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RacerX 01-16-2010 11:04 AM

Built Up Roofing (BUR) vs Modified Bitumen Roof (Torch Down)
I need some advice and/or opinions about these types of roofs. I have a flat section of roof on my house that needs to redone. I had this roof completely torn off and redone (BUR) approx 11 years ago. I spent a whole lot of money with a LICENSED contractor on this roof wanting not to have to deal with it again for a long time. Apparently it wasn't done correctly according to the roofers that have come out and bid the job. I was told that they didn't prime the edge metal correctly and this caused the edge to lift up/de-lam and water to wick in. It has destroyed all of the fascia on this part of the roof and some of the sheathing underneath. Other than the edges lifting up/ de-laming, the roof is still in relatively good shape. This is a FLAT roof with less than 1/4" per foot fall. Some of the guys bidding have suggested modified bitumen (torch down) as the way to go and some say that the BUR is the way to go. Which would provide me with the better roof? Which would last longer? Is it better to go with a 4ply (base, 2 11 lb. plys, granulated cap sheet) or a 5ply (base,3 11 lb. plys, granulated cap sheet)BUR? What about a 2 ply modified bitumen vs. a 3ply modified bitumen? I live So Cal. and we don't get a ton of rain. I would like this roof to last at least 10-15 year min. Thanks in advance for any advice or suggestions!

johnk 01-18-2010 07:54 PM

A roof is only as good as the applicator.IMO they both great systems if installed right.Doing research on your contractor is most important.Visit some of their old work and visit jobs currently in progress.This is the best advice.You could have a 1 layer roof outlast a 10 layer roof,all depends who put it on:wink:

MI-Roger 01-19-2010 08:05 PM

I don't agree with the terminology
All 4-ply BURs that I have encountered use 4 layers of 15 pound (or heavier) felts, the insulation and ballast do not count as plies. I wold call the two roof compositions you described as a 2-ply and a 3-ply roof, constructed using underweight material.

hammer71h 01-22-2010 11:09 PM

ask your contractor about a brand called is a granualted cap comes in 1 square rolls...if you use their base sheet upgrades the warranty to 15 years...i have installed two of these systems recently...and they look great...whats nice about them is they come in the same colors as most shingles...weatheredwood...gray...etc...


Grumpy 01-31-2010 01:54 PM

Any roofing system has various specifications ranging from 10-30 years. For example a smooth surfaced BUR roof with only 2 felt ply's is a 10 year rated roof. Therefore if that's what you paid for when you had your roof replaced years ago, you got what you paid for. Having said that there are many many BUR roof using coal tar pitch and 5 ply's of felt that are in service 30 years after they were installed.

Modified bitumen is a good roofing system. The reason I don't like it is not because of the product its' self, but the vast number of incompetent applicators. Having said that, you can get a 10 year modifie bitumen roof, which is the most common roof in the Chicago market. Or you can get a 20 year rated modified bitumen roof. I most commonly install the 15 year, 3 ply, modified bitumen roofing system. Why go to the time and expense of installing a 10 year rated roof, then again 10 years later? Why not go 20 years from the get go and save money in the long run?

A 4 ply system is a double layer of a fiberglass base sheet, an application of a smooth modified bitumen mid ply, and then a granulated cap sheet. The insulation does not count, although I would always install no less than a 1/2" fiberboard. Having said that, that's a torch applied specification. If one of these guys are bidding self adhering modified bitumen it's a little bit different. The insulation board isn't necessary and a 3 ply self adhering modified bitumen system is rated anywhere from 15-20 years. Self adhering modified bitumen is more expensive than torch applied, but there is no fear of burning your house down.

Both BUR and modified require a primer on any exposed metal or brick.

You ay he was licensed, how do you know? Did you see copies of the roofing license, no not carpentry license, also did you see copies of the certificates of insurance showing workers comp and general liability? What was your deciding factor when you hired the last roofer?

Mulehide is a product that I beleive is specific only to ABC supply. I am told ABC bought mulehide years ago and now their products are simply private labeled other manufacturers. I know in my area the mulehide is much more expensive than any other manufacturer. I personally prefer CertainTeed or Firestone for modified bitumen.

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