Image Credit: Image #1: Owens Corning
More Musings of an Energy Nerd
Homes insulated with fiberglass batts are leakier than homes insulated with cellulose or spray polyurethane foam. Until recently, fiberglass batt manufacturers shrugged off the damning air-leakage data, insisting that their batts could deliver the R-value promised on the packaging — and then changed the subject.
In recent years, however, manufacturers of fiberglass batts have begun facing up to their product’s Achilles’ heel — the fact that fiberglass batts are so air-permeable that they usually perform poorly. Worried that competing products are beginning to gain market share, batt manufacturers are finally addressing air infiltration.
A new kind of goop
Two leading fiberglass manufacturers, Owens Corning and Knauf, have developed similar air-sealing products that are best described as sprayable caulk. The Owens Corning product is called EnergyComplete, while the Knauf produce is called EcoSeal. When installed to seal leaks in wall assemblies, floor assemblies, and ceiling assemblies, these sprayable caulks improve the performance of air-permeable insulations like fiberglass batts or blown-in fiberglass.
Here’s how the systems work: an insulation contractor takes a high-pressure spray rig and sprays goop to seal leaks in stud bays and other framing bays. Once the sprayable caulk has cured, the cavities can be filled with batts or blown-in fiberglass.
It’s not flash-and-batt
To many builders, these systems sound like a variation on flash-and-batt (a system combining spray polyurethane foam and fiberglass batts). But sprayable caulk should not be confused with spray foam. A flash-and-batt job requires the installation of a 2-inch-thick layer of closed-cell spray foam on the interior side of the wall sheathing; the foam layer has a measurable R-value.
EnergyComplete and EcoSeal are different; they aren’t supposed to provide any R-value. Instead of installing a layer of foam that covers the sheathing completely, these products are used to seal the edges of each stud…
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42 Comments
I'll Wait
Between the high start up costs and the caveats (can't use with cellulose with one of them, the other can't be used for air tight drywall), I'll stick with acoustical sealants and gaskets.
Fantastic, informative blog
Fantastic, informative blog post Martin. This juvenile appreciates solid useful green building information. That is what GBA is about and why at least I am at this site. Off to eat a bear with a beechnut demiglaise...
What about after?
Ok, maybe I'm fussy, but the issue that I continually see with the sparyable products are that they are just a faster delivery method than the tube. My point being does the framing move enough while drying in the first year to degrade the sealing. I'm sure that it does after 10 years and the mterials have hardened and won't move with the substrate. Then we are back to needing an air sealing job but we no longer have access.
Btw... Juvi... No snacks unless you brought enough for everyone.
On caulk and tape longevity
Albert,
Everyone involved in superinsulation has to think about caulk and tape longevity. You're in the tape business, so of course you promote the use of tapes. But many builders wonder about tape longevity, just as you worry about caulk longevity.
I know of only one study that has looked at air barrier durability, and the results are encouraging. A 2004 Canadian study by Gary Proskiw and Anil Parekh found little evidence of air-barrier deterioration after 14 years.
I reported on the results of the study in the March 2005 issue of Energy Design Update:
"A recent study by two Winnipeg engineers, Gary Proskiw and Anil Parekh, provides reason for optimism. In December 2004, Proskiw presented the study,“Airtightness Performance of Wood-Framed Houses Over a 14-Year Period,” at the Performance of Exterior Envelopes of Whole Buildings IX conference in Clearwater Beach, Florida.
"Proskiw and Parekh compared blower-door results for 22 Winnipeg houses that have been extensively studied since they were built in the late 1980s. Blower-door tests were performed at all of the houses soon after completion. Follow-up testing was performed periodically on the houses, with the most recent blower-door tests performed in 2000.
"The 22 wood-framed single-family stucco-clad houses were all built with careful attention to air sealing. The study divided the houses into two groups:
• Nine of the houses had polyethylene air barriers, with poly seams sealed with [Tremco] acoustical sealant.
• Thirteen of the houses were sealed with gaskets using the advanced drywall approach (ADA).
"The houses, all completed during the late 1980s, were very tight, with original blower-door results averaging 1.14 ac/h @ 50 Pa. Measured again in 2000, the average airtightness of the 22 houses had deteriorated only slightly, to 1.45 ac/h @ 50 Pa — still below the stringent R-2000 standard of 1.50 ac/h @ 50 Pa.
