One of the key elements in planning construction or renovation work is the choice of structural panel. Among the most commonly used panels for reinforcing structures are MFP (Multi-Functional Panel) and OSB (Oriented Strand Board). Both materials have unique characteristics and applications, which makes the decision more complex than it might seem. Below is a comparison of their most important parameters.
Applications of OSB and MFP boards
MFP board is a type of multifunctional engineered wood panel, known for its high strength and resistance to moisture. It consists of thin wood layers arranged in different directions, which ensures uniform strength in all dimensions. MFP boards are often chosen for projects that require good resistance to external conditions and mechanical loads. They are frequently used in the construction of timber frame houses, as well as for reinforcing roofs or floors in masonry buildings.
OSB board, on the other hand, is a type of chipboard produced from long, thin wood strands arranged in layers and bonded together under high temperature and pressure. OSB boards are somewhat less strong and rigid than MFP boards, but they are also less expensive. Like MFP boards, they are commonly used in construction work, such as wall, roof, and floor reinforcement, especially in attics or suspended ceilings.
Waterproofing of structural panels
In timber and frame construction, two major threats can be identified – water and fire. Excess moisture, especially when it persists inside the structure for a long time, can have a very negative impact on the wood. For this reason, structural panels are typically covered with additional protective materials, such as vapour barrier membranes. However, it’s important to remember that these membranes cannot fully protect the structure from moisture penetration; they only reduce its ingress.
It should also be noted that laminated panels such as MFP and OSB are characterized by high diffusion resistance, meaning they act as vapour barriers themselves. Because of this, in timber frame houses, these boards must not be used on the external side of the structure. If moisture penetrates into the structure and the panels are installed on the outer side, they will prevent the moisture from escaping, which can cause it to remain trapped inside the wall or roof, ultimately leading to the degradation of the structure.
Therefore, MFP and OSB boards should always be used on the interior side of walls. MFP boards are significantly more resistant to moisture than OSB, which makes them a better choice for areas such as bathrooms or kitchens.
Fire Resistance of MFP and OSB Boards
As previously mentioned, fire is the second major threat to timber-based structures. Therefore, material selection in this case should be based on a parameter known as reaction-to-fire class.
- MFP boards are classified as D-s1, d0, which means they make a significant contribution to fire, produce almost no smoke during combustion, and do not emit flaming droplets or particles during a fire.
- OSB boards are classified as D-s2, d0, indicating a significant contribution to fire, moderate amount and density of smoke, and no emission of flaming droplets or particles during combustion.
In general, MFP boards meet fire protection requirements better than OSB boards in classes OSB1 through OSB4.
However, it is worth noting that the market offers special fire-resistant OSB boards, such as OSB STOP FIRE, intended for use in applications where increased fire protection is required.
Structural Rigidity
Due to their higher density, MFP boards have significantly greater cohesion and stiffness. They outperform OSB boards in terms of bending and tensile strength by approximately 122%, both along the longitudinal and transverse axes.
Furthermore, MFP boards offer twice the level of flexibility in the transverse axis compared to OSB boards.
In summary, MFP boards bear loads more effectively, reinforce structures more efficiently, and generally perform far better in terms of structural static parameters.
Formaldehydes in OSB and MFP Boards
Formaldehydes are widely used industrial chemicals. Their presence in building materials poses a health risk—inhaling their vapors can cause irritation of the respiratory tract, skin, and eyes.
In the manufacturing of OSB boards, specialized adhesives play a key role. These adhesives contain various types of synthetic resins such as melamine-formaldehyde, urea-formaldehyde, and phenol-formaldehyde. Consequently, formaldehyde is a key reagent in the synthesis of these resins.
During the production process—especially the hot pressing stage, where glue-soaked wood strands are compressed at temperatures up to 200°C—partial depolymerization of the resin occurs, which causes the majority of the formaldehyde to evaporate. Only trace amounts remain in the final OSB board. It is estimated that formaldehyde emissions can be detectable for approximately 1 to 3 months after production.
MFP boards, like other engineered wood products, are also bonded using adhesives; however, the adhesives used for MFP boards contain negligible amounts of formaldehyde. As a result, MFP boards comply with the E-1 emission class standard, meaning that harmful substance emissions are limited to less than 0.1 mg/m³.
According to the standards set by the Polish Institute of Occupational Medicine, the maximum permissible concentration of formaldehyde in the workplace is 0.5 mg/m³ over an average 8-hour workday.
It is worth emphasizing that, although the adhesives in engineered wood products may contain formaldehyde, the amount present in MFP boards is minimal—much lower than in some hair care products or in chipboards used to manufacture kitchen furniture, cabinets, or dressers—not to mention cigarette smoke.
Price – Which Is Cheaper: OSB or MFP?
- The price of an MFP board with dimensions 1250 x 2500 mm, thickness 12 mm, is approximately 29 PLN per m².
- The price of an OSB board with the same dimensions and thickness is approximately 18 PLN per m².
Dimensions of OSB and MFP Boards
The typical length of both MFP and OSB chipboards is 2500 mm, while their width ranges from 605 to 1250 mm.
Both MFP and OSB boards are available in various thicknesses: 10, 12, 15, 18, 22, or 25 mm.
- The most commonly used thickness for wall reinforcement is 12 or 15 mm.
- A thickness of 22 or 25 mm ensures exceptionally high bending strength under constant and operational loads, which is why such boards are recommended for flooring applications.
