Insulation Tape Question

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  #1  
Old 04-24-13, 03:58 AM
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Insulation Tape Question

Hi All, first time poster here,

My builder was kind enough to insulate the interior of my basement walls down from the floor joists to 6 inches from the floor. However, it looks like they 'rolled' the insulation along the wall in two sections. The photo attached allows you to see the 'seam' where the two sections of insulation meet. Most of the openings in the walls have been 'tuck taped' (red tape) pretty well, however it looks like the seam along the middle of the wall has not been taped, and the gaps under the floor joists. I've gone ahead and dri-core'd the whole basement so now I need to tackle the insulation issues before framing.

My questions are as follows:
1. Should I be tuck taping the opening in the vapour barier between the two rolls?
2. Should i be tuck taping around the floor joists, or can this be left open?

Sorry for the sideways pic...I'm a newb at this forum.

Many thanks,
 
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  #2  
Old 04-24-13, 05:54 AM
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Photograph 2 is one of the end results you don't want and from your picture it looks like what you are starting with. I'll let you review the link. BSD-103: Understanding Basements — Building Science Information

There are three sources of moisture and all can cause mold.
1. Actual water leaking through a wall, and virtually all wall will leak.
2. Moisture vapor. It passes right through concrete, even with the tar on the outside, and will continue to flow until it is as wet on the inside as it is on the outside. The solution is to allow it to evaporate to the inside before it accumulates (no vapor barrier).
3. Air leakage into a basement wall can result in a convective flow of warm moist air reaching to upper/colder portions of the foundation where it deposits its moisture and creates your problem.

Bud
 
  #3  
Old 04-24-13, 01:33 PM
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Hey Bud, thanks for the detailed reply.

I understand that there are better products out there, but unfortunately the budget is a bit constrained at this time. I understand that the vapor barrier and rolled insulation could potentially introduce odor, but couldn't this be combatted with a dehumidifier in the summer months. This seems to be common up here in Ontario.

If I did decide to keep the existing builder product, should I be sealing around the floor joists, and sealing the gap down the middle of the wall? Or does the wall need these gaps to breath? This insulation is right against the wall so I assume there are some water protected characteristics?

Your expertise is greatly appreciated.
 
  #4  
Old 04-24-13, 04:09 PM
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"I assume there are some water protected characteristics?" None that I know of.

The vapor barrier will trap moisture behind it and a dehumidifier can't really help.

Air circulation behind an insulated wall will carry moisture laden air to a cold wall and add more moisture.

I understand the squeeze you are in and that some people get away with putting fiberglass against a foundation wall, but photo #2 mentioned above is all too often the result. And it is not just the small, it is the health of the people living in that home, not to mention the issues involved with removing and certifying the home free of mold should you ever wish to sell. I can't say for sure you will have a problem, but it is a roll of the dice.

With a wall that dries to the inside you would want it air sealed very well. With a vapor barrier, the moisture level in the soil outside will work its way through that concrete and with no place to go, end up right behind that vapor barrier, and that is where you have all of that fiberglass and wood.

I won't bug you any more, but there are tons of articles on this topic. Number 2 on a list of red flags in a GBA article I just read was, Red Flag "Fiberglass batts to insulate the interior of a basement wall"
Green Building for Beginners | GreenBuildingAdvisor.com

Bud
 
  #5  
Old 04-24-13, 07:18 PM
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Hi Bud, I appreciate your comments but I still have some questions. You mentioned fibreglsss and wood being behind the barrier, and photo 2 in the article indicates that. Howevet,, my insulation that was installed by the builder has no wood behind it. It is simpy a concrete wall next to fiberglass and the vapour barrier. Are the dangers still there even though there is no wood back there? I now understand your statement that there are no wter resistent properties of the fibreglass, but isnt it supposed to be mold resistant? I'd love to know if that changes things.
 
  #6  
Old 04-24-13, 11:02 PM
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I'm not an expert on mold, and the fg industry claims that fg is resistant to mold. However, it appears to provide an environment where mold does grow, all-be-it fed by sources from outside the fg. And, moisture is known to reduce the insulation effectiveness of the fg.

Not all molds are dangerous, but because they can look similar to most people there is a panic that sets in and all molds become bad. I happen to like blue cheese and aged beef, but I wouldn't try creating my own. Open a package of bread that has started to mold and you just flooded your house with mold spores that will wait for some moisture to arrive. Mold grows in our refrigerators, so a cold basement is an acceptable climate.

