Do you report the absence of house wrap?

I know that just because you see a water resistive barrier behind vinyl siding, doesn’t mean it exists everywhere. I know that.

But when you’ve confirmed that it’s absent in many areas and likely absent everywhere, do you report it?

Do you report it as a significant issue? What do you say are the potential consequences? Does the age of the home have a bearing on whether or not you report its absence?

Inquiring minds want to know.

House wrap is not a “vapor barrier”.

House wrap is not a “vapor barrier”. In fact, it is specifically designed to allow vapor to pass through it.

I report it, lack of eave protection / roofing felts too. The problem is, what is the recommendation? Remove all exterior / roof cladding to add, I don’t think so.

I explain the purpose of the materials and the implications of them not being present, I sometimes recommend that they be installed when the cladding is replaced (if it’s near end of life).

Thanks. “Water resistive barrier” is the correct term.

Here’s the 2009 IRC code:

"R703.1.1 Water resistance. The exterior wall envelope shall
be designed and constructed in a manner that prevents the accumulation
of water within the wall assembly by providing a
water-resistant barrier behind the exterior veneer as required
by Section R703.2 and a means of draining to the exterior water
that enters the assembly. Protection against condensation in the
exterior wall assembly shall be provided in accordance with
Section R601.3 of this code.

Exceptions:1. A weather-resistant exterior wall envelope shall not
be required over concrete or masonry walls designed
in accordance with Chapter 6 and flashed according
to Section R703.7 or R703.8.

  1. Compliance with the requirements for a means of
    drainage, and the requirements of Section R703.2 and
    Section R703.8, shall not be required for an exterior
    wall envelope that has been demonstrated to resist
    wind-driven rain through testing of the exterior wall
    envelope, including joints, penetrations and intersections
    with dissimilar materials, in accordance with
    ASTM E 331 under the following conditions:
    [INDENT]2.1. Exterior wall envelope test assemblies shall include
    at least one opening, one control joint, one
    wall/eave interface and one wall sill. All tested
    openings and penetrations shall be representative
    of the intended end-use configuration.

2.2. Exterior wall envelope test assemblies shall
be at least 4 feet (1219 mm) by 8 feet (2438
mm) in size.

2.3. Exterior wall assemblies shall be tested at a
minimum differential pressure of 6.24 pounds
per square foot (299 Pa).

2.4. Exterior wall envelope assemblies shall be
subjected to the minimum test exposure for a
minimum of 2 hours.

The exterior wall envelope design shall be considered
to resist wind-driven rain where the results of testing
indicate that water did not penetrate control joints
in the exterior wall envelope, joints at the perimeter of
openings penetration or intersections of terminations
with dissimilar materials.

[/INDENT]**Commentary: **As part of providing a weather-resistant exterior envelope,
exterior walls are required to provide water resistance.
This section prescribes two basic components of providing
water resistance for an exterior wall assembly: a water-
resistive barrier installed between the covering and
substrate of the exterior wall and a means of draining
moisture that may penetrate behind the exterior wall assembly
back to the exterior. Section R703.2 is referenced
for the requirements of the water-resistive barrier
(see commentary, Section R703.2). This section
does not, however, contain a prescriptive requirement
for the means of drainage. The method to provide the
means of drainage is a performance criterion and must
be evaluated based on the ability to allow moisture that
may penetrate behind the exterior wall covering to effectively
drain back to the exterior. This can be
achieved in many ways including, but not limited to,
providing a rain-screen pressure-equalized type of exterior
assembly, or providing discontinuities or gaps
between the surface of the substrate and the back side
of the finish, such as through the use of noncorrodible
furring or two layers of Grade D paper.
For common types of construction, such as vinyl siding
or brick veneer, the typical practice of installing building
paper, flashing and weeps will comply with the intent
of this section. For stucco or adhered masonry veneer,
installing two layers of Grade D paper and flashing will
comply with the intent of this section. Discontinuities between
the exterior wall covering and substrate must be
such that they encourage the flow of moisture via gravity
or capillary action to a location where the water may exit,
such as at flashings and weeps. The absence of a
means of drainage may result in the accumulation of
moisture that becomes trapped between the wall covering
and the substrate. Over time, extended exposure to
moisture may contribute to the degradation of the wall
covering, building substrate or even the structural elements
of the exterior wall.
Exception 1 states that where the exterior wall envelope
is designed and constructed of concrete or masonry
materials in accordance with the requirements
of Chapter 6 and flashed in accordance with Section
R703.7 or R703.8, the water-resistive barrier and a
means of drainage may be omitted. This is because
the penetration of moisture behind the exterior wall
covering is not detrimental to concrete and masonry substrates.
Exception 2 permits the use of exterior wall coverings
that do not have a means of draining water or meet the
prescriptive requirements of Sections R703.2 and
R703.8, provided that the exterior wall envelope, with
penetration details, demonstrates wind-driven rain resistance
when tested. The test specimen(s) must incorporate
the penetration and termination details intended for
use. Only details that have not allowed water to penetrate
will be permitted to be used in the exterior wall envelope.
The minimum panel size specified represents
that which is commonly used in testing to ASTM E 331;
however, this does not preclude the testing of larger panels
if desired. The modifications to the test pressure differential
and test duration are intended to represent
more closely conditions that will be encountered in service.
The pass/fail criterion is based on the visual observation
of moisture on the interior side of the wall assembly.
For frame-type wall assemblies, such as stud walls,
this requires the observation of locations such as the interior
face of the exterior wall sheathing and wall framing
members for the presence of moisture during the test.
The test method is intended to assess the performance
of the method(s) and material(s) used to seal the interface
between the termination of the exterior wall covering
and the penetrating item(s) or abutting construction.
The test is not necessarily intended to test the performance
of the penetrating item.
Walls designed and constructed in accordance with
this chapter must also comply with the requirements of
Chapter 11 of the code. This requires that frame-type
wall assemblies be protected from moisture infiltration
from the building interior through the use of a vapor retarder
(see Commentary FigureR703.1) or by the ventilation
of the wall cavity within a frame-type wall assembly."

