Installing Housewrap
`
`When properly detailed, high-tech wrappings can reduce the flow of air
`into outside walls while allowing moisture to escape
`
`by Rick Arnold and Mike Guertin
`
`Tape completes the air barrier. Housewrap just stapled to the exterior sheathing does not create a complete air barrier. All seams and holes must
`be sealed with specialized tape before the siding goes on.
`
`Build tight, ventilate right. A slogan with
`
`roots in energy-efficient building is gaining ac-
`ceptance in mainstream construction. More
`builders are installing better insulation and seal-
`ing the warm side of walls and floors to keep va-
`por out of insulated spaces. They're installing
`ventilation systems to maintain healthful indoor-
`air quality. But from what we've seen, the same
`care isn't taken with air-infiltration retarders, also
`known as air barriers or housewraps.
`
`There are usually a couple of ways to do some-
`thing right and dozens of ways to do it wrong.
`Most of the housewrap installations we've seen
`in our area fall into the latter category. Sure, the
`walls might seem covered, but there are enough
`seams, gaps, tears and holes at critical spots to
`render the film ineffective (photo above). We
`asked some builders why they use air-infiltra-
`tion retarders, and we got some interesting an-
`swers: "What's an air-infiltration retarder?"
`
`"That's what's spec-ed on the plans." "It's better
`than tar paper," "I only use it because customers
`expect it." "It makes the house waterproof." "It
`dries in the building until the siding goes on."
`Because we know what housewraps are sup-
`posed to do, we apply the details that will make
`the barriers most effective. We've also learned
`how to coordinate installation with our framing
`habits to make installation easy. We've installed
`every major brand of housewrap and have
`
`Louisiana-Pacific Corporation, Exhibit 1022
`IPR of U.S. Pat. No. 8,474,197
`Page 1
`
`

`

`A two-man team makes the work go faster. Especially on windy days, it's good to have one
`person stapling housewrap while another unrolls the material.
`
`Overlapping sheets create a good seal. When installing housewrap on a new wall, the au-
`thors fold up the bottom foot or so of housewrap to overlap the wrapped wall below.
`
`Compressed air is quicker than a
`broom. Where possible, the authors install
`housewrap on walls before the walls are
`raised. Compressed air is used to blow wood
`chips and other debris off a wall before the
`wrap is rolled out.
`
`found little or no difference in installation. Al-
`though Tyvek was specified for this project, we
`usually request Typar because its gray color is
`easier on the eyes than bright white housewraps.
`
`Housewraps are an effective product when
`installed correctly—Air-infiltration retarders
`enhance the thermal efficiency of exterior walls
`by reducing air movement through walls and
`into wall cavities. A properly installed wrap
`slows or stops wind- or pressure-driven air from
`moving freely through gaps and holes in sheath-
`ing or around window frames and door jambs.
`Reducing drafts makes a house feel more com-
`fortable and saves energy. At the same time,
`housewraps allow moisture vapor that enters
`the wall cavity to escape. Without this feature,
`moisture could build up, and rot could begin
`inside the wall.
`Before housewraps entered the market, we
`used 15-lb. tar paper or red rosin paper beneath
`our siding. We surmise now that tar paper did a
`pretty good job of reducing air infiltration and
`was waterproof.
`On occasion, tar paper caused us problems.
`Stains bled through wood siding, and dissolved
`tar leaked onto vinyl siding. During remodeling
`jobs, we sometimes find concealed rot caused
`by years of condensation behind tar paper.
`Rosin paper probably helped to reduce some
`air infiltration and to let moisture escape. But it
`disintegrated if it got wet before siding was in-
`stalled or if small leaks occurred around win-
`dows and along cornerboards. On remodeling
`
`Louisiana-Pacific Corporation, Exhibit 1022
`IPR of U.S. Pat. No. 8,474,197
`Page 2
`
`