"Comparing the houses with polyethylene air barriers to those with ADA air barriers, Proskiw and Parekh noted that the houses with polyethylene air barriers showed slightly less deterioration in airtightness than the houses with ADA air barriers.
"During the 2000 site visits, Proskiw and Parekh looked for leaks. They determined that most of the observable air leakage was occurring at accessible locations not directly associated with either the polyethylene or the ADA portions of the air barrier systems. Some of the leaks were at floor drains, around doors and windows, and at mechanical and electrical penetrations through the envelope. During his presentation in Florida, Proskiw described these leaks as “basically, just old weatherstripping,” noting that most of them could be easily remedied.
"In their paper, Proskiw and Parekh conclude that there is no evidence to indicate that either polyethylene or ADA gaskets are unsuited for use as an air barrier material in residential wood-framed construction. As Proskiw pointed out in Florida, “No catastrophic failures were observed, so the durability of the polyethylene and ADA air barrier systems has been reasonably maintained over their 14-year monitoring period.”
"These results were especially encouraging in light of the fact that 18 of the houses enrolled in the study suffered significant vibrations when an environmental cleanup project required the excavation and removal of contaminated soil from the homes’ back yards."
Since it's been 22 years since they last measured, it seems worthwhile for someone to conduct another blower door test.
Thanks for this article Martin
I've been trying to find more info on teh Ecoseal product as i look for alternatives to CC spray foam for air sealing my crawl space. Glad to see it's possible for a DIY'er to get their hands on it. Can anyone tell me where can I rent the recommended sprayer in Massachusetts? Also, can this stuff be painted on? Probably tedius and would not penetrate cracks as well as a high pressure spray, but maybe it can be gooped on in excess if there's no concern of having an uneven surface.
Response to Steven
Steven,
To find out whether any tool-rental outlets in your area have a high-pressure airless sprayer to rent, you'll have to call up the rental outlets in your area.
I'm fairly sure you don't want to "paint" EcoSeal on your crawl space walls. For one thing, it's too thick. For another, it's too expensive -- about $250 for a 5-gallon bucket. If you do decide to use it, I think you should follow the manufacturer's recommendations and apply the product with a sprayer.
Thanks Martin.
I actually
Thanks Martin.
I actually called around before I posted, but now I think I have a source for an airless sprayer.
I was thinking it would be like applying joint compound, but yes, used in that way i'd prob go through a 5 gallon bucket quickly. I wouldn't be applying it to my walls, just under the subfloor at joints. In terms of cost, 5 or so buckets of ecoseal plus batts would be a fraction of the cost of spray foam.
The photo says it all
The builder in the photo has more to consider than air sealing, a 2 x 4 wall with OSB sheathing, maybe OK in Brownsville, TX. Copious air sealing will not make this wall efficient.
Photos can tell a lot
I have to say that I have not made up my mind about these products yet. But the pink stuff looks kind of nasty. Are they admitting that if used with cellulose it releases its toxic components :-)? Anyway, I would probably give the blue stuff a try. It is cheaper, looks cleaner and they sound more professional!
Pink stuff gets toxic with cellulose?
Methinks the vendor's ban on using cellulose to fill a cavity sealed with the pink stuff is a weak attempt to promote use an insulating material known widely now to perform so poorly when there is air leakage through it. It's either that or the fashion-conscious among their marketing folks feel the pink of the sealant and gray of the cellulose clash horribly.
A batt is still a batt, despite addressing the air leakage issue. A batt must be installed with great care if it is to perform to potential. Now if they could come up with a batt mfg process that would result in the batt expanding into all parts of the cavity over time, no matter how poorly installed, then they'd have a good combination.
Response to Dick Russell
Dick,
I don't think there is any need to come up with a complicated reason to explain why certified installers of EnergyComplete will only install Owens Corning fiberglass batts or Owens Corning blown-in fiberglass. The reason is simple: EnergyComplete is an Owens Corning product, and they are pushing what they manufacture.
Owens Corning doesn't make or sell cellulose. They just sell a single package -- pink Owens Corning goop plus pink Owens Corning fiberglass.
why try to put the air barrier in the same plane as the framing?
