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Helpful? 3

Air-Sealing Tapes and Gaskets

Which products stay sticky and flexible?

Posted on Jul 30 2010 by Martin Holladay, GBA Advisor

UPDATED March 8, 2013

After this article was published, Martin Holladay conducted a test of eleven air-sealing tapes on a variety of materials. To read the results of Holladay's testing, see Backyard Tape Test and Return to the Backyard Tape Test.

It’s hard to create a tight air barrierBuilding assembly components that work as a system to restrict air flow through the building envelope. Air barriers may or may not act as a vapor barrier. The air barrier can be on the exterior, the interior of the assembly, or both. without using tapes, gaskets, caulk, or spray foam. In this blog, I’ll look at two of these categories — tapes and gaskets. I’ll be focusing on air-sealing products, so I’ll ignore flexible flashing tapes used for waterproofing. (I'll address duct sealing in a future blog.)

[Author's note: since this blog was originally published, two U.S. distributors have begun selling high-quality European construction tapes. While these tapes tend to cost more than tapes from U.S. manufacturers, most builders who have tried them have been impressed with their performance. Moreover, European tape manufacturers (unlike U.S. manufacturers) offer tapes that are vapor-permeable. The two distributors are Small Planet Workshop of Olympia, Washington (distributor of several types of Siga tape, including Corvum, Rissan, Sicrall, and Wigluv tapes) and Four Seven Five of Brooklyn, New York (distributor of Contega tape, Tescon tape, Unitape, Rapidcell tape, and Budax Top tape).]

I’d like this blog to be a work in progress, so I strongly urge readers to post information on products that work well.

A multitude of tapes

To limit air leakage, builders use tapes to seal the seams of a variety of membranes and buildings products, including housewrap, polyethylene, OSB, and plywood. Tapes are also used to seal duct seams, to seal leaks around penetrations through air barriers — for example, to seal around plumbing vents — and to seal sheet goodsMaterial, usually plywood or oriented strand board (OSB), but sometimes wooden boards, installed on the exterior of wall studs, rafters, or roof trusses; siding or roofing installed on the sheathing—sometimes over strapping to create a rainscreen. to a variety of materials, including concrete.

Needless to say, no single tape works well in each of these applications, so builders need to familiarize themselves with a range of products.

Sealing seams in housewrap or Tu-Tuf

Lots of manufacturers make housewrap tape. Manufacturers include 3M (Construction Seaming Tape #8087), Berry Plastics (Barricade Seam Tape, Nashua Seam & Seal Construction Tape #628), Dow (Weathermate tape), DuPont Tyvek (Tyvek tape — formerly sold as “Contractors' Tape”), Johns Manville (Seal-It Housewrap Tape), Typar (Construction tape), and Venture (Sheathing and housewrap tape #1585CW). Venture tapes are available from Energy Federation Incorporated.

Maine architect Jesse Thompson has high praise for Dow Weathermate tape; according to Thompson, it has a “good and strong adhesive, and is readily available.”

Most housewrap tapes work well to seal seams in Tu-Tuf ground covers.

Housewrap tapes have aggressive adhesives and are suitable for use on a variety of materials. If you’re not sure what tape to use for a particular application, you can always try housewrap tape.

Sealing polyethylene seams

Polyethylene can be tough to seal, especially because some manufacturers coat their polyethylene with a slippery, powdery substance that resists adhesives.

I’ve heard good reports about two Venture tapes that successfully seal polyethylene. The first is Venture #938, a clear polyethylene tape with an acrylic adhesive. This tape may not work with all types of polyethylene, however; if it doesn’t work, try Venture #1585CW sheathing and housewrap tape, a polypropylene tape with a cold-weather acrylic adhesive.

Many builders distrust tapes for sealing polyethylene seams. The time-tested method for sealing a poly seam is to lap the seam over a piece of framing lumber, and to install a bead of Tremco acoustical sealant at the seam. The airtightness of the Tremco sealant depends on the seam being compressed between the framing lumber and a subsequent layer of material (such as drywall or plywood).

For sealing seams in crawl-space ground covers (and for sealing ground covers to concrete walls), some builders recommend the use of fiberglass mesh tape embedded in duct mastic.

