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Old 06-11-2013, 04:26 PM   #16
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Built up vs SPF roofing


Well, not to be argumentative, just to give the facts as told to me here- I just spoke with a reputable roofing company here in Tucson. According to them it is accepted by the Arizona Registrar of Contractors and is standard practice to not nail the base ply to the roof- it is hot mopped to the plywood and the person I spoke with was aware this is not always accepted in other parts of the country. So they call it a 3 ply- base plus 2 additional plies. It was noted that the sheets overlap 18". This would be a 25 year roof. A fourth ply would be recommended for a roof with high traffic usually a commercial roof and would extend the life 5-10 years.

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Old 06-11-2013, 05:13 PM   #17
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I find it odd in a area that should get plenty of expansion and contraction that they would not nail a base.

I know all areas are different but if nothing else, nailing a base makes tearing off the roof at a later date so much easier. Let alone less breaking from building movement.
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Old 06-11-2013, 09:06 PM   #18
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No argument, Your roofer, and your board of whatever it is are wrong. I will go a couple of steps further and say that your roofer and your board of registrars are incompetent, and probably are not familiar with the National Roofing Contractors Association Roofing and waterproofing manual, nor do they belong to the NRCA.

So go ahead and listen to them, and when you get a transmission crack right through the roof at the edges of your sheathing, and then you have to tear off everything including the sheathing because the roof is stuck to it, come back and read our posts.
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Old 06-12-2013, 01:59 PM   #19
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Accusations of incompetency are unfair.
I spoke with a very knowledgeable gentleman at the Arizona Roofing Contractors Association. Different manufacturers have different guidelines for adhering there products. I will feel comfortable with the technique of adhering the base coat by hot mop which is labor intensive, griddle iron or roller method. It is adhered in a way that removal later is not an issue.
More importantly though it was explained to me that techniques of roofing and materials are specific to the region of the country. Here in the southwest roofs need to withstand high heat and sun exposure as opposed to other areas of the country that have to withstand cycles of freeze and thaw.
Contractors here are trained through the National Roofing Contractors Association.
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Old 06-12-2013, 04:16 PM   #20
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Originally Posted by elmaur View Post
Accusations of incompetency are unfair.
I spoke with a very knowledgeable gentleman at the Arizona Roofing Contractors Association. Different manufacturers have different guidelines for adhering there products. I will feel comfortable with the technique of adhering the base coat by hot mop which is labor intensive, griddle iron or roller method. It is adhered in a way that removal later is not an issue.
More importantly though it was explained to me that techniques of roofing and materials are specific to the region of the country. Here in the southwest roofs need to withstand high heat and sun exposure as opposed to other areas of the country that have to withstand cycles of freeze and thaw.
Contractors here are trained through the National Roofing Contractors Association.
Have you looked at the selected roofing system manufacturers installation instructions? The ones that have to be followed to comply with the requirements for warranty?

Even though you are not going to get a manufacturers system warranty on a residence, don't you think you should follow their instructions for the installation of their product?

It is a very long standing fact that a base sheet needs to be mechanically fastened to a wood deck with cap nails before the installation of a roof installed with hot asphalt. I always require a layer of rosin seized paper, then a nailed base sheet, as it is cheap insurance against bitumen drippage through decking or insulation joints.

But go ahead and do what you want. at the end of the day, Its your roof.

By the way, how did you come to the conclusion that the "gentleman" you spoke with was "very knowledgeable"? How people make this determination has always interested me. History shows us that it often has a great deal more to do with the charisma of the "gentleman" than it does with practical knowledge.

I mean look at Ferdinand DeLesseps and Captain Edward J. Smith. Very Charismatic Figures.
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Old 06-12-2013, 05:37 PM   #21
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I am not doing what I want. I am going by what is locally accepted practice.This is becoming a pointless discussion. Why don't you call the Arizona Roofing Contractors Association and have the discussion with them. Apparently you refuse to believe that different practices apply for different regions of the country. Step out of your know it all mentality for a moment.
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Old 06-12-2013, 06:06 PM   #22
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Your third sentence is absolutely correct. Pointless. I have been doing this for about 40 years, and was trying to help you. You cannot be helped.
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Old 06-13-2013, 01:18 PM   #23
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For the record the only base sheet we have ever mopped down to the deck is on a concrete deck, all other deck types are mechanically fastened.

With that being said, no way in hell would I allow any of our employees to mop a base sheet or anything down to a wood deck at any time, more so on a house. In fact I would go absolute nuts on the "foreman" who decided to do such a thing. Luckily all of our employees know better. To me it is almost as bad as the hacks who torch down to wood decks. The risks far far out weigh the reward.

Although I personally do not have 40 years in the business, the owner of our company that's been around for over 30 years, who has a number of installer years under his belt wouldn't allow us to do it either. He happens to be my father BTW whom I've learned a great deal from. And also our super who has been with the company from the start, if he ever saw you moping down to a wood deck it would most likely be your last day on the job. He is probably one of the most knowledgeable hot roofers you will ever meet.


One thing to keep in mind is the fact asphalt is heated up to +400 deg's by the time it is applied and has dripped down through the cracks in your plywood, or 1x6's it has probably cooled to a 350+/- still plenty hot enough to cause damage.


The thing is people think that the base sheet is a layer of the roofing, it is not, its a protection layer for the roofing and the contents below. A base sheet has very little waterproofing qualities when there is a ton of cap nails drove in to it. It simply there to protect the objects/structure inside, and to protect the roof from the normal moment of the house.

