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superdairyboy 03-25-2011 11:47 PM

Repair and Maintence of a Torch down roof.
We have a very old commercial Building it has a torchdown roof. it is leaking in a couple areas.
Had a couple contractors out looking at it. 2 identifyed it as asphalt rolled roofing. and one Identified the roof correctly as a torch down. this contractor felt that it could easily be repaired and coated. he explained that torch down roofs every 5 years or so need a maintence coat.

As I've been reading to coat a torch down roof you are to use an acrylic roof coating like KOOL. is this correct? anyone recomend a specific type or brand? is it safe on Rubber? as we will mostly replacing a section of the roof with rubber. see bellow.

we have a knee wall on the building. it is brick, as it is a brick building. this is where we have the most problems where the Bitumen comes up the side wall and then on top of the knee wall. where it makes the 90deg bend to lay ontop of the knee wall there are cracks/tears. I will try to get pictures this weekend. My question is how should these be repaired?

last question there is a Large skylight that is causing some leaks. we are going to remove it and Plywood over. the one contractor who suggested repair said this can be replaced with EDPM rubber. my question is how is rubber tied into the Torch down? we will have approx. a 10x15ft section that will need to be covered once the skylight is out.

Talos4 03-26-2011 07:00 AM

First things first, "asphalt rolled roofing" and "torchdown" could be the same thing. Photos would be a big help.
It could also be smooth built up roof, to the untrained eye it looks like rolled roofing or torchdown or to many even rubber.

Coating modified bitumen roofs is recommended especially if they are smooth surfaced. Safe on rubber? Yes, more on the rubber in a moment.

Photos of the parapet wall repairs would help. Recommending a repair without knowing the actual condition of the flashings is difficult. It could be anything from a simple 3 course the seams repair or tear them out and start over repair.

Now to removing the skylight. EPDM (rubber) roofing is only compatible with EPDM (rubber) roofing. It is not compatible with "rolled roofing" or "torchdown" You must provide a separation between the two different roof membranes such as a tie in specifically made for this type of tie in.

For simplicity sake, just use the same type of material that's on the roof now.

But first you have to correctly ID that first. Post some photos, that will answer alot of my questions and will influence the answers of many.

superdairyboy 03-26-2011 07:37 AM

Will get them pictures. hopefully today. As for the torch down there is a guy in our area who does torch down. I know he did our neighbors roof. ours and his looks the same and the 3rd roofer id it as torchdown. the 3rd roofer is well know in our area. thus the reason i trusted his opinion. But anyhow I will get you some images.

superdairyboy 03-26-2011 09:08 AM

Ok here are the long awaited Pictures actually not that long awaited.

The roof does seem to have a coating of Alumnium roof coat. I baseing this on the empty bucket of it I found in the rafters.

I made a webpage for them instead of clogging up this post with 12 images

here is one image of the entire roof for all to see

OldNBroken 03-26-2011 10:11 AM

1 Attachment(s)
Looks like you have an old roof still in decent shape just needs a lot of attention. The walls can all be re-worked and consider an emulsion and mat maintenance coat in the field. Metal coping on the walls always lasts longer but costs a bit more.
As far as the skylight, it will cost as much or less to remove it, raise the curb eight inches so it's at the proper height from the roofdeck, and re-install it. Yes it looks old and crappy but we re-work those all the time. It's a shame to eliminate such a useful item just because the roof leaks. It's sitting too low on the deck.

superdairyboy 03-26-2011 08:35 PM

Yes Ihate to get rid of the sky light I have mixed emotions about it. the skylight it self is only approx 6ft x 10ft but the Light way below it down to the 1st floor this is a much larger open space. approx 10ft x 18ft.
This could easily be converted into usable apartment space and generate more income. I hate how that sounds but it is the truth.

the one corner where the skylight has sunk the decking it rotten. However never thought of taking the skylight off and framing a 12in wall for it to sit on.

I has seen emulsions mentioned before for torch down coatings. they also recomended coating the emulsion then with a white coating to help reflect the sun. I assume the emulsion is a better product then the alumnium roof coat or the acrylic coating. (actualy the acrylic is what would go on top of the emulsion correct?)

I will have to consider the raising the skylight concept and keeping it. Our code officer and a building inspector are coming out hopefully next week to do a walk through so we can discus the renovating we want to do on the 2nd and 3rd floors to make more apartments. Currently there are only 2 on each floor. however we have the potential to get 3 or 4 on each floor. removing the skylight gives us more room. we will see what they say we can do inside.

And as for the Knee Walls the repair that was done on the one side was done atleast 7 years ago. as we have owned the building that long and no one has touched the roof since. so that repair has been holding well and still looks good.

