Can You Roof Over Existing Shingles in Idaho, or Is a Tear Off Better?

In most cases, yes. Idaho building code allows a second layer of asphalt shingles over one existing layer, so a roof over is legal on many homes. Even so, most Treasure Valley roofers, including our team at Dodd Roofing and Exteriors, recommend a full tear off. Removing the old shingles lets us inspect the decking, fix hidden problems, and install a roof that lasts longer and keeps its full manufacturer warranty.

What does Idaho code say about layering shingles?

Idaho follows the International Residential Code, which limits a home to two layers of asphalt shingles. If your roof already carries two layers, an overlay is off the table and a tear off is required. An overlay is also not allowed when the existing shingles are curled, buckled, or water damaged, or when the deck underneath is soft or rotted. A permit is required either way, and our guide on roof permits in Idaho explains how that process works.

Why do most Boise area roofers recommend a tear off?

The biggest reason is what you cannot see. Shingles hide the roof deck, and the deck is where rot, leaks, and ventilation problems live. During a tear off we replace damaged sheathing, install fresh underlayment and ice and water shield, and reset flashing at chimneys and valleys. An overlay skips all of that protection. Stacked shingles also trap more heat, which shortens shingle life during hot Treasure Valley summers.

Is a roof overlay ever a smart choice?

Sometimes. If your roof has a single flat layer in good shape, no active leaks, and solid decking, an overlay can be the most affordable path for a home you plan to sell soon or a rental you want to protect on a budget. Keep in mind that home inspectors flag layered roofs at resale, and a future tear off runs roughly double the normal removal cost because two layers come off instead of one.

How much more does a tear off cost than an overlay?

A tear off costs more up front because of the added labor and disposal, but the gap is smaller than most homeowners expect, and the longer service life usually makes up the difference. Final pricing depends on size, pitch, and condition. Our post on roof replacement cost in Boise breaks down the main factors, and our financing options can spread the project into manageable monthly payments.

How do you find out which option fits your roof?

Start with a free inspection. We check the number of existing layers, probe the decking, and give you a straight recommendation with pricing for both paths when both are possible. Dodd Roofing and Exteriors serves Boise, Meridian, Nampa, Caldwell, Eagle, Star, Kuna, Garden City, and Middleton. Learn more about our roofing services or call (208) 295-9421 to schedule your inspection.

Contact Us