Taping rigid foam

According to some sources, housewrap tape is the best tape for seams in extruded polystyrene (for example, Dow Styrofoam). However, 3M representative Shawn Prestegaard recommends a different (and more expensive) tape for this application: 3M All Weather Flashing Tape #8067. This tape (#8067) is three times thicker than 3M housewrap tape (#8087).

According my backyard testing I performed in 2012 and 2013, the best tape for XPSExtruded polystyrene. Highly insulating, water-resistant rigid foam insulation that is widely used above and below grade, such as on exterior walls and underneath concrete floor slabs. In North America, XPS is made with ozone-depleting HCFC-142b. XPS has higher density and R-value and lower vapor permeability than EPS rigid insulation. is Siga Sicrall.

For sealing the seams of foil-faced polyisocyanurate (for example, Thermax, Tuf-R, or Energy Shield), many builders prefer to use a foil-faced tape with an acrylic adhesive (for example, Venture 1520 or Venture 1521). Others use Dow Weathermate housewrap tape.

Sealing seams in OSB or plywood

Whether or not housewrap tapes are effective at sealing seams in plywood or OSB is a matter of debate. (All experts agree that taping OSB is more effective when the OSB has been primed.)

Many manufacturers of housewrap tape, including Venture, recommend their tapes for use on sheathing seams; other manufacturers, including Berry Plastics, advise builders that their housewrap tapes should not be used to seal plywood or OSB seams.

Tyvek warns against the use of Tyvek tape for sealing seams in plywood, OSB, or XPS foam. “The tape is designed to stick to Tyvek wrap,” said Alan Hubbell, a residential marketing manager for Tyvek. “Plywood and foam will expand at different rates from the tape, and over time it will crinkle and wrinkle and pull off.”

Jesse Thompson, a Maine architect, suggests using 3M All Weather Flashing Tape (8067) to seal plywood seams. “It's thinner and more flexible than Vycor,” Thompson said, “but seems to stick even better to rough surfaces, especially in cold weather.”

Marc Rosenbaum, a respected energy consultant who often advises builders to establish an air barrier at the exterior sheathing, doubts that the adhesives in housewrap tapes are aggressive enough to last the life of the building. Rosenbaum prefers to use a rubberized asphalt product (in other words, peel-and-stick tape like Grace Vycor) — a more expensive option than housewrap tape, but likely to be more durable.

Ben Cross, a marketing manager for construction products at Berry Plastics, recommends that OSB or plywood seams can be sealed with either Barricade #732 butyl peel-and-stick tape, or with Nashua #330X Extreme Weather tape, a foil-faced tape with an aggressive acrylic adhesive.

Another option for sealing sheathing seams is ZIP system tape, a tape designed to be used with proprietary OSB panels called ZIP System sheathing.

Sealing SIP seams

Most manufacturers of structural insulated panels (SIPs) recommend a belt-and-suspenders approach to air sealing. Seams should first be sealed with spray foam; later, interior seams should be taped.

One manufacturer of SIP tape is R-Control.

Gaskets are better than caulk

When builders first learn about air sealing, they often depend heavily on caulk. After inspecting a home for leaks during a blower-door testTest used to determine a home’s airtightness: a powerful fan is mounted in an exterior door opening and used to pressurize or depressurize the house. By measuring the force needed to maintain a certain pressure difference, a measure of the home’s airtightness can be determined. Operating the blower door also exaggerates air leakage and permits a weatherization contractor to find and seal those leakage areas., however, they learn that caulk has a few downsides. That’s when they usually graduate to gaskets.

If you are following the Airtight Drywall Approach — that is, establishing an interior air barrier — gaskets are particularly useful. Typical locations for gaskets include:

  • Between the top of the foundation and the mudsill;
  • Between the subfloor and the bottom plate;
  • Between the window frame and the rough opening;
  • Between the bottom plate and the drywall; and
  • Between the top plateIn wood-frame construction, the framing member that forms the top of a wall. In advanced framing, a single top plate is often used in place of the more typical double top plate. and the drywall.

Three good sources of gaskets are Conservation Technology, Denarco Incorporated (269-435-8404), and Illbruck Sealant Systems.

