Here’s a pic of a flat roof on a garage. The roof is in good condition, but the parapet flashing is shot. How would you reair it? It looks like 30# felt, or some type of roofing fabric, painted silver. Actually, it looks a little heavier then 30#. And it is brittle.
My thought is to broom the gravel away from the base, cut away the existing flashing, install new galvanized base and counter flashing sealed with cold process goo, and fasten the counter flashing to the parapet with mushroom head drive anchors. But I’m concerned about sealing the base flashing to the roof covering.
The roof does have some slope, the downhill end has no parapet, and there are a couple of scuppers involved.
Whenever you are asked if you can do a job, tell’em “Certainly, I can!” Then get busy and find out how to do it. T. Roosevelt
Replies
scrape away all of the rock that you can... ALL of it... at least 2' back from the wall...
Cut away the parapet wall wrap..
add a kant strip at the base.... 6 or 8" face... ready made or build yur own..
hot tar in layers of 60# paper... at least 3 layers... re-wrap the wall...
nail the 1st and perhaps the 2nd layer down to the wall and roof...
cold process it if hot mop is out of the question...
fiber roof cement new to old... press or roll the joints / seams...
use a notched trowel to apply the cement... makes life easier...
wrap the scuppers flashing style with the 60#from outside edge back to the roof... do these 1st...
make it silver again...
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming
WOW!!! What a Ride!
There is a cant strip already. It just doesn't show very well because this wall cap is so loose and puckered away from the brick
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I may have put that on there twenty years ago!
Not really, but I can tell you what it is and how I would fix it - if the roof surface itself is OK.
I would definitely NOT mess with the roof - get a roofing contractor with a kettle and some know-0how to deal with that if it needs help, but what ain't broke - don't try to fix it. Stick to fixing the wall cap.
We used 20# perforated asbestos roofing paper seated in plastic roof cememnt - the stiff fibred stuff. Forget the trowel, it uses three times as much material and takes too long to do it. Work on a warm day, with a helper or two. You are going to need a few gallons of kero to clean up afterwards. Start by tearing off the loose crumbly paper on there now, but cutting it loose near the top of the cant strip so it doesn't tear down into the roof itself.
Draw straws to see which one of you will do the honors. When you lose, you roll up your sleeves and stick your paw right into the five gallon pail. Take a few gobs and throw them on top of the wall. You want to have some warming in the sun while you spread others out.
it sounds terrible at first, but the nice wartm squishy feeling is nice once you get used to it and you quickly learn technique for squeezing it out from your palm while spreading it with the edge of your hand or forefinger, coating a surface three feet wide. Your helper sets the new sheet of paper into it and pats it snug. Then you coat it over again with more roof cement. The sliver coat comes later, after it sets up for a few days. I would not be surprised if the original job was done by skipping the overcoat of roof cement and gioing directly to the silver coat, which would be why it is in such a state of failure. I don't see any paw prints in it. as a matter of fact, the red brick showing through suggests that maybe it was put on with cold process or hot mopped instead of using fibred cement. There was not enough body to it to hold up.
You may not be able to get asbestos paper and may not want to work with it. There are polyester fabrics available for work like this too, but I have not used them.
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Yep, this part was built about 40 yrs ago ... that's when you finished your apprenticeship, right?
How would you tie the new flashing into the existing roof membrane? The roof itself does not have any blisters or alligatoring, so I really don't want to disturb it any more than necessary.
Whenever you are asked if you can do a job, tell'em "Certainly, I can!" Then get busy and find out how to do it. T. Roosevelt
It would just lapp down over the cant strip by five or six inches to where the gravel sets
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the nice wartm squishy feeling is nice once you get used to it
You don't clean out your own Porta Potties, do you. You need to get on the ferry and come to the mainland a little more often.
Seriously, a sheet metal solution would be pretty easy and look a whole lot better. The only question is how to seal the flashing to the existing roof. Lots of options - don't know what would work best.
I invented getting used to it.