We ask a lot of the framing plane of a stick-built house: structure, plumbing chase, wiring chase, thermal boundary -- to try to put the air barrier there, too, seems like you're creating some unnecessary and difficult hoops to jump through. My guess is that's probably why they're getting those mediocre blower door results with this strategy. Seems like too much work to only end up with 3.0 or 3.5 [email protected]
Response to Martin Halladay: longevity
Martin thanks for the post. I'm really glad to have read about the study. Both the initial and 14 year tests show extremely good numbers.
I admit... I am unsure of the longevity of all of the methods. I'm in the air sealing business "first" for personal reasons, and secondary to that is supporting a particular method or vendor... And only if I
really believe they work. Tape has it's challenges also. The rough side of US OSB is a real problem on
a great project in Minnesota this week. It sticks, but the rough side OSB fibre is so loose that it can be
peeled off because the tape will stick to the fibre but the fibre won't stay on the panel. The smooth side
is always fine, but once the panels are up with the rough side out, what is a guy to do?
Now that I've aired my own issues, I'd like to note that the study really points out how well the
membrane and ADA methods have done over time. It doesn't talk about "gap filling" which is essentially
what I see these two sprayable products being. They are just a "filler" for the gaps in the framing to
sheeting, framing to deck, etc... It would seem that the more elastic the material is, the more it can
move with the assembly. From the durability standpoint, I'd lean towards something flexible like the
Energy Complete.
These projects that are getting sealed will hopefully stand a long time. The envelop air barrier won't be available for repair for 50+ years. Proper air sealing will reduce the energy load over it's life, and load reduction is what we (as a country) need. I'm in favor of methods that work and enough methods on the market that the builders choice becomes "which way am I going to seal it", in stead of "do I really have to seal it?... It just adds cost and the client doesn't care".
Thanks for keeping the discussion open and honest.
what happens when walls are covered in multiple layers of paint?
I am completely sold on exterior thermal break and air barrier. I am all for getting rid of the interior vapor barrier. I have only one nagging doubt that troubles me greatly: What happens after the drywall has been painted 50 times? Because, hey, it'll happen eventually. If we're building a 100 year envelope, it's going to get a whole lot of coats of paint over the years. Say you're doing a PERSIST wall, for example. And the wall can breathe out from the air barrier but not in from the air barrier...
Is this a real concern or is this silly? Please help me out here- I build in BC and we have lots of rotten buildings already, don't need any more. Any thoughts?
Response to Merrill Wittman
Merrill,
It's a good question. You are correct that the more layers of paint there are on a wall, the lower the permeance. However, I don't think that this is cause for worry.
There are several questions here, really:
1. If you use OSB sheathing without any exterior foam, should you worry about moisture build-up in the cold OSB?
2. If you have a wall with exterior foam, how important is it for the wall to be able to dry to the interior during the summer?
3. If a wall has six or seven layers of latex paint, has the wall's permeance dropped to the point where a homeowner needs to worry?
Here are my answers:
1. I don't like OSB-sheathed walls without any exterior foam. That's the type of wall promoted by the manufacturers of the sprayable caulk discussed in this article. OSB is vulnerable to rot when it gets wet, and cold OSB is likely to absorb moisture during the winter. To lower the risk, it's better to keep the OSB warm with exterior foam, or to switch to plywood sheathing. For more information on this topic, see How Risky Is Cold OSB Wall Sheathing?
2. Walls occasionally get wet. The most common way that a wall gets wet is due to bad flashing or wind-driven rain that gets past the siding. A secondary method of wetting occurs when warm, humid indoor air contacts cold sheathing during the winter. If you have exterior foam, most building scientists advise builders that it's important for the wall to be able to dry to the interior during the summer.
I advise anyone who installs exterior rigid foam (a) to include a ventilated rainscreen gap, and (b) to do a careful job of water management by integrating flashings with the WRB. If you do that, any water that gets past the siding should quickly dry to the exterior. The foam keeps the OSB warm, so the OSB won't accumulate moisture during the winter. These are very robust walls, so they don't really get wet enough to need to dry out to the interior during the summer -- especially since the rigid foam layer stops inward solar vapor drive.
