A client of mine is needing a custom app to control what shipping options become available when a certain weight is exceeded in the cart.
They use two shipping companies UPS and Canada Post
When the weight of the total order exceeds a certain limit then Canada Post is no longer available for selection and it must go through UPS only.
Sadly I cannot find any existing apps that can accomplish this.
Or try manual rates to remove specific weight ranges for a carrier.
If those dont work email me with your budget and details 'paull.newton+ByTheByte@g m a i l.c o m'
ByTheByte : With the Multi carrier shipping label app you can show rates from both UPS and Canada Post. In addition, you can create automation rules such that, if weight is exceeded for the order, only UPS is shown to customer at checkout and Canada Post is hidden. Attached screenshot of the Automation