For sealing cracks around windows, Conservation Technology recommends the use of “gap gaskets.” The two most useful sizes are #BG44, a 13-millimeter gasket that seals gaps from 1⁄4 inch to 1⁄2 inch, and #BG46, a 21-millimeter gasket that seals gaps from 3/8 inch to 3⁄4 inch.

Conservation Technology also sells Teno Tape, a “tacky rubber double-stick tape supplied in 3/4 inch by 132 foot rolls” that is “best for general-purpose seaming, provided there is a firm surface behind the seam so pressure can be applied to the tape.”

Iowa builder Rollie Peschon is a fan of Denarco gaskets. “I use Denarco SureSeal gasketing in between the plates and the subfloor,” Peschon wrote on a Web forum. “It’s a 3/8 by 3/8 inch, open-cell, urethane-impregnated gasket that becomes airtight when under at least 60% compression, I believe. Being open-cell allows it to be compressed to almost flat, yet still remain resilient if there is some shrinkage of the framing members. We tried closed-cell gaskets, but when remodeling later, found that once they are under compression, the closed cells were ‘popped,’ leaving the gasket with no memory. Denarco also has a UltraSeal, which is 3/4 by 3/4 inch gasket that we use for between sill plates, and top of foundation walls, where the potential for a larger leakage area is greater.”

Illbruck Sealant Systems sells Willseal 600, a pre-compressed, self-expanding polyurethane foam gasket. “It’s an impregnated sealing tape that comes in different widths,” says Hans Porschitz, a building systems associate at Bensonwood Homes in Walpole, New Hampshire. “It’s a memory gasket. As it gets warm it swells up and seals the joint airtight.”

Last week’s blog: “Green Building Vocabulary Disputes.”


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Image Credits:

  1. DuPont Tyvek
  2. Huber

1.
Fri, 07/30/2010 - 04:44

Construction Adhesive?
by John Brooks

Helpful? 0

I remember a framer at the JLC forum who proposed using construction adhesive between sheathing and framing in addition to the mechanical fasteneners.
I think his intention was structural enhancement not air control.
He was pretty well laughed at for "overkill"

I have often wondered about the air control quality of such a strategy?
Is the bond between sheathing/construction adhesive/framing backer reliable over time?


2.
Fri, 07/30/2010 - 04:58

Rollie Peschon
by John Brooks

Helpful? 0

Martin,
You mentioned Rollie in your blog.
I think he had one of THE best construction blogs I have seen.
http://imageevent.com/okoboji_images/deloreshouse;jsessionid=7iuejflor1....


3.
Fri, 07/30/2010 - 04:58

Using construction adhesive to stop air leaks
by Martin Holladay, GBA Advisor

Helpful? 0

John,
As far as I know, construction adhesive is a good air-sealing product. It is certainly the most common way to seal the crack between subflooring and rim joists; without construction adhesive, this is a potential air leakage crack. (That's why it's important for construction adhesive under subfloors to be installed in a continuous ribbon rather than a series of interrupted dots -- at least at the perimeter of the floor.)


4.
Fri, 07/30/2010 - 06:24

Gap Gasket
by Dan Kolbert

Helpful? 0

We've started using Cons. Tech's gap gasket in the past year. It seems to work well, and I like it both for its air sealing and also because it leaves a potential path for any leaks to make their way down to our window or door pans and escape.


5.
Fri, 07/30/2010 - 09:25

recent observation about construction adhesive
by j chesnut

Helpful? 0

I was removing an old door the other day and found the familiar brown construction adhesive was used between the entire vertical length of a 1x (used as the jamb stop) and a 2x (used as the door frame). The adhesive had turned very brittle and no longer had any holding power. When I pulled the boards away from each other the adhesive shattered into shards that fell to the floor. Hard for me to judge if something that turned so brittle but still trapped in place could serve as an air sealant.

A little context - door was on south exterior wall in a cold/very cold climate so has seen large temperature extremes. The door was probably around for 20-25 years.


6.
Fri, 07/30/2010 - 10:22

Owens Corning Energy Complete
by Carl Seville, GBA Advisor

Helpful? 0

OC recently introduced an insulation system that incorporates a spray-on gasket system with either loose fill or batt insulation that appears to be a good solution to the air sealing problem. The gasket is sprayed on all gaps to be air sealed. It doesn't require the same level of personal protection as typical spray foam insulation; it expands minimally and compresses easily. I haven't seen any test results on the product yet.