`

`jobs we have uncovered old rosin paper that
`had practically turned to dust.
`
`Follow the directions and use common
`sense—The instructions supplied by housewrap
`manufacturers range from cursory to highly de-
`tailed. The one thing most companies include is
`a warning about securing ladders leaning
`against wrapped walls. The top of an unsecured
`ladder can slide sideways across the slick mate-
`rial. Our approach to installing air-infiltration re-
`tarders combines common sense and those
`recommended installation details that we be-
`lieve are feasible.
`Our system begins with a foam sill seal be-
`tween the foundation and the mudsill. If every
`effort is being made to create a tight seal, we
`caulk the bottom edge of the wall sheathing to
`the mudsill to prevent infiltration at that point.
`We once installed a 2-ft. strip of housewrap be-
`tween the sill-seal foam and the mudsill, ac-
`cording to the instructions of one manufacturer.
`The idea was to lift this flap and wrap it over the
`band joist after we raised the exterior walls. We
`found this detail frustrating; the material blew
`around on all but the calmest of days. And we
`cringed as the flap was shredded by cords, tool-
`belts and hoses before the walls were up. In spe-
`cial cases, such as when we're building a wall
`with siding applied directly to the studs, we still
`might use this detail. However, most manufac-
`turers' instructions say to staple the housewrap
`to the bottom edge of the sheathing and to cut
`the housewrap flush with the bottom of the
`sheathing. The first course of siding should hold
`the housewrap tight against the sheathing.
`
`Start with a clean wall—As a rule, we lay out,
`frame and sheathe exterior walls before lifting
`them. So it makes sense for us to wrap them as
`much as possible before they are lifted.
`First we sweep or blow off debris on the wall
`(photo left, p. 45). Anything we miss will leave
`lumps for the siding installers. One crew mem-
`ber positions the roll of housewrap on the al-
`ready-sheathed wall. A second person holds the
`starting edge and staples the housewrap to the
`sheathing lining up the housewrap just by eye
`(photo top right, p. 45). Because the sheathing
`extends beyond the bottom plate to cover the
`band joist, we don't staple the lowest 12 in. of
`housewrap (bottom photo, p. 45). This allows
`us to lift the wrap and nail off the sheathing later
`without punching hundreds of holes in the
`wrap. Stapling high also makes it easier to fold
`up any housewrap from the wall or sill beneath.
`We roll out about 10 ft. before stapling off the
`sheet. It's important to tack the first corner and
`then to pull the wrap tight in all directions. Once
`the first 10 ft. are well-tacked, we roll out 3 ft. to
`4 ft. at a time, stapling along the edge of the roll
`
`Tying up the loose end. At one end of the wall, the wrap is folded over the corner stud and sta-
`pled. After this wall is raised, sheathing from the adjoining wall will be nailed over the corner,
`holding the wrap in place.
`
`Corners are the last to be wrapped. On the opposite end of the wall, housewrap that earlier
`had been rolled up on a furring strip is unrolled and fastened in place, which happens after the
`framing is tied together with the final pieces of sheathing.
`
`Louisiana-Pacific Corporation, Exhibit 1022
`IPR of U.S. Pat. No. 8,474,197
`Page 3
`
`

`

`Housewrap is cut to fit framed window openings. Instead of the standard X-cut for a window opening, the housewrap is cut to cover just the
`framing to eliminate large flaps that are likely to tear in the wind.
`
`Sealing the corners. The authors try to tape the corner seams of the
`housewrap as soon as possible after the wrap is installed to prevent any
`possible wind damage.
`
`Extending your reach. For sections of housewrap that are hard to
`reach, such as between-floor seams, a hammer-stapler is taped to a fur-
`ring strip to make fastening much easier.
`
`Louisiana-Pacific Corporation, Exhibit 1022
`IPR of U.S. Pat. No. 8,474,197
`Page 4
`
`

