Evaluating varying bids for a Flat roof in San Fran, CA

Roofing/Construction Questions
1

Hello everyone,

I am the new owner of a SF home with a 1200 sq. ft. flat roof that is currently tar and gravel. The roof on it now was done in 1992 and is at the end of its life. The roof has a good slope on it and I don’t have leaks as far as I know but it hasn’t rained much since i’ve lived here. I’ve been up there and saw the tar underneath the gravel in a hardened state and in some locations there is some fiber material peeking through. Its time for a new roof. We plan on keeping this house “forever”, either living in it or renting it when we grow out of it.

I got 3 bids to do this roof, each contractor came either highly recommended or has high reviews. Each contractor has slightly different preferred method of solving the problem. I’m completely stuck on who to pick.

Contractor one proposes:
1st layer #80 APP base fiberglass
2nd layer #180 APP finish granular using a torch-down method
4 year warranty
total cost $6500

Contractor two proposes:
1st layer certainteed flitlastic Self-Adhering but mechanically fastened base
2nd layer flintlastic Self-adhering Cap
5 year warranty
total cost $9000

Contractor three proposes:
Built-up-roof, 4 layers total: Fontana G-40 Base, 2 layers Certainteed Ply sheet and a Certainteed Cap
25 year warranty if 2 maintenance visits are agreed to and paid for (estimated at $600/ea. every 10 years, i.e. visit 1 at 10 years, $600, visit 2 at 20 years, $600) Warranty is also transferrable to a new owner.
total cost: $16850

Questions:

  1. Is this an easy decision, if so who to pick and why?

  2. I’ve been analyzing the lifecycle costs of each of these proposals but I don’t think that I have realistic numbers. I am estimating that the first two roofs will need to be torn down and replaced at 15 years and the third roof will need to be torn down and replaced at 25 years. My lifecycle costs point to the same price relationship between the 3 contractors as the opening bids. Are my assumptions reasonable? Its is reasonable to analyze roof lifecycle costs over 30 years?

I’m not thrilled about the torch down method due to fire risk. I’m both enticed and wary of self-adhesive roof plies. And I feel like I’m overpaying for the 3rd, OR will get a great deal until he goes out of business.

(I couldn’t paste in links to images of my roof to my first message, sorry)

2

[quote=“hey_bay”]Hello everyone,

I am the new owner of a SF home with a 1200 sq. ft. flat roof that is currently tar and gravel. The roof on it now was done in 1992 and is at the end of its life. The roof has a good slope on it and I don’t have leaks as far as I know but it hasn’t rained much since i’ve lived here. I’ve been up there and saw the tar underneath the gravel in a hardened state and in some locations there is some fiber material peeking through. Its time for a new roof. We plan on keeping this house “forever”, either living in it or renting it when we grow out of it.

I got 3 bids to do this roof, each contractor came either highly recommended or has high reviews. Each contractor has slightly different preferred method of solving the problem. I’m completely stuck on who to pick.

Contractor one proposes:
1st layer #80 APP base fiberglass
2nd layer #180 APP finish granular using a torch-down method
4 year warranty
total cost $6500

Contractor two proposes:
1st layer certainteed flitlastic Self-Adhering but mechanically fastened base
2nd layer flintlastic Self-adhering Cap
5 year warranty
total cost $9000

Contractor three proposes:
Built-up-roof, 4 layers total: Fontana G-40 Base, 2 layers Certainteed Ply sheet and a Certainteed Cap
25 year warranty if 2 maintenance visits are agreed to and paid for (estimated at $600/ea. every 10 years, i.e. visit 1 at 10 years, $600, visit 2 at 20 years, $600) Warranty is also transferrable to a new owner.
total cost: $16850

Questions:

  1. Is this an easy decision, if so who to pick and why?

  2. I’ve been analyzing the lifecycle costs of each of these proposals but I don’t think that I have realistic numbers. I am estimating that the first two roofs will need to be torn down and replaced at 15 years and the third roof will need to be torn down and replaced at 25 years. My lifecycle costs point to the same price relationship between the 3 contractors as the opening bids. Are my assumptions reasonable? Its is reasonable to analyze roof lifecycle costs over 30 years?

I’m not thrilled about the torch down method due to fire risk. I’m both enticed and wary of self-adhesive roof plies. And I feel like I’m overpaying for the 3rd, OR will get a great deal until he goes out of business.

