# Hot Mop - Torchdown - Foam - O My



## gekkie96 (Sep 29, 2012)

I have 4,500 sqft of flat roof on my MCM home in southern California. I have multiple quotes to re-roof the house with either a torch-down system, hot mop or foam roof. I'm leaning towards the foam roof and was wondering what others may think is a better roof selection that will last the longest without leaking. Below is a picture of the roof.

Thanks in advance
Aaron


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## ddawg16 (Aug 15, 2011)

Aaron....I just went through that decision process (minus the foam board option)....

I ended up doing torch down...hot mop will crack before the torch down will.

Being the perpetual DIY'r....I farmed out the roof to a professional....the guy I used was some of the best money I have ever spent. He is out of Venice....licensed....and even cleans up afterwards.

Let me know if you want his contact info.....

And...click on the 2-story addition link in my signature if you want pics....go to the end of the thread.


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## shazapple (Jun 30, 2011)

Keep in mind that usually when a system is cheaper it means it requires more frequent maintenance to stay leak free. All 3 are decent systems, but if you are looking for a long lasting solution I would vote for the "torch down" (modbit) roof. Ensure the installer has lots of experience because even a good product can be ruined by poor installation.


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## AndyWRS (Feb 1, 2012)

+1 on the Modbit

I looked into spray foam for my sisters flat roof in Westlake village, i discovered it was expensive. I think i searched these forums for ideas also, and over at CT. I went with the KISS approach. It may or may not be a better solution, it just wasnt in the budget to do foam so we did modbit. I also did not fully research the spray foam option, i did what her budget dictated.

Thats pretty large, make sure they address any ponding water issues. If its uninsulated you may want to even consider polyiso if your going to reroof, that would be the time to get it done. Being CA and our limited rain fall, homes do not seem to be built very well here.


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## 1985gt (Jan 8, 2011)

First of all take the spray foam estimate and throw it out the window. unless you wish to have someone recoat the roof every 5-7 years.


That leaves you with the torch down or hot mopped. 

Both are fine, in my opinion the hot mop is 100% better. If both systems are equal. Hot mop will not "crack" quicker, you can get the same granule surface modbit for the cap sheet. 

It boils down to the contractor, have them spec both systems the same, IE ISO, edge metal, layers of roofing. ECT.


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## JWilliams (Sep 22, 2010)

hot mopping is a dying art in my opinion. alot of roofers see it obsolete. but a hot mopped roof done right will last just as long or pretty close to any single ply membrane. and hot mopped wont "crack" before torch down will if you put the correct cap sheet or cover it in gravel.


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## AndyWRS (Feb 1, 2012)

Compare warranties, do both products have similar installation and manfacturer warranties.

I do think they are the same


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## Grumpy (Dec 12, 2003)

Numerous flat roofing options, and I don't like modified much anymore. After learnign to work with single ply membranes like PVC and EPDM, they are far superior. a properly install built up "hot mopped" roof is a good roof. It is a dyeing art, thanks to insurance companies. But PVC will last as long as a good hot mopped roof and is safer and easier and cleaner to install. 

Lots of flat roofing options, no two systems are created equal. Learn more about your flat roofing options: http://reliableamerican.us/services/low-slope-roofing.html


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## gekkie96 (Sep 29, 2012)

We decided to go the torchdown route, thanks for all the feedback. I will post before and after pictures once the new roof is up.


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## gekkie96 (Sep 29, 2012)

A little snag, need some advice.

We opened up a small section of the roof and it turns out we have 3 old roofs on top of each other.

*It breaks down like this:*

2x6 Tounge & Grove deck then
1/2 inch of insulation then
Tar & gravel roof then
1 1/12 inch of hard insulation then
Tar & gravel roof then another
Tar & gravel roof

My house has no attic and is basically floor to ceiling windows so insulation is very important... (this is an Eichler home)

I'm not sure if I should remove the top two roofs and leave the insulation and the other old roof and put the new roof on top or remove all 3 roofs and insulation to get to the deck and replace any bad wood and then put in new insulation and the new roof? On one hand I want to remove everything and replace any bad wood and start from scratch but then I worry about the cost and if I can afford to redo all of it. What do you think would be the smartest thing to do?