Here's another link with more info on fg and moisture.
http://www.buildingscience.com/docum...lation-systems

Bud
 
  #7  
Old 04-26-13, 07:34 PM
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Okay, thanks to Bud's informative articles, and some additional research, I've decided to rip out the diaper roll of insulation.
I plan on putting in RIGID foam sheets of 2" to give myself an R value of 8. After this is done, I will be putting in fibreglass in the studs because the foam sheets act as a vapour barrier.
I am now confused as to which sheet to use. I have been recommended to go with a 2" sheet, but It looks like some are good for outdoors, and some are good for indoors...or I'm reading it all wrong. My closest big box store is a home depot, so I'm kinda limited to their offerings. Would the following product be sufficient?
PlastiSpan HD | PlastiSpan HD EPS Rigid Insulation 96in X 24in X 2in | Home Depot Canada

Any help is appreciated.
 
  #8  
Old 04-26-13, 10:47 PM
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Hi Joe,
I haven't seen that product on our side of the boarder so did some reading at your link. Air filled, stable, and for a 2" thickness it has a perm number of 2.5, which means it is not a vapor barrier but a vapor diffusion retarder and that is good. You want the small amount of moisture vapor that passes through your concrete to be able to dry to the inside. The fiberglass insulation should be unfaced, although Roxul would be better, and the vapor will pass right through either. Install the rigid continuous and tape the seams with the studs next with no gap. Treated wood at the bottom with a capillary break under it. Use a top plate as well so these cavities do not allow air flow in-up-and out.

As for interior vs exterior your application is interior, but either would work. That's an opinion as the product is new to me.

Here is the link for the technical details in case others are more familiar with the details.
http://www.plastifab.com/TechnicalLi...Properties.pdf

Bud
 
  #9  
Old 04-27-13, 04:43 AM
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Hi Bud,

Once again, thanks for answering. Are you saying this product would be a good bang for my buck (loonie)? However, the sheet you sent me doesn't seem to indicate R8 like the HomeDepot.ca website says.

As well, I plan on ditching the diaper roll (maybe sell online), and buying new batts of insulation to stick between my studs. There will be no vapour barrier, as Holmes indicated in one of his episodes.

Essentially, Concrete, followed by the Rigid, followed by studs and inside of the studs will be the batts. I will cut pieces of rigid up inside the floor joists and spray foam around them. My floor is already a drycore flating subfloor, with 1.5inch gap around the perimter. The RIGID will more than cover this perimeter gap, and I plan on sprayfoaming down in any crevises or gaps. The studs will be framed and attached to the drycore which has a built in plastic membrane on the underside. Is this a sufficient break?

I was curious if you could let me know if you think this solution would work, especially this product...

Many thanks!
 
  #10  
Old 04-27-13, 06:02 AM
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Doh, I just realized the R value on that sheet is the minimum per inch. Given that I'm installing a two inch panel, I should double it...I'm still curious if you think my previous posted strategy is good tho!
 
  #11  
Old 04-27-13, 12:10 PM
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Sounds fine. Not sure if the can spray foam at the bottom is a problem if it gets wet. As long as you glue the rigid to the concrete with horizontal lines of glue, there should be no risk of basement air flowing up behind it. Putting the wall on top of the drycore will make future removal of same difficult, but only a flood would make that a possibility.

Bud
 
  #12  
Old 04-27-13, 12:49 PM
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While you wait for Bud's answer.... the f.b. with your store link; 2-1/2" thick (0.208) X 2' X8' = 3.33/4.5# = 0.74# or 3/4 pounds per cubic foot foam--- #1 in your link; Type (or close to) XI. That has a perm rating of 5 per inch = very open compared to XPS (1.5-1.2 per in.) at 2-1/2" = 3.125 perms vs. 0.656 perms.

Did you read the recommendations in Buds first link, "The foam insulation layer should generally be vapor semi impermeable (greater than 0.1 perm), vapor semi permeable (greater than 1.0 perm) or vapor permeable (greater than 10 perm) (Lstiburek, 2004). The greater the permeance the greater the inward drying and therefore the lower the risk of excessive moisture accumulation. However, in cold climates or buildings with high interior relative humidity during cold weather, the upper portion of a basement wall may become cold enough that a vapour permeable insulation will allow a damaging amount of outward diffusion during cold weather. A semi-permeable vapour retarder or foam or a supplemental layer exterior insulation can be used in these situations.

In all cases, a capillary break should be installed on the top of the footing between the footing and the perimeter foundation wall to control �rising damp.� No interior vapor barriers should be installed in order to permit inward drying.

