Tamko Underlayment & Deck Repair Nationwide

Tamko Underlayment & Deck Repair: The Los Angeles Owner’s Guide

Tamko underlayment and deck repair in Los Angeles typically runs $850 – $2,400 installed, depending on how much decking has rotted and whether we’re replacing the underlayment in a small section or across the whole roof plane. We stock Tamko-compatible underlayment on our trucks and can usually complete most deck repair and underlayment replacement jobs in one day. Most Los Angeles homeowners discover the problem the hard way: a soft spot underfoot, a leak showing up on the ceiling after the first real rain of October, or granules and water stains in the attic that weren’t there last spring.

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If you’ve got an older Tamko roof and you’re seeing water where it shouldn’t be, the underlayment or the wood decking beneath it is almost always involved. Here’s what you need to know before you call anyone.

Which Tamko Models This Applies To

Tamko’s residential roofing lines fall into a few families: Heritage shingles (including the Heritage Woodgate and Heritage Vintage series), the StormFighter and Elite Glass lines, and their metal roofing systems like MetalWorks. The underlayment underneath any of these is nearly always one of three Tamko products: Apex synthetic underlayment, MoistureGuard 15 or 30 felt, or the self-adhering TW-SA base sheet used on low-slope sections.

Here’s the compatibility detail that matters. Tamko’s Apex synthetic underlayment is rated for use under all their asphalt shingle lines, but it must be paired with Tamko’s recommended fasteners and cap nails to keep the manufacturer warranty valid. If a previous contractor laid down generic #15 felt under your Tamko Heritage shingles, the roof still sheds water, but the underlayment won’t perform the same in a wind-driven rain. When we open up a Tamko roof in Los Angeles, one of the first things we check is whether the underlayment is actually a Tamko product or a no-name substitute that was cheaper at the supply house.

For deck repair, the question is simpler: what’s rotted and how far does it go? Tamko doesn’t make the plywood or OSB decking, so any code-rated exterior plywood or OSB in the correct thickness works. Los Angeles building code generally calls for minimum 7/16-inch OSB or 15/32-inch plywood on standard rafter spacing, but we match whatever thickness is already up there so the roof plane stays flat.

OEM versus aftermarket on underlayment is an easy call for us: use Tamko’s own Apex or TW-SA when we’re repairing a Tamko roof. It costs a few dollars more per square than generic synthetic, and it removes any question about warranty coverage. We stock both on the truck, but we’ll tell you which one we’re using and why before we start.

Signs Your Tamko Underlayment & Deck Repair Is Failing

• Water stains on ceilings or walls after rain. Underlayment is the last line of defense under the shingles. When it fails, water reaches the decking, soaks into the wood, and eventually finds a seam or nail hole to drip through. By the time you see a stain, the wood above has been wet for a while.
• Soft or spongy spots when walking on the roof. This means the decking itself has rotted. It’s common near valleys, around plumbing vents, and along eaves where water runs off and sits. If your foot sinks, the plywood or OSB has lost its structural strength and needs replacement, not a patch.
• Granules in the gutter or at downspout elbows. Tamko shingles shed granules as they age, but a heavy, concentrated amount signals the shingle is wearing faster than it should. That usually points to moisture trapped underneath, which rots the deck from below while the shingle bakes from above.
• Bubbling or blistering on the roof surface. Trapped moisture expands in the Los Angeles heat and pushes up through the shingle. What looks like a surface defect is usually an underlayment or ventilation problem underneath. We see this a lot on older roofs in the Valley, where attic ventilation was an afterthought.
• Dark streaks or visible wood from inside the attic. If you can see daylight coming through the roof boards or dark water-stained wood around nails, the underlayment has failed and the deck is actively taking on water. In Los Angeles, with our dry summers, this damage often goes unnoticed until the first rain of November.

Replacement Cost & What’s Included

Here’s what Tamko underlayment and deck repair costs in Los Angeles, in real dollars.

The spread comes down to three things. First, how much decking is rotted. In Los Angeles, we rarely open a roof and find the damage is limited to the exact spot the leak showed. Water travels. Second, how many layers of old roofing need to come off before we can reach the deck. Third, whether we’re reusing the existing Tamko shingles or replacing a section of them to match.

Our price always includes removal of failed material, deck replacement, new underlayment, nails, sealants, and cleanup. It’s a written number before we touch the roof, and it doesn’t change at the door. Every repair carries a written guarantee, and under the 365-Day Done Right Promise, if the repair fails inside a year, we come back and make it right at no charge.

DIY or Call Us?

Here’s the honest answer. Walking a roof to spot obvious damage is something any homeowner can do safely if they stay on a ladder and look, rather than climb up. Check for missing shingles, lifted edges, and visible rot around flashing. What you shouldn’t do is pull up shingles yourself. The moment you break the seal on a Tamko shingle, you’ve compromised the water-shedding surface, and putting it back correctly takes a specific touch. Underlayment is not a forgiving material, and decking replacement on a roof in Los Angeles means working at height, with tools, on a surface that may already be structurally compromised. That’s a job for people who do it every week.

If you want a second set of eyes before you commit to anything, call us at (213) 674-2890 and we’ll come take a look. The estimate is free.

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