went wrong when they "did it like it said". It is hard to change old habits, especially when some of them HAVE worked under some conditions for years and therefore the contractor can't see the problem.

It will take time to get everyone on the same page. I just feel bad for those who follow what they think is good advice, only to harvest their own bumper crop of mold.

More reading if you haven't seen this link:
RR-0509c: Renovating Existing Basements — (http://www.buildingscience.com/documents/reports/rr-0509c-renovating-existing-basements/view?searchterm=basement)

Bud

More reading if you haven't seen this link:
RR-0509c: Renovating Existing Basements — (http://www.buildingscience.com/documents/reports/rr-0509c-renovating-existing-basements/view?searchterm=basement)

Bud

Well that info kinda says what I was thinking made the most sense to me with the 2" XPS against the wall and studs against the foam. My basement shows no visible signs of water infiltration and it is 40+ years old. When I purchased the home the block walls were painted and the paint still looks exactly the same 7 years later. Assuming I have no water problems I think the foam on the walls still seems like the best idea.

I don't understand why the BuildingScience.com "renovating existing basements" doesn't address what to use inside the stud cavities though. 2" foam does give an R-10 to R-12 rating but are they assuming an air tight seal between the foam and drywall so as to use the "dead air space" as additional R-value? While the air space would be somewhat dead, the fact is when you cut in receptacle boxes and switch boxes you will break that dead air space. I'd rather place another inch or 2 of foam in those cavities and not rely on true dead air space as a component of my wall R-value. I know dead air provides a great R value but it has to be truly dead air space or it is SEVERELY hindered in it's ability to do so.

I know for sure I will not be using any fiberglass in my basement walls so I guess my dilemma is whether to fill the stud cavities with another 1" of foam or to rely on the "dead air" to do the job. I'm leaning toward more foam at this point even though "dead air" is pretty cheap to install.

Shane, I think I also got this from another post of Bud's:

http://www.eere.energy.gov/buildings/building_america/pdfs/db/35017.pdf

It does talk about filling the cavity--go to page 9. It covers a lot of the buildingscience article and overlaps it significantly, but it's an awesome pdf.

I am totally sold on not having fiberglass batts hit the concrete because they will get wet, so I'm going to definitely have XPS against the foundation. The concrete itself could dry to the interior better with batts vs xps, but I'm more concerned with my actual interior wall than the concrete and I don't want moisture constantly in it, as is sure to happen if the sweating concrete is constantly finding its only way to dry is through my insulation, then having condensation issues closer to wood and drywall.

2" XPS is ridiculously expensive so as I break down costs more I may end up with 1" plus batts OR just 2" XPS. I will make that decision based on allowances I get from my local inspector. A neighbor has 1" up and was going to batt the cavities and the inspector told him that's fine. I'm not sure if inspector would have demanded a vapor barrier internal or not. If he does I suppose one option is to get, as advertised/mentioned on finehomebuilding, some membrane that changes its permeability based on moisture. Hopefully, though, my inspector will be fine with XPS then batts in the caivities and nothing else.

"I know for sure I will not be using any fiberglass in my basement walls so I guess my dilemma is whether to fill the stud cavities with another 1" of foam or to rely on the "dead air" to do the job. I'm leaning toward more foam at this point even though "dead air" is pretty cheap to install."

That sounds like it would be a big hassle though cutting all that foam for each cavity. I haven't seen it mentioned anywhere that I've read. As you said earlier it seems most links talk about ONLY foam, though for additional R you can putt in batts, per page 9 of the link above. There is another article on finehomebuilding--actually at least two--talking about XPS against foundation and they don't speak about batts for some reason...

My area says I need 10 R if it's continuous (presume foam) or 13 if not (batts?). Beyond that there are diminishing returns. My basement is substantially above grade, though, which while helping the dry-out aspect also means most of the walls are being buffeted by freezing winter winds, so I want higher than R10.

Skoorb I think we are looking at roughly the same finished product. I also have concluded that 2" is ridiculously expensive but may be worth the investment as I cannot believe there is any scenario where fiberglass works well inside a finished wall. I have decided on a 3/4" or 1" layer of the Dow Tuff R product directly against the block wall and then most likely another layer of the cheaper unbranded white foam between the studs. I have also decide on using the studs at 24" OC so as not to waste material when cutting foam and reducing my cuts to one per 4' x 8' sheet.

The Dow Tuff R and Super Tuff R lists it's R values as:

http://www.dow.com/PublishedLiterature/dh_01a7/0901b803801a7e37.pdf?filepath=styrofoam/pdfs/noreg/179-07932.pdf&fromPage=GetDoc

Knowing those numbers I will play around with the most efficient R value array and go from there. I really like the Tuff R product because of it's superior R per inch as well as it's radiant foil barrier. Checking my local Home Depot today I found the 3/4" was about $12.50 a sheet and the 1" was like $15.50 as sheet.

Gonna contact Dow and ask them what constitutes a 3/4" air space as I need to know if additional insulation stacked directly against the foil face will work the same as a an space or if they require an actual dead air space. Since I can achieve an R 9.3 in only 1.75" of space using this product AND it gives me a radiant barrier I just don't see how any system can compare to it. Regular 2" provides roughly an R-10 but is nearly twice as much and takes up about 15% more space plus it doesn't offer the radiant barrier.

