Three bids around $25,000 to relay a tile roof: how synthetic, rubberized and self-adhered underlayments compare
A Southern California homeowner posted three bids to lift and relay a 1998 concrete tile roof of about 3,300 square feet: $24,100 for two layers of Owens Corning synthetic, about $25,200 for two layers of Malarkey polymer-modified underlayment and $25,000 for one layer of self-adhered Westlake TileSeal with 15 new vents.
The bids, posted to Reddit's r/Roofing, land within about $1,100 of each other, less than 5% apart. On a lift and relay the crew removes and stacks the tile, strips the old underlayment to the deck, replaces worn flashing, installs new underlayment and resets the tile, swapping in new pieces for any that break. The tile goes back on the roof, so the homeowner is paying mostly to renew the waterproofing layer under it.
California's residential code, Section R905.3 in the GoCodebook reproduction cited by NC Roofing Solution, puts tile on solid sheathing on roofs no flatter than 2.5:12. Between 2.5:12 and anything under 4:12 it calls for two layers of underlayment, or one self-adhered layer that meets ASTM D1970. On those planes the single TileSeal layer can stand in for the two-layer bids if the product carries a D1970 listing, so get that in writing along with the slope of each plane.
The planned whole-house fan changes the vent math. Federal Building America guidance, fan maker QuietCool and California's installation form all size attic exhaust at one square foot of net free area for every 750 CFM the fan moves, The Roofing Brief reported. A QuietCool Stealth Pro 4.8X rated at 4,280 CFM needs 5.71 square feet. Screens and louvers can cut a vent's net free area roughly in half, so the 15 vents in the TileSeal bid count only at their rated net free area.
Ask each roofer the same things: exact product names and number of layers; whether all old underlayment comes off to the deck; which flashings get replaced and in what metal; how many spare tiles they expect to need; and the rated net free area of every new vent. The tile installation manual from the Tile Roofing Institute and the Western States Roofing Contractors Association calls for replacing damaged or rusted flashing on a reroof and for tile nails driven at least 3/4 inch into the deck or batten, NC Roofing Solution noted. With solar planned, ask how future mounts will be flashed through the new layer.
Why it matters: On a concrete tile roof the underlayment does the waterproofing. These three bids differ by less than 5%, so compare slope, layers, flashing metal and vent area line by line before choosing on brand.
Sources
- Tile Roof Underlayment Replacement: Lift and RelayNC Roofing Solution, Oct 9
- Whole House Fan: How to Size One, Vent the Attic and Compare ModelsThe Roofing Brief, Oct 20
- 3 bids for a tile lift and relay: which underlayment?Reddit r/Roofing, Nov 2