Last time, we talked about how to determine when you need a new roof, and how to avoid getting sold a roof before you really need one. If you missed that article, I recommend you spend just a couple minutes reading it first.

New roof options to consider

For the rest of my readers, welcome back! For the next couple articles we are going to take a look at the options available to you for your new roof. Some of this information is a bit technical, but you don’t need to be a contractor to understand it well enough to make an informed decision.

Tear off the old roof or leave it in place

OK, so the first choice you will have to make is whether or not to tear your old roof off before installing a new one, or installing the new over the top of the old. For most types of new roofing, laying a new roof over the old one is an option. But which is right for you?

Reasons to leave your old roof in place

Save money

When you tear your old roof off, of course you have to pay your contractor for the labor to do so. And you also have to pay for the disposal costs. You also will likely have to buy new underlayment if you tear your old roof off, which will not be necessary if you opt to leave the old roof in place. Tearing your old roof off will typically add at least a couple thousand dollars to your total price, which for some can make the difference between affordability and not being able to afford the job.

Reduce the mess

Pretty much the entire mess created in a roof job comes in the tear off stage. Even the most careful contractor will have a difficult time guaranteeing that absolutely no mess ends up in your landscaping or yard. And even one stray nail can cause a flat tire in your lawn mower. Eliminating the tear-off stage will guarantee you a basically mess free job. Especially if you have a lot of landscaping around your home, this can be an important factor.

Eliminate risk

Every roofing contractor who has been in the business for more than a few years will have at least one horror story about a time a rain shower popped up totally unexpectedly while he was in the middle of a roof tear-off that ended up raining in a customer’s home. Of course any reputable contractor will do everything he can to avoid this risk and have insurance to cover any damage that might occur if this happens to you. But while insurance can repair your potentially damaged drywall and insulation, it can’t replace the hassle of this mess. If you leave the existing roof intact and just go over it with the new roof, you eliminate even the slight risk that your house will be the one that becomes some contractor’s “you’ll never believe what happened” story.

For these reasons, for some homeowners, opting to leave their existing roof in place and just installing the new roof over the top is the right choice. But what are some of the benefits of tearing the old roof off first?

Reasons to tear off the old roof first

Necessity

If there is already two layers of shingles on your roof, installing a third layer is almost always not an option. If someone already installed a roof over of the existing shingles and the second layer now needs replaced, you have no choice but to tear both layers off now.

Exposing potential damage

If your roof has been leaking around a protrusion or against a wall or in a valley, there may be rot or mold in your decking that you are not aware of. Tearing the old shingles off is often the only way to expose hidden damage. If your roof deck is rotten or molding, the mold can continue to spread through your attic even after the leak is stopped. If you suspect you may have leaks in your existing roof, tearing off the old shingles down to the deck is usually a good idea.

All new roof edge trim

The aluminum flashing that goes on the edges of your roof typically do not wear out. But they do fade over time. If your goal is to make the exterior of your home look as good as new again, tearing off your old roof just to be able to replace your roof edge trim might be worth the additional cost to you.

New roof lies totally flat

Depending on how much texture your existing shingles have, they may cause visible “bumps” in your new roof. As long as your old roof is lying flat to the deck this will not void the warranty on your new roof. But you may not like the cosmetic effect this has on your roof.

Bring sub-roofing up to code

If your current roof is more than 20 years old, chances are very good that your current underlayment is not up to current code requirements. This increases the chances that ice build-up in your gutters or valleys in the winter will dam water and cause a leak even if your shingles are totally intact. If you have experienced this problem in the past, that is a strong indication that you should strip the old shingles off in order to install the ice and water guard layer properly.

The best roofing option

So which option is best overall? Well, when it comes right down to it, tearing the old roof off and installing the new roof directly to the deck gives you the best possible finished result. If you can afford it, tearing the new roof off first is the option I recommend to my clients.

But if the cost of tear-off is not in the budget, or you don’t want to for one of the other reasons mentioned above, putting a second layer over your existing roof is a perfectly acceptable option that will not void the warranty on your new roof. So it is far better to take advantage of this option than it is to put off installing a new roof when you really need one.

In our next article of this series, we will take a look specifically at the different roofing products available and how to choose which is right for you.