Wood Checking

What causes wood to check?
When wood is exposed to a hotter and/or dryer environment than it has been conditioned to, the surface wood will lose moisture faster than the core material which leads to checking.

How does checking effect strength?
Checking is usually misunderstood as a failure of the wood member.  Actually, checks generally have very little effect on the strength of glulam members.  Checks generally only effect shear controlled members.

For more information, see our Technical Bulletin on this issue.


Fiber Reinforced Plastic

What is fiber-reinforced plastic?
Fibers of carbon, aramid (Kevlar®), and glass are among the strongest materials available.  Their strength-to-weight ratios are up to 10 times that of steel, for example.  By encasing these fibers in a plastic carrier, a convenient high-strength reinforcement material is created.

Why is fiber-reinforced plastic bonded to wood?
To increase overall strength and reliability (less variation occurs), and to use less or lower grades of wood.

How is fiber-reinforced plastic bonded to wood?
Using a patented process, fiber-reinforced plastics can be bonded to wood with epoxy or Phenolic adhesives. This allows the use of resorcinol adhesives commonly used in most timber manufacturing facilities to be used to bond the FiRP® Reinforcement to wood.  This allows the FiRP® Reinforcement to be treated the same as a wood lamination.

With wood expanding and contracting with changing moisture content, how is a fiber-reinforced plastic compatible with wood?
FiRP® Reinforcement has a low stiffness perpendicular to the span.  This allows the uni-directional FiRP® Reinforcement to expand and contract, with the wood.


Advantages of FiRP Reinforced Glulam

What are the advantages of using FiRP® Reinforcement with wood?
There are many advantages.  Some are: use of less wood, use of lower grades of wood, creates stronger structural member, lighter weight member, less transportation cost, less material to treat, and associated economic advantages.

How does FiRP® Reinforcement lead to less wood needed?
By placing the FiRP® Reinforcement where most needed, load normally carried by the wood is instead carried by the FiRP® Reinforcement, thus less wood is needed.

How does FiRP® Reinforcement make a stronger structural member?
The FiRP® Reinforcement itself has very high material strength properties.  By using this high strength fiber-reinforced plastic in areas of large applied stress the fiber- reinforced plastic can carry the large applied stress rather than the wood.

How does FiRP® Reinforcement lead to a safe structure?
Safety is an issue of reliability, which in turn is a function of variability.  Using FiRP® Reinforcement decreases variability in the member strength.  By having less variability, reliability increases, and so does safety.

How is FiRP® Reinforcement being used in retrofit situations?
FiRP® Reinforcement panels are bonded to existing beams to increase strength and stiffness.  This allows in place rehabilitation of structural elements.

Nailing FiRP Reinforced Glulam

Can FiRP® Reinforced Glulam be Nailed?
Yes, FiRP® Reinforced glulam can be nailed similar to LVL.  Of course, it is advisable not to nail into the extreme outer fibers or directly adjacent to the reinforcement.

Treating FiRP Reinforced Glulam

Can FiRP® Reinforced Glulam be Treated?
Yes, all FiRP® Reinforced glulam beams can be treated.  Douglas Fir must be incised prior to treatment.

Cupping

Will FiRP® Reinforced glulam cup when exposed to excessive moisture content?
FiRP® Reinforced glulam beams will cup less than LVL.

All wood expands and contracts as the moisture content varies.  Glulam expands and contracts in a near uniform manner, due to the incoming moisture content of the wood used in manufacturing and form the orientation of each piece of lumber used.