Glad to hear you say that ... about the sheetmetal, not the potties. I was in the local roofing supply house today, and a roofer (who doesn'twork there) suggeste3d galvanized base and counter flashing.
Two questions: tie into the existing membrane, and expansion joints. We get temps from freezing (once in a while) to 110 (although 100 is the normal high). Would you just lap the pieces and seal with a good caulk?
Whenever you are asked if you can do a job, tell'em "Certainly, I can!" Then get busy and find out how to do it. T. Roosevelt
If I were doing it, I'd use copper. The galvanized needs painting and by the time you figure that in, the copper's about the same price. You'd probably only need expansion joints about every 25' with either material. I'd pre-tin and solder copper and overlap, caulk, and rivet galvanized. Also, don't make the whole thing out of one piece. Make a base flashing that extends from the roof plane up the parapet. Then make a cover for the top. The less girth each piece has will diminish the expansion and contraction force.
I invented girth.
You wouldn't need a base flashing as long as the existing roof and cant are sound. a cant flashing takes the place of the base flashing. If you added a base, that mean nailing it to the roof and poking holes into it. You would only need the counterflashing dropping down over the cant.
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That's all true, but I was responding in knowledge that he is in Texas and that is the standard practice there, going from previous conditions. Texas is where I learnt that technique. When you're playing cards, you need to follow suit.
But if i were able to clean that crappy cap off the wall fairly easy, I might consider a metal one. The roll near top of wall suggests a cast concrete cap on the brick wall overhanging by an inch or two. With polyurethene caulk, you might not have too hard a time sealing top of metal flashing there, but that is all a lot of speculation.
My background is BUR and yours is metal, so that is why we have differing approaches - neither one wrong.
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My background is BUR and yours is metal, so that is why we have differing approaches - neither one wrong.
Oh I agree - I was just amused at your application method.
I invented the wrong approach.
I know, the first time I saw uit dione, I went, "Yuck!" with a capital Y, but honestly, it is three or four times as fast and uses less material when you get the hang of it - compared to using a trowel - and is easier on your wrist. Not worth getting it on ya for three or four feet worth but a whole wall - only takes five minuites to scrub up.
Now somebody can get all over me about asbestos, VOCs, etc., LOL
now, just think about all this - you have shaken the hand that has done this fifty or sixty times...
;)
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Then what Ed is dealing with at the parrapet wall is not as old as the roof?
What is the chance that the coating and/or paper contain asbestos, and is it a problem for either type of remediation?
Dave
normally, it would not be as old, no. but I have to admit, Ihave never seen one so forgotten and lonely looking.
The asbestos would be mostly encapsualted. Unles it was done in the last ten or fifteen years, the silver coating probably has asbestos in it too. It is only a danger if it is turning dust fibres into the air.
I can remeber doing parrapet walls on a hospital roof once wherre the specs caled for three plies hottmopped all the way up, then the final caot was mopped hot and we had these 55 gal drums of asbestos fibre loose that we grabbed by handfulls and threw into the hot while it was still sticky. Then a top cap of metal was installed by the SM guys.
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Try epdm rubber roof. The folks at conservation tech are very helpfull. If you can strp that metal oiff of there and clean it appling the rubber is easier than it sounds.
Can the epdm stay exposed, or does it need to be protected from uv and stuff?
Is it self-stick?
Whenever you are asked if you can do a job, tell'em "Certainly, I can!" Then get busy and find out how to do it. T. Roosevelt
EPDM is fine in direct UV erxposure, but the adhesion is a problem. It goes on with contact cement, meaning that you need a smooth, clean contact surface to adhere to. It is a 40 year product, so you would be putting a 40 year flashing on a roof that might only have another five or ten years left in it.Kinda like putting a thousand dolars worth of tires on a four hundred dollar Ford
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Down here, it's ... a thousand dollar saddle on a ten dollar horse.
Whenever you are asked if you can do a job, tell'em "Certainly, I can!" Then get busy and find out how to do it. T. Roosevelt
Is there such a thing as a ten dollar horse, LOL
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If EPDM were an option, we wouldn't be discussing this because the entire roof would be replaced. EPDM is an entire system that can't be tied into old work.
