Roof Replacement: Tear Off or Roof Over?

Roof Replacement: Tear Off or Roof Over?So you’ve decided to replace your roof. Maybe it’s because it is beyond repair. Maybe it’s because the roof is past its useful lifespan. Maybe you’re planning on moving and you know that replacing your roof will increase your house’s sale value. Regardless of how you got here, you still have another important question: should you shingle over the existing layer or tear off the existing roof and install the new one directly to the roof’s deck? In many ways this is a question of now verses later. Learn which camp you fall into, and the pros and cons of either choice.

Roofing Over an Existing Roof

If your roof’s shingles aren’t in utter shambles, placing another layer of shingles down over them is an option. If there’s a lot of warped shingles; mildew, moss, or fungal infestation; or significant structural damage, it isn’t advisable to plaster over: you need to remove the trouble spots to keep your roof safe and level. However, if you’ve got an okay roof with just a bit of wear, you can save some time and money by having another layer put down over them. There is a catch however:

International Residential Code

R907.3 of the International Residential Code – which is the standard that all US buildings must be built to – covers new roof coverings on top of existing layers of roofing. Besides the point outlined above (deteriorated roof coverings), you can’t put down another layer of shingles if the existing roof has two or more applications of existing roof coverings (shingles). So if you’ve already roofed over once, you can’t do it again.

Tearing Off the Existing Roof

While roofing over has the distinct benefit of being quicker and cheaper, it is potentially putting a band-aid over a larger problem. Once you’ve got that second layer on, you’ve got twice the roofing issues that could crop up. First, you have twice the weight on your roof (it’s one of the major reasons for the R907.3 code), and that can be the tipping point for snow or ice to cause serious damage. The second is that if a problem occurs (such as a leaking roof) you’ve got twice the shingles to work through to find the source of the problem. In addition, it’s a longer time before you can check the state of your roof deck.

Checking Your Roof Deck

Your roof deck and roof felt support all the shingles and flashing above, and damage on their part can lead to a roof disaster. By peeling back to the deck, it gives your roofers an invaluable chance to check on its state. Wood rot and damage or poor installation of the felt nails or screws can spell big costs down the line, so in the long run a tear off can save money. In addition, if you want to prevent ice dams from forming, you can look at ice-and-water proof membrane along the eaves—but only if you do a total tear down.

Want to know which option is right for your roof or if your roof can be repaired instead of replaced? Contact All Weather Title of Marlborough, MA and our professionals can provide a free estimate for any or all of our home improvement services, including roofing, siding and windows.

Posted in Roofing, Roofing Systems.