Building Wraps & Underlays

About Building Wraps and Underlays

Building and house wraps are weather-resistant barrier systems that protect a house from moisture getting in through the walls. They perform similar functions, but underlays and building wraps or building papers are used for different areas of a house. The building wrapping paper forms a walling layer, while house wraps are usually made from synthetic materials.

An underlay is a moisture-proof barrier placed in between the top floor and subfloor layers. It's a thin covering, which makes the installation of other floor materials simple to complete. Homeowners can also use construction fence wrap, which is useful to protect new fencing and limit visibility from outside. 

However, installing high-quality building wraps and underlays are not the only methods to control moisture. Property owners must also be familiar with tanking and waterproofing measures.

Advantages and Application

Building wraps and underlays are designed so that they keep moisture from getting into the home’s walls, flooring, or roofing and causing rot and mould. Just like waterproofing tapes and sealants, using building wraps and underlays can lengthen the life of the materials that make up the home or building. It also means a large financial saving on replacing rotten materials over time. 

The application of the house or building wrap to walls is fairly straightforward. It does require some prior home DIY knowledge, however. 

Water-resistant Barrier vs. House Wraps

House wraps, water-resistant barriers (WRB) and rain screens are terms people use interchangeably. This can be confusing; while similar, they have different uses. House wraps are a type of WRB, but not every WRB is a house wrap. 

WRBs are water-repellent products installed behind cladding or siding to form secondary barriers. They can be made out of are several different materials and vary in design. 

Types

House Wraps 

House wraps and underlays are highly effective in keeping water out of the home. There are several types and styles of house wraps and building underlays available. 

Felt Paper

Felt paper house wrap products are less commonly used than in the past. It is still available, however, and is a worthwhile choice. 

Micro-Perforated

Micro-perforated house wrap is a great choice for good ventilation. It has tiny perforations to allow healthy air permeation.

Films Laminated

Films laminated wrap is highly designed to resist water penetration. It is a great choice for areas that get a lot of rain. 

Drainable

Drainable house wrap provides a continuous drainage gap. This helps to further prevent water or condensation moisture from causing rot to set in.

Underlays

Polyurethane Foam

PU foam is lightweight and comfortable. It comes in a variety of densities and thicknesses. It is also earth-friendly as it can be recycled.

Crumb

Crumb is a dense, flat rubber underlay useful for heavier footfalls. It provides superior protection.

Sponge Rubber

This underlay is comfortable and durable. It is also quite diverse as it comes in a variety of patterns and weights.

Combination

This underlay product uses a combination of materials for extra value. It has a felt top and rubber crumb base for durability, comfort, and protection.

Felt

Felt is a traditional, popular house wrap choice. It is also environmentally friendly.

Underfloor Heating Underlay

This is a specialised product. It allows for extra heating to infuse the home. It is also more compatible with underfloor heating systems. 

Pre-tackified Underlay

Pre-tackified underlay is a convenient product to install. It is self-adhesive. It comes in PU and needle felt materials.

Laminate Underlay

Laminate underlay is a recommended purchase for laminate flooring. It is more compatible with laminated materials.

Factors

Siding Materials

The type of siding used can seriously impact moisture penetration and build-up. Aspects of stucco and Cedar siding typically let water in through the wall systems. This isn't the only concern. Water can also get trapped in siding that is installed tightly against walls, which is common with wood and fibre cement. A drainage plane should be installed behind all cladding and siding to prevent water damage. 

Climate

The local climate is a major factor when installing house wraps and underlays. If an area gets more than 40 inches of annual rainfall, then a rainscreen is necessary. Even in drier climates, moisture can still build up from rainfall, due, or any leaks. 

Exposure

Depending on what walling is exposed to in terms of sunlight, heavy weather, foliage etc., the type of materials used will vary. Locations that get hurricanes and high winds will need house wrap and underlay products that can withstand extreme weather conditions. The regional building authority can advise which products work best. 

Material

As may be seen above, underlays and house wraps come in a variety of materials. They can also come in synthetic vinyl or vinyl building wrap. An effective product should keep moisture from getting into the walls. Woven and non-woven building wraps were engineered to do this. 

Synthetic (Woven) 

Synthetic house wraps are made of plastic with tiny holes in them to allow water vapour to get out. It is available in two kinds of building paper products. 

Non-woven

Nonwoven house or building wraps are micro-porous and non-perforated to let, allowing vapour to move through the material. 

Installation

House wraps and underlays are fairly straightforward to install. While they can be done via DIY, it's best to get product installation specialists to do the work. The experts will know how to use waterproofing sealants on any tricky corners, nooks, or crannies that may otherwise form a gap in the moisture barrier if not installed properly. 

Other Things to Consider 

It is essential to repair and seal any damage to the house wrap or underlay as soon it's noticed. Damage may occur in the installation process, or if high winds and rain ravage the home. Contact ArchiPro before purchasing house wrap and underlays to ensure proper installation and repair.

If you need assistance to find the right building wraps and underlays for your home or office, ArchiPro provides a connection to the various professionals, ready to assist with all requirements and questions. Simply click "Contact supplier" on the product's page, or visit the supplier's website directly from the product's page.