Metal roofing suits the Las Vegas valley because it is largely indifferent to the thing that destroys most roofs here: ultraviolet light. A coated steel or aluminum panel does not go brittle in the sun the way an exposed membrane does, and a well detailed panel roof will outlast several membrane service lives on the same building.
The trade is movement. A panel expands along its length when the sun hits it and contracts again overnight, every day, for decades. Everything that goes wrong with metal roofing in this climate comes back to whether the system was designed to allow that or was fixed down hard and expected to stay put.
Standing seam against exposed fastener
| Standing seam | Exposed fastener | |
|---|---|---|
| How it is fixed | Concealed clips that let the panel slide | Screws through the panel face |
| Fixings in the water path | None | Every fastener |
| Response to movement | Designed in | Resisted, then loosened |
| Installed cost | Higher | Lower |
| Maintenance obligation | Details and flashings | Details, flashings and every fastener |
| Typical fit here | Long term ownership, visible roofs, low slope runs | Warehouses and outbuildings where cost leads |
Both are legitimate. The mistake is buying an exposed fastener roof on the installed price and then treating it like a maintenance free roof, because the fasteners are a consumable in this climate and somebody has to own them.
What a specification should actually say
- Panel system, gauge and finish, named rather than described. Gauge and coating are where a cheap bid gets cheap, and both decide how the roof looks and performs after ten summers.
- How thermal movement is accommodated over the real run lengths on your building, including at flashings and curbs.
- Insulation, and whether the reroof triggers a code requirement to add to it.
- Every detail drawn: ridge, eave, rake, valley, parapet, curbs and penetrations. Panel roofs leak at details.
- What happens to the existing roof, and the moisture testing that settles whether it can stay.
- The warranty, split into the manufacturer’s finish and material cover and the installer’s workmanship cover, with the exclusions read.
Where panel roofs fail in the valley
- At exposed fixings, where washers have hardened and the screw has backed out
- At sealed details, where sealant was used instead of a designed movement allowance
- At rooftop equipment, especially units added later and flashed by whoever installed them
- In gutters and valleys, where grit accumulates and holds water against the panel
- At coating damage, where a scratch from dropped equipment has started to corrode
None of those is dramatic and all of them are cheap to deal with early. Commercial roof replacement in Las Vegas covers the wider reroof decision, and what extreme desert heat does to a roof covers the mechanisms across every system we work on.
Repair, coat or replace
A panel roof with sound panels and failing fixings is a maintenance job, not a reroof. A panel roof with coating failure but no corrosion through is often a candidate for a coating system, which buys years at a fraction of replacement. A roof with perforation, significant corrosion or a deck that has gone is a replacement.
Those are three very different numbers, and the only way to know which one you are looking at is for somebody to get on the roof and check fixings, finish and the condition underneath. We would rather tell you it is a maintenance job than sell you a roof you do not need yet.
What to do next
Tell us what the building is, what is on the roof now and what prompted the call. We come out, survey the panels, fixings, flashings and the assembly below, and come back with the options and what each one buys you in years. If the roof is leaking now, roof leak repair is the faster route and the survey can follow.
Common questions
Does a metal roof get hotter than a membrane roof in the valley?
The surface can run hot, and what matters to the building is the finish and the insulation rather than the material. A light colored reflective coated panel over proper insulation performs well here. A dark panel over thin insulation transfers heat into the space below all afternoon.
- Reflectivity is a property of the coating, not of the metal
- Insulation below the panel decides what reaches the building
- Metal cools quickly once the sun comes off it
- A ventilated assembly moves heat before it gets inside
- Color and coating are specification choices, so choose them
Treat the roof as an assembly rather than a surface. The question is not whether metal is hotter than membrane; it is how much heat arrives in the occupied space, and that is set by the coating, the insulation, any air gap and the color. Where cooling load is a real cost on your building, ask for the reflectance figures of the coating being offered and ask what insulation the reroof will carry, because those two answers between them decide the outcome.
Why do exposed fastener roofs leak here before standing seam roofs do?
Because every fastener is a hole with a rubber washer in it, and the valley climate works on both. Daily expansion and contraction loosens the fixing, ultraviolet exposure hardens the washer, and after enough cycles the hole is no longer sealed. A concealed clip system has no fixings in the water path.
- Exposed fasteners penetrate the panel and the washer seals it
- Thermal cycling backs fixings out over years
- Ultraviolet exposure hardens and cracks the washers
- Standing seam clips allow movement without penetration
- Exposed fastener roofs need their fixings checked regularly
That does not make exposed fastener panel wrong. It is a reasonable choice on a warehouse, an agricultural building or any structure where the lower cost matters more than the maintenance obligation, as long as somebody owns the obligation. Budget for a fastener survey at intervals, replace hardened washers before they leak rather than after, and keep a record. A screw down roof that nobody ever checks is the one that fails early here.
Can a metal roof go over an existing roof?
Often yes, and it is one of the reasons metal gets specified on a reroof. A framing system can be set over a sound existing roof, which avoids a tear off, keeps the building closed through the work and removes disposal cost. Three things decide whether it is allowed.
- The existing roof must be dry, with no water in the insulation
- The structure has to carry the additional load
- Code limits how many layers may remain in place
- Moisture testing is what settles the first question
- A corroded deck removes the option entirely
Get the moisture question answered before anyone prices the option, because covering a wet roof seals water into the assembly where it keeps corroding the deck out of sight. A scan maps how far any water has spread and core samples confirm it, and that is a small cost against the difference between a recover and a tear off. If the testing comes back dry and the structure takes the load, a recover is usually the better value of the two.
What does the daily temperature swing do to a metal roof?
It moves it. Panels expand along their length as the surface heats and contract again overnight, every day, by an amount that is small per panel and significant over a long run. A system that allows that movement lasts. One that restrains it tears at its fixings and details.
- Movement is along the panel run, so long runs move most
- Concealed clips let panels slide; exposed fasteners do not
- Restrained panels deform or tear at the fixing
- Flashings and curbs have to accommodate movement too
- Expansion joints belong in long runs by design
This is the single thing most worth checking in a specification here. Ask how the design accommodates thermal movement over the actual run lengths on your building, and look at whether flashings are detailed to move or simply sealed. Sealant is not a movement joint, and a detail that relies on it will open within a few summers. A roof designed around the movement it is going to experience is the difference between a long service life and a decade of chasing leaks.
Do metal roofs need maintenance in a dry climate?
Yes, and the items are different from a membrane roof. The work is fasteners, sealed details, panel to flashing junctions and anything holding dust or water, rather than seams and blisters. The dryness is what makes people skip it, and the heat is what makes it necessary.
- Check exposed fixings for backing out and hardened washers
- Inspect sealant at curbs, penetrations and terminations
- Clear grit and debris from valleys and gutters
- Look for scratches and coating damage that can corrode
- Keep a record for the warranty and for the building file
Once a year is the sensible interval, timed before the monsoon season rather than after it, so anything found can be dealt with before the first storm tests it. The [pre monsoon roof checklist](/checklists/pre-monsoon-roof-checklist/) covers what that walk should include. A panel roof on a routine annual check is an extremely long lived roof here; the same roof left alone until something drips is a repair bill with a stain underneath it.