So, while it's important to leave out the interior poly, it's not as if inward drying is essential to prevent wall failure. These walls are dry, warm, and robust.
3. What about those multiple layers of paint? Well, the permeance is lowered with each successive layer of paint. But multiple layers of paint still aren't as bad as polyethylene. The walls can still dry somewhat to the interior. And as they age, they are likely to develop small flaws in the drywall that aid drying.
I say, don't worry about it. I have never heard of a single wall failure that can be attributed to multiple layers of interior paint.
EcoSeal - online training and sourcing
Thanks for the comparison and descriptions of the two systems Martin. I looked into both last spring for use on projects - one positive experience and one still leaving me wondering.
I contacted the licensed OC contractor two times with no response. After a week I contacted OC directly and still nothing from the licensed contractor. Not sure if that reflects on OC or their licensed contractor for my area.
Knauf has a simple online training ( http://ecoseal.knaufinsulation.us/ ). I think it took me about 45 minutes. It mainly covered the limits of the product (3/8" gaps), spray equipment necessary, what gaps to seal and the orifice size for the spray tip. About 20 minutes after completing the online training, a Knauf rep called me to let me know where I could purchase the product locally and offer his support if I felt I needed any.
I haven't had any projects where this type of system seemed applicable yet so I can't reflect on ease of application or effectiveness. It would be nice to hear from anyone who has experience.
Response to Mike Guertin
Mike,
Thanks for the comments.
You wrote that it would be nice to hear from anyone who has experience with EcoSeal. My article quotes one GBA reader with experience, Chris Harris. To read more of Chris's comments, check out the lengthy discussion on the topic in GBA's Q&A forum: Knauf EcoSeal and Owens Corning EnergyComplete.
The names on the thread can get confusing; there are two people named Chris making comments (reader Chris Harris and Knauf rep Chris Brown). There are also two people with the last name "Brown" -- Ian Brown (the person who posted the original question) and Chris Brown (the rep from Knauf). Confused yet? Good luck.
FEI.. (for everyone's
FEI.. (for everyone's information). Spyder fiberglass sprayed in insulation used with a well sealed insulation cavity, should be quite attractive both price and performance wise. Batts are not necessary whether using Zip sheathing/tape or this blogs glob or SIGA type tape over plywood, or taped exterior foam sheeting..... Or....
We now have so many ways to seal a home up that this cat is more excited than a bear that just found a 23 acre stand of fruitful beechnut trees miles deep in the forest far from guns and windmill highways.
Permeability of the two products?
Thanks for the article Martin. I've been interested in these products, now just waiting for more stories from the field.
Do either of the products list a permeability? Chris Brown in the other discussion says Ecoseal is permeable, but is there a number? If it's low and with it one one side, rigid foam on the other and OSB in between... Sounds like vapor/microbe heaven. It probably is only intended to be applied in small swaths, however I could see it easily covering larger areas.
Response to Dan Whitmore
Dan,
An online search reveals that OwensCorning lists the vapor permeance of EnergyComplete, but Knauf does not list the permeance of EcoSeal.
According to this document, A sample of EnergyComplete consisting of "two 1-inch-diameter beads" has a dry-cup permeance of 40 perms and a wet-cup permeance of 110 perms. That means it is very permeable.
I'll try to get in touch with a Knauf rep to see if they have measured the vapor permeance of EcoSeal.
Martin
First of all, thanks
Martin
First of all, thanks for taking the time to contact us about EcoSeal. As building science continues to be a stronger force in the everyday aspect of building homes, new products and systems are evolving to help meet that challenge. The two specific products included in your blog are designed to do just that, help make buildings more energy efficient by reducing air leakage. Although there are some obvious differences between EcoSeal and Energy Complete, the fact remains that the two systems provide better alternatives than existed previously.
With regard to some of the comments that you attributed to me in your blog, I believe some were taken out of context, or did not contain complete information. Specifically I am referring to the reference where you state, "According to Brown, ACH50 in the 3.0 to 3.5 range has been most common in these typically constructed homes". While I did in fact state those exact words, they were only part of a post I made in the Q & A section of GBA on September 2nd. By including only that part of my statement in your blog, my description of "typically constructed" was not included. Therefore the ACH50 range quoted above is out of context.
