Torching perimeter then running the field perpendicular

My guys have been running a perimeter on torchdown roofs and then running the field perpendicular. I think they can just roll the top sheet straight to the edge and then trim it then heat it up and flop it over on top of the drip edge. I think it would be faster. Other than that I’m looking for ways to speed the torchdown guys up. :blush:

What way does the roof slope?. That normally depends what direction the material runs, unless it is a hipped roof.

I would offset those ends more so they aren’t all lined up. May not be that critical but just never liked things lining up like that. Probably the old hot tar habits coming back!


That would fail inspection here to, not just the ends but that pipe falls too close to a seam.
I wouldn’t worry about speeding you’r guys up,you probably need to slow them down a bit


It looks like they need to learn how to flash the pipes also.


Are you using some type of roller machine that is gouging those lines in the material?
Or is the material already came that way?

I can tell from picture it was either a two ply system or a layover. Those are not gouges

It is standard practice to run a perimeter with TD as well as Hot Tar. Would it actually hurt the roofing to go all the way to the rake edge? No. You would have more angle change laps going up along the rake edge, those can be a little tricky to ensure they are sealed in tight, especially if you are doing a two layer system off set by half sheet. In honesty I actually do this my self as it is easier. I do as a matter of practice install 3” circles over those angle change laps. You will also have an issue with installing the edge metal on top of the raised fascia, as need to put the nails in on the laps not between the laps as it buckles the edge metal.

In a commercial setting I always run with perimeter method.

As far as pipe flashings, again choices, on a two layer system, I install my base sheet, 1 layer smooth TD, then set in mastic the pipe flashing, asphalt primer the flashing, then install the top granulated layer TD. Others would install the roof complete then install the flashings and field strip them in, or making a donut hole tight to the base of the flashing and torching it in.

On the bottom or along where a gutter might be I do the same, run my base, then 1 layer smooth TD, then install the edge metal, asphalt prime it, then install the granulated layer over the top.

I have installing roofing for 41 years, do not get call backs. Recently did a roof replacement for a friend. I did a 1 ply granulated TD on this roof 19 years ago, happy we got the 19 years out of it, the only reason needed to be replaced was the metal 2” drains going down thru the roof rusted out.

My 2 cents worth

Those are creases in the material and loss of granules.
I know how the line is happening 6 inches from the seams and that is because he is torching the body of the roll first and then coming back and torching the seams.
The bending back of the seam to torch it
Caused the line
And also because it is probably not Certainteed…

I am just not convinced those are two-ply shadows i am seeing in the middle of those runs.

I am thinking these guys torch their rolls in a very strange way.
They set their roll.
They torched the whole roll at one time while it is flipped in half.
They torch all the the bottom of the roll while leaving the seam out for later.
Flip the torch down.
The fold the top down
and torch all the top half of the row.

The folding back and forth of the material and extreme heat being applied to these folds creasing of the material
Is what i believe is causing these lines
Not 2 ply shadows…

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The roof slopes right to left.

Thanks for the answers. The job is a roof over.

Why wouldn’t they just keep running it horizontal? I know some guys have trouble keeping this straight if there’s a bit of a slope, but this looks pretty flat?

To answer your question you can certainly run vertical plys all the way to the edge – I wouldn’t really think it would be any faster though.

Like someone else said, they should slow down a bit and at least make a straight cut on the ends of their vertical rolls where they overlap the horizontal one if they are going to do it this way.