[LETTER 1: CONTRACTOR TO SUPPLIER]

Date: August 26, 2026
From: [Contractor Name], Project Manager, Commercial Complex Project
To: [Supplier Name], Sales Director
Subject: Technical Dispute – Cracking and Deformation in Gypsum Board Partition System
Reference: Purchase Order PO-2026-0712, System Type: GB-100

Dear [Supplier Name],

We are writing to formally notify you of a technical dispute regarding the gypsum board partition system supplied for the above project.

Background:

Our company was contracted to install approximately 4,200 square meters of gypsum board partition walls using your GB-100 system. The installation began in June 2026 and was completed in August 2026.

Within three weeks of installation, we observed the following defects:

1. Cracking at board joints: Longitudinal cracks appeared along the tapered edges of the gypsum boards. The cracks are visible in approximately 35% of the installed area.

2. Deformation at ceiling junctions: The partition walls are showing visible deformation at the junction with the ceiling. The deflection is approximately 5-8mm over a 3-meter span.

3. Screw popping: Drywall screws are popping through the board surface in several locations. The screw heads are visible and the board surface is damaged.

4. Joint compound separation: The joint compound is separating from the board surface in several areas. The tape is visible and the joint is failing.

Our Assessment:

We believe the defects are caused by the materials supplied. Specifically:

• The gypsum board thickness is 12.5mm as specified. However, the board density appears to be lower than expected. We have weighed several boards and found the average weight to be 8.2 kg/m², compared to the typical 9.0-9.5 kg/m² for 12.5mm boards.

• The light steel keel (stud) thickness is 0.6mm as specified. However, the keel appears to be more flexible than expected. We have measured the deflection under load and found it to exceed the allowable deflection specified in the system manual.

• The joint compound supplied with the system appears to be too dry. We have experienced difficulty in achieving a smooth finish, and the compound is cracking after curing.

Request:

We request that you:

1. Send a technical representative to the site to inspect the defects.

2. Provide a written assessment of the cause of the defects.

3. Replace the defective materials at your cost.

4. Compensate us for the additional labor required to rectify the installation.

We have suspended further installation of your system on this project until the dispute is resolved.

We await your response within 7 days.

Sincerely,

[Contractor Name]
Project Manager

[LETTER 2: SUPPLIER TO CONTRACTOR]

Date: September 9, 2026
From: [Supplier Name], Technical Director
To: [Contractor Name], Project Manager
Subject: RE: Technical Dispute – Cracking and Deformation in Gypsum Board Partition System
Reference: Your letter dated August 26, 2026

Dear [Contractor Name],

We have received your letter dated August 26, 2026, regarding the gypsum board partition system at the above project.

Our technical team visited the site on September 2, 2026. We inspected the installation and reviewed the installation records. We have also tested samples of the materials from the site. Our findings are as follows.

1. Gypsum Board Density

You stated that the board density is lower than expected. We have tested the boards from the site. The average weight is 8.4 kg/m², not 8.2 kg/m² as you stated.

The specification for our GB-100 system is 8.0-9.0 kg/m². The tested boards are within specification.

You compared the boards to "typical" 12.5mm boards at 9.0-9.5 kg/m². That is not the correct comparison. Our GB-100 system uses a lightweight board that is specifically designed for the system. The board density is intentional. The lighter board is part of the system design.

2. Light Steel Keel Thickness

You stated that the keel is more flexible than expected. We have measured the keel thickness. The thickness is 0.6mm as specified. The deflection under load is within the allowable deflection specified in our system manual.

We have reviewed your installation. The keel spacing is 600mm. The specification for our GB-100 system is 400mm for walls above 3 meters in height. Your walls are 3.6 meters high. The keel spacing should be 400mm, not 600mm.

The excessive spacing is causing the deflection you observed. This is an installation issue, not a material issue.

3. Joint Compound

You stated that the joint compound is too dry. We have tested the compound from the site. The moisture content is within specification.

