Replies

1. 
   Ron_Budgell | Mar 17, 2001 01:26pm | #1

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   Hi Ron,

   Does your new roof have to go over the old? Sounds like trouble, especially at edges and flashings.

   If I was in your place, I would talk it over with the material distributor. If they couldn't come up with a better idea, I would apply a 2-ply roof, nailing on or glueing down the first layer as if it was a new roof. Waving a torch at old tar sounds to me like more excitement than i would want on a roof job.

   Ron

1. 
   Ron_Rosa | Mar 17, 2001 01:42pm | #2

   *I have re roofed enough of them not to worry. You really have to hold the torch on the surface of the old roof quite some time to get it ignited. You pretty much heat the roll of modified not the surface of the old roof. New flashings are going to be installed at all the edges. As far as installing the new roof goes I am confident it will be a good job. My only concern is the adhesion of the modified to the paint. It only has 1 roof on it now and rather than nail through it, I would rather adhere to it, to utilize it as a good base. It currently only leaks in 1 or two spots due to some wide spread cracking. I have noticed in the past when you install modified over this type of job, as the modified melts to the surface , it actually seeps into the cracks some what and forms a unified roof. Not to mention I would double the price of the job by installing a two ply over top. Fastning roof board over the old roof sounds like a good second option if a good primer cant be found.

1. 
   The_Tennis_Court_Builder_...on_t | Mar 17, 2001 01:53pm | #3

   *Nail down roof board first.near the stream,aj

1. 
   Tim_Kline | Mar 17, 2001 09:35pm | #4

   *b WBA At Your ServiceDitto AJ. Unless there is no wind where you live.

1. 
   Ron_Budgell | Mar 18, 2001 02:55am | #5

   *Ron, I shouldn't be talking, I sauppose. I've never tried to torch a new roof to an old one. It has never occurred to me that it might work. I really bonds to the old stuff. does it?I usually aim to melt only the thermofusible film joining the two plies over most of the surfaces to be bonded and put a bit more heat onto the laps to get some bleed to prove they are sealed. Is it slower work to heat it enough to bond to old tar?As for your aluminum paint, well, you know where the test lab is. For some odd reason, considering the kind of people you find doing it (like me) flat roofing remains a good money maker here in Nova Scotia. What's it like where you are?Ron

2. 
   Ralph_Wicklund | Mar 18, 2001 06:24pm | #6

   *There seems to be some difference in opinion and practice when it comes to torchdown MB.The method I learned and the way one of the roofers I use does it is to roll out a fiberglass material underlayment first (heavier than 30#), nail that down and then roll out the modified, torching the overlap 'til it bleeds a little. Another roofer I use rolls out 30# and then as they unroll the modified they hot mop under the entire roll as they go, trying not to let it run out too far. They throw down some extra granules at the lap to stick to the run out. No torch is used because of the hot mop but it sort of defeats the intended purpose of using the tochdown material. As long as it works I have no problem with either method.In both cases all the penetrations, edges and flashing are bulled as well

3. 
   Ron_Rosa | Mar 20, 2001 02:11am | #7

   *OK, There are two ways to apply. The one you mentioned is not one of them. Base sheet is the big difference. There are two types used one is solid and does not burn easy. One you can see light trough and catches on fire pretty quick. The first one you nail down and then heat roll hot enough for it to bleed a little. Then go back re heat the spots that need it only. The second type you use with a hot mop application. The second base sheet is rolled out then mopped so the tar seep's through the product and bonds the base sheet to the roof. You then let it cure for a day and install the modified with a torch in the same manner as the first. The only ways to install torch down is in these two manners . However there is a cold process modified that goes on with the proper modified bitmen adhesive. The main difference in the two applications of torch down is the second is a lot tighter and flatter job. It also costs a lot more. The nail down base sheet tends to bubble up a bit and then when you install the modified it just follows the base sheets characteristics and bubbles also. Good Luck all. Ron Rosa.

2. 
   Ron_Rosa | Mar 20, 2001 02:11am | #8

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   I have a large modified job coming up. It has fibered aluminium coating already applied on existing Hot Tar . In many spots it is flaking pretty bad. The roof needs to be replaced at his time. The owners had been told this{Aluminium roof coat} would cure there problem by some joker{"This product will seal your 12 yr old flat roof and stop all the leaks"}. My problem is I need to re roof this project with modified torch down over top. Should I power wash the loose paint off then torch down or does a product exist {Primer of some kind} that will help in bonding to aluminium coat. Thanks to all , Ron Rosa