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IKO Home Additions & ADU: The Houston Owner’s Guide
IKO-compatible home additions and ADU projects in Houston typically run $45,000 to $130,000 installed, depending on square footage, foundation conditions, and the fixtures you select before the first board goes up. We plan and build these jobs around IKO-rated roofing and sheathing components so the new structure ties into your existing house the same way the original envelope did. Most Houston homeowners call us after a sunroom or upstairs addition starts showing water staining at the roofline, or after a builder-grade ADU starts sweating at the ceiling joints during August humidity.
What you are really dealing with when an IKO-roofed addition fails is usually not the shingle itself. It is the transition. The seam where the addition roof meets the main house, the flashing at the crickets, the underlayment someone skipped because the roofline looked simple. Those are the joints that fail first in Houston’s alternating wet-dry cycle, and by the time the staining shows on the ceiling the water has already been working through the sheathing for months.
This page covers which IKO models you are most likely dealing with, what fails first, what a replacement or repair should cost in Houston, and when to call a contractor instead of grabbing a ladder. Elmstead Remodeling Houston is an independent service provider and is not affiliated with IKO. We quote the work honestly, with a written price before anything begins, and we install materials that match or exceed the original spec.
Which IKO Models This Applies To
IKO manufactures residential roofing and waterproofing products across several distinct product lines, and the one you have changes what we order for your addition. The Cambridge line uses an architectural asphalt shingle with a fiberglass mat, and it is the most common IKO product we see on Houston additions and ADUs built in the last 15 years. The Dynasty line is a step up in thickness and wind rating. The Nordic line is a true heavyweight shingle with a more pronounced shadow line. Older Houston additions from the early 2000s sometimes carry Marathon or Aristocrat series shingles, which are discontinued for warranty purposes but still repairable with the right underlayment approach.
Here is the compatibility gotcha most people do not learn until they are standing in a supply yard: IKO shingles are manufactured in different plant locations with slight color-batch variations, so a bundle purchased today will not always match the same named color from eight years ago side by side. If your addition roof is visibly failing and we cannot match the exact dye lot, the honest fix is often re-roofing the entire addition plane rather than patching one slope. That is a conversation we have before anything gets ordered, because a mismatched patch is worse than the original problem.
For the roof deck itself, IKO also produces an ice-and-water barrier and synthetic underlayment we specify on Houston additions. The barrier matters here more than homeowners expect: Houston’s summer storms drop an inch of rain in an hour, and wind-driven water finds every seam in a five-pound felt job. We install a self-adhered IKO barrier at all roof transitions and valley lines on additions and ADUs, every time, as a matter of spec.
Beyond the IKO components, we stock and install cabinets from KraftMaid, and countertops from Cambria and Silestone, so the interior of your addition matches the standard of the exterior shell.
Styles & brands we work with
Signs Your IKO Home Additions & ADU Is Failing
- Water staining on the ceiling near the wall where the addition meets the main house. This is the classic transition-flashing failure. The original builder caulked the seam instead of installing step flashing, and the caulk cracked under Houston’s sun. Water follows the seam down every time it rains.
- Shingle granule buildup in your gutters or at downspout outlets. A new IKO shingle sheds granules for the first few months. Granules still coming off in year two or three mean the asphalt mat is breaking down faster than it should, often from attic heat in an under-ventilated addition.
- Shingles curling at the edges or lifting at the corners in the morning. Morning curl means moisture is trapped under the shingle and expanding as it warms. This is common on flat or low-slope ADU roofs where drainage was never sloped correctly in the first place.
- A musty smell inside the ADU or addition after heavy rain. Smell means the water has reached insulation or drywall, not just sheathing. By the time you smell it, the repair is no longer a shingle swap. It is a rot assessment and likely a section of decking replacement.
- Soft spots or visible sag in the roof deck when viewed from the attic. Press on the underside of the roof sheathing. If it compresses more than a firm board should, water has been sitting in the OSB or plywood, and the deck needs to come out before new underlayment and shingles go on.
