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Brad Smith
Posted: May 01, 2011 09:54 PM
making roof watertight during reroofing
Questions for you roofing guys out there.

I am looking at a reroofing project where existing roof is a ballasted Epdm membrane on 4 inches of EPS insulation.
I have to remove ballast,membrane and insulation

Then mechanically fasten densdeck and spray approximately 2.5 inches R-15.

My question is what is the best way to tie in spf to existing membrane to ensure a complete watertight seal at end of each day?

Also is my Graco E-30 capable of doing this job? I will be working with another roofing firm who will be doing rip off and installing densdeck and they would like 50 square a day.

Also anyone looking for free labour for a few days so I could pick up tips on the spf roof applications?
Daniel X
Posted: May 01, 2011 10:54 PM
I assume you've done some roofs before seeing how you've already agreed to complete a 100' x 100' area each day...
Brad Smith
Posted: May 02, 2011 06:26 AM
I take it math isnt one of your stronger points.

We consider a roofing square to be 10 ft x 10 ft. So 50 square would be 5000 sq ft, or 100 ft by 50 ft.
Now that I educated you on how to properly calculate a roofing square could you recommend a proper way to tie in epdm to spf each evening to provide a watertight seal?
richard sucher II
Posted: May 02, 2011 08:33 AM
Our company has been foaming for over 30 years and we have been Firestone EPDM contractor for around 27 years. Having said that, the first thing that comes to mind is the number of squares that you are planning on tearing off each day. 50 squares sounds like too many. If your concern is how to tie-off, you also need make sure that you can spray that much area - looks like 4-5 sets of foam. Not much room for winds, sudden rain threat, mechanical problems, etc.
Assuming that you get the area sprayed, one suggestion for tie off would be to lift surrounding EPDM sheet and place 2x6 on its edge to build a dam. Make sure that your drains are clear and that you never isolate them. Many times during the tear off process debris is left on the roof and in a rainstorm the debris clogs the drains and causes the water to build up on the roof. Many times your tie off is over run.
Once you have built your dam, you can spray foam onto the EPDM flap to close the system for the night.
Another thing to keep in mind is that should you run into a prolonged period of rain, i.e., several days, your tie off better be good. Also, high winds that usually come with rain storms can wreck havoc with the best of tear offs. Make sure that there is plenty of rock ballast around so that you can spot rock as needed.
Better check your insurance policy. As well as the policy of your tear off sub. Are you the sub or is the tear off guy the sub. Who makes the call as to whether or not tear off starts in the early morning. Keep an eye on your weather radar; we do not proceed with 30% rain chances or higher. When in doubt, don't. Good luck.
Brad Smith
Posted: May 02, 2011 08:55 AM
Thank You for your reply.

I am a roofer by trade ( was union )for over 25 years and have installed many roofing systems,EPDM,PVC, Modified bitumen, BUR etc.

I started my own company 6 years ago, recently a few consultants are asking SPF to be uncluded in their bids as well.
The Job I am looking at is approximately 700 squares, pretty much wide open, 14 curbs, 12 sleepers, 16 b-vent flashings.

Even though I am the sub I would make the decision whether to rip off daily.

I have no worries working with this company as I worked for them for close to 20 years and know first hand their way of working and experience.

In my entire career I have only had one breach on my water dam, we were removing a ballasted pvc roof we were installing a epdm system.

My dam was a 2x6 as you described however we had a thunder storm of such a magnitude that drains couldnt manage the water and water went over my dam.
Damage was minimal considering it was a food processing plant.
My main concern with making a dam on the spf roof is having ridges develop where I stop and start each day, I guess I could feather it down where I am about to end and build it up level as I carry on.
Again I thank you for your informative reply, any other info from folks who have experience in this field would be greatly appreciated.
Daniel X
Posted: May 02, 2011 07:08 PM
I agree that 50 * 100 = 5000

But I thought that you were also doing the removal prior to the foam work, meaning you'd be working over the same area twice in one day (two scopes of work), my mistake.
Posted: May 02, 2011 07:37 PM
E-30 will let you spray with an 03, which is what I like to use on most roofs. H40 or PMC40 would be much better, but you have to work with what you have.