OldNBroken 03-26-2011 08:51 PM

Yes,repair the walls, then you embed polyester mat into a thin layer of emulsion. Let it set up and apply a topcoat of emulsion. Pucky all penetrations and perimeter. Let that set up then coat the whole thing with aluminum, acrylic, or elastomeric. I have actually been very impressed with the acrylic coatings I've been using. One other bonus is this is considered a maintenance coat and not a new roof so saves some hassles in that area.
Downside is you have to inspect it and recoat every two to five years or so depending on what type of coating you used and how well it holds up.

superdairyboy 03-28-2011 04:47 PM

Can you clarify "Pucky"? that is a new on to me.

Obviously we will have to add roofing material to the sides frame that the Sky light will sit on and then overlap it on to the roof. What material should we use? I familiar with Rubber roofing. but not torch down. and I will not even ask on here about that as I saw the 300+post topic when a guy asked about torch down.

And I want to use the best coat I can on this roof as I do not want to be coating this every couple years.

Talos4 03-28-2011 09:52 PM

I'm with "oldnbroken" save the skylight but get it higher off the surface.

Terms such as pucky, bull, plastic rag, felt, cloth, are pretty regional, You're going to get that. in more common terms, roofing cement and reinforcing cloth.

This going to get a little long, bear with me.

Now If I were inspecting your roof (which I do daily, it's my job) here's what I would recommend.

The field of the roof from the photos looks pretty good. The flashings need work. IMO, I recommend replacing the wall flashings and add a sheet metal coping cap on top of the walls.

A coating of emulsion and cloth is OK but not a long term solution. The flashings are delaminating from the walls. There is no good way of reattaching them.

The "hidden" cause to that may the wall itself, The brickwork may be failing due to moisture intrusion thru the broken flashings. Trapped moisture and mortar do not mix well over time especially given the freeze thaw cycles.

Personally I would ask you if I can due a core cut in the field and remove a small portion of wall flashing. This is to ensure that the insulation in the field of the roof is dry and what the condition of the walls is behind the membrane. Of course before I left everything would be repaired.

Why the core cuts? It removes a major amount guess work on my part. I want to know and be able to inform you what the condition the roof system is. If the insulation on the roof is 50% wet, you've already said the decking around the skylight is rotted. how far does that extend? what good is fixing the flashings really going to do with saturated insulation over the field of the roof? What if the walls are deteriorating?

I don't want to guess at what's going on and then be wrong.

IF, if the walls are Ok, I would still recommend removing and replacing the existing flashings. The flashings are the weakest part of the roof system. They move with the walls and deck. They have the most stress.

I'd possibly line the walls with plywood if they are in bad shape. I recommend a good heavy SBS modified bitumen membrane at least 140 mil thick. It can be cold applied avoiding any "problems" associated with torching. Strip in the lap seams with plastic and cloth, wait a couple months for the oils in the new membrane to cook out and apply a coating.

Please do not try to use an acrylic coating over the aluminum coating, The are coatings that boast you can coat over an asphalt based coating. I haven;t found one yet that is really good at holding up. Use a good fibered aluminum coating.

Coatings are not a new roof, Coatings don't "fix" leaks, they don't improve the "R" value, it's a maintenance product, yes you do have to re-coat 3-5 years even if you pay top dollar for the product. More often for less dollars.

You need to make an informed decision, it is your money after all.

Look for a contractor that will be honest with you and tell you that the conditions are either right for repairs, or you'll be throwing money away by trying to fix a roof that needs replacing.

What you do with that information is up to you.

If a customer is looking for someone to only tell them what they want to hear, I'm not the man for the job.

That's my $.02 worth. The $.02 charge will be waived if I get the work. :)

superdairyboy 03-28-2011 10:57 PM

Nope I do not mind a long Post. it helps and thanks for your time. My reply with also be long as I want to make sure I understand it all.

When you say Flashings i think of Aluminum bend on a brake. is this what you mean by flashings? if so there is definitly no aluminum on the walls.

Nope we will repair the roof. it makes the most sense. the walls can be reworked the skylight raised and so forth. this is all in my realm of doing.

just getting the proper instructions to do the job correctly is the goal now.

Just to clarify the "SBS modified bitumen membrane at least 140 mil thick" would be used on the walls and on the framing to raise the skylight. this would then over lap the existing roof/field. by several inches or more like a foot? how is this glued down? with Lap cement?

You mentioned plywood for the walls. would that plywood be attached to the tops or sides or both? I assume a good lathering of Silacone sealant between the bricks and the plywood then screwed down with tapcons.

With the skylight frame the membrane would extend up the frame sides. then an aluminum flashing "L" shaped that would over lap the membrane. Skylight would then be attached on top of the aluminum flashing. Using sealant between the skylight base and flashing.

Assuming I'm somewhat correct with my above questions the following questions progress off of the above.

Strip in Lap seams. I'm familiar with rubber roof seam strips. is this done similarly? or do you mean to add an extra strip on top of the membrane that is over lapping the field from the sidewalls.

