20+ Year Solution

Comprehensive roofing solution for 20+ years:

Previous steps:

If you are at this point you have hopefully read through our recommendations on how to check out your existing roof and prepare it to receive a new roof and checked out the 10+ year section. Instead of repeating the 10+ year section this section builds upon it. What extra things are required to get a 20 to 30 year roof? The combination of design, materials, workmanship and timely maintenance makes just about anything last longer. This is especially true for roofing. If any of these items is poor the roof is likely to fail before 10 years. If all of these items are good we would expect any roofing system installed today to last for 20 years. After being so generic, what follows will attempt to be specific on how to obtain the best design, materials and workmanship. It will also touch on some different roofing systems and the details manufacturers require to get their longer warranties.


The 10+ year system discussed many design issues that need to be considered when re-roofing and should be addressed by anyone who wants to propose a new roof on your property. There are four different categories of people that can design your re-roofing solution: architects, roofing consultants, roofing contractors and roofing material manufacturers. All of these people will have different opinions on what should happen. One could reasonably expect architects, roof consultants and roof manufacturers to overdesign the roof in order to protect themselves or potentially make more money. One could expect a roofing company to overdesign (to make more money) or underdesign (to get the work from a competitor). Make sure the design issues in the 10+ year section are addressed with satisfactory answers. If you can’t get satisfactory answers find someone else to work with. Make sure to ask for options. Make sure more than one roofing manufacturer is specified or the prices will be higher. How do you start? It’s almost as tough as picking a mattress.

  • Option 1 – look for a consultant. In our experience architects are not as experienced with roofs as consultants. Consultants are solely focused on roofs while architects focus on many different aspects of building. The consultant can help select the roofing contractors and manufacturers. In theory the consultant will be the most objective. Use the yellow pages, internet, roofing systems manufacturers, roofing materials distributors, building associations and roofing contractors for recommendations.
  • Option 2 – pick a handful of contractors and solicit bids. Narrow the designs bid to one or two and get them priced apples to apples by other contractors. In many cases this will encourage the other contractors to highlight any weaknesses in the design. Use the yellow pages, internet, roofing systems manufacturers (check their web sites for award winners), roofing materials distributors, building associations and roofing consultants for recommendations.
  • Option 3 – contact a few manufacturers and ask them to specify something and recommend contractors. Using the manufacturer to specify a design usually results in a good solution however that solution will lock you into that manufacturer’s products. If one manufacturer’s products are specified there is no incentive for that manufacturer to provide the best prices on their materials – so you may want to ask two manufacturers. Also be careful of over design – it’s your money they are putting into their pocket. The major manufacturer’s we see in New England are Firestone, Carlisle, Versico, Mansville, Sika-Sarnafil, Duro-last, Dow/Stevens, Genflex and GAF.


If you have a building of any size it would be worth obtaining a manufacturer’s warranty for many reasons (previously specified). In the previous section we listed a number of manufacturers that have all been around for a few decades. There are other manufacturers. Check them out carefully as you would any other company you expect to do long term business with. Do their products have a track record? What is the size of the company? Does it have reserves specifically set aside for warranty payments – if so how much? Confirm they will send an inspector out to look at the finished roof. The web sites of manufacturers have a wealth of information as to what their products are and what the different warranties are. Watch out for new products without a proper track record. Lab testing does not equate to what a product experiences in the field – there are just too many variables to account for.


There are generally 3 parts to making sure superior workmanship is done. First is to get an experienced roofing company with experienced installers. Second is to have a knowledgeable independent party check the work as it is happening. Third is to have an independent party check the work after it is finished. Doing the due diligence on the roofer will mostly result in the first and obtaining a manufacturer’s warranty will take care of the third. Finding an independent party to check the work as it is happening is more costly and rarely happens.

How can you tell whether a contractor does quality work that will last decades is a tough question. All of the usual investigative methods will apply – how long in business, referrals, what have you done similar to our project, etc.. Some additional thoughts – roofing materials manufacturers license contractors to install their products. Manufacturers will only warranty roofs installed by their licensed contractors. As time goes on manufacturers keep track of calls made against those warranties. Some manufacturers measure that quality and quantify with awards. Usually the awards are only publicized if the contractor puts on a certain amount of their product. So a call directly to the manufacturer of choice can yield some interesting referrals, especially if you ask the correct questions – like who has the best experience in the last 5 years / 10 years that is within 50 miles of my property? How many installations would that encompass? Coming at it from the other direction would be to find out what manufacturer a contractor is quoting, then call up that manufacturer for their recorded experience with that contractor. If you can skip any local manufacturer’s representatives and go straight to the main offices you might even get a more data driven answer as opposed to someone’s judgement (which may also be useful).

Another item to check is the experience modification rating which can point towards the safety experience of the company. A number of 1 or below is good. In Massachusetts you can find that number on-line (https://www.wcribma.org/mass/Products/ExpRatingSrch/searchratings.asp). Other states may also provide this – the contractor should also be able to provide this on his insurance agent’s letterhead.


Maintenance has been discussed before. If you do not limit access to the roof, at least protect it as much as possible, periodically inspect and repair damage, the roof will fail early. The better job you do the longer into the 2nd or 3rd decade the roof will last, especially as the roofing systems materials and installation methods improve.

Extended Warranties:

Manufacturers have their own requirements for issuing longer term warranties. We focus here on single-ply systems as that is the majority of the New England market and what we are most familiar with. This gives you some idea of the differences.

20 year systems generally have to use heavy duty fasteners on the insulation (and membrane if mechanically fastened system), enhanced perimeter (either with extra membrane or special metal details), thicker or reinforced membrane and thicker insulation or cover boards. Fiberboard insulation is not acceptable.

25-30 year warrantees are not obtainable for ballasted systems – mostly due to the dirt that will accumulate between the rocks and dry rot the rubber (like car tires on an old car). Expect to have to completely strip the existing roof to the deck, utilize 60 mil. or thicker reinforced EPDM, or 90 mil. thick non-reinforced EPDM. All materials used will have to be by the same manufacturer. No tie-in’s to adjacent roofing areas would be allowed. Enhanced perimeter, seam and penetration details are usually required. Pull-out tests to determine whether the deck will provide sufficient integrity to install the roofing system on are often required.

TPO systems: Most of the same rules that apply to EPDM apply equally to TPO with the main exception being less extra work at the seams. Since TPO (and PVC) seams are heat welded they are already about 3x stronger than any joining EPDM together. As the membrane already is reinforced, you can usually obtain up to a 25 year warranty with .060 TPO membrane. To get a 30 year warranty will require a thicker membrane (likely .080″ thick).