Let me know if you still plan on fiberglass insulation of any kind because I did read the .pdf u referenced and it did say it would work as long as RH stayed below 50% but I'm just so skeptical after seeing so many pictures and knowing so many people who had problems with it.

That Tuff R says it's closed cell. I think that means it serves as both an air and vapor barrier, right, in which case it would limit movement of moisture more than the "normal" rigid foam? If so, isn't that to be avoided, as the normal foam can allow some level of moisture and drying in both directions? Isn't the foil-face specifically something we're reading to avoid to achieve the "no vapor barriers in a basement wall" goal?

The only thing I'd mention about foam against the foundation and then more foam in the cavities is that if you're committed to the idea about not having loose insulation in the cavities because of moisture issues, you're still having those potentially rottable-wooden studs free in the cavity. Although you'd lose an extra inch of living space because of the stud wall further from the foundation, wouldn't it be better to jam as much rigid foam against the foundation as possible and _then_ have the stud wall?

BTW for what it's worth I am also looking into what I should have as a subfloor and for Dricore in their pictures they show rigid xps against the foundation wall, too, just like is being discussed here.

Checking my local Home Depot today I found the 3/4" was about $12.50 a sheet and the 1" was like $15.50 as sheet. Prices at my home depot for .75,1,1.5,2" pink owen cornings rigid foam are about $6.70, $9, $11, $14.50. Similar prices on DOW Styrofoam-brand blue rigid at Lowes except that for 2" the DOW is $17. $9 at Home depot buys Kraft-faced (didn't look at unfaced) batts capable of covering 40 square feet, so that approach certainly is a cheap one.

With the money I'm sinking into the basement though I may swallow the pricier pill on all this, especially since it's early in the game and my bank account hasn't taken a beat-down yet :) I'll never have, with rigid foam alone, an R equal to the 1" rigid plus batts unless I really get silly with the expense, but I may take that lower R to insure I have no fiberglass in there.

Now, some people think the best thing, which is priciest, is to have somebody pre-spray the foundation wall with foam. You can get it a few inches thick. You could forget about removing it later, though, I bet.

Well now I'm all confused. That PDF says rigid XPS for walls with signs of minor water penetration but suggests using the icynene spray foam insulation - which is a complete air and vapor barrier if the basement shows no signs of water leakage. Is a homeowner to assume that if the walls aren't leaking now that they never will leak?

I don't have signs of water leakage but I have also already excavated 50 linear feet around my house to install new footer drains, gravel and rigid XPS on the outside wall of the foundation. I plan on doing another 50 feet or so this summer so I am just going assume a dry wall and use the foil face vapor retarding closed cell foam. I am a big believe in radiant heat loss and the only real way to combat that is with a foil faced cover.

I guess I look at that .PDF that talks about excavating the floor for drainage mat and gravel/footer drains which seems like a ton more work and mess than excavation around the foundation.

As for the floor I have been looking at going foam and Enka drain system but I have an older home and the basement height is only 7' 8". I plan on installing a drop ceiling when I finish it so as to have access to HVAC/electrical/plumbing and whatever else connections in the ceiling joists. If I install a shallow drop ceiling AND the floor system that .PDF recommends I will be down to 7' ceilings so I will have to weigh the value of the flooring system.

Skoorb, does your local lowes carry the white unbranded foam? it is substantially cheaper and is what I plan to run after I install a layer of the more expensive vapor resistant foam. After seeing the prices you listed I'm thinkin I must be crazy but I swear I looked last week and 2" rigid XPS was like $26 a sheet. I could get a better R value out of the 1" XPS + 2" white open cell unbranded foam (R 12.8 for the combined foams vs R-10 for the 2" XPS) for about $2 cheaper per 32 SQ FT. I will have to double check now though and see if I am mistaken about the prices I wrote down.

Wow just checked my local Lowes online and around here the .5" XPS Dow is $14.77 a sheet. That's the price you listed for 2" foam around you? I guess it's time to call some local supply house and see if Lowes/Home Depot are outta line on pricing at the moment.

Shane my lowes does carry that foam, although not in as many options as the blue stuff.

If you saw 2" at $26/sheet either it's very pricey where you are or you were looking at larger sheets than 2X8' I would guess ;) I don't know if the owens corning at sub $15 is inferior to the lowes at a couple bucks more per sheet. When I get to that I'll bring them up online and look at the detailed specs for each one (and then hope I know what I'm reading enough to make the right choice, but really I bet they are basically the same thing).

"Wow just checked my local Lowes online and around here the .5" XPS Dow is $14.77 a sheet."

That is crazy expensive. I have a sheet of the 2" in my basement. I just checked, it says it's DOW Styrofoam "Extruded foam insulation". I have also down there some 1/4" thick fan fold foam (I bought this foam last year and use it to make RC planes) and it calls itself "extruded polystyrene". It costs about $34 for a full batch of it, which are sheets 2x4', i think and you get 25 of them in the fan type configuration.