If it was a built up, 50 squares a day would be tough, but with epdm, I don't think you will have a problem. If the 4" of eps was mechanically fastened, it should come up quick. If they used adhesive, may be a little more work.

I would run two 4-5 man crews if I were you. Pull off and remove all balast before you get started. RK Hydrovac would probably charge you around $.25 or less a sq ft if you don't want to do it yourself.

1st crew would start at around 3:00 a.m. tearing off and get a good start. By 7:00 to 8:00, your second crew can come in and get started laying out densdeck and fastening in an FM190 Pattern or whatever the architect calls for. Once you get enough down, second crew begins to spray while the first crew finishes putting down the remainder of the densdeck and fastening.

I would suggest that you put down 1" of foam and prime at the end of each day so you don't get behind. One you have the whole roof done or whatever you choose (Quarter or half), you can come back and put your full thickness on the roof. If you can put the full thickness down (4 1/2 to 5 sets at 5000 sq. ft X 2 1/2") more power to you, but I don't think you will with the E-30.

Priming is important though. You don't want to leave the foam exposed to the UV Rays to long, so prime at the end of each day. If you let sit for more than a week with just prime, you may have to pressure wash and prime again. Using prime, you only need about 1/2 gallon per square, so don't load it up, otherwise you may see your foam popping off.

Tie ins or easy. Just foam in to your tie ins like you would do a regular pass. You will leave a 2" to 3" hump when you tie in depending upon the depth of what you sprayed that day and what your old roof is. The next day, you can take a skill saw, knife, etc... and cut the foam away from the old roof and grind down to flat if necessary. Once you get the foam back to flat, apply primer and allow to dry before re-foaming.

If you don't get to far ahead of yourself, this job will be very easy. Keep your demo crew ahead by a half day and all will work out fine. If you try to do both demo and foam yourself, you will be there 60-90 days easy and half your crew will quit once it gets hot. Hell, by the end of the first week in the heat, you will be thinking about quitting also...lol.

Call me on my cell at 225-229-4910 if you have any questions or need any help.



P.S. Watch your weather. If rain is in the forecast and you still think that you can work, keep your demo guys a couple pass distances ahead of you and try to keep up with them. If you can't keep up with them and the weather keeps getting worse, pull them off and have them help you catch up.
Posted: May 02, 2011 08:09 PM
Email me. I have a picture of a tie in that I tried to enlarge. Same scenario, working ahead trying to beat the weather and left the ac units for last.

We were installing new curbs and the existing roof was built up with 2 1/2" of Polyiso that was completely saturated. We tore off the old roof within 6" of the saturated polyiso, put densdeck down on the dry section and then foamed into the wet saturated roof. You can see the hump around the ac unit. Next day, we cut the new foam back to the new densdeck and then lifted up the units, tore off all of the wet built up and polyiso, allowed metal deck to dry, then installed the densdeck, followed by the curbs and then foamed into the new foam that we just cut into.

Email me and I will send you the picture.

Posted: May 02, 2011 08:18 PM
Hey tumpline! Just in case you have not sprayed roofs before. If you try to spray roofing foam in hot weather like you were wall insulation, you may have some trouble keeping it smooth.

If it is turning white as soon as it comes out of the gun, drop your temps down. It should look like coke when it first hits and as soon as it hits should start turning white and expanding. Your outside pass lines will lay down smooth if you do like that.

If you spray to hot, you will see every feather, bump and every time you scratch your butt in the foam. If temps outside are in mid 70's or hotter, I spray with the A at 115 and B at 125 and hose in middle. If it is colder than 70 outside, put band heaters on your drums and try to warm it up before it hits your reactor. If you try to make the reactor do all of the work, you will have washboards between your passes and bumps or valleys in your passlines to the right and left.

You have to be perfect to spray hotter or it really shows. Keep that material just hot enough and you will look like a pro first time out. If it is to cold, your yield will be terrible. Play with it and get a good feel.

If you spray off ratio, pull it up. Even if you think you might get away with it, pull it up. Better to do now than 6 months or a year when you have to pay the full crew to go out and correct.

There is no room on a roof for hiding mistakes. It will find you no matter what.

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