7.
Fri, 07/30/2010 - 12:12

Gaskets and Air Tight Electrical Boxes
by Russ Hellem

Helpful? 1

We have been selling the Conservation Technologies drywall and sill gasket for quite sometime now and have had very good success with the product. We have blower door tested several projects that used the gaskets at any wood to wood connection and utilized the drywall gasket for air tight drywall. Most of these projects have very little urethane foam sprayed in them and are insulated with densepack cellulose in the walls. One of the projects tested out at .56 ACH50, and the others were at .89 ACH50, 1.1 ACH50, etc.... Another key to this is the use of the airtight electrical box and a foam gasket around the flange. We have tried both the Lessco Airtight boxes and the Air Foil boxes and have found that the Air Foil boxes are easier to install and more user friendly for the trades. Another issue we had with the Lessco box was that they tend to push out when using densepack cellulose in the wall cavities. You can see some examples of the boxes on our website @ http://energetechs.com/test-test-test/foam-sealing-products/electrical-b...


8.
Fri, 07/30/2010 - 12:47

Agree re: Constr. Adhesive
by Dan Kolbert

Helpful? 0

I too would be hesitant to use construction adhesive as an air seal for the same reason. We've been using Cons. Tech's building gaskets under our walls and sills for a while and think they're a great product.


10.
Mon, 08/02/2010 - 07:12

Polyether sealant for sheathing seams
by Mike Guertin

Helpful? -1

From what I understand, polyether sealants have been used for a while in commercial construction to seal joints. Polyethers have a number of advantages over other sealants commonly available to residential builders. One company - York Manufacturing - recently started promoting a few polyether sealants for home construction.
I tried a couple products, GreatSeal LT-100 and GreatSeal PE-150 to seal seams in XPS and OSB with good success. A flare shaped attachment turns the round bead into a ribbon of sealant to coat seams efficiently without need to smear by hand. The sealants gun at low temperatures - much lower than you can effectively apply any self-adhering flashing tape. And according to the literature, have very low VOC content. Of course, like any other new product, the only way we'll know how it performs long-term is to wait 30 years and pull a few walls apart.
http://www.yorkmfg.com/all_sealants.asp


11.
Mon, 08/02/2010 - 20:29

Air Sealant Tapes and Gaskets
by Doug Walker

Helpful? 1

Having been in the industry as a sealant and adhesive manufacturer for over 33 years now, I feel so sorry for the residentail builder and remodeler who is trying to sort out 1) what sealant or adhesive (caulk, gasket or tape) to use and 2) what is truly "green" in this era of significant greenwashing while standards what constitutes a sustainable product are still being identified in our small but important part of the industry. If leading commercial consultants are still sorting this out due to the rapdily increasing value and need of air and vapor barriers, must be hard for the residential contractor unless he shops at the knowledgeable specialty waterprofing distributors, or does a lot of careful research. First, very little sticks to polyethylene, it's used as a bond release in many applications. What was described by Martin Hallady as a solution for the Trenco Acoustical Sealant will work equally as well with any good quality sealant. As MIke Guetin points out, polyethers (a,k.a. hybrids, STP's or modified silicones) are used in commercial work, but in fact are still a very small part of that market, newer to these aplications, so I suggest also consider a good quality silicone or urethane depending on your application. Sealing around doors and windows, and for a redundant or secondary seal when using gaskets (they take compression sets also) these will give you the best air, vapor and WATERproof seal. Without question using peel and sticks for sealing sheet membranes is the best way to go there. I get my sealants at work for free, and yet bought rolls of Grace's product when residing sections of my cedar shingled house last year. As for construction adhesives, they've come a long way, but buy the right one and install in a continuous bead as several recommended if you're looking for them to double as an air seal. Realize all of them will be stiff when cured, so won't take much movement like a sealant as the materials they're adhered to expand and contract at differrent rates. So relying on them as both a glue and an air seal will be effective only when both materials, ie the wood to wood, or wood to concrete expand and contract at the same rate and when adhesion is great to both substrates. Want to elimiate a lot of these lap, seam and connection problems, consider a liquid air and vapor barrier such as Prosoco or Sto's, fast replacing sheet membranes in critical commerical applications. Had I resided my entire home, I would have eliminated many (not all), the various peel and sticks, sheet membranes, adhesives and sealants used to upgrade the performance of my 35 year old rotting barrier wall to a modified rain screen. But if I had, guess I would never apreciate first hand what a the pain in the neck you guys go through finding and using the products we make!


