Roofing can seem rather simple and straight forward. I mean it’s not like it’s rocket science. Just show up, load your materials, and start doing the job, right? How difficult can it be?
Not so fast. There are many variables that go into determining how to design and price a roof replacement. But how do you go about determining those variables. One of the most critical steps that help a roofing contractor or designer develop a roof design is the core cut.
What is a roof core cut?
Simply put, a core sample is when a contractor or designer takes a small cross section out of the roof assembly to determine the overall roof system composition.
But a roof core cut can sound like a bad idea. Usually you are trying to avoid punctures and cuts to your roof system. But like doctors, we are experts and know how to perform roof surgery and patch up the patient without doing any harm.
Roofers use a special core cut tool to extract a small area of roofing down to the roof deck. Once the core is pulled the results are documented and then the core is put back and the hole is repaired.
What does a roof core cut tell us?
The roof core sample is analyzed for:
- Thickness – How thick is the current roof system?
- Layers – How many layers of roof or roof assemblies are in place?
- Composition – What are the different layers and weights of those layers?
- Slope – Is the slope on the roof system in the insulation or in the roof deck?
- Hazardous Materials – Is there a potential for hazardous materials (e.g. asbestos) in the assembly which require further testing?
- Roof Deck – What is the roof deck that is supporting the roof system?
- Moisture – Is there water trapped in the roof assembly?
So why do these factors matter?
“Okay, so professional roofing contractors and designers gather this information. But what does it really matter?”
These factors are what determine the final price of the roofing project. Without these factors, the accuracy of pricing associated with replacing the roof system cannot be determined.
Some of these factors affect pricing as follows:
- Building Code – Buildings with more than two roof systems in place typically require complete removal down to the roof deck as per building code. The only way to determine if the roof system is one or two layers is to complete core cuts.
- Fastener Length – Any fasteners used in a roof system will need to penetrate the decking by a specific amount. As a result, it is critical that the overall depth of the roof system be determined in order to order the correct screw length. Fasteners that are too long will increase the cost of the roof project and can also cause damage to obstructions under the roof deck (e.g. conduits).
- Disposal Fees – Roof systems with multiple layers of material have different weights. In addition, different weights exist for each material type. As a result, the overall cost of disposing of a roof system that is being removed will be affected by the composition of the roof. Core cuts reveal the overall weight of the roof assembly which impacts pricing for disposal.
- Hazardous Material Disposal – The presence of asbestos and other materials in the roof assembly impact the removal and disposal process. Asbestos for example has specific requirements for handling and disposal. Costs associated with this must be incorporated in pricing associated with roof replacement.
- Slope – Many building codes and manufacturers require positive drainage for the roof assembly. Positive drainage is either achieved through slope in the roof deck or by adding tapered insulation. Core samples often reveal if the slope is in the building structure or if it has been enhanced by tapered insulation. Designs and costs associated with roof replacements are deeply impacted by this factor.
- Insulation R-value Required – Core samples reveal the overall r-value of the roof assembly. In certain situations, it may be required to upgrade the r-value to meet building code. As a result, the core cut is required to help determine the material type and associated r-value of the insulating materials found in the roof assembly.
- Deck Type – Deck type may be revealed through underdeck inspections. However, there are times where the view of the decking is obstructed due to interior ceilings and other factors. Knowing the deck type is critical as it affects the method of attachment of the new roof assembly. Without this critical factor, the roof system may not be properly designed.
Core cut analysis is a critical step in determining the design of the roof system. Without an accurate design, professional roofing contractors cannot offer an accurate price. Basing price on assumptions without confirming accurate information leaves the contractor and customer open to a project where a contractor may cut corners to remain whole on the project or change order the customer for the difference.
If building owners and buyers are seeking accurate pricing for roofing projects, it is in their best interest to insist that the contractor complete the necessary steps such as core analysis in order to gather sufficient information required to build the design and develop correct pricing.
