A new roof installation is different from a replacement: there is no old roof to learn from, so every decision about underlayment, ventilation and flashing has to be made on paper first. Across New Jersey we install roofs on new homes, rear additions, second-story expansions, dormers and detached garages. The goal is a roof that looks like it was always part of the house and performs the same way in a nor'easter as the original roof beside it.
Additions are where most new roof installations in NJ go wrong. The new slope has to tie into the existing roof without creating a flat spot or a valley that holds water, and the step flashing where the addition meets the old wall has to be woven into the shingle courses rather than caulked on afterward. We match the existing pitch where we can, line the new valleys with ice-and-water shield, and carry the ventilation plan across both sections so the attic does not end up with one hot, damp corner.
On every new roof we install synthetic underlayment across the deck, ice-and-water shield along the eaves and valleys, metal drip edge at the rakes and eaves, and balanced ventilation: soffit intake paired with ridge exhaust. New Jersey's humid summers and freeze-thaw winters make that ventilation step essential, because trapped heat shortens shingle life and trapped moisture rots sheathing from the inside. When the house also needs gutters, we size and hang them as part of the same project so the drip edge and gutter line meet cleanly.
New Roof Cost in New Jersey
Pricing for new roof installation depends on the roof area, pitch, how many valleys and wall tie-ins the design has, and the shingle line you choose. A tie-in roof for a typical rear addition often runs $2,800 to $5,200, while a full new roof on a 1,400 to 1,800 square foot home commonly falls between $9,500 and $16,000. Replacing an existing roof instead? See roof replacement for what a tear-off involves.
Technician insight
The weak point on most addition roofs is not the field of shingles, it is the 18 inches where the new roof meets the old wall. Woven step flashing and a continuous strip of ice-and-water shield there prevent the slow leak that otherwise shows up inside the first winter.
Rear Addition Roof Tie-In
A homeowner added a rear family room and needed the new roof to join the existing colonial roof. We matched the original pitch, lined the new valley with ice-and-water shield, wove step flashing into the shingle courses along the old wall, and extended the ridge ventilation across both sections. The addition reads as part of the original house and the valley stayed dry through its first winter.
Roof Installation Services We Offer
✓New Construction Roof Installation
Complete roof systems for new homes, installed to the plans with underlayment, ice-and-water shield, ventilation and drip edge.
✓Home Addition Roofing
New roof sections that tie into the existing roof with matched pitch, woven step flashing and continuous ventilation.
✓Dormer and Second-Story Roofing
Roofing for new dormers and second-floor expansions, including the valleys and wall flashing those designs create.
✓Detached Garage Roof Installation
Shingle roofs for new or rebuilt garages and outbuildings, matched to the main house.
✓Underlayment and Ice-and-Water Shield
Synthetic underlayment over the deck plus self-adhering membrane at eaves and valleys for freeze-thaw protection.
✓Roof Ventilation Installation
Soffit intake and ridge exhaust sized to the attic so the new roof runs cooler in summer and drier in winter.
Roof Installation Cost in New Jersey
| Service | Typical Range | What Affects It |
|---|---|---|
| Full new roof installation (1,400–1,800 sq ft home) | $9,500–$16,000 | Roof area, pitch and shingle line move the range |
| Home addition roof tie-in | $2,800–$5,200 | Matching pitch, flashing and ventilation to the existing roof |
| Detached garage roof | $3,000–$7,000 | Depends on garage size and roof shape |
| Architectural shingle upgrade | $1,200–$2,800 | Step up from three-tab on the same roof area |
Ranges are typical for New Jersey and confirmed with an exact written quote before any work starts.
How it works
- 1
Plan Review and Site Visit
We review the plans or the addition framing, measure the roof planes and note where the new roof meets the old.
- 2
Written Estimate
You receive an itemized estimate covering materials, flashing details, ventilation and any gutter work.
- 3
Permit Coordination
Roofing is scheduled to fit your construction permit and the framing inspection timeline.
- 4
System Installation
Underlayment, ice-and-water shield, drip edge, flashing, shingles and ridge vent are installed in sequence.
- 5
Final Walk-Through
We walk the finished roof with you, check every tie-in and clear the site of debris and nails.
Pricing
New roof installation pricing in NJ is driven by roof area, pitch, the number of valleys and tie-ins, and the shingle line.