It can take as little as ONE day to tear off and replace an asphalt shingle roof.
If it is a clear, hot, summer day, then a roofing crew of 5-6 can tear off and replace a 40 square asphalt shingle roof in a single day (a square is roofing terminology for shingles. 1 square = 100 square feet of shingles).
If temperatures are mild, then they can install up to 50 squares in a single day. This is assuming the roof is not steep and is not architecturally complex. This is the simplest of scenarios. You can broadly calculate other jobs using this as a baseline.
But many factors can change this time frame. Calculating roof replacement duration requires a few primary factors with the addition of some uncontrollable outliers: weather and structural damage.
Obviously, the weather can stop an installation cold in its tracks for as long as it desires, and structural repair can prolong the job anywhere from half an hour to a full day depending on the extent of the damage.
But for the sake of normalizing a time frame, assume the weather is favorable, and there are no structural damages to the roof.
Primary Factor #1 - Type of Material
Since every installation is going to be different due to other factors like roof style, pitch, size, and weather, it would be disingenuous to give you a definite time frame for each type of roof. So instead, we rated different roofing materials from easy to difficult and gave you a ballpark based on average install times it would take during prime conditions with an average roof.
Easy = (1-2 days) Moderate = (2-5 days) Difficult = (5-14 days)
- Asphalt Shingles (easy)
- Metal (moderate)
- Membrane (moderate/difficult)
- Wood Shakes (moderate)
- Tile (difficult)
From here, you can add time by incorporating these other following factors to give yourself an idea of how long the job would take.
Primary Factor #2: Size of Roof
Primary Factor #3: Complexity of Roof Architecture
Roofs come in so many different shapes and sizes, which can increase the complexity of the installation. Shallow pitch roofs (the slope of the roof) make it easier for the crews to get around on, which speeds things up, whereas steep pitch roofs make movement very precarious, slowing things down.
Along with the pitch, there is design. Some roofs are simple, like Open Gable or Hip Roofs, and can make for a quick installation. But then there are those wonderfully complex roofs with valleys and dormers all over, which can increase installation time.
Conditional Factor #1: Weather/Season
No matter how big or small a roofing company is, we ALL serve one master… the weather. Just know this, the roofer is just as frustrated with extended rain as you are. We all want to get the job done.
Seasons also play a significant role in roofing. Summers can get brutally hot, forcing roofers to take frequent NEEDED breaks. Whereas the winter months can either bring relief for us here in the South or bring the roofing industry to a screeching halt in the North.
Conditional Factor #2: Damaged Structure
Damage to your roof can often be discovered after ripping off your old roof system. Solutions can be as simple as replacing a single piece of plywood or as complex as removing most of the deck and rebuilding underlying support structures.
Honorable Mention: Tear Off vs. Roof-over
Personally, Roofs Restored never does roof-overs (residential nor commercial), but it is not unheard of for roofing contractors to “re-roof” over your existing roof system.
While this does save time by doing away with the tear-off process, it adversely adds weight to your roof, voids your warranty, and in some cases, is not even allowed by building codes.
Honestly though, this is rare. Most roofers, even your “Chuck in a Truck” roofers, tear off your existing roof before installing the new one. But it DOES happen. So just be aware.