In Arizona, does it not get to 100 Degs during the day? Does it not get to 40's or so at night? Unless it is a consent temp, the structure will move. thus putting pressure on the roofing system. Asphalt roofs are not known for their expansion and contraction properties. That's why you see built in expansion joints where on single ply roofs for the most part you do not.

Good luck in what ever you do.
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Old 06-13-2013, 03:46 PM   #24
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I understand that nailing the base ply to a wood deck is manufacturer recommended, preferred method, etc. It has been explained here in great detail and makes perfect sense. But unless you have been to Arizona and seen a type of construction that was very common here for many years through the 1970ís then you must allow for the possibility of something else being done when necessary such as for aesthetics, without scorn for those that do it that way. I would have to also believe that this type of construction was not exclusive to AZ. The type of construction is the following. There are many houses with roof overhangs of about 2 ft with the beams and roof decking exposed. There are garages, carports and patios when you look up, the beams and roof decking are exposed. I have overhangs on all sides of my house and a garage with beams and roof decking exposed. I see no nails protruding through the plywood. If there are nails could they be of just the right length that they do not protrude? I am guessing the nails you use would have to protrude.
I did speak with another contractor who explained that what he does is nail down the base every where except where the roof decking and beams are exposed. There he drip mops to adhere the base coat- if I understood him correctly.
As a homeowner/layperson I cannot know for sure but I suspect that after speaking to those that should be in the know, that hot mopping or some other method other than nailing at least sections of a base ply, is done by many roofers in AZ. Do you deem them all incompetent? What would you recommend for those exposed areas where protruding nails is not desirable?
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Old 06-14-2013, 01:07 PM   #25
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Originally Posted by elmaur View Post
I understand that nailing the base ply to a wood deck is manufacturer recommended, preferred method, etc. It has been explained here in great detail and makes perfect sense. But unless you have been to Arizona and seen a type of construction that was very common here for many years through the 1970ís then you must allow for the possibility of something else being done when necessary such as for aesthetics, without scorn for those that do it that way. I would have to also believe that this type of construction was not exclusive to AZ. The type of construction is the following. There are many houses with roof overhangs of about 2 ft with the beams and roof decking exposed. There are garages, carports and patios when you look up, the beams and roof decking are exposed. I have overhangs on all sides of my house and a garage with beams and roof decking exposed. I see no nails protruding through the plywood. If there are nails could they be of just the right length that they do not protrude? I am guessing the nails you use would have to protrude.
I did speak with another contractor who explained that what he does is nail down the base every where except where the roof decking and beams are exposed. There he drip mops to adhere the base coat- if I understood him correctly.
As a homeowner/layperson I cannot know for sure but I suspect that after speaking to those that should be in the know, that hot mopping or some other method other than nailing at least sections of a base ply, is done by many roofers in AZ. Do you deem them all incompetent? What would you recommend for those exposed areas where protruding nails is not desirable?

You never told us you had an exposed plywood deck/ceiling, and you have completely changed from what we all understood to mean full mopping, to sprinkle mopping the base sheet in exposed areas, and mechanically fastening in areas where the fasteners would not protrude.

Perhaps the original people you talked to did not completely describe the methods they used when they originally described what they were going to do?

I was in Scottsdale Arizona many years ago at a NRCA convention and I noticed that a lot on one story ranch houses had large rocks on their roofs. I have always wondered what the heck they were there for. Now I finally know. They were there for ballast against blow off.

Sprinkle mopping is really hit or miss, and is really a poor way to attach a base ply, but at least now I know why they do it.

This means that you have no insulation in your ceiling or roof assembly. This is insane, with the energy costs we have today.

Maybe you should go with SPF. It will be ugly, but it will work, and it wont blow off.
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Old 06-14-2013, 01:12 PM   #26
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On exposed decking we just use shorter cap nails, even sprinkle moping leaves you open to dripping and if the asphalt is to set up it won't stick worth beans.

A good option on this roof would be install an iso base set in adhesive (2 part low rise foam) then a EPDM with white coating. Being in Arizona I would think the more ISO the better IMO.

No fasteners poking through your exposed beam roof.
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Old 06-14-2013, 02:25 PM   #27
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I just took a shower.

In the shower I thought about your situation. I have been seeing your home as having a nailable deck. Due to your circumstances it is not. The answer then becomes much easier.

The answer to your original question is neither.

The right roof for you is a fleece backed white heat welded thermoplastic. This roof can be applied with adhesive. the fleece backing provides a shear plane, and the white surface reflects about 85% of thermal radiation.

Google Fibertite and Sarnafil. I spec the white Fibertite 45XT Fleecback and 60 mil Sarnafil Fleeceback. You will need to call the rep for Fibertite or Sarnafil in your area and have them give you a good, small contractor to do your home.

You can also adhere insulation to your deck with a low rise urethane adhesive for increased R-Value.

Either of these roofs will give you 30 years or so, and your cooling bill will go down. You can pressure wash either membrane if it gets dirty. These are very good products with an excellent history of performance.

Sorry for my previous tunnel vision. I was stuck on your first two either- ors.

Next time, just tell us exactly what you have, and let us suggest the membrane.
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Old 06-14-2013, 03:09 PM   #28
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I will look into the Fiberlite and Sarnafil. Thanks for all the info.

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