Poudre Fire said the commercial structure fire at 1438 Riverside Avenue, between Lemay Avenue and Pitkin Street, started around 4:45 a.m.
The website for Signs Now said they make indoor and outdoor signs, banners, tradeshow graphics, vehicle wraps, wall logos, and more.
"When crews arrived they found a large volume of fire inside the building along with fire coming from a roll-up door in the rear," fire department Captain Patrick Love wrote in a press release. "Shortly thereafter the fire breached the roof."
"Firefighters attacked the fire defensively, which means from relatively safer areas on the exterior, due to structural stability concerns," fire department Captain Patrick Love wrote in a press release.
Firefighters said the building had no sprinklers, which firefighters said would have prevented much of the damage.
"Once the fire was brought under control and city building officials inspected the building, firefighters were able to access hotspots for final extinguishment," fire department Captain Patrick Love wrote in a press release.
Love said firefighters were able to contain the fire to the one building. When the fire was out, firefighters found the building suffered heavy fire, smoke and heat damage.