12.
Tue, 08/03/2010 - 09:01

peril
by Michael Blumenthal

Helpful? -1

I remember the rush in the '70s to Urea-formaldahyde insulation,carbon monoxide poisoning from wodburning stoves and to tight a seal and MOLD. Whatever the optimum solution, it's still important to insure fresh air exchanges.


14.
Wed, 08/04/2010 - 13:01

Comparison to Foam
by John Cunningham

Helpful? 1

We'll be interested to see your comparison of these approaches vs going straight to spray foam. Performance, Cost, and Labor time advantages / disadvantages. We are advocates of using a single system, often open cell spray foam as a way to get the air sealing benefits rather than flash and bat or other techniques. In new builds we believe that there is a good performance and economic case for this - but would be interested to see 3rd party data. Air in a retrofit situation is another conversation as well.


16.
Wed, 08/04/2010 - 13:20

Air sealing with tape, etc go
by ED GILSON

Helpful? -1

Air sealing with tape, etc go hand in hand with radiant barriers. I noticed the radiant barrier between the rafters in this graphic.
Ed Gilson Mfg rep


17.
Thu, 08/05/2010 - 22:59

Two Comments/Questions
by Kohta Ueno

Helpful? 0

Great column, Martin. A few comments:

"For sealing the seams of foil-faced polyisocyanurate (for example, Thermax, Tuf-R, or Energy Shield), many builders prefer to use a foil-faced tape with an acrylic adhesive (for example, Venture 1520 or Venture 1521). Others use Dow Weathermate housewrap tape."

We've moved away from using foil tape in this application--admittedly, it wasn't Venture Tape, but off-the-shelf Home Depot foil tape. We knew it was a bad sign when the contractor said, "Yeah, it's great using this stuff... it comes right off the polyiso if you put it on wrong!" Uh oh... It also started to visibly come off the wall during construction. We ended up switching to Dow Weathermate tape, and have been pretty happy with the tack and adhesion.

"For sealing seams in crawl-space ground covers (and for sealing ground covers to concrete walls), some builders recommend the use of fiberglass mesh tape embedded in duct mastic."

Out of curiosity, why the fiberglass mesh tape? It makes sense to use it when mastic is spanning a crack, and needs some reinforcement to take the tensile loads (e.g., duct sealing across a gap). But attaching crawl space polyethylene to walls or penetrations is more of a matter of buttering both sides, and directly attaching them (e.g. plastic-to-plastic, or plastic to wall). Some pictures of my adventures with crawl space sealing here: http://www.flickr.com/photos/70684282@N00/sets/72157624663055242/


18.
Fri, 08/06/2010 - 04:05

Thanks, Kohta
by Martin Holladay, GBA Advisor

Helpful? -1

Kohta,
Thanks for your comments -- good stuff!


19.
Wed, 08/11/2010 - 10:01

reply to Kohta Ueno
by Todd Rheaume

Helpful? 0

Just a little FYI - when I contacted Dow to get a data sheet of their tape they referred me to Venture Tape as the manufacturer.


20.
Thu, 08/12/2010 - 09:45

New Energy Star standard says no to construction adhesive
by Li Ling Young

Helpful? 0

My experience with construction adhesive is that it is a temporary measure for use while the building is going together. I'd advocate abandoning it as a sealant. EPA says construction adhesive is not to be considered a sealant.
In response to whether finicky air sealing details are more expensive than just spray foaming the house... Spray foam insulation doesn't go everywhere that air could leak. I've seen enough distessingly leaky spray foam houses to stand firmly on the side of a dedicated air barrier, apart from the insulation. Given the relative geometric simplicity of the exterior of a home compared to the interior, exterior air barrier systems like Huber Zip are looking very attractive. Get back to me in 50 years when we know how the tape is holding up.