Up to two inches of unfaced extruded polystyrene (R-10), four inches of unfaced expanded polystyrene (R-15), three inches of closed cell medium density spray polyurethane foam (R-18) and ten inches of open cell low density spray foam (R-35) meet these permeability requirements." From; BSD-103: Understanding Basements — Building Science Information
Your choice of closed-cell EPS is very vapor open for the colder climate. Foam board on a wall; slows exterior vapor drive/liquid water, air-seals the concrete to prevent indoor-air condensation there, and insulates the colder concrete raising the dew-point of the cavity- protecting the insulation/framing from mold. Your dryloc paint will slow any moisture passing (though only 4-5 perms, if remember correctly), and foamboard (in correct thickness for your location) will prevent condensation. What is closest city to you?

Gary
 
  #13  
Old 04-27-13, 05:53 PM
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Thanks for the reply.

My closest city is Toronto, Canada.

I think part of my problem is deciding on the proper product. Home Depot Canada seems to have a limited selection of rigid products, as can be seen via the following link:
SEARCH - - Home Improvement, Home Renovation, Tools, & Hardware | Home Depot Canada matchallpartial&Dx=mode matchallpartial&D=insulation&Ntt=insulation&N=173076&Pagesize=24&No=0
 
  #14  
Old 04-27-13, 10:02 PM
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Using the depot closest to Toronto, here are the selections; SEARCH - rigid+insulation+board - Home Improvement, Home Renovation, Tools, & Hardware | Home Depot Canada

I'd use the C-200 with drilock, or C-300 without because the denser product will slow the water pass-through better; (footnotes, last table) http://www.icc-es.org/reports/pdf_fi...C/ESR-1061.pdf

With Roxul in cavity- R-15; Roxul | Roxul Safe'n'Sound For Wood Studs 16 In. On Centre | Home Depot Canada

Using your local 3 months (coldest) temps Monthly and Yearly Weather Averages for Toronto, CAN averages = 24*F With that, at 68*F in basement;

1-1/2" FB + Rox. = 35%Relative Humidity and lower = no cavity condensation

2" FB + R.= 39%RH 2-1/2" FB + R. = 42%RH above grade and to "frost depth" for your location is 42-60" acc. to wiki, lol; What is the frost line depth in Toronto Ontario

Below that the temps follow the surface temps (lagging about 1-2 months) but adding 10*F warmer about 6' deep. 32-41*F plus 10* = 42-51*F, now read page 4: http://www.buildingscience.com/docum...g-your-basment

Gary
 
  #15  
Old 04-28-13, 04:41 AM
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Gary, thanks for the great reply. You have clarified things further.
I had originally looked at the C200 and C300 products, but their descriptions indicated they were for exterior use. This is why I had switched gears and started looking at the previously mentioned project.

I have read the sheet you have set me on the Corning product, but it doesn't specifically state internal use. Am I missing something here, or is this product actually intended for outside use?

Many thanks,

Joe
 
  #16  
Old 04-28-13, 04:57 AM
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Hi Gary,

I just put two and two together. Sorry for my slowness. I thought 'dryloc' was a feature of the foam board. With some additional googling (I could not find a board with this feature at HD) I realized it is a waterproofing technique. I think you may have mis-read my original email when I indicated I am using Dricore. Dricore is a sub-floor product up here that contains a thin plastic membrane under it to help with waterproofing.

With that being said, I do not have an additional paint on my walls, so I will just be installing the RIGID and the Roxul.

I'm curious why the 2" Corning c-300 is a dollar cheaper than the 2" c-200 - both are 2 inches thick, and now given that I am not using the dryloc product, which of these is better for my situation? When I compare the two products the only difference is the weight and the PSI. Is one more suited for the pressure placed on a floor, and one better for a wall? Or would the cheaper 'floor' one be just as good?
 

Last edited by yukonjoe; 04-28-13 at 07:41 AM.
  #17  
Old 04-28-13, 12:50 PM
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Sorry for the mix-up, I am familiar with dricore, Delta FL, Enkadrain, etc. I am with a head cold and it shows... The denser product the better, C-300 is 1.5#, better than the 1.3# by a little. Closed-cell 2# is optimal. As the "colder climate" in post 12, diffusion may happen in your location.

Be sure to use compatible adhesive in a one foot grid patterns to limit air-flow/convective loops behind the rigid board, not just glob it on; MYTH: LEAVE AN AIR SPACE BEHIND THE INSULATION IN THE BASEMENT TO AVOID CONDENSATION.
Use canned foam under and between joints or furnace mastic/tape with fibers on the joints, foam tape does come loose under certain conditions; http://www.buildingscience.com/docum...a-foam-shrinks

Add fire-blocking under the joists above to block fire from vertical to joist cavities, from a wall outlet- spreading across the ceiling, up a plumbing stack to attic- house burns down and up. And every 10' horizontally per our codes; Chapter 6 - Wall Construction

be sure the insulation batts touch the f.b., no convective loops again; https://docs.google.com/viewer?a=v&q...fHFsk1RrK9G2HQ

Set the bottom plate on 1" strips of f.b. for a capillary/thermal/air break from the cold slab, or on the dricore- though it is imperative to foam air-seal all cracks at dricore edges to the foamed concrete wall. I'd rather cut the dricore (if in place already) back , seal the edges, build the wall- knowing the slab air is not getting past the frame wall. The less basement air to the frame cavities- the better, this includes any moisture/air from the dricore cavity space (whole surface of floor area). I'd even run a bead of cheap caulk under the plate on/under f.b. or on dricore for insurance.

