Best choice for ponding water


#1

I have a BUR + cap sheet flat roof which drains fairly well, but there are areas where water will pond up to 1" deep.

My plan is to add some drains, but I also want to cover over some areas which look a bit worn. In general, what is the best material for this re-cover if there is some ponding? Which one will bond best to the existing roof?

  1. asphalt + 1 layer fg + asphalt + cap sheet

  2. one layer of granule covered torchdown

The torchdown stuff is new to me, but a lot of local roofers are recommending it, and I wonder if this is because it is a better product, or because it’s less risky to install.

Thanks.


#2

hello flat roof
if its not leaking because of the ponding and only ponding an inch here and there i would tear it off then put down some peal and stick torchdown underlayment and then torch one layer of granulated torchdown. i wouldnt worry about the ponding.

if you have a house built of cedar an old spanish style with termites or any other house that easily catches on fire, make sure you have a very experienced installer, and make shure someone is there for a couple of hours after roof is torched to make shure everything is ok.
dont torch it, then everyone run out to dinner.

good luck.

gweedo


#3

I would suggest Everguard TPO by GAF.
gaf.com/Content/Documents/10881.pdf
Good Luck!!!
J


#4

IMO, if you’re ponding about 1" or less & it’s NOT leaking, especially if the ponding isn’t in an area where you have seams, then I’d say leave it be.

PS to Gweedo. “Peal” is the loud sound of a horn or siren.

“Peel” is what happens to your skin 4 days after you go fishin’ for Snook & fall asleep in your kayak.


#5

its not ponding unless it is still there after 48 hrs of dry weather.


#6

There’s always tapered insolation to give the roof a little slope for the water to run off,and I like the modified torch downs


#7

Tapered insulation systems are prohibitively expensive for most residential work.

1" is not much of a pond…


#8

[quote="-Axiom-"]

Tapered insulation systems are prohibitively expensive for most residential work.

1" is not much of a pond…[/quote]

GAF wouldnt give any warranty on the modified unless the roof was sloped for runoff,we did a lot of tapered on residential,I guess we had a good salesman and thats what the homeowner wanted,you get what you pay for.


#9

The last time I priced out a tapered system for a residential it was something like $6k for less than a 3 sq area, just for the insulation…

So I do it the hard labor intensive way.


#10

[quote="-Axiom-"]The last time I priced out a tapered system for a residential it was something like $6k for less than a 3 sq area, just for the insulation…

So I do it the hard labor intensive way.[/quote]

Not many homeowners will jump on that,the company I worked for only uses GAF materials and were getting 2 tractor trailer loads of materials in every week,not sure what they were paying for the tapered but I bet it wasnt much.I dont sell roof jobs ,I just do them so I cant really say how much tapered costs.


#11

A couple of replies said 1" of water isn’t too bad, and maybe leave it alone, I wish I could, but there are some leaks near the low spots, and even though it hasn’t rained much the last couple of years, I would say some of the water lasts 2-3 days depending on weather.

A tear off and re-roof is an option, but there are Title 24 requirements, and one big? concern is any wood replacement cost. I know that the 1st layer of the roof was mopped, instead of nailed, to some new plywood about 15 years ago, and so if the roof is torn off, will the plywood get damaged? It wasn’t a solid mop, just drizzled, but still some wood could get pulled off. Is this likely, and thus a good reason to patch and re-cover as much as possible?

Also, how well does a torchdown layer adhere to an older layer of cap sheet? Is some sort of a coating needed first? Different people have been telling me different things.


#12

ok flatroof,
your gonna screw around and end up with a big mess.

listen very carfully.
you have to get rid of the slopped on mess you have up there. if some is stuck to the wood then clean it off the best you can and move on. if you have to replace some plywood, so be it.
then get your new roof, either a 3 ply glass or a torchdown.
forget about the drains, forget about the ponding.
get the old roof off and the new roof on.

and torchdown adheres to old cap sheet like crap.

good luck.

gweedo.


#13

[quote=“flatroof”]I have a BUR + cap sheet flat roof which drains fairly well, but there are areas where water will pond up to 1" deep.

My plan is to add some drains, but I also want to cover over some areas which look a bit worn. In general, what is the best material for this re-cover if there is some ponding? Which one will bond best to the existing roof?

  1. asphalt + 1 layer fg + asphalt + cap sheet

  2. one layer of granule covered torchdown

The torchdown stuff is new to me, but a lot of local roofers are recommending it, and I wonder if this is because it is a better product, or because it’s less risky to install.

Thanks.[/quote]

Does the roof leak? How old is the roof? Reason being, I don’t know that I would replace the roof if it is in reasonable good condition. You can deal with the ponding separately, by building the low areas up with extra layers of membrane or tapered insulation and membrane.

I don’t come around here much anymore, so you will probably need someone else to explain it all to you. Bottomline, don’t let someone sell you a roof just because your’s ponds. A 2- or 3-ply BUR with a modified bitumen cap sheet should last you 15-20+ years. Of course, a lot of that has to do with the roofing contractor that installed your roof.


#14

gweedo wounders why his allmighty cerb has been
advizing less here.

gweedo.

start a thread when ya get time.