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Temporary roof repair question

  • 1.  Temporary roof repair question

    Posted 05-31-2019 13:57
    I'm working with a small "friends of" group, to try to keep a former mansion in the center of what is now a public park from being demolished by the county who owns it.  County ownership has not been kind to the building, and although the main hip roof (asphalt shingles, fairly steep slope) is still in decent condition, there are 15 or so large dormers, which have been stripped of their copper valley flashing, so water has an easy entrance into the building (and has for years).  The roof sheathing and framing is now deteriorating, and the county is wary about anyone walking on the roof, even to do repairs.  Someone has proposed closing these valleys temporarily with spray foam insulation, which could be done from a high-reach and is waterproof enough to last a few years at least.  To be clear, we'd be using the spray foam as waterproofing, not for any insulation value - the building is vacant. This is just to try to get it buttoned up so we can start to dry it out.

    I can't think of why this wouldn't work - any thoughts or feedback welcome.

    Kathy Dowdell

  • 2.  RE: Temporary roof repair question

    Posted 06-03-2019 17:33
    Kathy - interesting idea, the only issue I see is foam is very sticky and difficult to remove. Maybe that matters less since the sheathing would likely be replaced, and maybe the framing too. Just another idea but heavy duty tarps, tacked down w/ wood strapping can last for 1-3 years based on experience.

    Gene Greene, AIA, NCARB
    Principal, Historic Architect



  • 3.  RE: Temporary roof repair question

    Posted 06-03-2019 17:39

    The fix you described sounds like it would work for the purpose you are trying to achieve.  Possibly afterwards once the building is dried out then permanent repairs to put the dormers/copper flashing back in the valleys can be done.


    Greg Taylor, AIA, NCARB, MBA

    Gregory Taylor, AIA,NCARB,MBA
    Managing Architect
    Childress Engineering Services
    Richardson, TX

  • 4.  RE: Temporary roof repair question

    Posted 06-03-2019 17:46
    Not a bad idea. To keep in mind:
    If the foam makes a ridge/dam on the up side it may just redirect the water. Make sure it is redirected in a positive way.
    Sometimes facilitating the water through the roof and then catching it and directing it out on a temp basis will do less long term damage. Primarily you don’t want it ponding and keeping areas damp for extended periods of time.
    Good luck

    Charles A Phillips, AIA, AIC-pa
    433 Phillips Rd
    Nacogdoches, Tx 75964

    640 Brookstown Ave
    Winston Salem, NC 27101


    From iPhone

  • 5.  RE: Temporary roof repair question

    Posted 06-03-2019 17:59
    Edited by Marsha Levy 06-03-2019 22:07
    I would avoid the use of spray foam, especially open cell spray foam like Icynene.  Open cell spray foam is not watertight, and cannot act as a roofing material.   I am aware of a project where a roof leak went right through Icynene sprayed on the underside of the deck below.  Once it is sprayed onto a surface, foam is very difficult to remove.  Historic preservation agencies I've worked with will not approve of its use in walls, as it is not considered reversible.  There are spray foam roofing systems that have a liquid membrane applied on top of the foam, but removal may be an issue.  For temporary, inexpensive roofs, I've used acrylic coatings over a reinforcing fabric.   One product I've used is called Acrymax, and there are now others like it.  I've applied it over a variety of substrates.  It can be installed over rusted metal.

    Foam that is sprayed in a 2-component system can also generate a lot of heat when it cures.  The temperature during curing should be verified if you do have foam.

    The acrylic products can be used as temporary valley flashing over wood decking.

    Marsha Levy AIA
    Boca Raton FL

  • 6.  RE: Temporary roof repair question

    Posted 06-03-2019 21:53
    That's an interesting use for spray foam, although an arborist suggested it to seal up a split tree and that seems to have worked. The exterior surface will be degraded by the sun, but slowly, and you are not looking for a permanent fix. Just be sure to use closed cell foam because open cell will be a sponge and make things worse. Do it when the wood is dry and try not to mound up the center of the valley which would push water back under the shingles. It would be nice to shape the foam into a valley, but the only thing I know that can be used to shape uncured foam is an ice cube and I don't think that would work on this scale and location. Perhaps you could come back with the lift later and spray paint on the foam to protect it from the sun.

    William Badger AIA
    Badger and Associates, Inc.
    Manchester Center VT

  • 7.  RE: Temporary roof repair question

    Posted 06-03-2019 22:37
    Wow, that's some problem.  I would certainly look for an alternative to the foam. Even if the foam would work, I would be inclined to come underneath with comparatively inexpensive, temporary 2X wood bracing that extends back to wall top plates or other features that could take some of the roof load.  Sounds like the roof structure could use it to help guard against a collapse, regardless of the valley flashing solution. Once the roof was braced enough to allow workers, then a more conventional temporary flashing method could be installed at the valleys and any other locations where water is coming in.

    Norman Alston, FAIA
    Norman Alston Architects
    Dallas, Texas

  • 8.  RE: Temporary roof repair question

    Posted 06-03-2019 22:57
    If you can reach the valley with some sort of bucket truck and you will not physically get on the roof. 
    Just remember that the spray foam is only temporary, and will only last maybe 2-3 years. The sum's UV will deteriorate the foam. 

    Blaine O. Johnston, A. I. A.

  • 9.  RE: Temporary roof repair question

    Posted 06-03-2019 23:08
    How about self-adhering membrane or tarp? and do the whole roof to catch all the adjacent areas, so all the sheathing / framing can dry out.

  • 10.  RE: Temporary roof repair question

    Posted 06-04-2019 10:42
    I am a fan of spray foam for many applications - but not6 this.

    The first axiom is "Do no harm." Applying spray foam to the exterior will require that any future efforts will require a significant demolition effort to remove it.