It is not a huge issue Martin, but I just wanted the GBA community to understand clearly the type of house construction I was referrng to when I used the term typical, which was used deliberately. Air sealants, no matter which type is used, can't be the silver bullet when little to no other attention is paid to gross areas of air leakage when the building is constructed. When given a structure where framing details are correct and other trades understand the significance of proper construction technique and sequence, then the application of air sealants can and does make a significant difference to the overall performance of the structure. As I also referenced in that previous post, test results below 1.7 at ACH50 are starting to be more common. There is no reason not to believe that they will get even better as construction detail improves and air sealing contractors become better at their jobs. After all, it is a relatively new trade or process.
Proper air sealing must be done from a holistic approach. It is not just about the sealants, no matter what product might be chosen. If the structure itself is poorly constructed, applying air sealants will help, but not entirely solve the problem. Its like putting lipstick on a pig!
I continue to be amazed at the number of builders who think they are air sealing their homes by having a little low expanding faom squirted around their windows and setting their base plates on sill sealer! Obviously there remains much work for all of us to do.
Response to Chris Brown
Chris,
Thanks for your clarification concerning "typically constructed homes." I have edited the blog to include a reference to your latest comment.
Chris, do you have a response to Dan Whitmore's question about the vapor permeance of EcoSeal? Has the vapor permeance of this product been measured?
Albert Rooks mentioned . . .
Albert Rooks mentioned a project in Minnesota that ran into a difficultly applying SIGA tape to US manufactured OSB as an air sealing application. The matter does seem to have been resolved with the use of a primer provided by SIGA.
http://www.minnephithouse.com/?p=905
Vapor permeance for EcoSeal
I have received a letter from Brett Welch of Knauf that discusses the vapor permeance of EcoSeal.
Welch did not provide a rating in perms. Instead, the letter states, "Water vapor transmission testing has shown that the permeability of EcoSeal is roughly equivalent to blown cellulose insulation or 50% more permeable than 1 inch of wood fiber board."
Thanks J Chesnut and Chris Brown
I'm waaaay away from the shop for a bit am really glad to hear that the situation is resolved. It's too bad that the rough side is sooo rough but I guess it's nice when you start sliding off a roof!
Chris Brown: Im glad to hear the low ACH numbers. The higher numbers were a puzzle. I could not agree more with your comment: Good air sealing starts with a good design. Lack of a plan will not bring successful results.
Not a fan of either.
I am young enough to love new ideas and new ways to do things in the industry. I did research on the EcoSeal when it first came out. I use Knuaf when I have to use fiberglass insulation (not often but the EcoBatts make me feel better if I do have to use or flash and batt). Your cost was right on for the sprayer, another contractor already said the price for 5 gallon buckets of this stuff of about $250.00. Plus your everyday labor to do install.
I am looking at this product as retrofit, keep that in mind. A good compressor is costly (Home Depot sells cheap ones that are good enough for small projects though). Now to air seal attics you have hoses running through a home, you need a set up area (Iin NJ we have more cold than hot as many of you do), there are so many things I can point out wrong with this system for retrofit it would take another article just to present the downside to it. Heres what killed me when investigating EcoSeal ....
From EcoSeal's website if your not seated please sit down..........
Actual field trials have shown that a 5-gallon pail of EcoSeal will yield approximately 2000 linear feet
of a ¼ inch “bead”. Our experience tells us that a “typical” 2000 square foot house will use about
three five gallon pails of EcoSeal.
(3) 250.00 = 750.00 NJ sales tax (.07) 52.50 $750.00 (1.50) Mark Up = $1,125.00 plus tax = $1,177.50. But hey I am not done yet, there is still labor to put it in. I am going to say an 8 hour day 2 man crew (lots of hoses and set up, plus I am air sealing the attic 100 percent) $840.00 (I get $1,500.00 per attic with 2 man including material such as 1 part spray foam). $2,017.50 to air seal an attic? Not happening, general public does not even know what air sealing is, selling it higher is worse.
16lb can 1 part spray foam at a 1/4 inch bead yields like 20,000 linear feet, and costs me $65.00 (no attic unless brand new can offer 1/4 cracks sorry after the wood dries and house settles there are finger sized holes up there even bigger).