The difficulty you experienced in achieving a smooth finish is likely due to the application method. The compound should be mixed with water according to the instructions on the bag. The instructions specify 5.5 liters of water per 20 kg bag. If less water is used, the compound will be too dry and will crack.

We have reviewed your installation records. The records show that your applicators used 4.5 liters per bag. This is below the specified amount. The insufficient water is causing the cracking.

4. Screw Popping

You stated that screws are popping through the board surface. We have inspected the screw locations. The screws are over-driven. The screw heads are below the board surface, breaking the paper facing.

The specification for our system requires the screw head to be slightly below the board surface, but not so deep as to break the paper. Your installers have over-driven the screws. This is an installation issue.

5. Joint Compound Separation

You stated that the joint compound is separating from the board. We have inspected the joints. The separation is occurring where the joint tape was not properly embedded.

The specification for our system requires the joint tape to be embedded in a bed of compound and covered with a second coat. Your installers applied the tape directly to the board without a bedding coat. This is an installation issue.

Summary of Findings:

Conclusion:

The defects you have observed are caused by installation errors, not material defects. Specifically:

1. The keel spacing is 600mm. The specification requires 400mm for walls above 3 meters. This is causing the deflection.

2. The joint compound was mixed with insufficient water. This is causing the cracking.

3. The screws were over-driven. This is causing the screw popping.

4. The joint tape was not properly embedded. This is causing the joint separation.

The board density is within specification. The keel thickness is within specification. The joint compound is within specification.

Recommendation:

We recommend that you:

1. Re-install the partition walls with the correct keel spacing (400mm).

2. Re-mix the joint compound with the correct amount of water (5.5 liters per 20 kg bag).

3. Re-train your installers on the correct screw driving depth.

4. Re-train your installers on the correct joint tape embedding procedure.

We are willing to provide technical support and training to your installation team at no cost. We are not responsible for the cost of re-installation, as the defects are caused by installation errors.

We value our relationship with your company. We hope to resolve this dispute amicably. We are available for a meeting at your convenience.

Sincerely,

[Supplier Name]
Technical Director

End of Correspondence

What This Dispute Reveals

This dispute is a common one in the building materials industry. The contractor blames the materials. The supplier blames the installation. Both parties have evidence. The truth is usually somewhere in between.

Key Technical Points:

1. Keel spacing matters. The supplier specified 400mm spacing for walls above 3 meters. The contractor used 600mm. The wider spacing caused the deflection. The supplier is correct on this point.

2. Joint compound mixing matters. The supplier specified 5.5 liters of water per bag. The contractor used 4.5 liters. The drier compound cracked. The supplier is correct on this point.

3. Screw depth matters. The supplier specified the screw head should be slightly below the surface without breaking the paper. The contractor over-drove the screws. The supplier is correct on this point.

4. Board density matters. The supplier specified 8.0-9.0 kg/m². The tested boards were 8.4 kg/m². The supplier is correct. The contractor's comparison to "typical" boards was not valid for this system.

5. Who is responsible? The installation errors are the primary cause of the defects. However, the supplier has some responsibility for not providing adequate installation training or supervision. The supplier's system manual specifies the requirements, but the contractor did not follow them.

What Buyers Should Learn:

1. Read the system manual. The installation requirements are specified. If the contractor does not follow them, the warranty may be void.

2. Train the installers. The supplier should provide training. The contractor should ensure the training is delivered and understood.

3. Inspect the installation during the work. Problems are easier to fix during installation than after the walls are finished.

4. Document everything. The contractor's records (water addition, keel spacing) were used against them. The supplier's records (specifications, installation manual) were used to defend their position.

5. Get technical support from the supplier. The supplier offered free training. The contractor did not request it. The dispute could have been avoided with a phone call.

6. 
   

The contractor says the materials are defective. The supplier says the installation is wrong. Two letters, two versions

Contractor says materials are defective. Supplier says installation is wrong. Two letters. Two versions of the truth. Full text of both dispute letters.

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