`

`Tape discourages air infiltration around door and window openings. On windows and doors with nailing flanges, tape is applied so that it
`seals the seam between the flange and the housewrap.
`
`of housewrap. Staples are spaced every 16 in.
`along the edges and every 24 in. in the field.
`On one end of the wall, we leave the air barrier
`about 4 in. long and then wrap it and staple it to
`the corner stud (top photo, p. 46). Later, when
`the walls are raised, this 4-in. overlap will be cov-
`ered and held in place by the sheathing from
`the other wall that makes up that corner.
`When framing walls, we typically leave off the
`last 16 in. to 48 in. of sheathing on one end so
`that once the walls have been raised, we can
`come back and tie together the outside corners.
`On this end of the wall, we roll out enough
`
`housewrap to cover these unsheathed sections
`and to extend 1 ft. around the corner of the
`house. The loose wrap is rolled around an 8 ft.
`furring stick, which is then tacked to the wall.
`This keeps the housewrap from blowing in the
`wind and being torn off. After lifting the walls,
`we nail on the final pieces of corner sheathing,
`unroll the housewrap and staple it around the
`corner (bottom photo, p. 46).
`While the walls are on the deck, we take care
`not to step onto a housewrap-covered door or
`window opening. You can't fall any farther than
`the thickness of the wall, but a step on a win-
`
`dow opening will rip out the surrounding sta-
`ples in the housewrap.
`When we have to install housewrap after the
`walls are lifted, it's much tougher to keep the
`job straight and wrinkle-free because someone
`has to be holding up the roll, maintaining ten-
`sion on the wrap and unrolling the wrap all at
`the same time. Inside corners also can be a chal-
`lenge: You must be careful not to short-sheet the
`corner or not leave enough material to go all
`the way into the corner. Short-sheeting can be
`avoided by pressing the housewrap into the cor-
`ner with a furring strip before it is stapled.
`
`Louisiana-Pacific Corporation, Exhibit 1022
`IPR of U.S. Pat. No. 8,474,197
`Page 5
`
`

