Hydrogap Drainable Housewrap


HydroGap – The Best-Performing Housewrap. Period.


3rd party testing* shows that HydroGap REMOVES over 93% of bulk water while the leading housewrap TRAPS over 99%.

Did you know that major siding manufacturers, such as James Hardie and Boral, have recently issued drainage requirements behind their products? Drainable housewraps with a drainage efficiency of at least 90% when tested according to ASTM E2273 are now recommended or required behind certain exterior sidings.

Drainage efficiency isn't the whole story. We suggest that you question how long it takes to reach the 90% – how fast does your housewrap remove the moisture? The longer moisture remains trapped, the longer it has to cause mold, rot and premature failure.

HydroGap Drainable Housewrap eliminates excess moisture in a matter of minutes and prevents the damaging effects of mold and rot. Its unique design provides up to two times the performance over other drainable housewraps and removes over 100 times more bulk water than standard housewraps.

* As tested by CTL Group

Why it Works

See how our patented 1mm spacers provides a continuous drainage gap.

Fiber cement over HydroGap

Fiber cement over flat housewrap

Head to Head: HydroGap vs. Standard Flat Housewrap

Infographic Download

View all the benefits of using HydroGap over the leading housewrap by downloading our InfoGraphic.

Features & Benefits



1mm Gap

Removes 100x more bulk water versus standard housewraps & drains 2x faster than other drainable housewraps

Tri-laminate Substrate

Superior strength & water hold out. Moisture barrier layer is protected between two non-woven layers


Allows installation in any direction, reduces waste

Compression-resistant spacer

Allows for a consistent 1mm gap behind your cladding

Vapor permeable

Will not trap moisture within the structure

97% drainage rate (ASTM 2273)

Meets all existing codes for drainability

UV Sustainability

Can be exposed for 120 days

Easy to install

No special tools or design changes required

5ft x 100ft roll

Allows for convenient one-person installation

Non-slip / non-glare surface

Reduces risk of slipping and does not reflect sunlight


HydroGap vs. Standard Housewraps

Typical housewraps usually are either 1 or 2 layers and can be either woven or non-woven.

HydroGap has a 3 layer, non-woven substrate to provide superior tear, water and air resistance.

Typical housewraps provide only a water-resistant barrier which can trap water behind claddings.

HydroGap's drainage space removes 100x more bulk water while acting as a water-resistant barrier.

HydroGap vs. Slicker Rainscreen

Hydrogap combines a water-resistant barrier and drainage system into a single product application.

Slicker provides the maximum amount of drainage but does not offer a water-resistant barrier.

Hydrogap is ideal for areas that receive lower levels of rainfall and moisture and behind claddings that do not need to be ventilated.

Slicker provides superior drainage and ventilation for maximum drying potential in locations with high wind-driven rain and behind moisture-absorptive claddings.

HydroGap Compatibility

Based on Location & Cladding

The amount of moisture in your location greatly effects the type of exterior moisture management solution you choose. HydroGap is recommended under the following claddings within the shaded rainfall exposure areas:

Rainfall Amounts

Rainfall Amounts

Rainfall Amounts

Consider This

Claddings such as wood and stucco and manufactured cement are porous and therefore absorb more moisture than others. Given this, they also need the ability to not only drain but to also dry. In order to achieve this, ventilation is required. A Rainscreen application would be the better way to build your wall assembly, it provides drainage as well as enough space to allow for continuous airflow to dry out the cladding.