See the difference
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After
Before
After
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AfterReplacement Cost & What’s Included
In Houston, re-roofing and rebuilding the shell of a home addition or ADU falls between $45,000 and $130,000. The lower end covers a smaller addition (200 to 400 square feet) with a simple roof plane, no structural changes, and mid-grade finishes. The upper end covers a full ADU with its own bathroom, kitchenette, upgraded electrical service, and a more complex roofline with multiple valleys and transition points against the existing house.
| Project Scope | Houston Installed Range |
|---|---|
| Home addition (foundation to roof, tied into existing structure) | $45,000 – $130,000 |
| ADU construction (separate living space with kitchen/bath) | $90,000 – $220,000 |
| Garage conversion (existing slab, interior build-out) | $30,000 – $80,000 |
| Roof shell repair on existing addition (IKO re-flash and re-shingle) | $8,000 – $20,000 |
Every quote is a written, line-item price before any work starts. You will see the shingle count, the underlayment specification, the flashing detail, the labor, and the dump fees as separate lines. You will also see that shoe covers and drop cloths are already in the quote, not bolted on as a change order. We do not bid low and grow the price after the crew arrives. Graham Stein writes the scope himself on most Houston projects, and if something in the field changes, the change is written down and priced before the next cut is made.
The 365-Day Done Right Promise covers every completed addition and ADU project. If something is not done right, we make it right. That is the standard we would want in our own homes, and it is stamped on every contract we write in Houston.
DIY or Call Us?
Some parts of this job are safe and useful for a homeowner to do before calling us. Walking the roofline from the ground with binoculars to count lifted shingles, checking the attic for soft sheathing, clearing granules out of the gutters so you can see what is coming off the roof. Those are observations. They inform the conversation.
The actual work is not a ladder job. Working on a roof with a pitch steep enough for an addition involves fall risk, and re-flashing the seam where an addition meets a house means removing and reinstalling structural materials that hold two roofing planes together under wind load. This is not a YouTube tutorial project. A wrong flashing detail leaks, and the leak runs inside the wall cavity where you cannot see it until the drywall stains six months later.
Most Houston addition and ADU failures we see start as a $400 flashing repair that got ignored and became a $15,000 deck-and-sheathing replacement. If you see staining or smell moisture, call (254) 272-5240 and we will walk the roof with you, explain what we see, and hand you a written scope. The estimate is free.
FAQs
An IKO architectural shingle roof with correct ventilation and proper flashing should last 20 to 25 years in Houston. The limiting factor here is not the shingle. It is the trapped heat in an under-ventilated addition attic, which cooks the asphalt mat from below and cuts lifespan to 12 to 15 years when the original builder skipped proper intake and exhaust. We evaluate the ventilation on every addition we inspect, because the shingle warranty will not cover heat-related degradation from poor attic airflow.
Sometimes, yes. If the problem is a single flashing transition or a small mechanical damage area, and the surrounding shingles are sound enough to lift without breaking, a section repair is correct. If the deck underneath is soft or the shingles are past half their useful life, patching is a waste of your money. We will tell you which one you have after we open the area and look at what is underneath. Call (254) 272-5240 and we will put an honest repair-or-replace recommendation in writing.
Most additions run 8 to 16 weeks depending on scope, and a full ADU with kitchen and bath runs 4 to 8 months. Weather, permit reviews, and material lead times all factor in. We give you a written schedule before work starts and we update it in writing when something changes. No one likes surprises on a project this size.
We keep common IKO Cambridge and Dynasty shingles in standard Houston colors, plus the self-adhered barrier and synthetic underlayment, available through our local supply accounts. Specialty colors and the heavier Nordic line are ordered per job, which adds a few days. What we do stock on the truck on day one: shoe covers, drop cloths, and quiet tool settings for the hours your kids are sleeping.
Written by Graham Stein, Owner, Elmstead Remodeling Houston at Elmstead Remodeling Houston, serving Houston and nearby areas.
