Boral Underlayment & Deck Repair Nationwide

Boral Underlayment & Deck Repair: The San Diego Owner’s Guide

We stock and install Boral-compatible underlayment and deck repair materials throughout San Diego, with most underlayment replacement jobs running between $1,800 and $3,400 depending on roof size, pitch, and how much decking needs replacement. A failed underlayment usually announces itself the same way: a water stain on the ceiling after rain, granules building up in the gutters, or shingles that suddenly look wavy along the eaves. On homes across Clairemont Mesa and Point Loma, the story we hear most is a roof that passed inspection a decade ago and has quietly been losing its moisture barrier ever since.

Call (619) 810-5520

Which Boral Models This Applies To

Boral’s roofing products fall into a few distinct lines, and each uses a specific underlayment spec. The Boral Inspire line, which is a stone-coated steel product, requires a high-temperature-rated synthetic underlayment rated to at least 220°F. The Boral TileSeal and Boral CedarLite systems both specify a heavyweight 30-lb-or-better synthetic or Type 30 felt underlayment, and the deck beneath must be rated for the added weight of the finished roof. If your San Diego home was built before 1995 and has the original Boral roof, there’s a good chance the underlayment is the old asphalt-saturated felt, which has a service life of about 15-20 years in coastal salt air before the oils dry out and it starts to crack along the nail lines.

The compatibility gotcha most owners hit: Boral’s stone-coated steel products use a different batten-and-clip layout than Boral’s composite shake and tile lines. A deck set up for one won’t correctly hold the other, and edge flashing details differ by product line. If you don’t have the original install documentation, we identify the deck layout by lifting a few tiles at the eave and measuring the batten spacing. That tells us which Boral system you have and which underlayment rating applies.

We always recommend OEM-spec underlayment for Boral roofs, not a budget no-name roll from a big-box store. The cost difference is typically $400-$700 on a full underlayment replacement, and the cheap stuff will cook off a stone-coated roof surface in four or five San Diego summers. That’s a warranty claim and a second tear-off you don’t want.

Mercer Roofing Co San Diego is an independent roofing contractor and is not affiliated with Boral. We install and repair Boral systems using materials that meet Boral’s published specifications.

Signs Your Boral Underlayment & Deck Repair Is Failing

• Water staining on ceilings or around skylights. This is not always a shingle problem. Underlayment is the actual waterproofing layer, and once it splits or tears, water finds the deck seams and follows them inside.
• Shingles or tiles lifting visibly at the eaves or along valleys. When decking rots beneath the fasteners, the nails lose grip and the shingle edges start to curl. This is a deck problem as much as an underlayment problem.
• Granules filling the gutters after every rain. A Boral composite roof losing surface granules is often a sign that trapped moisture is breaking down the product from the underside. The underlayment failed first.
• Soft or spongy spots when walked by a professional. You should not be walking your roof, but if you’ve had a solar installer or gutter crew up there and they mention soft spots, that’s deck rot. The fix is opening the roof, replacing the rotted deck sections, and laying new underlayment.
• Daylight visible from the attic through the roof deck. If you can see light through the deck boards, the underlayment has separated, and water has a clear path into your home. We see this most often on older San Diego tract homes in Tierrasanta and Mira Mesa where the original underlayment was installed in the 1980s.

Replacement Cost & What’s Included

For a full Boral underlayment and selective deck repair in San Diego, expect to pay between $1,800 and $3,400 for a typical single-story ranch home of 1,500 to 2,200 square feet. Two-story homes and steep-pitch roofs add $600 to $1,200 for safety equipment and extra labor. If we’re only replacing underlayment on a single roof plane, the range drops to $900-$1,500.

The price includes removal of the existing shingles or tiles, careful deck inspection, replacement of rotted deck sections, new Boral-spec underlayment, re-installation of the roofing material, and full cleanup with a magnet sweep. Every job gets a written price before we start, and the work is covered by our 365-Day Done Right Promise: if it’s not right within a year, we make it right. Every underlayment we install carries that guarantee in writing, and if a repair fails, the second visit is free.

One thing that drives cost in San Diego specifically: permit fees. The county and most incorporated cities require a re-roof permit for full underlayment replacement, and those fees run $200-$500 depending on jurisdiction. We pull permits on every full underlayment job, and the permit fee is listed as a line item on your quote.

DIY or Call Us?

You can safely check for underlayment issues by going into your attic with a flashlight on a sunny afternoon and looking for light penetration, dark moisture rings, or rusted fasteners on the underside of the deck. That’s a free diagnostic and it costs nothing. What we don’t recommend is pulling up shingles or tiles yourself. A Boral roof is held together by a system: underlayment, battens, clips, and fasteners that have to be re-installed in the right order or the roof leaks worse than before. It’s high work with sharp edges and a lot of climbing, and the fall risk is real. If the deck is rotted, stepping on the wrong spot is how people go through. Call (619) 810-5520 and we’ll send a background-checked, photo-badged technician to inspect it for free.

FAQs