(I couldn’t paste in links to images of my roof to my first message, sorry)[/quote]

If you currently have a BUR (Built Up Roof, tar & gravel) and it was properly applied you should be able to get it refurbished.
With regular maintenance a good BUR should last upwards of 50 yrs.

Of the 3 choices you posted the 3rd (BUR) is by far the best and longest lasting system.

Personally I like torchdown, it’s an excellent roof system if properly applied.
The problem is that many who apply it don’t do it right in addition to the obvious fire hazard.

Since you plan to keep this place forever look into a PVC roof, at least get a bid or 2.
IMO you should stay away from the TPO, the manufacturers haven’t quite figured out how to make it wear at a predefined rate yet.

3

Built-Up Roofing (BUR) or more commonly known to the layman as “tar & gravel” roofing, consists of several plies of #15 Asphalt felt paper (usually 4-5), adhered together with hot bitumen. Another layer of hot asphalt is poured on top and clean crushed stone is embedded into the hot asphalt. The stone is simply there to prevent the sun’s UV rays from deteriorating the asphalt. BUR is heavy and is the most rugged of flat roofing systems. It is not easy to damage a BUR system. Usually we have to take an axe to them to start the removal of and old BUR.

However, it has disadvantages too. Most modern BUR roofs are made of asphalt from crude oil rather than from coal tar as in the old days. Coal tar was a longer lasting product (up to 30 years) with some self-healing properties if damaged. BUR using asphalt from crude oil lasts only about 12-15 years. However, the fact that coal tar is so terribly irritating to the skin and eyes means it has long since passed as a product of any favour with roofers. Asphalt from crude oil is also a labour intensive roof system, and dangerous for the fact that one is working with cauldrons of a liquid that is heated to between 400F – 500F degrees. As such, its popularity is also waning. A disadvantage of going with a BUR system is that essentially the roofing contractor is the manufacturer of the roof system on site. There is no manufacturer warranty on the roof system, just on the component products. There is no manufacturer training or certification of the installers of BUR systems. So it is buyer beware. Typically, BUR warranties are from the roofing contractor and range from 2 to 10 years – but usually 5.

4

** “A disadvantage of going with a BUR system is that essentially the roofing contractor is the manufacturer of the roof system on site. There is no manufacturer warranty on the roof system, just on the component products.”**

I see this as a distinct advantage.

Manufacturers are trying to design product with a specific life expectancy so that they may sell more product.
Manufacturers have no interest in making a product that lasts 50+ yrs, if they did they would be doing so with PVC & TPO.

When myself and others recommend against TPO it’s not because TPO isn’t any good it’s because the manufacturers choose to make it as cheap as possible.
If they make TPO good it would cost as much as PVC and hence no reason to do so.

5

[quote=“Roofmaster.net”]Built-Up Roofing (BUR) or more commonly known to the layman as “tar & gravel” roofing, consists of several plies of #15 Asphalt felt paper (usually 4-5), adhered together with hot bitumen. Another layer of hot asphalt is poured on top and clean crushed stone is embedded into the hot asphalt. The stone is simply there to prevent the sun’s UV rays from deteriorating the asphalt. BUR is heavy and is the most rugged of flat roofing systems. It is not easy to damage a BUR system. Usually we have to take an axe to them to start the removal of and old BUR.

However, it has disadvantages too. Most modern BUR roofs are made of asphalt from crude oil rather than from coal tar as in the old days. Coal tar was a longer lasting product (up to 30 years) with some self-healing properties if damaged. BUR using asphalt from crude oil lasts only about 12-15 years. However, the fact that coal tar is so terribly irritating to the skin and eyes means it has long since passed as a product of any favour with roofers. Asphalt from crude oil is also a labour intensive roof system, and dangerous for the fact that one is working with cauldrons of a liquid that is heated to between 400F – 500F degrees. As such, its popularity is also waning. A disadvantage of going with a BUR system is that essentially the roofing contractor is the manufacturer of the roof system on site. There is no manufacturer warranty on the roof system, just on the component products. There is no manufacturer training or certification of the installers of BUR systems. So it is buyer beware. Typically, BUR warranties are from the roofing contractor and range from 2 to 10 years – but usually 5.[/quote]

So much wrong info in this post.

The felt used in BUR roofs is not #15 felt…

A type 3 or 4 asphalt roof properly installed will easily out last 10-15 years. A coal tar roof will outlast most structures being built today.

There is still training and certification from manufactures, why else would they warranty their roof systems?

2-10 years would be standard on a residential. 10-25 years on commercial.

A simple google search would have told you the above information.

@ the OP Two of us answered in the other forum you posted in.