Underlayment

Q: What class of vapor retarder is Tesla Underlayment?

A: Tesla Underlayment is a Class-A vapor retarder, which is a requirement for the ASTM D1970 / ICC AC188 classification. This means the Underlayment is vapor closed – not open. Unvented roof assemblies (warm roofs) have been notorious for creating moisture problems and the building code prescribes how these roof assemblies need to be designed to mitigate risk. There are many factors that contribute, e.g. the climate zone, type of insulation used (air permeable vs air impermeable), whether you are designing a vented (cold) vs unvented (warm) roof assembly, and air-tightness of your thermal envelope, e.g. between joints, penetrations, etc.

Q: Tesla Underlayment has been exposed for more than 6 months, what should I do, and will this impact the warranty?

A: Proceed with caution. When the top layer of the underlayment is exposed to the sun, the polymer fibers on the surface will degrade. This can make the surface feel like it is crumbling or chalky, which can make traction difficult and dangerous. This risk increases with UV intensity and duration, which varies with seasons and geographic location. Prolonged exposure has not been fully studied but can lead to UV degradation of the adhesives bonding the layers together and/or compromise the adhesive bonding the underlayment to the roof sheathing.

Q: Can I install Tesla Underlayment over existing ice and water shield or other underlayments?

A: The synthetic adhesive used in our underlayment has been tested in contact with a mix of existing ice and water shields and did not show any adverse effects. Tesla Underlayment is a fully adhered, high temperature, non-asphaltic underlayment designed to be installed directly onto plywood or OSB. In areas of the country that require ice dam protection, you may already have an underlayment adhered to the roof sheathing, which may be difficult or impossible to remove without replacing the sheathing.

Tesla cannot guarantee the performance of any other underlayment installed under the Tesla Underlayment or Solar Roof tiles and in doing so, you are installing at your own risk.

PV Tile

Q: Why is roof deck planarity so important for Solar Roof, and what happens if the deck is wavy?

A: A flat, planar roof deck is required for proper Solar Roof installation. A wavy deck will telegraph through the tiles, creating visible unwanted waves or dips in the finished surface.

The only solution is to fix the deck before installation.

Once tiles are installed, corrections are nearly impossible. Adjusting tiles will not fix a wavy deck. Any correction requires removing all tiles, repairing the structure, and reinstalling.

Use the L/96 specification to check and correct planarity:

• L/96 Rule: Maximum allowable gap = span length (in inches) ÷ 96
  • Example: On a 48" (4 ft) span, max gap = 0.50" (½”)

Q: Is there an alternative to standard wall flashing and siding prep?

A: Assess the viability of reusing existing and review the work instructions in the Solar Roof Installation Manual.

Metal-Related

Q: Why are rust spots appearing on the solar roof metal and glass tiles?

A: Those are metal shavings from cutting metal tile or flashing on the roof. It is highly recommended to use an enclosed cut station on the ground to limit the spread of metal shavings during cutting. These metal shavings will rust if left in gutters or anywhere on the roof. As a best practice, blowing shavings off the roof in an effective way will assist with preventing this from occurring after installation.

Q: If tiles need to be replaced in 10 - 15 years down the road, would there be a visual difference in quality from old vs new tiles?

A: There will be natural changes to color and gloss over time, and if tiles are replaced decades after installation there may be differences in color due to weathering. However, Tesla metals meet the American Architectural Manufactures Association (AAMA) highest paint durability spec, AAMA2605. This ensures that the Metal Tile and Flashings will fade a maximum of 5 ΔE units and maintain 50% gloss retention after being exposed in high-stress environments like South Florida for 10+ years.

Q: How does saltwater affect the metal on a Solar Roof?

A: Please review the General Exclusions section in the Solar Roof Warranty, which can be found in Partner Portal: Refer to Tesla Solar Roof Limited Warranty (USA).

Miscellaneous Design & Installation

Q: What is the minimum stringing requirement on a single mounting plane?

A: As a rule, to install active PV on a given mounting plane (MP), the MP needs to be big enough to accommodate five active tiles.

Q: Can I use materials outside of what Tesla specifies?

A: The Solar Roof is designed to be installed as a system, and including parts outside of the Tesla provided bill of materials (BOM) could void the product warranty; however, we do provide a comprehensive list of consumables that are expected to be procured outside the scope of the BOM in the CI Procurement List. Parts not included in your BOM or the CI Procurement List require approval from our product team.

Q: How do I install a snow fence on a Solar Roof?

A: Tesla offers an Anchor Bracket Kit (PN 1877133-00-X) that can be installed under a Metal Tile, allowing a snow fence to be mounted to the anchor bracket.

Snow fence installation should be planned prior to or during the initial Solar Roof installation. If PV or Glass Tiles are in the snow fence location, replace them with Metal Tiles first. For detailed work instructions, refer to the Installation Manual ‘Bracket Fastening’ section.

Q: Can I use a different fastener than what Tesla specifies?

A: Tesla nails and screws have been engineered and tested for reliability. Our roofing nails are stainless steel, ring shank nails due to the inconsistency we saw in the withdrawal strength of hot dip coated nails. Electrogalvanized roofing nails did not meet our corrosion resistance testing.