When you begin to notice issues in your roof, or you notice that your roof lifespan is coming to an end, it’s probably the time to make a big decision. 

You might ask yourself, Is it even possible to build a new roof over an old roof?

When your roof is in bad condition, such that repairing is not the best option but is still useful to be completely replaced, it’s best to consider an overbuild roofing. While doing this, you need to know the building codes, the conditions of existing roofs, and your house’s structural stability.

Ready for a Roofing Quiz?

Can You Build a New Roof Over Your Old Roof?

Overbuild Roof

It’s possible to build a new roof over your old one if it is in good condition and meets the roofing requirements. 

However, contacting any roofing contractor near you is best to know the best choice when reroofing. 

When reroofing, you cannot mix the roof materials. For example, installing shingles over wood tiles or slate is not advisable.

There are a lot of factors to consider when rebuilding a new roof over the old one.

A reroof is a good option under the following conditions:

  • When your roof is at the end of its life, the other element and the covering board are still in good condition.
  • Your shingles are worn out due to age and are not leaking.
  • Your roof is not twisting or missing. 
  • You want a different design or color for the roof.

However, there are some reasons why your roof might not be good for a reroof:

#1. Absence of Asphalt Shingles

Your roof does not qualify for a reroof when you don’t have asphalt shingles. You can only place a shingle on shingles. It is best not to mix materials or place shingles over wood, tiles, or slate.

#2. Curling and Missing Shingles

You cannot install a new roof over the old one if you have curling and missing shingles. It can only be possible if the roof is flat and level

There are various causes of curling shingles, so it’s best to call professionals to know the cause and replace it before you reroof.

#3. Two Layers of Roof

When you add a new roof to your old roof, you are adding more weight to the roof, and most building codes accept only two roofs for a building. So if you have reroofed once, it’s best not to add another roof.

#4. Local Building Codes

It’s best to know the building codes of your area. Most building codes allow two-layer roofs. However, some building codes only allow single-layer roofs.

Benefits of ReroofingDisadvantages of Reroofing
It’s cheaper and more convenient to install.Overbuilt roofs may violate the roof warranty.
Reroofing makes your work easier and faster.Reroofing adds more weight to your roof.
It strengthens the roof and makes it more protective. Accessing the sheathing board will be very difficult.
It also prevents moisture from entering your house.Reroofing makes it difficult to fix any leak problem.

How Much Does It Cost to Overbuild a Roof?

To install a new roof on the old one, budget about 4,000 to 16,000 dollars, depending on the material and roof size. 60% of the project cost goes to the labor and the overhead. 

When you want to overbuild your roof, the cost varies depending on the roof’s pitch, roof size, materials, and the area of your house. 

Furthermore, adding extra components to your roofs, such as a skylight, outlet, and ventilation ducts, will increase the cost. 

Different materials you can use to overbuild roofs also vary in price. These materials and the cost include:

#1. Asphalt Shingle

Suppose you want to overbuild a roof with asphalt shingles, budget 5,000 to 11,000 dollars. On average, you can spend 7,211 dollars for a house of about 2,000 square feet. 

Reshingling your home with asphalt is the most inexpensive alternative. Asphalt shingles last from 10 to 30 years, depending on the quality.

#2. Metal Roof

Expect to spend more when you want to reroof your house with a metal roof. 

The cost of installing a metal roof over an old one is about 7,000 dollars to 14,500 dollars, depending on the roof size and gradient. 

A metal roof per square costs about 600 to 700 dollars. Metal roofs might last up to 50 years.

#3. Wood Shingle

It’s best to budget between 450 to 900 dollars per square or 4 to 9 dollars per square foot to reroof a standard-sized house with wood shingles. Nonetheless, the wood and extra wood treatment will affect the cost.

#4. Slate Roof

Slate is one of the most expensive roof materials, which costs about 1,480 dollars per square for the material and installation. 

So to reroof your house with slate, it’s best to estimate about 14,800 to 44,500 dollars for all the costs.

#5. Tile Roof 

There are different tile roofs: Spanish, concrete, and clay. If you are going to overbuild your roof with tile, you need to upgrade the roof to bear the weight of the tiles. 

The cost to overbuild a roof with tiles ranges between 1400 to 1600 dollars per square. 

What Is a Roof Overframe?

The roof over-frame is the extra roof framing added to the original roof frame and sheet. The roof over-frame is mainly seen where a garage roof intersects with the house roof gradient. 

When installing an over-frame, it’s best to put in mind the following:

  • The over-frame cliff must align with the roof and emerge as a straight line for the total size of the cliff. 
  • The lowest cut of the jack rafter should entirely bear on a 2x board named Sleeper. However, the board’s size depends on the jack rafter’s size. 
  • Also, the jack rafter should not lean directly on the roof sheathing.

The materials you need for a roof over-frame include:

  • Talon guns
  • Chalk line
  • Circular saw
  • Carpenter Square
  • Expansion ladders
  • Sheathing H bolts
  • 8D sheeting nail gun, 16D sinker for subfascial, and 16D galvanized for finish fascia.

Is an Overbuild Better Than a Complete Renovation?

Several factors determine whether you should overbuild or renovate your roof. Roofing experts recommend roof inspection at least once every year. 

After inspection, the experts will tell you if an overbuild roof or a complete renovation is best for you. Overbuild roofing is when you lay a new roof over the old ones. 

A complete roof renovation is when you tear off the failing and damaged roofing system and replace it with an entirely new roof.

If you plan to sell the house later, investing in a complete renovation is not advisable since it’s very expensive. 

If reroofing puts your roof back in shape and makes it look attractive to potential buyers, it’s best to go for it.

You can check with the property appraiser if a complete renovation or an overbuild roof will add more value to your house. 

If both choices add the same value, you can opt for a complete renovation of your roof.

Also, considering the costs of renovation and reroofing is another factor that affects your choice. If you want to change your roof at a lower price, it’s best to go for an overbuild roof.


Overbuild roof is the best option if you don’t need a complete roof replacement and have a good roof that is slowly losing its function. It’s easy and cheap to install. 

However, your roof must meet the building requirement. Therefore, it’s a good idea to contact a roof professional to advise you on the best option.

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