@wleigh1021 did you put anything under your heating pad so that your heat wasn't stolen downwards?
The storage tub has a pretty thick bottom. Then the brooder I use is a dog play pen and I put 2 old blankets and a cheap tarp from dollar tree under it covered in shavings. This keeps the whole area from getting too cold from the concrete floor of the garage. If you look in bottom right corner you can see blankets and tarp.