21.
Sun, 09/19/2010 - 14:54

Thermal Bypass
by Mark Siddall

Helpful? 0

I'm double posting this one because I think it has relevance. I hope that the article found at the end of this link is of interest:
http://www.aecb.net/PDFs/Impact_of_thermal_bypass.pdf

Cheers
Mark


22.
Wed, 09/07/2011 - 20:12

zip tape and cons. technology gaskets
by jesper kruse

Helpful? 0

I highly recommend using zip tape to seal gaps in plywood (prime first for better result). It's thinner and more pliable than vycor. I find vycor to be stiff and hard to get to stick in cold and wet condition.
I also use the gaskets from conservation technology and I'm very happy with them.


23.
Thu, 03/08/2012 - 00:03

What kind of primer?
by Jeff Nelson

Helpful? 0

What are you guys who are taping OSB seams using? Is this just exterior paint-type primer or is there something specific for this application?


24.
Thu, 03/08/2012 - 03:51

Primers for OSB
by Martin Holladay, GBA Advisor

Helpful? 0

Jeff,
Here are two primers for OSB that I've heard good things about:

Tescon primer from Four Seven Five

Siga Dockskin primer from Small Planet Workshop


25.
Wed, 06/27/2012 - 12:48

adhesives, tapes and primers
by floris keverling buisman

Helpful? 0

Wanted to add a few notes here regarding the pro clima products that we import with foursevenfive.com in relation ship to this post and disccusion:

Construction adhesive dry and become hard - once it is dry it will crack/em-brittle, especially when building elements expand/contract with temperature/humidity.
Acoustical sealant is not meant to be an airbarrier and use is thus off-label.
The OR-F adhesive is designed for make airtight connections - it doesn't dry - it remains sticky/flexible and can thus assure long term airtightness when connecting membranes to concrete. Some additional info about this and other airsealing junctions in our recent blogpost: http://foursevenfive.wordpress.com/2012/06/21/when-buildings-move-airtig...

Regarding primers:
We have yet to find OSB that our tapes (TESCON Vana/No.1, UNITAPE) do not adhere well to without primer. Wiping oil residue off with mineral spirits can help make a better bond.

Other tapes do indeed benefit from the TESCON Primer RP we carry, or when you want to tape to cementitious materials (brick, concrete) etc.


26.
Tue, 01/15/2013 - 03:13

Caulking/sealing at our house
by David Coote

Helpful? 0

We did some thermal imaging at our place last year after which we're now starting some retrofit work.
We has some great advice from GBA on how best to approach the thermal imaging. Perhaps some GBA folks could help us with advice on caulking and sealing. I have a contractor coming around tomorrow who I think is mainly familiar with caulking. The article above is food for thought as to the best sealing approach.

We identified several leaks. One major source of airflow is between the baltic pine boards in our floors. Perhaps these would be a good candidate for taping? We also appear to have significant leaks coming through our skirting boards in several places. What would be the best approach to sealing these? Taking them off and refitting them would be expensive. I guess gaskets around the electricity sockets?

Thanks

David


27.
Tue, 01/15/2013 - 04:40

Response to David Coote
by Martin Holladay, GBA Advisor

Helpful? 0

David,
You didn't explain whether the pine boards are your finish floor or your subfloor. In either case, if you have air infiltration through floor boards, the best solution is to remove the finish floor -- either temporarily or permanently, depending on the type of flooring -- and to install a layer of plywood subflooring.

If you have leaks at your baseboard (skirting boards), the usual solution is to caulk the gap between the baseboards and the flooring -- and in some cases the gap between the baseboard and the drywall or plaster. Use an inconspicuous caulk.

Gaskets don't do much on electrical boxes. The best solution on an electrical box: turn off the circuit breaker; remove the cover plate; caulk the back of the box where the wires penetrate the box; caulk the crack between the drywall and the box; replace the cover plate.


28.
Fri, 02/01/2013 - 23:49

Thanks, Martin. I think the
by David Coote

Helpful? 0

Thanks, Martin. I think the boards are placed directly on the joists so this would constitute both the finish floor and subfloor, I guess. Twould be good to rip them off and replace with tighter boards but obviously a major expense as well as the inconvenience.

