XtremeCorners - 2-1/2” x 2-1/2" Plastic Corner Guards Box of 30

Tamlyn XC25 XtremeCorners — Prefabricated Seamless Sill Flashing Corners for Windows and Doors

The Tamlyn XC25 XtremeCorners are prefabricated, seamless flashing corners engineered specifically to waterproof the most vulnerable areas of window and door installations — the sill corners. Designed for builders, contractors, and construction professionals, XtremeCorners integrate directly with standard self-adhered flashing membranes, making them a core component of the Tamlyn water management system. The XC25 model features a 2-1/2" (A) by 4" (B) profile, sized to suit common residential and commercial sill conditions.

Unlike field-fabricated corners using multiple overlapping flashing pieces or expensive premium sill pan systems, XtremeCorners eliminate the complexity and inconsistency of hand-detailing. The seamless, factory-formed construction removes the risk of gaps, folds, or improper laps that commonly lead to water intrusion at these critical transition points — delivering consistent, code-compliant performance on every install.

Key Features & Benefits

Prefabricated Seamless Corner

Factory-formed in a single piece, the XC25 eliminates seams at the most leak-prone corner locations. This seamless construction means there are no field joints to fail over time, reducing callback risk and long-term moisture-related liability for contractors and builders.

Direct Integration with Self-Adhered Flashing

XtremeCorners are designed to work seamlessly with standard self-adhered flashing tapes and membranes, including Tamlyn's own XtremeFlashing Tape. This compatibility simplifies the detailing process and ensures the corner transitions lay flat and adhere properly without extra prep work or special tools.

Cost-Effective vs. Sill Pan Systems

Premium sill pan systems add significant material and labor cost per opening. XtremeCorners provide a highly reliable waterproofing solution at a fraction of the cost, allowing contractors to protect every opening on a project without compromising the budget or water management performance.

Simplified Sill Detailing

Detailing sill corners with multiple flashing pieces is time-consuming and error-prone. The XC25 reduces the number of components and steps required at each corner, speeding up the installation process and lowering the skill threshold needed to achieve a watertight result consistently.

Key Component of Tamlyn Water Management System

XtremeCorners qualify as an approved component of the Tamlyn Drainable Wrap system, supporting eligibility for the 25-year product and labor warranty when installed as part of the full Tamlyn water management assembly. This gives owners and developers documented warranty coverage for the entire wall system.

15-Year Product Warranty Coverage

XtremeCorners carry a 15-year limited product warranty against manufacturing defects when installed per Tamlyn guidelines. This provides contractors and project owners with documented protection and confidence in long-term product performance.

Common Applications

Window Sill Corner Flashing

XtremeCorners are purpose-built for window sill corners, which are the highest-risk water infiltration points in a window assembly. They ensure a continuous waterproof transition from the sill to the jamb at both corners.

Door Sill Corner Flashing

Door sill corners face the same vulnerabilities as window sills, particularly in exposed or high-rainfall environments. The XC25 provides the same seamless protection for door rough openings, integrating with door pan flashing and self-adhered membranes.

New Residential Construction

Ideal for high-volume homebuilding where consistent, repeatable detailing across dozens or hundreds of openings is essential. XtremeCorners standardize the sill corner detail across all trades on a project.

Commercial Construction

Suitable for light commercial applications where proper water management detailing is required by code or specification, particularly when used as part of the Tamlyn Drainable Wrap system to qualify for extended warranty coverage.

Renovation and Retrofit Window Installation

When replacing windows in existing structures, proper re-flashing of the rough opening sill corners is critical. XtremeCorners simplify the detailing process in tight retrofit conditions where field-cutting multiple flashing pieces is impractical.

Tamlyn Drainable Wrap System Installations

XtremeCorners are a required or approved component when installing TamlynWrap Drainable Wrap or ProSelect Commercial Wrap systems to qualify for the 25-year product and labor limited warranty. They are explicitly listed in Tamlyn's warranty system documentation.

Compatible Materials

• Standard self-adhered flashing membranes
• Tamlyn XtremeFlashing Tape
• TamlynWrap Drainable Wrap
• TamlynWrap ProSelect Commercial Wrap
• TamlynWrap ProSelect Self Adhered
• XtremeSealant / Tamlyn BrunnoSeal
• XtremeSeam Tape
• Window and door rough opening framing (wood, engineered lumber)
• OSB and plywood sheathing substrates

Product Documents

• Catalog Page — XC25
• Product Brochure — XtremeCorners

Technical Specifications

Frequently Asked Questions

Q: Does the XC25 require any special adhesive or tools to install?
A: No special tools are required. XtremeCorners are designed to integrate with standard self-adhered flashing tape. The corner is positioned at the sill corner and lapped with XtremeFlashing Tape or equivalent self-adhered membrane per Tamlyn installation guidelines.

Q: Can XtremeCorners be used with non-Tamlyn flashing products?
A: XtremeCorners can physically integrate with other self-adhered flashing systems; however, use of non-Tamlyn components will disqualify the installation from coverage under the Tamlyn 25-year product and labor warranty. For warranty eligibility, the full Tamlyn system must be used.

Q: How many corners are included per box of XC25?
A: Each box contains 30 XtremeCorners. Since each window or door opening requires two sill corners, one box covers 15 openings.

Q: Is project registration required for the warranty to apply?
A: Yes. The 25-year product and labor warranty requires project registration with Tamlyn. The 15-year product-only warranty on XtremeCorners does not specify registration but requires installation per Tamlyn guidelines. Contact Tamlyn at 1-800-334-1676 or submit registration to [email protected].

Q: Are XtremeCorners suitable for both residential and commercial applications?
A: Yes. XtremeCorners are appropriate for residential new construction, renovation, and light-to-mid commercial projects where proper sill corner flashing is required by code or specification. They are an approved component in the TamlynWrap ProSelect Commercial Wrap system.

Q: What is the difference between using XtremeCorners and field-fabricating sill corners with flashing tape?
A: Field-fabricated corners require cutting, folding, and overlapping multiple pieces of flashing tape, which introduces seams and potential failure points. XtremeCorners are factory-formed as a single seamless piece, eliminating those joints and delivering a more consistent, reliable water barrier with less installation time and lower risk of error.