Weep Screed and Clearance to Grade

Almost every wall assembly depends on a gap at the bottom, and almost nobody knows it is there for a reason. This page covers what a weep screed does, why siding keeps a clearance above soil and hard surfaces, and how that clearance gets quietly destroyed years after the siding was installed correctly.

Walls are designed to get wet and then dry

The starting point most homeowners have not been told: no exterior wall is expected to be perfectly watertight at the cladding. Wind-driven rain gets past siding laps, joints, and penetrations, and that is anticipated. The assembly manages it — the weather-resistive barrier behind the cladding sheds that water down and out, and the base of the wall is where it leaves.

Which means the bottom of the wall is not just an edge. It is the drain. Block it and water that the system planned to release has nowhere to go.

What a weep screed does

On stucco walls, a weep screed is the formed metal flashing at the base, fixed at the bottom of the framing. It performs two functions:

• It terminates the stucco in a clean, controlled edge instead of a ragged one running into the ground.
• It drains the assembly. Water that gets behind the stucco runs down the drainage plane and exits through the screed's perforations or open lower lip.

That drainage function is why anything covering the screed matters so much. Soil, mulch, a new path, or a raised planter across the bottom of the screed closes the exit, and water that the wall was designed to release stays inside it.

Siding assemblies without a stucco screed rely on the same principle in a different form — a starter strip, a flashing, and a maintained clearance so the base can drain and dry.

Why the gap exists — three problems, one detail

Splash-back is a fourth, smaller benefit: rain hitting a hard surface throws dirty water up against the wall, and a clearance keeps the worst of that off the cladding.

How much clearance?

The authority is the manufacturer's current installation instructions for your specific product, read alongside your local building code. Manufacturers publish different figures for different products and different conditions below.

As general orientation only: a clearance in the order of six inches above earth is commonly specified, with a smaller clearance — often around one to two inches — above hard surfaces such as paving, decks, and roofing. Roof-to-wall junctions have their own requirement, because water sheeting down a roof surface behaves differently from water at grade.

Do not treat those numbers as your specification. Look them up for your product. Getting this wrong is one of the ways a manufacturer warranty is invalidated, and it is easy to check.

How the detail gets destroyed

This is the part worth acting on, because in our experience the siding is usually installed correctly and the clearance is lost later:

• Raised planting beds against the house. The most common. A landscaper builds a bed against the wall, the soil level rises, and the clearance is gone.
• Mulch topped up annually. Each year adds an inch or two. Nobody notices the cumulative effect, and after several years the bottom course is buried.
• New concrete or paving poured to the wall. A patio, path, or driveway extension poured tight against the siding, permanently, with no expansion gap.
• A deck built up against the cladding without maintaining clearance and flashing at the junction.
• Re-roofing that raises the roof surface where it meets a wall, closing the roof-to-wall clearance.
• Regrading that slopes soil toward the house instead of away, which sends surface water to the base of the wall as well as raising it.

None of these look like damage. They look like improvements. That is exactly why the resulting rot is usually discovered by a siding crew years later, when the wall finally comes off.

A check you can do this weekend

1. Walk the perimeter and look at where the siding stops. Can you see a clear gap, or a metal screed with its lower edge exposed?
2. Anywhere the bottom of the siding disappears into soil, mulch, gravel, or concrete, mark it.
3. Look at the slope. Does the ground fall away from the house, or toward it?
4. Check behind planters, under decks, and along the fence-side elevation nobody walks down. That is where it is always worst.
5. Press the bottom course gently in any buried area. Soft is a finding.
6. Check where irrigation sprays. Heads striking the wall do their own damage — see what siding stains are telling you.

Putting it right

Caught early, this is landscaping work rather than construction. Cut the soil or mulch back to restore the clearance, re-grade so the ground falls away from the house, keep planting beds off the wall, and move irrigation heads. Where concrete has been poured against the wall, restoring clearance means saw-cutting and removing a margin — more disruptive, but far cheaper than the alternative.

If the base of the wall is already soft, the repair is a construction job: the affected cladding comes off so the sheathing, framing, and barrier can be inspected and repaired, then the base is rebuilt with proper flashing and clearance. See siding repair, and if you are planning a full re-clad, our James Hardie siding page covers the replacement route.

Working with Heritage Exteriors

Heritage Exteriors (CSLB #1055919) checks base-of-wall clearance and drainage as part of assessing any siding project across Sacramento, the Bay Area, and Lake Tahoe — it is one of the first places we look, because it is one of the most reliable predictors of what we will find when the wall comes off. Request a free estimate or call (916) 546-2991.

Reviewed August 2026. Clearance figures are general orientation only — the authority is your product’s current installation instructions and your local building code.