Here's a picture of the roof open


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## gwa (Sep 17, 2010)

You should remove everything down to the wood deck. The bottom layer of insulation only has an R-Value of 1.36, so it doesn't add much. Tear it off and mechanically fasten polyiso followed by a cover board. Then you're ready for the APP mod bit roof system.


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## gekkie96 (Sep 29, 2012)

I'm thinking the same GWA. What would a sheet of 2' polyiso cost about?


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## gwa (Sep 17, 2010)

I'm sure one of the contractors can answer that for you.


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## AndyWRS (Feb 1, 2012)

Ideally you want to tear off all layers. The polyiso is not cheap, i would think your looking at $29 per sheet just for material. 

Does the contract have anything about extra layers or did the estimator just miss it? Polyiso + installation + the possible extra layer charges could really add up. You may actually need to leave a layer of tar and gravel ( meaning tar and very little gravel because all the loose gravel should have been removed prior to roof #2) to avoid having to spend thousands on a complete tear off and new insulation.

If i was going to live there a long time, and i had the $, i would tear it all off and put new insulation and then roof it. 

At least the weather is good here atm.


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## 1985gt (Jan 8, 2011)

Tear off and start from bare wood. Nows your change to add tapered ISO to give the roof some slope if needed. Sounds like the "contractor" should have taken a test cut before giving you an estimate. Looks like you got a redo on your hands. I would possibly look at a different contractor. This all should have been done before he gave you an estimate.


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## JWilliams (Sep 22, 2010)

I agree with 1985gt. They should have cut test sections before even giving an estimate.


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## Windows on Wash (Aug 30, 2011)

Core hole would have told them what they needed to know.

No time to skimp on ISO in this case. Your roof will be much cooler and leveled out. 

Depending on the shape and size, slope ISO is a great option as well. Might cost a small fortune in some cases but worth a looksee.


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## ddawg16 (Aug 15, 2011)

gekk.....I know a good roofer in your area.....let me know if you want his info....and no, no relation to him....he just did my roof....did a great job...and has been used by a contractor friend for years.


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## gekkie96 (Sep 29, 2012)

*ddawg16 *feel free to refer your roofer via PM.

*Windows on Wash* can you expand on ISO I haven't heard of that, unless you're talking about polyiso?

Out of 5 contractors only one did a test cut, sort-of scary if you ask me...

Can a GC that holds a class B license legally do a roof?

Am I able to share my bids on the forum without disclosing contractor info or is that frowned upon?

Thanks Everyone and Happy T-Day!


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## ddawg16 (Aug 15, 2011)

gekkie96 said:


> *ddawg16 *feel free to refer your roofer via PM.
> 
> *Windows on Wash* can you expand on ISO I haven't heard of that, unless you're talking about polyiso?
> 
> ...


You can't recieve PM's....yet....I think your post count has to be higher....email me if you want [email protected]

I can't answer the license part....but, I've seen quite a few posters list the bids minus the actual name.

Personally...I think it's good....It helps the rest of us in understanding the process. I wish I knew 4 years ago what I know now....and knew about this web site.


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## gekkie96 (Sep 29, 2012)

Emailed you ddawg16


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## gekkie96 (Sep 29, 2012)

A roofer just told me that I can't put more than a 1 inch polyiso insulation on my roof because the city wont allow anything thicker, I find this a little hard to believe, is there anyway to find out if this is true or not in Granada Hills, I already left the city inspector a message but he never calls back.

This roofer also bid me a price for R30 5 inch polyiso and then told me about this so called city limitation and said the price only decreases $400 for the 1 inch polyiso, I think he might be playing games, any thoughts?

Thanks


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## Windows on Wash (Aug 30, 2011)

gekkie96 said:


> *Windows on Wash* can you expand on ISO I haven't heard of that, unless you're talking about polyiso?
> 
> Thanks Everyone and Happy T-Day!



