Updated August 2026. Impact windows and doors only keep a Florida house dry if the opening is detailed. Concrete block is porous. Water that gets into the block around the buck will show up as stains, failed sealant, and mold long after the glass itself is fine. Statewide treats waterproofing as part of the install, not an add-on.

Quick answer

On CBS (concrete block) homes, waterproof the substrate at the opening before the window or door goes in. Statewide’s usual system is a compatible primer plus a fluid-applied membrane (we use Tremco Vulkem 360 with Vulkem 191 Primer on typical block; TREMprime Non-Porous Primer on dense/smooth substrates). Skip the primer or the wrong product and the membrane does not stick. That is a leak waiting on the next storm.

Why block openings leak in Florida

  • Porous block: CBS soaks water during rain and wind-driven rain. The opening is where that water wants to travel.
  • Movement: Heat and wind flex the opening. A rigid smear of caulk is not a membrane.
  • The tested window is not the whole system: Miami-Dade / FL approval assumes the opening is prepared. A dry product in a wet buck is not the tested assembly.

What Statewide actually does at the opening

  1. Clean and inspect the block. Remove dust, failed sealant, and loose material.
  2. Prime. Vulkem 191 Primer on typical concrete block. TREMprime Non-Porous Primer on dense or smooth substrates.
  3. Apply Vulkem 360 in the layers the product requires so the membrane can move with the block.
  4. Install the impact window or door into that prepared opening, then inspect the detail before we leave.

Product names above are the Tremco system we use on most CBS jobs. If a different approved system is specified, we follow that spec. We do not invent a substitute on site.

What goes wrong without it

  • Water behind the interior finish around the opening
  • Sealant that lets go after a couple of wet seasons
  • Mold on the drywall return
  • A window that still “passes impact” on paper but wets the house in a storm

FAQ

Is this the same as caulking the exterior?

No. Exterior sealant is the last weather line. Waterproofing the block is the layer that keeps water out of the wall if that sealant is ever stressed. You want both.

Do vinyl and aluminum openings get the same detail?

The membrane is on the block, not on the frame brand. The opening prep is the same idea. The window still has to be the approved system for the opening size and design pressure.

Can you waterproof after the windows are already in?

Sometimes you can repair from the exterior if the finish allows. It is cheaper and cleaner to do it at install. If you already have stains at the opening, we will look at it before promising a retrofit membrane.

Get the opening detailed with the windows

Statewide Windows & Doors will spec the impact units and the waterproofing as one job. Call (561) 816-4010 or request a free estimate. Bring photos of the current openings if this is a replacement.