I wanted this to work because of the VOCs, the only thing they did was give me another sales point on why my customers should use air sealing with cellulose or spray foam.
The pink guys are off their rocker with that training/sprayer price. Someone is truely looking to rip contractors off over there and I mean it, save the money and go get BPI certs, and new tools. I am totally disgruntled about that price, mom and pop shops spring that money in a bad econ to maybe better their business. Unreal.
Frank
Response to Dick Russell
A batt is still a batt......I am with you there.
See the Colorado Study, it isn't just about the infiltration highway of a fiberglass batt, fiberglass loses it's curve as it gets colder!
80 percent heaters, atmospheric water heaters, and fiberglass batts should be outlawed period.
Recent Conversation w/ Owens Corning Rep
Oddly enough, we had an Owens Corning rep stop by the office last week to drop off literature and present the energy complete system. He had a nice wall sample that showed the install and reviewed the features.
A couple of questions came to mind that I didn't get complete answers to...
1. The foam on the face of studs when compressed by drywall has a noticeable thickness and I wonder if it would cause any issues with sheetrock install. Same issue at top and bottom plates.
2. There is no chemical bond b/w the foam and the sheetrock. It appears to only be a compression seal created when the sheetrock is fastened to the stud. Maybe this is fine...
Also, he had some cases studies that listed ACH50 numbers around 1.2, which seems a bit suspect in a house with batts and no exterior foam. There must have been some serious other measures taken, but that was unclear.
Its an interesting product, but a bit of a non-starter for me if it requires using batts.
OSB
Martin,
This might be a bit off topic, but earlier in the discussion you mentioned avoiding using osb without exterior foam. Do you have the same opinion of Zip sheathing products?
Response to Chris harris
I would hate to be the rockers on those jobs. Look how thick the bottom plate looks. I guess it is no big deal with thicker rock, but in the past I had rock crack and bust due to the smallest things under it. I would rather silicone the bottom plates for ease and cost.
Response to Chris Harris
Chris,
Q. "The foam on the face of studs when compressed by drywall has a noticeable thickness and I wonder if it would cause any issues with sheetrock install? Same issue at top and bottom plates."
A. This question is answered in my article above. (David Wolf of Owens Corning provided the answer.) I wrote that there is no problem compressing the EnergyComplete bead between framing and drywall "as long as the material is installed in a bead that is no more than 3/8-inch thick. 'A 3/4-inch glob would challenge the compressiblity of the foam,' says Wolf. 'If there is too much — more than 3/8 inch — you have to take a utility knife and cut off the excess [after it is cured]. You cut the top half of the bead off.'"
Q. "There is no chemical bond b/w the foam and the sheetrock. It appears to only be a compression seal created when the sheetrock is fastened to the stud. Maybe this is fine?"
A. Yes, it acts as a gasket, not glue. Gaskets have been successfully used for the ADA for a long time, and they can work very well. I don't know whether EnergyComplete works as well as other types of gasket material, but it is certainly possible that it does.
Q. "Earlier in the discussion you mentioned avoiding using OSB without exterior foam. Do you have the same opinion of Zip sheathing products?"
A. Zip System sheathing is a relatively new product, and it hasn't been installed for long. I don't know about its durability. However, of you want any type of wood-fiber sheathing to last a long time -- whether OSB or plywood -- it makes sense to keep it warm and dry. Exterior foam sheathing does just that.
Thanks
Thanks Martin....
Other Uses
I've used the latex "foam" product (Dep) before with unsatisfactory results (especially in regards to it serving as a cozy home medium instead of a bug "barrier") thus I don't have a lot of initial confidence in these products for long term sealing effectiveness. On the other hand, the EnergyComplete product sounds like (no pun intended) a great product for sound abatement in interior walls. While the cost is initially high, many people might happily absord the one time cost (in new construction) to gain a peaceful living environment. I think OC should look into this and consider rebranding and marketing their product for this purpose as it's compressibility would allow it to be sprayed directly on all the framing, plates and outlets prior to drywall thus dampening the transmission of sound waves from one side of the wall to the other. Certainly much more efficient than covering all this area with lines and gobs of acoustic caulk.
