Miscellaneous

Some manufacturers have enlarged their OSB product range by developing own products for specific applications (aluminum faced radiant barrier, flame retardant boards, airtight cellulose laminated layer, plywood coated boards, etc).

No. QSB is a brand of a European wood-based panel manufacturer.

The name stands for Quality Strand Board, but the product is not OSB.

It is a single layer highly pressed P5 particleboard that meets the requirements of EN 312 as structural board for use in humid conditions.

However, the mechanical performance values (bending strength and bending stiffness) of QSB are significantly lower than OSB’s, for the same panel thickness.

Radiant Barrier OSB is an OSB board coated on one side with a special fine perforated reflective aluminium foil that is applied to the panel via adhesive laminating.

They are used in roof and external wall’s sheathing to effectively reduce the transmission of radiant heat from the sun, in other words to reduce the heat loss in winter and the excessive solar gain in summer.

In order to allow the proper functioning of these boards, a ventilated gap of a minimum of 25mm must be provided between the board’s aluminum side-face and the thermal insulation of the wall/roof.

They are always installed with the ALU-face towards the support (interior).

The one-side rough surface is typical of the old fashioned multi-daylight press with mat forming on wire-mesh.

It brings an advantage for carpenters, when the product is used for roof sheathing (especially for high-slopes roofs), where the smooth surface of standard OSB can become slippery when wet.
Unfortunately, it is not possible to create the rough surface with continuous ContiRoll pressing.

The corrosion problem is mainly relevant for zinc metal coverings. It has nothing to do with whether the rigid underlay (roof decking) is made up of OSB or timber.

The reason for these problems is the zinc chemically reacting with water. Here it is absolutely necessary to provide an underlayment which prevents the water drops (for instance, from condensation) from coming into contact with the bottom of the zinc. 

For slopes < 160 zinc-roof manufacturers recommend/demand special underlay (roofing membranes), such as DuPont “Tyvek Metal” for instance.

For copper, aluminium or steel, this kind of corrosion problem is not relevant.

Because OSB is a tested and reliable product, with excellent performances and proven track record of constant quality.

EGGER also offers a lot of other advantages, such as:
 

• Long term and reliable partnerships with customers
• Commitment for quality and continuous development of the product range
• Market related stock program
• Provides intensive marketing and technical support in application techniques
• Good product range and complementary products (DHF)
• In trend alignment to the market development and needs

The thickness of the boards depends on:
 

• Application (wall, floor, roof)
• Type of board chosen
• Span of the supports

Maximum allowable load that the structural element must support, which normally results from the static design of the building.

There are of course design tables that relate to the board’s thickness with span and load for different loading scenarios (single-span / double-span loading, uniformly distributed or point wise loads) and for different classes of importance of the building (single-family houses, schools, offices, etc). By request, EGGER provides technical support to the customers for choosing the right panel’s thickness.

According to our experience, we recommend the following minimum thicknesses of the boards for a typical 600-625mm c-o-c span of the supports (beams, studs, rafters):
 

• Internal wall ≥ 10mm
• External wall ≥ 12mm (better 15mm)
• Domestic floor ≥ 18mm (better 22mm)
• Roofing ≥ 12mm

Please note that fresh concrete is full of water, and since the curing process is highly exothermic (releases a large amount of heat), common practice recommends additional “showering” of the casted open elements (floors and beams) in the first 24hrs on a hot summers day. This helps to avoid excessive shrinkage that could result from a fast water evaporation from the casted concrete.

This is why we recommend the use of moisture resistant & sturdy panels for concrete shuttering, such as OSB 3 (or better OSB 4 TOP) of minimum thickness of 20mm.

To ease the board’s removal from the cured concrete, it is highly recommended to treat the inner side of the boards with a mould release agent, prior to casting the concrete into the formworks.

Also, in order to avoid any buckling of the boards during curing process, the formworks must be secured with sufficient wood battens on the sides. The right dimensioning and distribution of these reinforcing elements across the formworks stands with the contractor, based on his own experience.

If handled with care in both mounting and dismounting, the boards for concrete shuttering may be used up to 3 times or more, provided that panels of right thickness and mould release agents were used.

The standard CEN TS 12872 gives the following definition of cold and warm roofs:

Cold Roof

• Roof design in which the boards and some of the supporting joists are placed above the insulation.
• The panels are considered to be under conditions corresponding to service class 2 (humid conditions, 65% < RH ≤ 85%).

Warm Roof

• Roof design in which the boards supported by joists are placed below the insulation.
• The panels are considered to be under conditions corresponding to service class 1 (dry conditions, RH ≤ 65%).

The most obvious advantage is the speed of completion:

For a house owner that decides to build the house on their own, this means less stress: shorter time is spent coordinating the people on the job-site or purchasing the materials, less trouble with renting special equipment (concrete pumps, formworks, etc.), and can mean earlier site lock-up with reduced exposure to theft and weathering.

For a potential client that is buying the house from a developer, it means that he/she can move in faster (sometimes, this means saving some money from a flat rental somewhere else).

For a developer, it means earlier cash recovery and improved cash-flow.

The prefabrication makes all the above even more obvious, and provides higher savings.

Other benefits:
 

• Reduced total self-weight of the building → means reduced sizes for foundations = less concrete and reinforcing steel
• Thinner external walls → means more space gained inside
• Ecological, made of natural products (wood) → healthy and friendly living environment
• Suitable for Low-Energy and Passive houses