Yeah, I know that, but who is this "We" Kimosabe`;)
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Ok ... been talking with my local waterproofing supply house. Ever hear of a product from Sandell "Copper flashing fabric"? It's a sandwich of asphalt-fabric-copper-fabric-asphalt that is applied with mastic. The factory tech rep says it is appropriate for this application.
Whenever you are asked if you can do a job, tell'em "Certainly, I can!" Then get busy and find out how to do it. T. Roosevelt
Ed, interesting thread and ideas. I have lurked on this forum for several years but although I understand residential construction, I do not have the practical knowledge to be able to participate in most discussions. I have been in commercial flat roofing for the past 15 years. This year we installed / replaced over 1,000,000 sq.ft. of flat roofs.
The copper flashing is a through-wall flashing used in masonry cavity walls and not meant for exposed flashing for built-up roofs. Data sheet;
http://www.sandellmfg.com/SPEC%20DATA%20SHEET%20PDFS/TSDS%20Copper%20Fabric%20Flashing.pdf
EPDM can be used in this application. All of the manufacturers have a detail to tie in EPDM to asphalt roofs, but it has to be done correctly.
I would NOT use torch applied membranes...... period. no question. There have been too many large fires ($20 - 50 million in losses) started with the improper use of roofing torches. We use torch applied membranes on a regular basis (we've installed anywhere from 1,000 sq.ft. - 50,000 sq.ft. in the past year) but DO NOT use on a wooden structure of this age.
Metal flashing is intended as a UV protection for bituminous membranes and is not intended as a waterproofing layer. The silver paint on the flashing on your garage act the same way to protect the flashing from UV. Metal expands and contracts much more than the structure and the asphalt roofing. Any caulking used to seal the joints in the metal or from the metal to the roofing would be broken in a short period of time.
Depending on your budget, skills and how long you want this repair to last will determine what you want to do with this parapet. I'm not sure how long asphalt roofs last in Texas. Up here (Canada) I've seen flat roofs like this on garages last up to 30 yrs. Typically flat roofs on industrial / commercial buildings last 20 yrs. If this roof is pushing that time frame then maybe you should consider total replacement by a flat roofing contractor. If it less than a repair could be done by yourself or a flat roofing contractor.
Either way you should clad the back of the parapet in plywood. The brick surface is too rough to ensure a good bond of the membrane (either EPDM or asphalt based) The gravel should be swept back from the base of the parapet and imbedded gravel should be scraped off until the roofing is smooth.
I hope I have helped somewhat, but it is difficult to diagnose the patient over the net.
Scott.
Was I incorrect? I haven't done EPDM but have worked on jobs where it was used and to me it appears to be a system that can only work together with itself.
Dustin, the EPDM manufacturers have an uncured membrane which is compatible with asphalt. This can be set in hot asphalt or cold material. The main EPDM membrane is then glued to the uncured membrane. If you have Autocad I can point you to the detail on the Firestone web site.
Thanks for the Sandell link. It's interesting that with such thin copper apparently they don't have to worry about expansion and contraction at all. For most copper work, you have to use red rosin paper as a bond breaker to keep it from sticking to the felt. This is one of those unusual solutions that I try to keep somewhere in my memory in case some day I encounter a problem for it. ;-)
-- J.S.
Hey, it's great to find some good solid information on this. Don't be so shy in the future.
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Well hot-dam we finally got some expert advice!
First a few details: It's not my house, it's a good long-term client. The particular roof in question is the detached garage. It is stone veneer with a almost-flat built up roof on metal bar joists. The roof membrane itself is in very good condition, it's the parapet flashing that's bad. Apparently some of the damage has been caused by the teenage boy, who used to climb out of the bedroom window in the background with his buddies, and play on top of the garage (they are connected). And since the boy is a certified juvenile delinquient, much of the damage is probably "vandalism" rather than age. The client has put the house on the market (at something over a million) and needs to get a few problems corrected. They saw damaged sheetrock on the garage ceiling, so I investigated and found the damaged parapet flashing.
