Denver Duplex Reroof: Class 4 Shingles and a TPO Flat Roof
Project Overview
- Location: Denver, CO
- Building Type: Residential brick duplex with a steep shingle roof and a rear flat roof
- Size: 1,100 sq ft
- Roofing System: IKO Nordic Class 4 shingles on the steep roof; Versico 60-mil TPO, mechanically attached, on the flat roof
- Duration: 2 weeks
- Completed: December 2025
- Manufacturer: IKO and Versico
- Warranty: IKO limited lifetime warranty on the shingles and a 20-year Versico warranty on the flat roof
Roof Condition
This older brick duplex in Denver had two different roofs and two owners. The steep front roof had multiple layers of roofing, original wood shingles under asphalt, sitting on spaced board sheathing with no solid deck. The rear flat roof was worn out, and part of the brick parapet wall was failing.
- Multiple layers of roofing on the steep front roof, original wood shingles under asphalt
- Spaced board sheathing with no solid deck
- Worn-out rear flat roof
- Part of the brick parapet wall was failing
Evaluation & Approach
A duplex roof only works when both sides are done together. Stopping at the property line leaves a seam down the middle of the roof that neither owner controls. Doing both halves as one project gave each owner the same deck, the same underlayment and the same membrane, with one continuous roof. New OSB was required because shingles cannot be nailed properly to spaced boards. Class 4 impact-rated shingles are the right call in Denver hail country, and wrapping TPO over the parapet protects the old brick from water.
Why This Approach
- Doing both halves as one project gave each owner the same deck, the same underlayment and the same membrane
- One continuous roof instead of a seam down the middle
- New OSB gives the shingles a solid deck to nail to
- Class 4 impact-rated shingles are the right call in Denver hail country
- Wrapping TPO over the parapet protects the old brick from water
- IKO limited lifetime warranty on the shingles and a 20-year Versico warranty on the flat roof
Scope of Work
- Steep Roof Tear-Off: Removed all layers of wood and asphalt shingles down to the framing boards.
- New OSB Deck: Installed 7/16 inch OSB over the spaced sheathing.
- Underlayment, Drip Edge and Flashings: Installed synthetic underlayment, pre-painted drip edge, new step flashing and counter flashing at walls, and headwall flashing under the front windows.
- IKO Nordic Shingles: Installed IKO Nordic Class 4 shingles, continuous ridge vent and ridge cap. Roof pitch runs 10/12 to 12/12, so shingles were hand loaded.
- Flat Roof Tear-Off: Removed the old flat roofing.
- Parapet Rebuild: Rebuilt the failing brick parapet section with a 2x10 wood nailer on top and cover board on the wall faces before the TPO went over it.
- Insulation: Installed two layers of 2.6 inch Versico SecurShield polyiso for R-30 to meet code.
- TPO Membrane: Mechanically attached Versico 60-mil white TPO, adhered TPO up and over the walls and installed pre-painted drip edge on walls and eaves.
- Skylights: Installed two new double-dome skylights.
- Gutters and Downspouts: Finished with new 5 inch black gutters and downspouts.
Result
Warranty: IKO limited lifetime warranty on the shingles and a 20-year Versico warranty on the flat roof
- One Continuous Roof: One continuous roof across both homes
- Solid Deck and Class 4 Shingles: A solid new deck and IKO Nordic Class 4 shingles up front
- R-30 TPO Flat Roof: An R-30 TPO flat roof with new skylights and a rebuilt parapet in back
- New Gutters and Two Warranties: New gutters, an IKO limited lifetime warranty on the shingles and a 20-year Versico warranty on the flat roof