`

`More than one way to handle openings—At
`door and window openings, manufacturers sug-
`gest that an X-shape be cut in the housewrap
`with the slashes beginning in each corner of a
`door or window. The problem with this ap-
`proach, we've found, is that you're left with large
`triangular pieces flapping in the breeze.
`To prevent this, we feel for the edges of the
`openings, staple them off and then cut a rectan-
`gular piece out of the opening, about 3 in. small-
`er than the opening itself. We save the large rec-
`tangular pieces we cut out to fill in here and
`there. Staples fastened about every 16 in. to
`24 in. at openings prevent the wind from tear-
`ing off the wrap (top photo, p. 47). The house-
`wrap photographed for this article survived trop-
`ical storm Bertha unscathed.
`
`Second-floor wrap overhangs the first—Sec-
`ond-floor walls get the same basic treatment as
`first-floor walls. We make sure to leave enough
`housewrap overhanging the bottom edge of the
`sheathing to lap the first-floor housewrap by 6 in.
`to 8 in. We usually have to fill in a foot or two of
`housewrap at the top of the wall with strips from
`the roll or with the pieces we saved from the
`window cutouts.
`When you're installing housewrap, it doesn't
`matter whether the writing is right side up or up-
`side down, but air barriers do have an inside
`and an outside. Manufacturers don't tell you to
`install their wraps with the printed side facing
`out just for free advertising. (We've been waiting
`for some town to impose a fine either on the
`housewrap manufacturer or the builder for vio-
`lating a local sign ordinance. We can't put a
`small sign in the yard to advertise our company,
`but Tyvek can turn a whole house into a bill-
`board.) The material's performance may be di-
`minished if it's installed inside out.
`We handle the intersection of walls and roofs
`in a couple of different ways, depending on the
`soffit detail. On a house with a trussed roof, we
`cut the housewrap along the top of the second-
`floor top plate and nail a soffit nailer to the wall
`over the housewrap. The nailer ensures that the
`top edge of the wrap won't be caught by the
`wind and torn off the house.
`On roofs with regular rafters, we usually don't
`use soffit nailers, so we wrap the air barrier over
`the wall and staple it to the top of the lower top
`plate. The second top plate holds the house-
`wrap securely.
`In winter we often get freezing rain that can
`encase our framing for days or weeks. When
`we're concerned that a top plate will become
`coated, we extend the housewrap up and over
`the top plate a few inches. After the walls are
`lifted, we staple the extra wrap inside the wall.
`We don't cut off the excess until we're ready to
`set roof rafters or trusses. This approach can save
`
`a lot of time chipping and scraping ice off the
`top plate. Once the walls are up, we fill in the
`wing walls, dormers and other areas that are im-
`practical to prewrap. For those hard-to-reach
`spots when stapling housewrap, we duct-tape
`our hammer-stapler to a 1x2 furring strip for an
`extra bit of reach (photo bottom right, p. 47).
`
`Seam tape finishes the job—To get the best
`performance from housewraps, we seal the
`seams with seam tape (photo bottom left, p. 47).
`Seam tape adheres aggressively to housewraps
`but still needs to be pressed on by hand for best
`results. We tape what seams we can while walls
`are down. After the walls are lifted, we tape all
`the seams we can reach easily right away to
`lessen wind damage. We leave the second-floor
`overlap and other high seams for our siding in-
`stallers to tape while they're on their staging,
`which is safer than working from a ladder.
`Sealing windows and doors is easy when they
`have nailing flanges. We just tape the flanges
`(photo facing page). When we install windows
`with wood casings or brick mold, we first caulk
`the backside of the window between the cas-
`ing and the jamb. Next we run a bead of caulk
`around the opening of the housewrap. We place
`the unit in the rough opening and press it in
`place. The caulk seals the unit to the housewrap.
`Occasionally, flanged windows are installed
`before the housewrap goes on. That's no prob-
`lem; we simply trim the wrap to the edge of the
`flange and then tape. We also tape any punc-
`tures or tears bigger than
`in.
`We've seen some crews lapping housewrap
`over window and door flanges and over step
`flashings in an effort to better waterproof their
`houses. But we never rely on housewrap for this.
`Most wraps will resist water during construction,
`but manufacturers note that their products
`aren't waterproof. Don't use them in place of
`standard flashing materials. There are materials
`and details that we use to make our homes
`more watertight (such as self-adhesive rubber-
`ized membranes and copper flashings), partic-
`ularly those that are near the ocean.
`We never bother lining up the 8 in. o. c. marks
`printed on some air barriers with the framing.
`We've found the marks to be consistently in-
`consistent. They commonly vary
`in. or more in
`8 ft. The marks could be useful, but we rarely
`get a roll that maintains proper spacing.
`Be sure to wear sunglasses when working with
`any of the white wraps. The reflection on a sun-
`ny day can be blinding.
`
`Rick Arnold and Mike Guertin are contributing
`editors to Fine Homebuilding. They also are part-
`ners in U. S. Building Concepts Inc., a construc-
`tion-consulting and management business. Pho-
`tos by the authors, except where noted.
`
`Skip the
`housewrap,
`tape the
`sheathing?
`The whole point of using and
`properly installing an air barrier is
`stopping the uncontrolled flow of
`air into and through a house's wall
`cavities, and permitting moisture
`vapor within walls to escape.
`Because the homes we build are
`fully sheathed, the only places that
`air and moisture can enter wall
`cavities are through the seams
`between the sheathing, through
`holes in the sheathing and through
`the connections between framing
`and sheathing. With a new tapelike
`product called Gap Wrap
`(Benjamin Obdyke Inc., John Fitch
`Industrial Park, 65 Steamboat
`Drive, Warminster, Penn. 18974-
`4889; 800-523-5261), these areas
`can be sealed. Moisture that enters
`the wall cavity eventually will
`make its way out through the
`sheathing and siding. The issue
`then becomes whether housewrap
`is necessary.
`A product such as Gap Wrap has
`some advantages and some
`limitations. It's cheaper than
`housewrap and requires less labor
`to install. The 4-in. tape can be
`applied by one person, regardless
`of wind conditions. Some
`additional caulking may be
`necessary in areas that don't lend
`themselves to being sealed with
`tape, such as wood-to-concrete or
`wood-to-metal connections,
`especially in cold weather.
`Installing Gap Wrap on oriented
`strand board (OSB) can be tricky.
`We've found that the tape does not
`adhere as well to the coarser
`surface of some OSB panels as it
`does to plywood, but the company
`is working on a glue for OSB.
`There are situations where a
`product such as Gap Wrap won't
`work. On buildings where siding or
`T-111 plywood is applied directly to
`the framing, for instance, properly
`installed housewrap will create a
`better air barrier.—R. A. and M. G.
`
`Louisiana-Pacific Corporation, Exhibit 1022
`IPR of U.S. Pat. No. 8,474,197
`Page 6
`
`