Once all the repair work is done. the entire roof including the side walls and skylight frame should be coated in emoultion. Let to set and then coated again in an Acrylic or fibered aluminum?

I think I understand what you want me to do just trying to clarify and make sure I do this correctly.

I also think I have found a local roofing supply store (beside a lowes and home Depot) that will be able to help out too.

Once it finaly gets warm up here in in NEPA I'll be ready to tackle this. Currently on the inside of the building I'm working on exposing all the old cast iron drain pipes a couple have cracks and are leaking. so they are getting replaced with PVC. and now is the time to do it since I can put in new roof drains too.

Grumpy 03-29-2011 09:33 AM

The UV protectant silver coat appears to be in fair condition. However it is a UV protectant and won't do anything for the leaks. The modified bitumen beneath appears to be in decent condition. What you need be most concerned with is the seams and penetrations.

Based on the little photograph, I think you could keep that roof going for awhile longer. But keep in mind a smooth black modified bitumen roof is rated to last only 10 years, adn when silvercoated rated to last 12 years, byt the manufacturers. You can keep them going longer, but when not properly installed they don't even last that long.

Something else to keep in mind. I don't know where the leaks are been seen on the interior but I am guessing based on that picture and my experience that you may have 3 or 4 layers of roofing. Water will migrate horizontally when there are multiple layers. it could be coming in 20 or 30' away from where you are seeing the leak on the interior.

If I were your roofer, and again based on that photograph, I would be suggesting replacement of the skylight. The curb should be built up at least 8" above the height of the roof. Then inspect every inch of seam and each penetration and repair as necessary. Typical I would fire prime the roof surface to burn off the silver coat then patch with torch applied modified bitumen.

I would tear off the walls and redetail the walls with modified bitumen membrane. At the side walls with terracotta coping I would remove the terra cotta coping and reset atop the modified. At any front walls with limestone coming I would install a new wood nailer and metal coping.

learn more about roof coatings at: Roof Coatings

A problem you may run into is the quality of the existing silver coat. We do pull tests to determine if the existing coating is adhered very well. Often times the cheap coatings flake off very easily. This makes the repair much more difficult. As you can imagine if you apply a new elastomeric system over the existing it will adhere to the existing. If then the existing flakes off the new elastomeirc membrane will appear to blister and eventually wrinkle. I've seen it numerous times as a matter of fact.

Talos4 03-29-2011 10:01 PM


Flashings = the membrane that starts at the roof surface and goes up and over the top of the walls.

The Mod bit is typically used today to flash walls and skylight curbs. Especially on a roof with a mod bit cap sheet.

When you say glued down, technically it "can" be with cold applied adhesive. BUT, with that coating the existing roof surface should be heavily primed or as Grumpy suggested, burn off the coating with a torch.

I would highly recommend torching the sheets in place.

For the plywood, at the very least the face of the walls should be covered. NO SEALANT sandwiched between the wall and plywood. Your membrane is the waterproofing. The ply wood is simply and smooth sturdy base.
If you worried about water getting into the wood after re flashing the walls, you got bigger problems.

Strip the lap seams, where the sheets overlap each other there should be bleedout from the top sheet when it's heat welded to the bottom sheet. but as with all things what is supposed to happen doesn't always happen and when someone not familiar with torching mod bit attempts to heat weld it can get pretty ugly. 3 course those seams, added insurance for the cold welds and areas missed by the torch.

One thin layer of roofing cement 1/8" to 1/4" thick, 4=6" wide bisecting the seam. 6" strip of reinforcing cloth then another layer of roofing cement.

Once done, forget the emulsion and mat, also really forget the acrylic coating stick with the fibered aluminum coating.

(climbs on his soapbox) This is just my opinion it may or not be shared by others and is not meant to discourage you but,

These posts get long winded because there's alot of information regarding this work that just doesn't translate into a message board thread. We haven't even started talking about products, tools and technique yet.

This is not a DIY project. There are some people and companies in our trade that have a hard time doing this type of work. Unless a contractor been a black line (asphalt based) contractor for several or many years the experience just isn't there. Unfortunately it's becoming a single ply world. Don't get me wrong there are some great PVC's out there, but single plies just don't require the same skill set that asphalt roofs do.

I realize I'm a bit of a dinosaur in this respect but where I work, the smell of roofing asphalt means $$$$$$. the smell of melting plastic means someone just put another hole in the diaper.

I'll try help but, my writing skills do not come close to match my skill with a detail torch and trowel.

superdairyboy 03-29-2011 10:24 PM

Ok nope that all makes sense. today I did notice there is some form of metal flashing I can see from the ground on the tops of the knee walls. This must be under the Mod-bit.

the only other thing i'm not totaly clear on here is how it the Mod-bit secured to the top of the knee wall?

Thnaks again for your time

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