Flat roof leaks adobe home


  #1  
Old 02-02-05, 07:36 AM
Casey
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Question Flat roof leaks adobe home

We live in an adobe home. The home has a flat roof that leaks. The entire area of the perimeter has parapet walls about 4 ft. high with scuppers to allow drainage from the roof. There is insufficient slope to the roof. If we have crickets built to direct the water toward the scuppers, what is the best roofing material? We have modified bitumin currently but we experience leaks. What about metal? We live in the foothills of the Rockies & get snow and hail.
If a metal roof is installed, what kind would be best? My husband and I are not able to do any work on the roof so all must be hired.
 
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Old 02-02-05, 08:16 AM
J
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You need to get positive slope-to-drain. Tapered insulation is probably better than wood crickets. How old is the existing roof? I'll bet the leaks are at penetrations or at the bottom of the parapet walls near the cant. Is the mod-bit all of the way up and over the top of the walls and covered with a metal cap or is there a tie-off somewhere on the surface of the wall? Check the tie-off, if there is one. Metal is probably not an option. Low-sloped metal is designed for large industrial type buildings an is difficult & expensive on small jobs. Also, parapet walls are almost impossible to deal with in low-sloped metal.
Jim
 
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Old 02-02-05, 08:39 PM
Casey
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Adobe flat roofed home

Thanks you for your reply, Jim. The house is 8 years old. The original roofer didn't give sufficient slope for drainage but we were clueless then. NOW we know. A new roofer has recommended crickets. I will ask about sloped insulation. No, the MB did not extend up the parapet walls. This new roofer recommended going over the parapet walls with MB. The home is stucco over the adobe and no mention has been made about a metal cap. However, that sounds logical since we get hail. Since metal roofing is out, do you feel another layer of MB would be the way to go this time? Also, what would you
recommend for length of the scuppers? An enormous amount of water cascades from these at times of downpours or melting snow. Just this weekend we received 3' so when melt comes we will have niagra falls. Our scuppers exit the parapet walls just over the placement of vigas for support of the load on the scuppers.
 
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Old 02-03-05, 04:28 AM
J
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Are you in Taos/Santa Fe? Mod Bit will be OK again. The other single plys are also OK (EPDM (rubber) & TPO are common). With Adobe/Stucco, the parapet walls may have "rounded" tops...if so a metal cap on top of the wall may not work. If not, make sure that the new roofing goes up the walls higher than any expected snow and the tie-off/reglett detail is good.
Tie-off to the scuppers is also a critical detail. What's a vigas? Downspouts under scuppers can reduce noise & mess from cascading water. Decorative cisterns?
Jim
 
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Old 02-04-05, 08:23 PM
Casey
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Thumbs up Flat roof leaks adobe home

No, we live in the southern end of Colorado at about 6500 ft.

Vigas are the Spanish name for the large log roof supports that extend beyond the face of the outside wall.

Our parapet walls are rounded at the top. However, when we built this house copper caps were molded around each protrusion of the vigas to prevent rot on the ends of these huge log supports. I would guess the same thing could be done for the tops of the parapets. They could be galvanized sheet metal and painted and they would never be noticed. I had never thought of this and believe that is an excellent idea.

Thanks for the recommendations. I now have some good ideas to discuss when the roofer arrives. You have really helped!
 
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Old 02-06-05, 12:23 PM
E
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As one respondant mentioned, a tapered insulation system is a better way of dealing with the ponding.
But if you are going to go to that expense {they are expensive}, you should have the old roofing stripped, and any repairs needing to be done to the underlying deck, done prior to installing a tapered system.
The "modified" membrane is a fine roof product if properly/correctly installed over a surface with any kind of positive drainage.
 
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Old 02-07-05, 06:39 AM
Casey
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Question Flat roof leaks adobe home

Help me understand, please. Is tapered insulation wedge shaped? If not, how is this insulation applied so that one gets a slope? Of what is this insulation made? Can one walk on the roof after using insulation for slope? Is this a kind of rigid insulation board?
I'm clueless!
 
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Old 02-08-05, 05:01 AM
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Tapered insulation is a "system" which will include a combination of rigid dimensionally uniform "boards" and rigid boards which are tapered. These board are laid down in such a way as to provide a continous slope, providing positive drainage towards the area you want it to drain to. They would be attached to the deck with special screws and wide metal plates {like washers}. There will be a minimum slope required by your local building code authority. Where I am it ranges from 1/8-1/4 in. fall per ft {depending on jurisdiction}. The steeper the pitch desired, the more it costs due to the simple fact it takes more insulation.
There are a a number of insulation materials used in making these boards. One preferred type would be Isocyanurate {known as "Iso board"}. It's a type of light-weight foam which happens to have excellent r-vallues.
Although it can be easily dented, it is walkable once covered with the roof. A better thing to do {although certainly a chunk more money} would be to install 1/2 CDX plywood over the insulation prior to roofing it. Besides providing a more rigid/solid surface, this would incorporate the insulation in a more permanent fashion. This is MY opinion. But I tend to think about "down the road". Down the road, if/when the roof needs to be stripped and replaced, the inslulation might very well suffer from the stripping and need to be repaired, sections replaced, etc.
And I've found that this rigid insulation tends to degrade some as it is, over the years. Isolating it with the plywood would tend to protect it. But it's all about money and a homeowner's needs/interests.
Bottom line, as in all roofing applications, this tapered insulation needs to be installed according to manufacturer's specs. Frequently this system is installed with insufficient screws, allowing boards to buckle, which also happens to affect the roof covering.
Sorry to be long-winded here. Flat roofs rank right up there in terms of skills required, attention to details needed, and not the least:COST.
One last thought, when spending such a chunk of money on the insulation, it would not be wise to install it over old an deteriorating roof. Again though, it's about cost.
 
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Old 02-08-05, 07:20 PM
Casey
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I thank you so much for I am winging it when it comes to specific information regarding roofs of any kind. Sort of like when one knows how to pump gas into a car and not much else. Often you can be told you need something that you don't, or you have no idea if you have needs no one is addressing.

I also like the idea of looking down the road and not repeating past mistakes if possible.

I have a well known roofer in our nearest town coming out in the morning to have a look and give some advise. I will take all these good suggestions and good information and see what this guy says. Wish you could be the mouse in the corner so nothing gets by me, but I'll do the best I can.

Thank you again, what a great resource this site has been for me!
 
 

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