    And the foam fails to address the points you mention regarding the worthiness of the sheathing. It appears that the first question that needs to be addressed is the issue of the sheathing's worthiness. If it is sound, the metal flashing needs to simply be replaced.

    What is the age of the shingles? If the slope is steep, underlayment is not an issue, but if they are 30+ years old, their condition is deteriorated whether it is showing with any 'baked' streaking or granule separation or not.

    As a worst case - ignore the real problem - don't do a comprehensive assessment - get a band-aid on there fast - I'd suggest scraping the granules and applying a peel-n-stick flashing product from a lift or cherry-picker.

    William Eberhard AIA
    Managing Partner
    Eberhard Architects LLC
    Cleveland OH

  • 11.  RE: Temporary roof repair question

    Posted 06-06-2019 14:24

    Many years ago, we shrunk-wrapped (not sure of the right term) the top of a building owned by The Trustees of Reservations to buy time until the building could be restored.  We called a company that wraps yachts, some of which are pretty massive, for winter storage.  Same technology, just a different object.


    Jean Carroon, FAIA, LEED Fellow
    Principal - Design, Preservation and Sustainability 
    Goody Clancy
    420 Boylston Street
    Boston, MA 02116
    617 262 2760 (main) 617 850 6651 (direct) 617 285 5936 (mobile) 

    Goody Clancy


  • 12.  RE: Temporary roof repair question

    Posted 06-04-2019 14:33
    I don't think that spray foam is a good idea, it is a relatively thoughtless "builder's solution" - easy to grasp, but not effective.  The foam is likely not able to perform under UV attack by the sun, under ice and snow, it holds moisture in the wood, and will be full of ripples & puddles.  The main rafters should be examined from below, they may be good enough to support some workers weight to get some heavy tarps nailed down on the dormers.  Call a good PE like Jim Cohen http://www.jcconsultingengineers.com/ to evaluate it and determine a plan of action that is acceptable to the county & its insurers.

    Christopher Pickell AIA
    Pickell Architecture, LLC
    Flemington NJ

  • 13.  RE: Temporary roof repair question

    Posted 06-04-2019 21:16
    Edited by John Alvarez 06-04-2019 22:04
    The use of spray foam for water proofing is a bad idea. Application of a perceived band-aide to buy a few years only kicks the can down the road. Spray foam is not very reversible which will turn the future rafter repair into a rafter replacement.  Keeping the water out is a great goal, but using spray foam to achieve it is asking for more trouble because there will be pockets where water is trapped which will accelerate the rot.  If the roof structure is a concern, it should be temporarily shored from below and then a temporary roof using tarps or a rubber membrane should be applied.  Of course, this solution is probably more expensive than applying spray foam from a bucket truck, but spray foam expands right after application and spraying it in a fashion that won't create water dams would be impossible. As others have suggested in this thread, a temporary membrane might be the best solution if shoring could be installed.

    Jack Alvarez AIA
    Landmark Consulting, LLC
    Albany NY

  • 14.  RE: Temporary roof repair question

    Posted 06-04-2019 21:51
    Am I correct in understanding that the valley flashing was looted, but the balance of the asphalt roof in is still in place, so there are just valleys in play here?  30 lengths where the dormer roof meets the rake of the larger roof plane?

    First off, I would confirm that the deterioration is extreme enough and widespread enough that an experienced roofer can't manage, albeit carefully. Some lengths of roll roofing and adhesive/sealant might be the most roof-ey temporary solution. Not elegant but, literally, a bandaid.

    Spray-on membrane in roofing is one of my least favorite systems, but it is made for being impervious and exposed to the elements. I would think that that would be a better strategy than just plain closed cell spray foam.

    Allowing the saturated stuff, below, to dry out is another consideration....but that is the case regardless of strategy.

    An interesting problem!  Good luck!

    Peter Franks AIA
    The Franks Design Group, P.C.
    Glenwood IA

  • 15.  RE: Temporary roof repair question

    Posted 06-04-2019 22:49
    Let’s remember that all of the “better “ solutions are probably better but you need to triage your project and decide what you can actually get done, and keep the patient on life support, especially with volunteers and little or no money. If the better solutions are possible for your project, great! If the better means it isn’t going to happen, choose the better than nothing “sort of OK” solution, score a win and use the psychological boost to move toward a real roof solution.
    Good luck!
    Charles A Phillips, AIA, AIC-pa

    433 Phillips Rd
    Nacogdoches, Tx 75964

    640 Brookstown Ave
    Winston Salem, NC 27101


    From iPhone

  • 16.  RE: Temporary roof repair question

    Posted 06-05-2019 17:24
    Under no circumstances use a spray on foam insulation in a historic building. You need a reversible solution and that is not it. Moreover, it can lock in moisture, as others have said. There are other, less intrusive methods that are effective in this case.

    Mark Hewitt FAIA
    Mark Alan Hewitt Architects
    Bernardsville NJ

  • 17.  RE: Temporary roof repair question

    Posted 06-06-2019 18:14
    I concur with the others about the foam. Foam will not breathe, or breathe adequately for the assemblies to dry out. Allowing the assemblies to dry out is as important as stopping the water infiltration. You need to do this to prepare for the restoration work.

    Possibly one part of the solution is to batten down breathable tarps, set from the high lift. (Some tarps are specifically advertised as such.) The other part is to insure air movement inside, for drying out both the underside of the roof and the floor structure below it, if that was affected also. 

    Once accomplished, you will need access "up close" to document the historic fabric, inspect the structural condition, and to test for mold. This will need to start with checking the structural adequacy of the floor directly below, if it was affected also by the water infiltration.

    Good luck.

    Joe Catalano AIA
    Sierra Madre CA