Yes...Poly Iso insulation is what I was referring to.

Happy Thanksgiving to all!!!


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## 1985gt (Jan 8, 2011)

gekkie96 said:


> A roofer just told me that I can't put more than a 1 inch polyiso insulation on my roof because the city wont allow anything thicker, I find this a little hard to believe, is there anyway to find out if this is true or not in Granada Hills, I already left the city inspector a message but he never calls back.
> 
> This roofer also bid me a price for R30 5 inch polyiso and then told me about this so called city limitation and said the price only decreases $400 for the 1 inch polyiso, I think he might be playing games, any thoughts?
> 
> Thanks


I can't comment on your city code but it doesn't seem right.

if the difference between 5" ISO and 1" Iso is only $400 unless your roof is around 1 sq... I would walk away from them.

It costs me around $80 per square for 2.5" ISO, and 42 for 1" That's my cost, that does not include mark ups at all, so thats around 40 per square difference, not to mention the screws 37 dollars a box of 2 1/4 preassembled compared to 68 for 6" preassembled. 5 or so squares per box. so $8 per square of 2 1/4" $14 for the 6".

You can kind of see where I'm going with this, yes you can post estimates just block out the identifying info.


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## gekkie96 (Sep 29, 2012)

We decided to go with a 1.5 inch foam roof, here's the contract let me know if you think we missed anything and if this is a good deal? The company is reputable based on research.

*APPLICABLE SPECIFICATIONS FOR POLYURETHANE SPRAY FOAM ROOFING SYSTEM TO BE INSTALLED TO THE BUILDING REFERENCED ABOVE BASED ON
SQ. FT. 4500*

*SPECIFICATIONS:*

Clean and prepare (existing roof) deck surface as necessary for the proper application of spray foam roofing system.
Remove the existing roofing material down to T&G deck and remove from jobsite. 3 layers of roofing and insulation.
Replace badly delaminated plywood or substrate as necessary at $95.00 per 32 sq. ft. area installed. (No plywood replacement suspected at this time however, plywood replacement cannot be determined until roof is removed and will be an extra to contract.)
Install new metal foam stop at perimeter. Metal will be brown.
Install new down spout and drain at corner of roof at right front corner of the roof
Mask as necessary to protect from overspray. Cover pool and spa, any over spray on house or property will be cleaned and removed.
Prime roof deck with SWD 2000 sealer at the rate of 1/2 gallons per 100 sq. ft. as necessary.
Apply 1.5 inch thickness of SWD "Quik-Shield" 125 (2.5-3.0 lb.) density polyurethane foam to the roof surface.
Build up apparent low areas to promote positive drainage.
Apply *SWD 1929-F "Quik-Shield" elastomeric base coating at the rate of 1 gallon per 100 sq. ft. in a contrasting color to top coat.
Apply *SWD 1929-F "Quik-Shield" WHITE elastomeric top coating at the rate of 1-1/2 gallons per 100 sq. ft. (SWD "Quik-Shield"
Coating is Energy Star, CRRC California Title 24 Compliant with a solar reflectance of %82 and emittance of 91%.)
Broadcast #9 granules into wet finish coat at the rate of 30 lbs. per 100 sq. ft.
Clean and detail premises to remove any job related debris.
Issue 15 year NO LEAK renewable warranty with no exclusions.
Permits will be included and pulled by CONTRACTOR.
Tear off crew will hang and seal plastic to entire interior ceiling of house. Customer will cover belongings in house.
Fascia board can be replaced at 7.00 per ft, primed.
T&G wood panels can be replaced at 7.00 per ft primed.
Any repairs requested by city inspector will be done at no additional charge to customer, roof will be completed to city code. And a final inspection will be completed by city inspector.

*Payment Terms:*
PROGRESS PAYMENTS WITH 100% DUE UPON COMPLETION

*BASE PRICE: $20,000.00*

I will post pictures of the project from start to finish so others can see the process for a foam roof.


