New construction stucco in Tucson

New stucco is the one situation where you can get the whole assembly right rather than managing someone else's shortcuts. Weather-resistive barrier, lath, flashing at every opening and penetration, weep screed set at the correct height above grade, control joints where they belong, and then the coats themselves. None of it is visible afterwards, which is exactly why it is worth watching.

The main decision is three-coat versus one-coat. Traditional three-coat is scratch, brown and finish, applied over lath with cure time between coats, and it produces the most durable wall. One-coat systems apply a single thicker coat over rigid insulation with a finish over it, and they are faster and cheaper, which is why most Tucson tract construction since the nineties uses them. Both work when done properly. Three-coat is more forgiving of imperfect workmanship.

What a correct installation includes

• Weather-resistive barrier lapped correctly, shingle style, over the sheathing
• Lath fastened at the specified spacing into framing, not just sheathing
• Casing bead and flashing at every window, door and penetration
• Weep screed set with proper clearance above finished grade
• Control joints at the spacings the standard requires
• Adequate cure time between coats, not rushed for schedule
• Damp curing in Tucson heat so the material does not flash-dry and crack

How new stucco should run

Preparation and lathing, which is the part that determines the next thirty years. The barrier keeps water off the sheathing, the lath gives the stucco something to key into, and the flashing at openings directs water back out. Openings are where nearly every stucco water failure in Tucson originates, so how they are detailed matters more than the finish anyone will actually look at.

Then the coats. On three-coat work, scratch and brown coats with cure time between them, and in Tucson heat that means damp curing rather than letting the sun pull the water out. Stucco that dries too fast does not develop full strength and cracks early, which is the single most common defect on summer-poured Arizona work.

Then finish and colour. Integral colour in the finish coat or a coating applied afterwards, and texture chosen to match the neighborhood and the architecture. Worth agreeing a sample panel on site before the whole house is done, because texture and colour both read differently at full scale and in direct sun than they do on a small board.

Marana is the fastest-growing part of the metro, so much of the work there is new construction, additions, and first-generation problems on homes only ten or fifteen years old.