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Flat roof repair/replacement

[email protected] | Posted in Construction Techniques on February 8, 2011 03:47am

I have some forest lookouts that need reroofed.  The existing roofs are 2X6 tongue and groove doug fir sheathing, on 2X8 joists at 24-inch on center both ways.  They are square, and about 22-feet on a side.

The roofs were finished with 6-layers of 30-lb felt layed in alternate directions, and hot tarred between each layer. 

It was a good design fifty to sixty years ago when they were built, but they have finally aged to the point I need to replace them.  They might have lasted forever, but the radio guys drilled a few holes in them down through the years, that didn’t get sealed up correctly, and some water got in. 

I’m looking for advice on alternatives, or should I just do any repairs that are needed to the 2X6 sheathing, and install a new felt and tar built up roof? 

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Replies

  1. fwmal | Feb 14, 2011 05:03pm | #1

    A two ply SBS Modified membrane is a great replacement for the built-up roof membrane. It can be done in a complete cold application now, if it is easier to not torch down the cap sheet in this situation. As with any roof, keep people from drilling holes through it.

    1. DaveRicheson | Feb 16, 2011 10:11am | #8

      Drilling

      Knowing how to drill through and properly flash a built up roof is real problem. I can teach anyone how to build and fit a pitch pocket in about 30 minuites. most installers of auxillary equipment don't have clue, nor are they ever held liable for the damages from thier lack of knowledge.

      They either need to learn how to correctly flash any penetrations they make or show that they have a roofing contractor that does follow on thier work. Most of the time the person ordering an install is not the same one that is responsibile for the roof, so they don't know that the little antenna they want installed can cause a massive amount of damage down the road. For that reason we do not allow any equipment to be placed on our roofs without prior approval and our supervision.

  2. Clewless1 | Feb 15, 2011 08:00am | #2

    One of the monolithic roofing products might be a better way to go. More cost on the materials, but the install would be a lot easier. Not sure what the current choices are ... in the recent old days it was e.g. EDPM and hypalon ... now I've heard of PVC and TPO. Not sure the width of some of these products. You might get away w/ one sheet. You have a low slope to at least one side I assume. There is also another product ... can't think of the name ... it's a super nice coating product initially put down in a series of layers and then maintained by simply a recoat on the top. Very durable and nice. http://www.hydro-stop.com/

    This stuff is pretty nice ... expect maybe about $3.50/sqft for materials. You'd have to get certified to do it yourself, but I understand that is relatively a very doable thing (they tend to encourage your own maintenance which requires application knowledge).

    It'd be a shame to attempt a hot tar install and burn down your fire tower. ;)

    1. [email protected] | Feb 15, 2011 01:36pm | #3

      Thanks

      I may have found a manufacturer who will preform a roof system for us to install.  They did several for one of the other Forests last year, and I have asked them to send me information on the company, and product. 

      Now if Congress would just pass a budget, so I know how much money I have to spend life could be simple. 

      1. Clewless1 | Feb 16, 2011 01:03am | #4

        oh ... riiggght ... I forgot ... it's the Federal gov't. You're on your own, buddy.  ;)    Sounds like you might have a good idea brewing. Be prepared for plan B, just in case. 

  3. DaveRicheson | Feb 16, 2011 06:21am | #5

    Different view.

    50 to 60 years for a BUR is excellent.

    Since you are spending tax dollars, I think I would demand that whatever roofinf system you use last at least that long. :-)

    Seriously, built up roof are still good roof when installed properly, and they take very little maintenance. A four ply BUR done correctly will last another fifty years.

    1. DanH | Feb 16, 2011 07:16am | #6

      Depending on the access, hauling in a tar pot for a BUR may be a PITA.

      1. DaveRicheson | Feb 16, 2011 09:58am | #7

        Time to update your knowledge of built up roofs.

        There are cold applied built up roof systems that are equal to "hot mop" roofs. They have been around fo enough years to have a proven track record.

        I went to Cleveland for a week long school at Tremco over 12 years ago and they were on the market then. I have since been a project coordinator on four cold applied BURs and two hot mops.

         A truck load of five gallon buckets and felt rolls can go just about anywhere.

        1. DanH | Feb 16, 2011 06:58pm | #9

          Well, all I ever see around here is the large commercial work, which seems to be mostly hot.  The smaller jobs are generally "rubber", based on what I've observed.

  4. [email protected] | Aug 13, 2012 05:07pm | #10

    Remoteness is the killer

    These things are remote (4 + hours from townon really bad roads), and the town is remote (2.5 to 3 hours from either of the regional hub cities near us).  It is hard to get a roofing company to even come to the one that is easiest to get to, to give me an estimate. 

    And, I would really prefer too replace the roofs with hot mopped tar, since we got a forty year life out of that.  EPDM is more fire resistant, which is a real concern in these locations, and we don't have to figure out how to get a tar heater to the sites.

    The one that needs actual repair work is about 6-hours one way from town, on a road that is a pain on a dirt bike or 4-wheeler, and has about 2-hours of 4-low, first geat creeper time to get there with a truck.  We have discussed my two guys trying to trim back the asphalt roofing, and repair the T&G.  I have real concerns in doing a replacement hot mopped roof.  I know that 50 years ago, they heated the tar in a 14X22X6-inch pan on a two burner coleman stove, (we still have the pan).  I also know the OSHA folks would go nuts if they found out we were doing it that way, and if there was an accident I could end up headed down the road. 

    So, were headed towards EPDM, at about $10,000 per roof. 

  5. jhonson | Aug 21, 2012 08:41am | #11

    Roof replacement does not have any solution. Replacement should only occur if the product has reached its life expectancy, or it has been incorrectly installed. The SureCoat Roof System has been enginered to recondition and protect the design flaws of traditional roof materials including single ply system.Hence, the SureCoat Roof System used on repairs will bond into a full reconditioning system at a later time

    1. DanH | Aug 21, 2012 08:44am | #12

      I tried SureCoat Roof System and my house exploded.

      SureCoat Roof System products are made from the fur of baby seals.

      1. seeyou | Aug 21, 2012 07:42pm | #13

        SureCoat Roof System products are made from the fur of baby seals.

        Damn, Dan. Can't you get anything right? Their products are made from aborted fetuses BY baby seals.

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