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## AndyWRS (Feb 1, 2012)

Interesting. I would have expected more $ for 45sq and 3 layer T/O. I see the warranty is 15yrs, what is the expected life expectancy of that type of roof system ?

I think his plywood replacement # is pretty high. Our attitude is your paying enought for a roof as it is, we are going to keep the #'s on wood replacement as low as possible. I think $95 a sheet is high.

Not sure what city your in, but you will most likely need smoke detectors ( 1 per bed room + 1 per story) and CO detectors ( 1 per story ) installed as part of the roofing inspection process. They may have a self cert form or they will want entry to confirm the installation of them.


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## gekkie96 (Sep 29, 2012)

AndyWRS said:


> Interesting. I would have expected more $ for 45sq and 3 layer T/O. I see the warranty is 15yrs, what is the expected life expectancy of that type of roof system ?
> 
> I think his plywood replacement # is pretty high. Our attitude is your paying enought for a roof as it is, we are going to keep the #'s on wood replacement as low as possible. I think $95 a sheet is high.
> 
> Not sure what city your in, but you will most likely need smoke detectors ( 1 per bed room + 1 per story) and CO detectors ( 1 per story ) installed as part of the roofing inspection process. They may have a self cert form or they will want entry to confirm the installation of them.


A foam roof expected life is around 20-30 years depending on who your talking too but it does require a new top coat every 7-10 years but this extends the warranty when you do it. Were not worried about the plywood cost as we have no sheeting its all T&G and $7 per ft was lower than any other roofer we got bids from. We do have smoke detectors in all the bedrooms and other areas of the house but good to know.

We went with this roofer as he did our neighbors roof 7 years ago and they are really happy with it.

This price was not the lowest but also not the highest I think this company is able to be more competitive because they manufacture the foam as well...


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## Grumpy (Dec 12, 2003)

Core cuts should be done at the start of the job. Sometimes I have customers who refuse, but I always at least ask. Furthermore, if the customer refuses I wrote it clearly in my proposal that I am guessing.


tear off down to the wood.

insulate, if you have a cold deck design, honor it and improve the insulation beneath the wood. If you have warm deck design increase the insulation as much as you can afford. Also if you have cold deck design, don't forget proper ventilation.

All details, flashings etc must be replaced.


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## 1985gt (Jan 8, 2011)

My thoughts on spray foam is it is one of the worst roof systems out there. There is no way of creating a smooth surface, or one that drains properly with out the use of ridged ISO boards. I've never seen the coatings last 7-10 years on a low sloped foam roof, on a moderate sloped metal roof I have. Birds will pick at the foam, hail will create breaks, and cracks or breaks will go unnoticed as the foam will help hold in the moisture. Keep your warranty papers handy you will need them, good luck.


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## jagans (Oct 21, 2012)

By code you are supposed to tear off after you have two roofs in place. You currently have 1/2 inch of rigid fiberglass insulation, multi-ply built up roof, probably asphalt but may be coal tar pitch, The recover roof is 1.5 inch rigid fiberboard, followed by an asphalt BUR with a granule surfaced cap sheet. 

Get a RCI registered roof consultant to come out and design a new roof for you. It will be the best money you ever spent. For starters, you need to get slope to drain in the design. Modified Bitumen does not do well in ponding conditions, and NO MANUFACTURER WARRANTS A PONDED ROOF, AND NO MANUFACTURER WARRANTS RESIDENTIAL LOW SLOPE ROOFING. You need a good design and specification, and a good commercial low slope roofing contractor. Low slope roofing is water proofing, not water shedding, and it must be done correctly.