HydroGap Approved Compatible Products

  • Fiber Cement
  • Wood (including shingles & shakes)
  • Vinyl & Insulated Vinyl
  • Manufactured Stone
  • Stucco
  • Metal
Self-Adhered Flashing
  • Benjamin Obdyke HydroFlash®*
  • OSI® WinTeQ™ TeQ::Flash™ BUTYL Flashing
  • Protecto Wrap® Super Stick Building Tape™
  • 3M™ All Weather Flashing Tape 8067
  • Venture Tape V785 VentureFlash
  • JELD-WEN Self-Adhered Flashing
  • DuPont™ StraightFlash™
  • Pella® SmartFlash™ BUTYL Flashing
  • Nitto Denko No. 6922 (Double-Sided)
  • Staples
  • Cap Fasteners*
Seam Tape
  • Benjamin Obdyke HydroFlash® 2.5"
  • Or 4" width self-adhered flashing from list below to the left
Sill Treatments
  • Benjamin Obdyke HydroFlash®*
  • Benjamin Obdyke HydroFlash® and HydroCorner®*
  • SureSill™
  • Minimum 9" self-adhered flashing
  • See self-adhered flashing list
Caulks & Sealants
  • OSI® WinTeQ™ TeQ::Seal™ Sealant
  • Loctite® Premium® construction adhesive
  • Loctite® PL Premium® S40 polyurethane
  • GeoCel® 2300 Construction Tripolymer
  • GeoCel® Pro Flex®
  • Fortifiber® Moistop® Sealant
  • Bostik® 915™ polyurethane sealant
  • Bostik® 915FS™ polyurethane sealant
  • Dow Corning® 732 multi-purpose sealant
  • NPC® Solar Seal #900
  • Titebond® Heavy Duty construction adhesive
  • Titebond® WeatherMaster™
  • Titebond® WeatherMaster™ ULTIMATE MP
  • Tremco® Vulkem® 116
  • DAP® Flexible CLEAR Sealant


Application & Installation

Custom Garage - Quakertown, PA

This video details how to install HydroGap® Drainable Housewrap and HydroFlash® Self-Adhered Flashing.

Custom Home - Lewes Beach, DE

This video uses building science technical data to show how HydroGap maintains space between the siding and the wall.

Custom Home - Lewes Beach, DE

This video demonstrates how to install HydroCorner Sill Treatment to windows.

From the Jobsite

Custom Garage - Quakertown, PA

Custom builder, Brooke Rush, explains why he choose Hydrogap for this custom garage.

Custom Home - Lewes Beach, DE

Paul Camenisch explains why he chose a Slicker rainscreen over a drainable housewrap.

Technical Specs & Information



Test Standard

AC 38 Test Requirement

HydroGap Results

Dry Breaking Force

ASTM D 5034

Machine ≥ 40lbf
Cross Machine ≥ 35lbf

Machine 58.04 lbf
Crosswise 50.64 lbf

Hydrostatic Head

AC38 Section 3.3.2 (4.2.1)

Withstand 55cm of water for period of 5 hours

PASS - no penetration

Water Ponding

CCMC Guide MF07102

No water observed passing through membrane


Boat Test

ASTM D-779

Water resistance by dry indicator method


Water Vapor Transmission


Minimum Permeance (perms) 5
Min. Vapor Transmission 35 (g/24 . m2)

Method A: 16 perms
Method B: 14 perms
Transmission: (g/24 . m2) 104.6

Cold Mandrel Bend

AC38 Section 3.3.4

No cracking at 1/16" diameter bend with temperature: 32°F

No cracking

Air Permeance

ASTM E 2178

At 75 Pa calculated Flow rate ≤ 0.02 L/(s.m2)

Metric: 0.0082 L/(s.m2)
Standard: 0.0161 cft/(min.ft2)

Drainage Efficiency

ASTM E 2273

Min. Drainage Efficiency ≥ 90%

96% Drainage Efficiency

Surface Burning Characteristics


Flame Spread Index (FSI) < 100
Smoke Developed Index (SDI) < 450

FSI = 0
SDI = 75

Ultraviolet Light Exposure

AC38 Section 4.1.2

UV exposure of 210 hours


For the Homeowner

Why moisture management is important

Increasingly, builders, contractors and architects face the need to incorporate good moisture management solutions when designing and building structures to ward off problems such as mold, mildew or structural damage due to improper moisture management.

Outside Pressure

The pressure outside your house is greater than the pressure within. Combine that with exposure to wind and if proper moisture management is lacking, then water has the potential to be driven into your wall.

How moisture can get in

Consider just how many holes are protruding through your wall. This example shows the potential for hundreds, even thousands, of holes for moisture to enter. A good moisture management solution is needed to prevent the water from entering your wall.