As for it's intended creation, I'm not convinced it's worth the cost and effort over other alternatives when effectiveness and added benefits are also taken into consideration. OC should just do like Pfizer did with their blue pill and market their product for the problem it solves best (assuming it works as well as I think it would for effective and efficient sound control. ;)
Why not use thickened latex paint?
I am rehabbing a shed, adding 2 x 2s to make room for more insulation. I plan to insulate the walls (Mooney walls) with fiberglass or cellulose. To fill the little cracks in the exterior wall and top plate, to prevent air flow in the insulation, why can't I just use water based paint, thickened with a bit of cornstarch?
Latex paint (some exterior grade, some interior and no-VOC) is free to me as I have a dozen or so mostly empty paint cans. If I can thicken it to a "goop" consistency and then apply with a brush directly to the joints in the framing, will I accomplish the same thing as OC Energy Complete or the Knauf ecoseal product? After it dries, I can then blow in insulation.
Any thoughts on this? Besides the insulatnig value, it would be a nice way to dispose of extra paint, instead of having to mix it with kitty litter and put it in the trash.
Response to Rich
Rich,
You're thinking like a backyard tinkerer. Plenty of marvelous inventions have been developed through backyard tinkering, so you might be on to something.
You have described the first step: an idea. The next step: develop a prototype (in this case, a recipe) and test it.
Here's my guess: your recipe won't be as effective at sealing air leaks, nor as durable, as Energy Complete or EcoSeal. But I'm just guessing. You're the backyard chemist, so you can run your own tests.
Martin --
I actually did
Martin --
I actually did do this. The cornstarch wasn't a great thickener -- you might need a lot of it and I didn't want to introduce too much organic matter for insects to eat. So I ended up just leaving the paint out in a tray and using it when it was partly dried out. Also I painted the interior of the T111 siding so that it would be less porous.
I can post a photo or two if people want that.
It definitely does cut down the drafts in the shed, so I don't see any reason for others not to try this. Maybe someone with blower door equipment can try it and get some hard data before and after.
Haven't had time to add the cellulose insulation; might be able to do that if we get a few more warm days.
-rich
Thick latex paint?
Rich,
Good for you for conducting this experiment!
There are two unknowns, as I see it: How effective the paint was at reducing air leakage, and how durable your method will prove to be as the framing expands and contracts with changes in humidity and temperature.
Thorough comparison
Martin, thank you for this detailed description of both products. Very informative!
caulk and building gaskets?
Right now I am between using Kanuf's ecoseal + EPDM building gaskets, and/or caulk + EPDM building gaskets....
I'm wondering why people seem to use 'acoustical sealant' / caulk ......... is acoustical sealant/caulk latex based or silicone base? or both?
My initial thought was that using 100% silicone would last the longest....stay flexible the longest....
(material wise might be the cheapest too... but more labor intensive than ecoseal "sprayable caulk")
Any thoughts for or against silicone caulk to seal up everything? (any/or EPDM building gaskets)
I figure if fake breasts are made of silicone... the air sealing of my house would last as long as they do......
Any other pros / cons i am missing here?
(Knauf ecoseal - fastest, reasonable cost, latex based... might not be as flexible as silicone and epdm)
(Caulk + gaskets - cost? more labor intensive.... durability? long time if done right?)
Importance of airsealing edge of stud bays?
Martin,
Do you think it is necessary to air seal the edge of stud bays if I am taping all seams on the plywood sheathing?
If so, would a a caulk or sealant work? I'm trying to go low VOC.
Response to Grey Wolf
Grey,
How far to go with your air sealing efforts depends on your goals. While taping the wall sheathing addresses some leaks in a house, it doesn't help with air leaks between the wall and the foundation, between the wall and the ceiling, or around windows and doors.
Addressing leaks in each stud bay matters more for some types of insulation than for others. It tends to be more important, for example, if you are insulating with fiberglass batts than if you are insulating with dense-packed cellulose.
If you have carefully sealed the seams of the wall sheathing with high quality tape, the next place to focus is penetrations and intersections with the foundation and ceiling. If you are insulating with fiberglass batts, I would pay particular attention to electrical boxes and wiring penetrations.
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