Steep-slope roof system For a roofing company, South San Francisco homeowners are an ideal customer base. You’re smart, you’re curious, you care about the environment, and you want to improve your quality of life by upgrading your home. If you’re looking to install a new roof or repair your existing roof, you’ll naturally have questions. We’re here to empower you to ask the right questions. A roof is more than just shingles-- it’s an entire system. In part one of our roofing system series, we’re going to talk about shingle roofs and steep slope roofs. If this doesn’t apply to your roof, hold tight. We’ll have you covered in an upcoming blog post.

Questions to Ask

To a non-roofer, learning about roofing systems in your spare time and on the weekends is a tough sell. We get it. But when you’re making a large investment in your roof, it pays to know what you’re actually paying for. Many homeowners don’t take the time to learn roofing system essentials, or they rely on their roofing contractor to fill in the blanks. The problem is, many contractors aren’t forthcoming with that information. Whether it takes too much time, or whether they don’t want you to know what they’re doing, it differs on a case-by-case basis. When you have a new roof installed, you need to make sure it will last for years to come. Many people just ask for a bid, get their bid, and think a shingle is a shingle. They leave it at that. A new roof is a big investment, so we want you to know about the entire roofing system, and what each part entails. That way, you’ll know what to ask your contractor. Don’t worry, though, because it won’t take long at all.

The Anatomy of a Steep-Slope Roofing System

If you have a steep-slope roof, there are at least three parts of your roof you need to know about:
  • Roof Deck - The deck is the underlying structural foundation that supports the roof, usually referred to by roofers as a substrate. Generally, your decking is made from plywood, oriented strand board, or other wood-based materials.
  • Underlayment - The underlayment creates another weatherproof barrier between your home and the elements, and provides protection for your roof deck and the home underneath. You might not ever see it, but it’s important, even in our relatively snow-free climate.
  • Roof covering - Your shingles.
Everybody Needs a Roof covers all this and more, and does it all in plain language. If you still find yourself in a curious state after this post, it’s worth a read. When you’re installing a new roof or repairing your existing roof, you need to have a short conversation about your roof deck. Your decking is important, as it provides the entire support base for your roof. If it’s rotted, moldy, damaged, or installed as an afterthought, you’re going to have problems in the future. It’s not a part of your roof you’ll ever see, or even think about daily, but you need to ask some basic questions. Which decking materials are you using? How will the wind and rain affect them? How long will they last? It can be a short conversation, but it needs to happen. Next, we come to the underlayment. Many roofing contractors still operate in an antiquated manner when it comes to underlayment. They use a felt material, which is decent, but won’t get you the most bang for your buck. We use a synthetic underlayment that lasts longer, and also lays flatter over the decking, which prevents the appearance of the wrinkles felt underlayment often causes. It’s also important to ask about leak barriers. We’re fond of leak barriers because they’re effective against South San Francisco weather. In other regions, they prevent ice dams. Here, the wind-driven rain can work itself in and cause damage. We use leak barriers in critical areas like chimneys, skylights, and roof-to-wall transitions. When you nail through a leak barrier, it seals the nail in like a gasket. They’re really a simple but amazing piece of technology, and most roofers aren’t using them. We also use roof cement in critical areas. We use it as a complement to the roofing system as a whole. It creates redundancies, which further fortifies your roof and the home underneath against damage. It adds that extra layer of protection to your roof. Ask your contractor about roof cement. Lastly, you need to ask about ventilation. Your attic or crawlspace needs proper ventilation, and it’s something many roofers don’t even talk about. Good ventilation keeps your shingles from baking, and it also insures your home is healthy. Without ventilation, you might get mold or mildew-- which literally affects your health. Most times, a simple attic fan works wonders. We bring all this up during our overall project assessment. We want to talk about each part of your roof, so we can create an overall healthy, effective, aesthetically-pleasing, and long-lasting roofing system.


When it comes time to install a new roof or fix up the old one, you need to see your roof as a system. Each interlocking part serves its purpose, and your shingles need a good deck, solid underlayment, ventilation, and other little touches to live up to their full potential. Take it from a roofing company, South San Francisco has plenty of steep-slope roofs. We want to make sure homeowners get everything they can from their roofing systems, and know the right questions to ask their contractor. ~Mr. Roofing San Francisco’s residential & commercial roofing experts