Roofing Components and Installation Details Every Austin Homeowner Should Know
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What does flashing do, and why use screws instead of nails?
Flashing is the metal that seals the spots where your roof meets a wall, which roofers call a roof to wall condition. A typical piece goes about 4 inches up behind the siding and about 4 inches out over the shingle, so water sheds onto the roof surface instead of slipping behind the wall. It is galvanized metal, so when we replace a roof we usually do not replace good flashing. We pull it out of the way, remove the old shingles, then reinstall it.
How that flashing is fastened is where many roofs fail. Most companies still use a nail because it is the fastest and cheapest method. In our experience a nail backs its way out in roughly 10 to 12 years, and once it lifts, water starts getting in. Driftwood Builders Roofing uses a 2 inch wood screw instead, often with a grommet. The screw holds the flashing in place for the life of the roof, around 20 years, without the pull-out problems a nail creates.
- Nail: cheap and quick, but tends to work loose in about a decade.
- Screw: a 2 inch wood screw that stays seated and keeps the flashing tight.
If you are interviewing an Austin roofing company, ask how they fasten flashing. It is a small detail that quietly decides whether you get a leak years later.
Why do drip edge and starter shingles matter at the roof edges?
The edges of your roof take the most abuse, so two components there do a lot of quiet work. The first is drip edge, a small piece of metal, roughly 2 inches by 2 inches, that gets nailed to the decking about every 12 inches all the way around the perimeter. The vertical leg drops down over the fascia board and wicks water away from the wood. When the back of the gutter sits behind the drip edge, any water rolling off the roof has to hit metal first and drop cleanly into the gutter, never touching the fascia. We install it around every house we do, and you should never let a roofer skip it.
The second edge component is the starter shingle, which goes along the eave at the bottom of the roofline. Starter shingles are a little heavier than field shingles and carry an extra line of adhesive, so they seal down and resist lifting when high wind hits the edge. That stops a domino effect where one lifted course peels back the rest of the roof, which on a windy North Austin day is exactly the kind of detail that keeps a roof intact.
- Drip edge: protects the fascia and routes water into the gutter, installed around the full perimeter.
- Starter shingles: heavier, extra adhesive, locked at the eave to fight wind uplift.
Tongue and groove, plywood, or skip sheathing: what is the decking under my shingles?
Everything on a roof rests on the decking, and not all decking is ready to accept shingles. On many homes built around the 1970s we find tongue and groove boards used instead of plywood. The problem is the gaps. There are obvious large gaps, but even the small ones cause trouble, because when we shoot a nail through a shingle and it lands over a gap, the nail disappears into open space. We cannot see it or feel it, and the next time it rains there is a leak. The fix is to cover the tongue and groove with a full sheet of plywood across the house, creating a flat surface that holds a nail and keeps the roof watertight.
Skip sheathing looks similar but is not the same thing. Skip sheathing has deliberate spaces, or holes, between the boards, often found under old tile. The solution there is different: we add an extra layer of board and batten both horizontally and vertically, then install a 22 gauge metal standing seam roof on top.
| Decking type | Issue | Our fix |
|---|---|---|
| Tongue and groove | Gaps let nails miss and water in | Sheet over it with plywood for a flat nailing surface |
| Skip sheathing | Open spaces between boards | Add board and batten, then a standing seam metal roof |
| Plywood | None, this is the goal | Standard nailable surface for shingles |
Covering decking adds cost, but skipping it is how leaks start. If you are unsure what is under your shingles, a roof inspection will tell you.
What is rolled roofing, and when does a low slope need it?
Not every part of a roof has the same pitch, and the wrong material on a low slope is a recipe for leaks. On a steeper section, say a 6 by 12 pitch, asphalt shingles work fine because water sheds quickly over their short exposure. But many Austin homes have a flatter section that is barely sloped at all, and shingles do not move water reliably across a near-flat run.
That is where rolled roofing comes in. Rolled roofing comes in significantly longer sheets than individual shingles, so on a low slope the water that drains down from the steeper roof above just slides right off the long sheet without finding a seam to leak through. The rule of thumb is simple: steep sections take shingles, and low or near-flat sections take rolled roofing or another low-slope product.
- Steep slope: asphalt shingles shed water fast over short exposures.
- Low slope: rolled roofing uses long sheets so water glides off without leaking.
Putting shingles on a low slope is a common mistake that leads to interior leaks. Matching the material to the pitch is part of doing the job right.
How do ventilation and proper nailing protect the whole roof?
Two installation details affect the entire roof system rather than one edge or section. The first is attic ventilation, which works as a balanced in-and-out system. Around the base of the roof, usually about every 8 feet, are soffit vents, sometimes called set vents, which act as intake and pull cooler air in. Near the top are box vents, also called an air hawk or turtle vent, which let the hot air escape. You want intake at the bottom pulling air in and exhaust vents at the top releasing it, so air moves continuously through the attic. There are many ways to vent a roof, but the goal is always that balanced airflow.
The second detail is nail placement, and it is one of the most common things previous roofers get wrong. The nail belongs in a specific spot on the shingle so each course locks the one above it in place. When an old roofer drives the nails too high, the shingles are not held properly, and on a steep slope they can slide right off. We have torn off entire roofs and redone them for exactly this reason. Correct nailing is invisible once the roof is finished, but it is the difference between shingles that stay put and shingles that fail.
- Intake vents: set or soffit vents at the bottom pull air in, roughly every 8 feet.
- Exhaust vents: box or turtle vents at the top let hot attic air out.
- Nail placement: nails set at the correct height lock each shingle course; high nails let shingles slip.
Across Cedar Park, Round Rock, Leander, Lakeway, Georgetown, Pflugerville, Buda, and Kyle, these are the details that separate a roof that lasts from one that leaks early. If a previous job has you worried, you can request a free estimate from Driftwood Builders Roofing, a GAF Master Elite contractor serving Austin since 2005.
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Frequently Asked Questions
Does flashing get replaced when I get a new roof?
Usually not. Flashing is galvanized metal, so if it is still in good shape there is nothing wrong with it. We pull it out of the way, remove the old shingles, then reinstall the same flashing rather than buying new.
Why are screws better than nails for roof flashing?
A nail tends to back its way out over time, in our experience around 10 to 12 years, and once it lifts it lets water in. A 2 inch wood screw holds the flashing in place for the life of the roof, roughly 20 years, which is why Driftwood Builders Roofing fastens flashing with screws.
Do I really need drip edge on my roof?
Yes. Drip edge protects the fascia board and routes water into the gutter so it never touches the wood. Driftwood Builders Roofing installs it around the entire perimeter of every house, and you should not let a roofer leave it off.
What are starter shingles for?
Starter shingles run along the eave at the bottom of the roof. They are heavier than field shingles and have an extra line of adhesive, so they seal down and resist high wind, which prevents the edge from lifting and peeling back the rest of the roof.
Why can’t shingles go on a low-slope roof?
Asphalt shingles shed water well on steeper pitches but not on near-flat sections, where water can sit and find its way in. On a low slope we use rolled roofing instead, which comes in long sheets so water slides off cleanly without leaking into the house.
What happens if roofing nails are placed too high on the shingle?
The nail needs to sit at a specific spot so each course holds the shingles below it. When nails are driven too high, the shingles are not secured and can slide off, especially on a steep slope. We have had to tear off and redo entire roofs that were nailed too high.
