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Tamko Underlayment & Deck Repair: The Jacksonville Owner’s Guide
We stock and install Tamko-compatible underlayment and deck repair materials across Jacksonville, with most underlayment replacements running $1,800 to $4,200 installed depending on roof size and deck condition. If decking itself has rotted, expect $85 to $140 per 4×8 sheet replaced, labor included. Most Tamko underlayment failures we see start as a small ceiling stain or granule-heavy gutter runoff, then spread quickly in Florida humidity. The good news: this is a repair we can usually price and schedule within a few days, not weeks.
Here’s what Jacksonville homeowners need to know about Tamko underlayment, what fails first, and what a proper repair actually costs.
Which Tamko Models This Applies To
Tamko makes a few distinct underlayment products, and matching the right one matters. The two we work with most in Jacksonville are Tamko TW Metal and Tile Underlayment (a self-adhering SBS-modified membrane, often found under metal roofs and tile in coastal areas) and Tamko Moisture Guard (a peel-and-stick underlayment specified for shingle roofs at eaves, valleys, and around penetrations). They are not interchangeable, and installing a generic felt where the spec called for a modified membrane is how roofs fail early.
If you don’t know which product is on your roof, check the permit packet from your original install or look at any exposed underlayment edge in the attic for printed branding. Tamko stamps its product name on the membrane face. No label? A moisture meter reading and a look at the decking from inside the attic will usually tell us what we’re dealing with.
One compatibility gotcha we see on older Jacksonville homes: some roofs built before 2010 used Tamko AwwraP, which is no longer in wide distribution. When that roof needs underlayment repair, we spec the current Tamko Moisture Guard or TW equivalent rather than hunting discontinued stock, and we note the product change on the written proposal so there’s no confusion later.
On the OEM-versus-aftermarket question: for underlayment specifically, we install Tamko-branded or manufacturer-equivalent membranes, not no-name peel-and-stick from a big-box shelf. The difference is what happens during a Jacksonville summer. Cheap membranes can soften and slide on a 95-degree roof deck, especially on lower slopes. A quality SBS-modified membrane holds its bond.
Styles & brands we work with
Signs Your Tamko Underlayment & Deck Repair Is Failing
- Interior ceiling stains that appear after heavy rain, not during it. Water moves slowly through failed underlayment and damaged decking. By the time you see the stain, the membrane has already been passing moisture for weeks or months. This is the most common call we get in Arlington and San Marco.
- Granules collecting in gutters or at downspout elbows. If the shingle surface is wearing, water is reaching the underlayment more aggressively. That accelerates membrane breakdown, especially on south-facing slopes in Jacksonville’s sun.
- Spongy or soft decking when walked on from inside the attic or outside. Once OSB or plywood decking loses its structural rigidity, the underlayment above it has already failed. Soft decking means water has been sitting against the wood long enough to compromise it.
- Visible underlayment cracking or peeling at the eaves or rake edges. On low-slope roofs or around fascia boards, exposed underlayment that has become brittle or curled is already past its useful life. Florida’s UV exposure hardens and shrinks the membrane edges first.
- Mold or musty smell in the attic after rain. Moisture trapped between a failed membrane and decking breeds mold quickly in Jacksonville’s humidity. If you smell it, the decking is wet and has probably been wet for a while.
Replacement Cost & What’s Included
For a typical Jacksonville single-story home, full underlayment replacement with Tamko-compatible materials runs $1,800 to $3,400. Add a second story or steep pitch and you’re looking at $2,800 to $4,200. If decking replacement is needed, budget $85 to $140 per 4×8 sheet, installed with fasteners and sealant. These are installed prices: material, labor, fasteners, and full cleanup.
| Scope | Typical Jacksonville Installed Price |
|---|---|
| Full underlayment replacement (1-story, walkable pitch) | $1,800 – $3,400 |
| Full underlayment replacement (2-story or steep) | $2,800 – $4,200 |
| Decking replacement (per 4×8 sheet) | $85 – $140 |
| Localized underlayment repair around penetration or valley | $450 – $900 |
What drives the range is roof size, pitch, how many flashing points need to be worked around, and how much decking is involved. We write the price before we pull a shingle up, and the number on that paper is the number you pay, even if we find an extra sheet of bad decking once we open the roof.
Every underlayment and deck repair we do in Jacksonville is covered by the 365-Day Done Right Promise: if the repair fails within one full year, we come back and make it right at no charge. That guarantee is in writing, on every job, passed to you before we start.
See the difference
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After
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AfterDIY or Call Us?
Walking an attic with a flashlight to check for water stains or feeling the decking from the inside is safe and useful. We encourage it. What we don’t recommend is opening the roof from the outside and trying to patch underlayment yourself. Jacksonville roofs get slick with afternoon condensation and heat makes membranes gummy. A fall is not worth saving a few hundred dollars.
The other reason this usually goes wrong as a DIY job: water travels. The visible damage point is rarely the only failure, and a homeowner patches the spot they can see while the real leak is six feet uphill, running under intact shingles. We’ve fixed more failed DIY patches than we can count. If you suspect underlayment failure, call us at (904) 719-6346 and we’ll put eyes on it. The estimate is free, and we won’t sell you a repair you don’t need. Like Travis says: if it’s not right, we’re not done.
FAQs
In Florida’s heat and humidity, expect 15 to 25 years from a properly installed Tamko modified membrane, with the shorter end applying to low-slope roofs and southern exposures. The underlayment often outlasts the shingles above it, but if decking was wet when it was installed, the membrane can fail much sooner. Call (904) 719-6346 if you want us to assess what’s on your roof now.
Yes, if the decking is still sound and the failure is localized around a valley, chimney, or pipe boot, a targeted underlayment repair works. If we discover the decking underneath is soft or the membrane has failed over wide areas, a larger replacement is the honest fix. We’ll scope it during the free estimate.
Most underlayment replacements in Jacksonville take one to two working days, depending on roof size, pitch, and how much decking has to be replaced. A localized repair around a chimney or valley is usually done in a single day. We’ll give you a firm timeline in writing before any work begins.
Our crews keep Tamko Moisture Guard and TW underlayment in common roll sizes on the truck, along with OSB and plywood decking sheets, fasteners, and sealants. For unusual roof profiles or large deck replacement jobs, we bring the materials with us on job day so we’re not running back and forth to a supplier. We also carry comparable product lines from GAF, Owens Corning, and CertainTeed.
No. The price goes on paper before the first shingle comes off, and that number does not move at the door or mid-job. If we find hidden deck damage during the repair, we stop and talk to you before any additional work happens. You’ll always know the cost before any work begins.
Get Your Tamko Underlayment Repaired Right
If you’re seeing ceiling stains, attic moisture, or granule buildup in your gutters, don’t wait. Every week of Jacksonville rain moves water further into your decking and raises the repair cost. Call (904) 719-6346 and we’ll schedule a free estimate. You’ll get a live person on the phone, a background-checked uniformed technician at your door, and a written price before any work starts. That’s the Garrison Standard, and we put it in writing on every job we do in Jacksonville.
Written by Travis Oakley, Owner, Brennan Roofing Co Jacksonville at Brennan Roofing Co Jacksonville, serving Jacksonville and nearby areas.