I believe you about not using the copper fabvric exposed, but ... I talked with Sandell tech support and told them what I wanted to do with it, and he said that would be a good application.
Either way you should clad the back of the parapet in plywood. The brick surface is too rough to ensure a good bond of the membrane (either EPDM or asphalt based) The gravel should be swept back from the base of the parapet and imbedded gravel should be scraped off until the roofing is smooth. Looks like you didn't finish. Ok, so I fasten 3/8 ply to the back side of the parapet, sweep back the gravel, apply asphalt-based membrane on the ply and down onto the roof, then 1: what do I do with the top of the parapet wall, and 2: how do I seal the parapet membrane to the roof? Please give me brand names of products, so I can ask for them and if they're not available, at least the sales rep will know where to start. Sometimes I ask for help from the sales person, and unless I ask for a particular product, they are not at all helpful. Maybe they all graduated for the Home Depot building school.
Whenever you are asked if you can do a job, tell'em "Certainly, I can!" Then get busy and find out how to do it. T. Roosevelt
LOL, I have a double down solution.take the juvenile delinquent up there, and stick HIS hand on the plastic cement to spread it around;)
Glad to be of help
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I had considered usding his face to sprread the mastic ...
Unfortunatley, he is a totally spoiled brat, and daddy can't see it. Momma wants the boy out of the house and down the road, but daddy just keeps giving him money.
Whenever you are asked if you can do a job, tell'em "Certainly, I can!" Then get busy and find out how to do it. T. Roosevelt
Ed, my best advise would be to hire a professional. i.e. a commercial flat roofing contractor.
I have been in construction for over 25 years, including post secondary school. I know how to frame a house and have done several projects around the house including a very complex 3 level - not-a-straight-board-anywhere deck around our pool, basement framing, drywalling etc. But,...... I would not frame a house for a client. I am not a carpenter.
Likewise, I don't believe you are a roofer. Flat roofing is a different animal than shingling. We have separate crews for each and they generally don't intermix. Getting the correct tie-in from the flashing material is critical. Sweeping back the gravel will NOT work. It has to be removed completely from the asphalt flood coat without damaging the underlying roofing. As well I'm not sure what the situation is at the ends of the walls and how you would terminate the flashing at those points. This needs to be done correctly or will fail in a short period of time.
Even though the teenage kids punched holes in the existing flashing it was destined to fail being so baggy form the wall.
Your client has a $1,000,000 house. It deserves a proper repair. Both for your sake, your future reputation, your clients sake and the future owner who could be a potential future client for new renovations. If your repair fails in a year or two your reputation and liability is at risk.
The other issue to consider. You say the existing roof is in good condition. Smooth gravel does not indicate a roof in good condition. Is there asphalt left between the layers of felt or has it become brittle, which is a sign of a failing roof. A professional would be able to assess this.
You also say they had leaking in the past. For how long? Is there any rotted wood decking that should be replaced?
I know its not what you wanted to hear but I believe it is the best idea.
Good point on the rotted wood decking. I believe the roof system is in good condition based on my experience as a commercial facility manager, where I had lots of flat BUR to contend with. There is no alligatoring, splits, blisters, or soft spots, Also no penetratioons in the roof.
Whenever you are asked if you can do a job, tell'em "Certainly, I can!" Then get busy and find out how to do it. T. Roosevelt
Ed, what did you end up doing?
Althought the roof may not show visible signs of defects, as a roof ages the asphalt degrades and becomes brittle. When you try to scrape the gravel you break apart the felts and cannot get a proper tie in.
Still thinking about it. I solved the leak at the master BR fireplace ... it has rained very hard twice since then and nary a drip ... so she is happy and not in a hurry to fix the garage. Well, she wants it fixed soon, but since it doesn't leak into finished space it's not urgent.
Whenever you are asked if you can do a job, tell'em "Certainly, I can!" Then get busy and find out how to do it. T. Roosevelt
If it's not leaking, why not leave it alone thru the winter and do it right after the weather gets nice in the spring?
