A good professional company can often do a complete tear-off of a roof and put the new roof on in the same day, but there are limitations and you should know what they are going into your project.

Factors that can take longer 

• Multiple facets — Roofers call this kind of roof “cut up”.  If a roof is very “cut up”, it means that extra time and effort has to go into cutting each shingle and making it fit well in the area.
• Rotten Wood — When a roof is torn off, the discovery of rotten wood can effectively shut down any productivity on a job site.  The roof has to be able to hold a nail and compromised wood just doesn’t have the gripping power to hold the nails down and thereby hold the shingles down.  A good roofer will not simply deck over rotten wood.
• Cracked joists — While rare, the joists, think of this as the beams that provide the skeleton of the roof that gives your roof shape, are sometimes cracked.  This is a fairly rare problem but it can mean that a lot of roof decking will have to be removed, the joist repaired, and then the decking can go back on.  If your house has a cracked joist, there will be a sag in those areas which will only get worse with the passage of time and weight from snow and ice.
• Shorter days — As the roofing season wanes, daylight hours tighten the schedule.  In the height of the summer, roofers can work from 7 am until 9 pm in many instances.  In the fall, those windows of productivity continue to shrink.  Daylight savings time is fairly devastating to roofers in northern climates as it reduces usable daylight hours to as few as 6 hours.
• Extra layers — Sometimes it’s just not possible to tell how many layers are on a roof.  A few years ago we were doing a roof in Milwaukee and the person who owned the home prior to our customer had a custom bent fascia trim bent up to hide and obscure 6 layers of asphalt shingles below the 7th layer.  From the ground, it looked like it was one layer.  We had to get an additional dumpster and the job that we had hoped to do in a day took 3 days.
• Cedar shingles — Sometimes older parts of the city have cedar shingles underneath asphalt.  Although this is often visible from an attic inspection, sometimes tar paper can hide the additional layer.
• Chimneys in deteriorated shape — A roofer is responsible for putting a flashing on a chimney, but if a chimney is left in neglected shape for a long period of time, that chimney could actually start to fall and crumble.  This is not your roofers’ fault.  We recently did a roof where the chimney really needed tuckpointing over 10 years ago.  When we went to put chimney flashing on the chimney, it swayed and one of the stones on the top fell off.  Understand that chimney guys are good at masonry and roofers are good at building roofs.  There is rarely any overlap between these two skill sets.

Factors that speed things up

Simple rooflines — every roofer loves a simple two-sided gable roof.  They are efficient and reduce any possibility of having a leak in the future.  Fewer perforations (pipes, vents, etc) mean that a roof can go quickly.

Long daylight and cool weather — Nothing can slow down a job more than 100-degree heat.  If a customer opted for a dark color (which will drive up their energy bills) a roof can be 40 degrees hotter up there.  Frequent water breaks are necessary for the health and welfare of a crew.

So what does a one-day install really mean?

It typically means that the company will be able to remove a roof and install it on the same day.  However, that may not address debris, cleanup, or nail finding.  A roofer is in a high-risk job.  They know that there can be unanticipated rains or weather that could put a homeowner and their belongings at risk if an unanticipated and unforcecasted weather pattern hits.  So goal #1 should always be to close up that roof as soon as possible.  Many of the underlayments on the market today are synthetic and many of them do a nice job keeping your home safe from the storm.