"R703.2 Water-resistive barrier. One layer of No. 15 asphalt
felt, free from holes and breaks, complying with ASTM D 226
for Type 1 felt or other approved water-resistive barrier shall be
applied over studs or sheathing of all exterior walls. Such felt or
material shall be applied horizontally, with the upper layer
lapped over the lower layer not less than 2 inches (51 mm).
Where joints occur, felt shall be lapped not less than 6 inches
(152 mm). The felt or other approved material shall be continuous
to the top of walls and terminated at penetrations and building
appendages in a manner to meet the requirements of the
exterior wall envelope as described in Section R703.1.

Exception: Omission of the water-resistive barrier is permitted
in the following situations:

  1. In detached accessory buildings.

  2. Under exterior wall finish materials as permitted in
    Table R703.4.

  3. Under paper backed stucco lath when the paper backing
    is an approved water-resistive barrier.

Commentary: Asphalt-saturated felt or any other approved water-resistive
material is required behind all types of materials
used as exterior wall coverings because of the possibility
of moisture penetrating the substrate behind it.
This felt or other material protects the wall construction
from potential rotting.

The water-resistive membrane may be omitted
where there is a low possibility of moisture penetration
or the potential for moisture penetration is not a great
concern. The water-resistive membrane may be eliminated
when approved paper backed stucco lath is
used; the paper backing functions as the membrane if
the backing paper is not punctured. The paper backing
must be an approved water-resistive sheathing paper."

I think I shall start reporting it. There is no solution, but the information could help a buyer make an informed decision. I would not want to buy a house without it…“what else did the builder scrimp on” would be going through my mind.

I’ve not even been looking for it, since just because you see it doesn’t mean it’s everywhere nor does it mean it’s put on right.

But I had a house today with water intrusion in the wall, probably due to a poor flashing job and the lack of house wrap.

I don’t think it was in the IRC until 2006. Does anybody know?

Weather resistant barrier is the term more commonly used in building science. That term is inclusive for air leakage/exchange and other functions.

I caught a brand new home with vinyl siding without house wrap, a few months back. The buyer had to argue with the local building inspector, before the building inspector agreed to make the home builder tear off the siding and install house wrap.

The one I did yesterday was 2 years old. I see the requirement in the IRC as far back as 2000 (that’s the oldest book I have).

From the Vinyl Siding Institute.

The Vinyl Siding Institute (VSI) is the trade association for manufacturers of vinyl and other polymeric siding and suppliers to the industry.

**[FONT=HelveticaLTStd-Bold][size=4]Water-Resistive Barrier

[/size][/FONT]*[FONT=HelveticaLTStd-BoldObl][size=3]Vinyl siding has always been designed as an exterior cladding, not a water-resistive barrier.
Vinyl siding is designed to allow the material underneath it to breathe; therefore, it is not a watertight covering.

***[/size][/FONT][FONT=HelveticaLTStd-Roman][size=3]Because of its design and application, it provides a supplemental rain screen that enhances the water-resistive barrier system by reducing the amount of water that reaches the underlying water-resistive barrier.

[/size][/FONT]**[FONT=HelveticaLTStd-Bold][size=3]What Is a Water-Resistive Barrier System?
**[/size][/FONT][FONT=HelveticaLTStd-Roman][size=3]It is a system that includes water shedding materials
and water diversion materials. Water-resistive barrier systems commonly consist of a combination[/size][/FONT]
[FONT=HelveticaLTStd-Roman][size=3]of exterior cladding, flashed wall openings and penetrations, water-resistive barrier material, and
Effective water-resistive barrier systems will shed the water initially, control moisture flow by capillary and diffusion action, and minimize absorption into the wall structure. The level of water resistance required is determined by the applicable building code and structure.

[/size][/FONT]**[FONT=HelveticaLTStd-Bold][size=3]Best Practice:
**[/size][/FONT][FONT=HelveticaLTStd-Roman][size=3]To achieve designed performance, vinyl siding must be installed over a water-resistive
barrier system that includes

  1. a continuous water-resistive material and
  2. properly integrated flashing around all penetrations and where vinyl siding interfaces with other building products such as brick, stone, or stucco.