-- J.S.
Cuz winter here lasts about 3 weeks, and thats the end of January.Whenever you are asked if you can do a job, tell'em "Certainly, I can!" Then get busy and find out how to do it. T. Roosevelt
but since it doesn't leak into finished space it's not urgent.
What about mould and rot that will continue until the area is dried up.
Dear Kimosabe,
I was under the impression that this was an open forum for discussion, EPDM is not an option as far as I had read so I issued my post. You and I have had posts together in the past and I don't get the stone busting now???!!
You missed the smiley face hint that I was joking. I thought it humous the verbiage you used in saying that "we" are participating in this discussion when up to that point you had not joined in the discussion is all. It seemed a little odd and gave me a chuckle that I was trying to share back with you. thus the Tonto/Lone Ranger joke reference. No offense intended. I was also unaware of the detail for joinning EPDM to BUR haviong been advised when I took the classes on it to avoid contact between the two - but that was almost twenty years ago
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ed
don't go mixing rubber membranes with hot applied membranes. the two aren't compatible.
carpenter in transition
Thanks, piffen.
We encapsulated a similar detai; on a parrapet wall with painted galv. a few years ago, because of the asbestos content. Acctually covered a nice copper flashing just above the cant. This one did not go over the limestone cao on the wall, so a reglet was cut beneath the stone and the galvanized counter flashing tucked, wedged and caulked. Turned out to be an expensive fix, but solved our wall leak problems,and avoided the asbestos removal cost.
As a "deep pocket" utility company we have to be concerned with worker protection. If it is covered in OSHA 1910 we comply, or in most cases over comply as a CYA thing.
BTW, Tremco makes a cold mop BUR that is holding up guite well after 10 years. It is a lot slower to apply, but on an occuppied office building we couldn't risk a hot mop. Half the building would have gone home sick at the first wiff of hot tar in the building.
Dave
Ed,
Is that silver roof really connected to that beautiful limestone building with the steel casement windows and terracotta tiles ?
I think I would go with some of each, here. The parapet cap would look and work best as copper but the sidewalls of the parapet should be a membrane similar to the material used under the gravel. More than likely, this was a 3 ply hot builtup. While I understand the interest in not disturbing the existing roof, your photo shows that the existing membrane on the parapet is cracked almost all the way down to the roof deck. This will probably force you to strip the gravel off of an area wide enough to tie in the new parapet membrane with the existing roof membrane. I would probably have a roofer look at this because I would lean toward using a hot applied process over the cold application.
carpenter in transition
If this original roof really is forty years old, you are right, and he needs the whole darn thing totally replaced, but he reported the roof to be in good shape. Out in that part of the country, it is very common for a good BUR roof to go thirty years, buit the wall caps need redoing every ten years at best. - standard practice there that way - hail
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I've fixed crap like that more times than i like to remember and have one to do now...
what i'd do:
remove all that silver crap... get your rocks back at least 24 inches.. I'm guess'n there is some type cap under that silver paper...
I'd use torch down I'd cut 7 3/4" cant strips from 3/4 plywood (6... 8ft strips per sheet) i use the torchdown cut in 2" strips to hold the cant strip like set'n em in a hot tar base i then cover it all with torch down i like 12" torched to the old roof... i cover the the cant with 30lb felt so the torchdown floats over it then i like to torch a min of 6" to the wall... i can work with about 6ft at a time with one helper... it'd be cool to be able to do it long and only have a seam every 33ft.. but just too hard to work......
on tall walls i like to diamond cut a 1/2" saw cut in the brick wall about 7" above the top of the cant strip and glue or peg a metal flashing that will over lap the top edge of the torch down... doing this i have never had a problem in thousands of feet run... (yet)
this fix is cheap as far as material... but hot and does take some time... on a flat roof i can do a sq of torchdown with my dragon wagon in 15 min max... 30 sq a day easy with one helper... doing walls like above... maybe 100ft on a good day less than 3sq of material...
pony