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## 1985gt (Jan 8, 2011)

jagans said:


> By code you are supposed to tear off after you have two roofs in place. You currently have 1/2 inch of rigid fiberglass insulation, multi-ply built up roof, probably asphalt but may be coal tar pitch, The recover roof is 1.5 inch rigid fiberboard, followed by an asphalt BUR with a granule surfaced cap sheet.
> 
> Get a RCI registered roof consultant to come out and design a new roof for you. It will be the best money you ever spent. For starters, you need to get slope to drain in the design. Modified Bitumen does not do well in ponding conditions, and NO MANUFACTURER WARRANTS A PONDED ROOF, AND NO MANUFACTURER WARRANTS RESIDENTIAL LOW SLOPE ROOFING. You need a good design and specification, and a good commercial low slope roofing contractor. Low slope roofing is water proofing, not water shedding, and it must be done correctly.


Actually there are some manufactures who warrant low slope roofs. What's the reason for getting a RCI registered consultant? Any roofing contractor worth his salt can design a proper roof.


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## jagans (Oct 21, 2012)

*Warranty*

What manufacturer provides a full system warranty on RESIDENTIAL Low slope roofing systems? I am really interested in knowing this.

The key word in your statement is "Worth his salt" It has been my experience that most residential STEEP roofing contractors are quickly out of their element when it comes to low slope roofing.

Most roofers recommend what they are used to, and therefore comfortable installing, or in some cases what they are licensed to install. There is nothing wrong with this as long as they are not trying to put a square peg in a round hole. When I am called out to investigate a failure, this is usually the case. 

There are, without question, roofers that are fully capable of designing and installing any type of roof, and installing it well. They are very few, and very very far between. The same is true of roof consultants, engineers, and architects.

If you start with an RCI Registered Roof Consultant, you at least have someone that has proven proficiency in the theory behind the art through education, lab, and field experience.


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## 1985gt (Jan 8, 2011)

jagans said:


> What manufacturer provides a full system warranty on RESIDENTIAL Low slope roofing systems? I am really interested in knowing this.
> 
> The key word in your statement is "Worth his salt" It has been my experience that most residential STEEP roofing contractors are quickly out of their element when it comes to low slope roofing.
> 
> ...


IB or Fibertite, I believe one of them do and I though Durolast does also, I don't know for sure as IB and Fibertite do not have a presence in our area, and I honestly could care less about durolast, as they dont back their warranties on commercial installs. 

I tend to agree with you but with already overly priced roofing products adding the expense of a consultant on a residential roof is not something most home owners can afford. Sadly they are at the mercy of the roofing contractor who may or may not be qualified.


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## jagans (Oct 21, 2012)

*Fibertite*

I use Fibertite on a regular basis. They dont warrant residences any more. They did several years ago. Great product. So is Sarnafil. I dont know IB.


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## 1985gt (Jan 8, 2011)

IB does I just looked, life time for as long as you own the home.

http://www.ibroof.com/IBinfo/res_residential_roofs.html

The only PVC we install is Versico. I don't know of any others that offer a manufactures warranty besides IB.


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## jagans (Oct 21, 2012)

*SPF Experience*

My opinion regarding foam is that it is a good insulation, and it is great for Quonset huts and oil storage facilities, but that is because the only time I see them is after they fail. There are a lot of them out there though so I guess they work. I worked for an engineering firm that had the contract to inspect the foam roofs warranted by Dow Chemical (Silicone Coating) and the problems that we saw were:

1. Lack of basic roofing knowledge on the part of the contractor, ie foaming over through wall flashing etc.

2. Spraying in conditions that were not conducive to foam roofing. Humidity etc. The stuff was really touchy.

3. Lack of proper preparation. (Foaming over a wet roof, etc.) 

4. Thin coating.

5. Mechanical damage by the dreaded HVAC trolls. Flipping their screwdriver into the foam for fun etc.

The guy who ran the program liked them. I think that foam is insulation, not waterproofing.


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## jagans (Oct 21, 2012)

*Ib*

Thats a pretty safe bet by IB. The average homeowner length of ownership is 10 years. Is it transferable?

I just went through the same thing with my furnace. Heat exchanger lifetime warranty to the original homeowner. Nice trick.

Just another reason to NOT base your purchase on warranty


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## 1985gt (Jan 8, 2011)

Yeah I'm pretty sure it was non-transferable, it would be what they are banking on i'm sure.


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