Refer to the manufacturer’s instructions for specific product applications and recommendations.
Whichever product(s) you decide to use as part of a water-resistive barrier system, be certain the materials meet the applicable building code by contacting the manufacturer of the waterresistive barrier material(s).
Always consult the applicable building code for minimum water-resistive barrier requirements in your area. Keep in mind that additional measures may provide better protection against water intrusion than the minimum requirements of the building code.

  • Air Barrier: Retards air passage, is water vapor permeable, and is liquid moisture resistant. Air barriers are assumed to be vapor permeable because they are commonly installed on the cold side of exterior walls where a vapor retarder might be inadvisable. If a vapor retarder is appropriate in such a location, don’t call it an air barrier, even though it does perform that function. Air barriers offered are mechanically fastened sheets (“housewraps”) and spray or roller applied coatings. An air barrier can function as a water-resistive barrier (see below).

  • Vapor Retarder: Retards passage of both air and water vapor. Must be sealed at joints and penetrations. Vapor retarders are used on the “warm” side of walls to preclude condensation inside the wall or insulation. Vapor retarders offered are mechanically fastened sheets, self-adhesive sheets, mastic and spray coatings.

  • Water-resistive barrier: Neither air barrier nor vapor retarder but is liquid moisture resistant. Water-resistive barriers only protect the construction from damage due to precipitation. (The term “water-resistive barrier” is from the ICC International Building Code, 1404.2, which requires a minimum of one layer of No. 15 asphalt felt behind exterior wall veneer, unless other conditions are met.) Water-resistive barriers offered are No. 15 asphalt felt, waterproof Kraft building paper, and “housewrap” sheets installed lapped but not sealed. An air barrier can be used as a water-resistive barrier.
    Many other materials and components specified in other sections can make up part of the entire “weather barrier”. This section does not contain any provisions that define the air or vapor performance of those other materials.


Been calling it out for years regardless of what the local AHJ says.
Doesn’t make me many friends either except for the clients.

with Vinyl Siding
Only method of repair is to strip and replace…

I always lift vinyl or aluminum siding at several locations to look for the presence of a weather barrier. When missing, I do include the purpose of weather barrier systems in the report, with a photograph of the bare sheathing. Have found many homes constructed in the 1990’s and early 2000’s without any barrier. Never had a client too concerned, yes the agents typically are not too happy! I recently had a water intrusion issue in my home constructed 1988. The “builder” neglected to cover the damaged wall with Tyvek, water seeped behind the siding and eventually destroyed the OSB and entered the wall cavity. A proper weather barrier with drainage would have prevented the damage.

I was mistaken earlier. The first code requirement for a water resistant barrier behind vinyl was 2006 (IRC). See table R703.4 if you want to look it up.

I find it (lack of) often, especially with vinyl and OSB. Some AHJ and builders enforced using a WRB and some didn’t. More are starting to.

This it what I write, leave it up to buyer to decide how important it is.

There was no water-resistive barrier visible at random sample locations at the exterior sheathing (OSB). Vinyl siding has always been designed as an exterior cladding, not a water-resistive barrier. Vinyl siding is designed to allow the material underneath it to breathe; therefore, it is not a watertight covering. Most of the model building codes, and thus the local codes based on them, recognize that the manufacturer of a product usually has a good idea of how its product should be installed in order to provide best performance. However this type (the way it is currently installed) of installation may have been recognized by the local building codes at time of construction.

Best Practice: To achieve designed performance, vinyl siding must be installed over a water-resistive barrier system that includes 1) a continuous water-resistive material and 2) properly integrated flashing around all penetrations.

LINK: Vinyl Siding Institute, Inc. F.A.Q

2006 around here.
Any newer home I will peek around the windows to make sure they are tapes as well as house wrap.
Was looking one day and found the only sheet of osb that did not have the pre-installed barrier on it. Must have ran out. oops!

The 2000 and 2003 IRC say “No” to a required “weather resistant sheathing paper” under the siding. See Table 703.4. In 2006, the IRC changes that box in Table 703.4 to a resounding “YES”! (thank god), and barriers like “Housewrap” have been selling like hot cakes ever since…

The earlier thread here presented the code nicely on this subject , but stopped at the exceptions to the requirements for a barrier behind the siding… Section 703.2 exceptions (Exception #3 in the 2000 and 2003 versions and Exception #2 in the 2006 version) takes you to Table 703.4. That little table is critical to determining whether or not a barrier is required behind different types of siding materials…

So, call it out as a deficiency if the house was built to the 2006 code or newer versions, but if built to 2003 or earlier veriosn, you can’t call it out as non-compliant with the Code, but:

(1) you can point out that newer versions of the code now require the barrier, because it is a really good idea…


(2) if you can find out who manufacturered the siding when the home was built, and can find that their installation directions specifiy using the barrier, then regardless of what Table 703.4 says, the barrier is required. Period. The Code aways defaults to following manufacturer instructions… (IRC Chapter1)