The Hidden Risks: Why Marine Epoxies Aren’t Always Ideal for Repairing Wood in Historic Buildings.

Preserving the integrity of historic buildings is a delicate balance between maintaining authenticity and implementing necessary repairs in an efficient manner. When it comes to repairing rotted wood in these structures, marine epoxies have become a popular choice. However, while marine epoxies offer several advantages, they also come with significant drawbacks that must be carefully considered.

Historic buildings often contain unique wood details that showcases craftsmanship from a bygone era. When damage occurs, restoration experts face the challenge of repairing without compromising the historical integrity and save as much of the original material as possible. Marine epoxies are known for their strength and durability, making them appealing for rotted wood repairs. However, their application in historic buildings presents several concerns.

Complex Mixing and Application of Marine Epoxies

One of the primary drawbacks of marine epoxies is the level of difficulty in metering, mixing, and applying. Unlike epoxies engineered for wood repair in architectural applications, marine epoxies can be challenging to achieve the desirable ratio of hardener to resin. When working with marine epoxies it can be difficult to achieve a working consistency without slumping and sagging, especially on vertical profiles such as repairing brick molding and window sash “sticking”.

Insitu repairs in less than ideal conditions can make accurate mixing and application a unique challenge. The job site environment can make metering, mixing, and filling decayed wood surfaces especially difficult.

These issues noted above are compounded by extreme heat or cold encountered on job sites.

Marine epoxies require adding a thickening agent such as colloidal silica or micro balloons during the mixing process to achieve a putty like consistency stiff enough to mold and shape without running, slumping, or sagging. Often times considerable sanding is then required to blend the material into the surrounding wood to achieve a seamless repair.

In addition, this “mix your own” formulation can add considerable time and product waste to a project.

Adding Fillers

Conventional marine epoxy systems require a silica based filler to create a putty-like consistency.

Brittle Epoxies and Wood Repair

Another concern is the brittle nature of marine epoxies. Because wood is constantly expanding and contracting due to humidity, marine epoxies can often crack under the stress. In boat building and boat repair marine epoxies are often used in conjunction with a fiberglass mesh to give the material cohesive strength. Installing fiberglass mesh is not a practical solution with most architectural repairs.

Fiberglass Cloth

Fiberglass cloth, mesh, or milled fiberglass is often used with marine epoxies to enhance the cohesive strength.

Moreover, the application of marine epoxies requires a considerable learning curve to implement correctly and efficiently. Improper mixing or application techniques can lead to subpar results, loss of time in the field, or even further damage to the wood substrate.

With Dura-Fix, Epoxy Consolidation is Not Required

The manufacturers of marine epoxies often advocate the practice of “consolidation” in architectural applications.

Consolidation is the application of a thin coating of a low viscosity epoxy apparently designed to penetrate and consolidate the decayed wood fibers. This material is sold with other names such as wood hardener, penetrating sealer, rot penetrator, or primer. Rarely does this practice achieve its desired goal. These materials only penetrate the decay to a depth of 1/32” of an inch, Even less penetration is achieved on a vertical surface as gravity carries the material downwards.

( curiously, it is worth noting that manufacturers of marine epoxies do not recommend the consolidation of decayed materials on boats.)

In conclusion, while marine epoxies possess undeniable strength and durability, their application in historic wood repair comes with significant drawbacks. From their difficulty to mix and apply to the brittle nature of the material, preservationists must carefully weigh the risks and benefits before incorporating marine epoxies into restoration projects. Ultimately, the goal remains the same: to safeguard the unique heritage of historic buildings for future generations while ensuring responsible conservation practices.

Dura-Fix Flexible epoxy wood filler solves the problems of accurate mixing in the field with our dual cartridge dispensing system. This dispensing system guarantees accurate mixing ratios without adding fillers and virtually eliminating waste.

Dual Cartridge Dispensing

Accurate metering is achieved with our unique dual cartridge system. Resealable. Eliminates product waste.

Flexibility is built into the backbone of the system offering a high degree of cohesive strength. Age hardening inhibitors are added to ensure years of performance.

Dura-Fix is engineered to move with wood.

Our warm and cold weather formulas offer a wide range of application temperatures.

The recommended surface prep for rotted wood is to remove all decay to sound, bright wood. No epoxy consolidation is required. For consistency, durability, and productivity we invite you to consider the Dura-Fix System on your next historic preservation project.

More information on Dura-Fix is available here

Large or small repairs in minutes

No need for time consuming build-ups. Execute repairs quickly with no slump or sag