Would it be possible to cut plywood to fit between the joists and underneath the floorboards? This could give a nice seal? One problem would be in areas where the crawlspace is very tight. Perhaps we could roller something on there?

Or to use some tape on the underside of the boards to cover the cracks?

We could possibly caulk into the cracks from above with a dark caulk but I would be concerned about the caulk popping up from the cracks.


29.
Sat, 02/02/2013 - 04:43

Response to David Coote
by Martin Holladay, GBA Advisor

Helpful? 0

David,
If your floor consists of a single layer of boards, with air infiltration occurring between the boards, it's time for new flooring. I would install either a layer of building paper followed by new boards, or a thin layer of plywood followed by the finish flooring of your choice. That is likely to be the easiest solution.

If you want to try to solve the problem from the crawl space side, the classic solution would be two-component spray foam.

If you don't want to use spray foam, I suppose you could mess with rectangles of plywood or rigid foam between the joists. That's fussy work, though. I would use rectangles of rigid foam rather than plywood. You have to air-seal the edges of every single piece you install.


30.
Sun, 02/03/2013 - 01:15

Thanks, Martin. There would
by David Coote

Helpful? 0

Thanks, Martin. There would be a lot of houses in Melbourne of similar vintage to ours (1930) which would have the same problem. A likely assumption made by the builders was that these houses would have wall-to-wall good quality wool carpet. The carpets would add some insulation and, of course, block airflow through the floorboard cracks. There's been a trend over the last 20 years or so to rip up the carpet, polish the boards and have these as the flooring. The boards do look spectacular once polished. Lovely rich caramels. But as the boards are now 80 years old or so they have cracked, the houses may have moved a bit - all that reactive/expansive clay! - opening up gaps between the boards and the boards may have been not well laid at construction time. And baltic pine is a soft timber and not well suited to high traffic use.

So replacing would be great but expensive and a pain.

The spray foam sounds like a good approach. Do rodents like to establish homes in the spray foam? Or is it too tough for them? I'm guessing southern hemisphere rattus rattus would show similar behaviour to their northern hemisphere forebears.


31.
Sun, 02/03/2013 - 13:01

Response to David Coote
by Martin Holladay, GBA Advisor

Helpful? 0

David,
I have heard of many problems with rodents in fiberglass batts, but not of rodents in spray foam.


32.
Wed, 02/13/2013 - 15:26

Updated Info
by Jill Neubauer Architects

Helpful? 0

Hi
This was a very informative article and discussion. Any chance that we could get an updated version...What are current experiences with tapes, sealants and gaskets?

We are currently reconsidering what products to spec for air sealing plates, sheathing, etc. and it would be great to know the current state of the industry and what seems to be performing better than others.


33.
Wed, 02/13/2013 - 15:30

Edited Wed, 02/13/2013 - 15:31.

Updated Info
by Jill Neubauer Architects

Helpful? 0

Also, it makes sense that gaskets work better than sealants. What product would be appropriate b/w the back face of sheathing and the side face of the sill plate and wall bottom plate?

Also, b/w underside of sheathing and top of rim?

Thanks


34.
Wed, 02/13/2013 - 15:36

Response to Chris Harris
by Martin Holladay, GBA Advisor

Helpful? 0

Chris,
You'll have to be patient for a few more weeks. The next issue of Fine Homebuilding will have my article on air sealing tapes. That article includes lots of new information.


35.
Wed, 02/13/2013 - 16:28

Thanks
by Jill Neubauer Architects

Helpful? 0

We all could use a little more patience...

Any info regarding sealants at sheathing/ plates overlaps? I assume you can use the same gasket products as you would be sill plates and floor sheathing....

Thanks


36.
Fri, 11/14/2014 - 07:11

3M Sealing Tape 8777
by Jose Castro

Helpful? 0

Does anybody have any experience with 3M Sealing Tape 8777?
It's the closest we can get in Chile.


37.
Fri, 11/14/2014 - 08:16

Response to Jose Castro
by Martin Holladay, GBA Advisor

Helpful? 1

Jose,
If that is the only available tape, it sounds like a good choice. 3M is a reputable company, and the technical specifications sound good. Here is a link to a page with more information:
http://multimedia.3m.com/mws/media/740845O/3mtm-sealing-tape-8777.pdf?&f...


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