ADA the drywall; Info-401: Air Barriers

Gary
 
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Old 04-29-13, 03:30 PM
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Hi Folks,

I went into my local Winroc today. I didn't realize this place sells to the general public and not just to contractors.
I had a great chat with the sales rep. He made a few recommendations to help keep the price down. He recommended going with the 1.5inch C-200 RIGID Board from Corning. This would give me an R value of 7.5. He then suggested R13 batt insulation...to which I said "Roxul?" and he said, no, just Fibreglass insulation. He explained that Roxul is made of a different combination of materials, volcanic rock, etc and that it has some properties that make it a little more fire retardent than just plan fibreglass, however for a basement, he didn't see the value of the fireproofing for the almost doubling in price.
His price on the Corning sheets were somewhere around $17, and his price on the pack of 16" Fibreglass was $19.

What do Bud and Gary think on this one? Will I really notice a difference between the fibreglass and the Roxul product, or is it just to help me sleep better at night? Or am I completely missing the boat on this one.
When I priced it out, the Fibreglass and RIGID would cost the same as doing just the 2" RIGID alone.
 
  #19  
Old 04-29-13, 04:30 PM
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The exposed area (above grade) of a basement wall is so bad at sucking out heat that once you add the 1.5" of rigid, whatever you put after it is of far less importance. When I have a tight budget customer (really tight), I recommend 1" of rigid down 1' below grade and up into the joist cavities, all well air sealed. It is an 80% job at 25% of the cost. What you are proposing is a 98% job and you will really enjoy it.

Bud
 
  #20  
Old 04-30-13, 04:04 AM
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Great thanks Bud! Will take it under consideration!
 
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Old 04-30-13, 12:32 PM
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I agree with Bud, again, lol. Above-grade and a couple feet below-grade are critical. With the R-7 for your location and at 68*F in basement, the f.b. cavity side temp will be 39*F at 24*F outside temp. That is 35%RH of basement air = no condensation. Anything higher, in other words, either lower outside temp or higher indoor RH, you may get condensation. Thicker foam = safe with higher indoor humidity, or lower outside temps; BSD-163: Controlling Cold-Weather Condensation Using Insulation — Building Science Information

If you have 1-2' of concrete wall above-grade, your chances of moisture drive from outside are less as this portion will help dry the concrete (it has somewhere else to go). A vapor barrier helps slow the inward drive in the areas Bud said, so long as room above grade exists. Here is a paper to appreciate for you, locally; pp. 15,16, 22, 23, 35-38, 64, 65, and 47; I may have some pages wrong- still sick... ftp://ftp.cmhc-schl.gc.ca/chic-ccdh/..._Web_sept5.pdf Don't confuse below with above grade...

Bud, using the 3 months average for Freeport, ME. and R-5 w. R-13 at 68*F= 36*f.b. temp and 37%RH.

Gary
 
  #22  
Old 12-04-13, 04:25 PM
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Okay gents,

One further question. Once the roxul is installed between the studs, do I need a vapour barrier again? I was under the impression that the rigid foam would act as the vapour barrier, and that adding another one would just create a nice pocket for things to grow in!

As always, your advice is appreciated.
 
  #23  
Old 12-04-13, 06:41 PM
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The rigid foam is considered a vapor diffusion retarder, it allows a very small amount of moisture to pass through, which allows some drying to the inside (which is good). Adding a plastic barrier over the Roxul would be discouraged.

Did you go with 1" rigid?
What are you covering the interior with?

Bud
 
  #24  
Old 12-05-13, 04:18 AM
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Hi Bud,

I went with the 1.5 inch boards to give myself R7.5. On top of that I added the framing, and between the studs is R13, to give myself a total of R20.

The studs will be covered in regular dry-wall - except in the bathroom where I will go with the special one to combat mold.

Just to clarify the statement "Adding a plastic barrier over the Roxul would be discouraged. " - does this apply to both Roxul as well as regular cheaper fibreglass insulation (non-roxul formula)? I may go with regular fibreglass to help keep my under budget.
 
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