Should You Wrap Your House In A Blanket? Exploring The Pros And Cons Of House Wrap Over Wood Siding

House wrap is a protective layer that prevents rain, sleet, and snow from entering the wall cavity of a house, thus preventing wood rot, mould growth, and flooding. It is not completely impermeable, and water can still enter the wall cavity from inside the house. House wrap is typically installed over the sheathing and behind the siding.

While it is possible to install house wrap over existing wood siding, it is not recommended. If the existing siding is removed, it is possible to add a moisture barrier and then install the house wrap before adding new siding. This is considered the best way to ensure the house wrap is effective and avoids trapping moisture.

House wrap should be installed over sheathing and behind siding

House wrap is a protective layer that goes around a house's exterior to prevent rain, sleet, and snow from seeping into the wall cavity. It is important to note that house wrap is not completely impermeable or waterproof. While it blocks moisture from entering the wall cavity of the home, it is designed to be permeable to allow moisture to escape from the inside of the home.

House wrap is intended to be installed over the sheathing and behind the siding. It is a lightweight, paper-like material that is placed between the siding and the sheathing. This means that if you are planning to install house wrap, you should consider removing the existing siding, adding sheathing, then installing the house wrap before reinstalling the siding.

The process typically involves repairing any rot or damage to the existing structure, adding furring strips or foam insulation, and then installing the house wrap. The house wrap should be stapled or nailed securely, with proper flashing and taping at the seams and around window openings.

It is important to choose a durable house wrap with high water resistance and UV protection. The ideal perm rating for house wrap is between 10 and 20 perms, balancing inward and outward moisture flow. You can also consider adding foam insulation between the vinyl and the house wrap to increase its effectiveness.

House wrap is considered a necessity by most contractors and housing authorities, as it provides extra protection against moisture and improves the insulative abilities of the home. While it may not be required by local building codes, it is strongly recommended to help prevent water and air leaks, as well as reduce the risk of wood rot and mould growth.

House wrap is not completely impermeable or waterproof

House wrap is an important feature of any building, protecting it from the elements. It is a synthetic material that acts as a water-resistive barrier (WRB) and is designed to prevent rain, sleet, and snow from seeping into the structure. House wrap is also effective at preventing wood rot, mould growth, and flooding.

However, it is important to note that house wrap is not completely impermeable or waterproof. While it does a good job of preventing water from entering the wall cavity from the outside, water can still enter the wall cavity from inside the home. If water becomes trapped in the wall and is unable to escape through the house wrap, it can create rot, mould, and mildew issues.

House wrap is permeable, allowing moisture to exit the home instead of becoming trapped inside the wall cavity. This permeability is measured in US perms, with one perm equal to one gram of water vapour per hour per square foot per inch of mercury. Most house wrap products have a perm rating between five and 60 perms, with the ideal rating falling between 10 and 20 perms. This balance ensures effective moisture protection while also allowing moisture to exit the home.

The durability of the house wrap is a critical factor to consider. House wrap remains in place for years, so it needs to be durable enough to withstand potential splitting, tearing, or cracking. When choosing a house wrap, consider the tensile strength of the material, its resistance to temperature extremes, and its resistance to surfactants that may be present in housing materials.

Additionally, it is important to understand that house wrap is not intended to be an effective air barrier. Only a few specialised products are designed to prevent cold air from entering wall cavities, and they must be installed meticulously.

In summary, while house wrap provides excellent protection against moisture entering a structure, it is not completely impermeable or waterproof. It is essential to choose a durable and permeable house wrap product and to ensure proper installation to maintain the integrity of the building envelope.

House wrap does not always serve as an effective air barrier

House wrap is a protective layer that covers the exterior sheathing of house walls to protect the wall framing. It is designed to protect homes from rain, sleet, snow, and other types of moisture that may seep through the exterior siding.

While house wrap is an effective barrier against moisture, it does not always serve as an effective air barrier. Most types of house wrap are not designed to prevent cold air from entering wall cavities. Only a few special products can perform this function, and they must be installed meticulously to create a reliable air barrier.

Staple-up house wraps, such as Tyvek, are challenging to detail as an air barrier. The staple holes in these types of house wraps can allow air to pass through. Additionally, rips and tears in the house wrap caused by ladders during installation can also compromise its effectiveness as an air barrier.

To improve the air sealing of a staple-up house wrap, it is recommended to tape the plywood seams. This approach is more straightforward than trying to detail the house wrap itself as an air barrier.

In summary, while house wrap is essential for protecting against moisture, it may not always be effective at preventing air infiltration. For an optimal barrier against air and moisture infiltration, it is crucial to select the appropriate type of house wrap and ensure careful installation.

The durability of the house wrap is key

House wrap is a protective layer that covers the exterior sheathing of house walls to protect the wall framing. It is designed to protect the home from rain, sleet, snow, and other types of moisture that may seep through the exterior siding.

The primary purpose of house wrap is to prevent water from reaching the wall cavity of the home, so it is necessary to find a product with a high level of water resistance. House wrap is designed to be permeable so that moisture can exit the home, instead of getting trapped inside the wall cavity. However, it is important to select a product with the right balance of permeability to prevent water from entering the wall cavity. The ideal perm rating for house wrap tends to fall between 10 to 20 perms, balancing the inward and outward flow of moisture in the wall system.

UV stability is another important factor to consider when choosing a house wrap. If the house wrap is not resistant to UV radiation, it can begin to break down during the construction period, so it is recommended to invest in a house wrap with built-in UV protection.

In summary, the durability of the house wrap is crucial to its effectiveness in protecting the home from moisture damage. When selecting a house wrap, it is important to consider factors such as tensile strength, temperature resistance, surfactant resistance, water resistance, and UV stability to ensure the product will provide long-lasting protection for the home.

House wrap is not always necessary

House wrap is a protective layer that prevents water, snow, and sleet from entering the wall cavity of a home, thus preventing wood rot and mould growth. It is mostly made of permeable materials that allow water vapour to pass through while preventing water droplets from getting through. However, house wrap is not always necessary, and there are situations where it can be skipped.

Firstly, house wrap is not always required by local building codes. While it is a crucial component of construction in many areas, some locations do not mandate its use. Therefore, if your city's building codes do not require house wrap, you might be able to forgo it. However, it is important to note that most building professionals still recommend installing house wrap, even if it is not mandatory, as it provides added protection for your home.

Secondly, if you already have sheathing installed on your home, you may not need house wrap as urgently. Sheathing, such as T111 plywood siding, can act as both a cladding and shear layer, providing some protection against the elements. In this case, you may prioritise weatherproofing and insulating your home over installing house wrap.

Thirdly, if you are working on a tight budget, you may consider forgoing house wrap to cut costs. While it is a valuable investment for protecting your home, it can be expensive, with basic house wrap material costing around $0.40 to $0.60 per square foot. The installation can also add to the overall expense.

Finally, if you are working on a time-constrained project, you may opt to skip house wrap to save time. Although it is typically a quick project that only takes a day or two, forgoing it can help expedite your remodelling or construction timeline.

In conclusion, while house wrap is highly beneficial for protecting your home from moisture and improving energy efficiency, there are situations where it may not be necessary. These include cases where it is not required by local building codes, when alternative protective measures are in place, or when budget and time constraints are a factor. However, it is always recommended to consult with building professionals and contractors to make an informed decision based on your specific circumstances.

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