New Construction & Renovation · 7 min read
Exterior Cleaning After New Construction or a Renovation: What to Clean, When, and What to Avoid
The builder is finished, the punch list is almost done, and the outside of your new home, addition, or commercial space still looks like a job site. Mortar smears on the brick, concrete splatter on the windows, mud on the siding, and a film of dust on everything. It is tempting to rent a pressure washer and blast it all off the first weekend.
The better approach: clean soon, but not too soon, and with the right method for each new material. New mortar, concrete, and coatings are still hardening, new glass scratches easily, and construction residue can react with some surfaces. This guide covers what industry and manufacturer guidance says about timing and methods, so the first cleaning helps your new exterior instead of damaging it.
What Construction Leaves Behind
| Residue | Where You See It | Why It Needs Care |
|---|---|---|
| Mortar smears and splatter | Brick and stone veneer, sills, walkways | Hardens over time and gets harder to remove |
| Concrete, stucco, and masonry dust or runoff | Windows, doors, decking, siding | Can leave stubborn deposits on glass and react with some deck surfaces |
| Mud and soil splash | Lower siding, foundation, garage doors | Usually washes off easily once dry |
| Labels, tape, and protective film | Windows, doors, trim | Removal methods can damage some glass coatings |
| Paint, caulk, and sealant overspray | Glass, brick, concrete | Often needs targeted removal, not pressure |
New Brick and Stone: Wait for the Mortar to Harden
The Brick Industry Association's Technical Note 20, Cleaning Brickwork, is the standard reference here. It says mortar must be hardened before cleaning and that it is generally best to schedule cleaning at least seven days after the brickwork is completed. If only water is used, cleaning may begin 24 to 36 hours after the brickwork is done. It also warns against waiting too long: after about a month, mortar smears and splatters become increasingly difficult to remove.
The same guidance recommends:
- Following the brick manufacturer's cleaning recommendations, often printed on the card with the brick delivery.
- Testing the cleaning method on a small area first and letting it dry before judging the result.
- Keeping water pressure at or below 400 psi at the nozzle unless the brick manufacturer allows more, with a wide fan tip held at least 12 inches away.
- Protecting windows, doors, metal, and nearby plants from cleaning solutions.
- Avoiding unbuffered muriatic acid, which can stain brick and damage mortar joints.
For more on brick specifically, see our guide on whether you can pressure wash brick.
New Windows and Glass: Prompt, Careful Cleaning
Glass is one of the most easily damaged parts of a new building. A glass industry bulletin published with the International Window Cleaning Association, Construction Site Protection and Maintenance of Architectural Glass, lists the problems most often seen on job sites: stubborn deposits from concrete and masonry runoff, chemical attack from overspray, weld splatter, and hard water spotting.
The bulletin's key points for owners and builders:
- Glass exposed to harmful materials during construction needs prompt cleaning by professional window cleaners.
- Some conditions cannot be removed with normal glass cleaning, and more aggressive procedures can themselves damage the glass.
- Protective films should not be left on longer than their useful life, because removal can damage some glass or coatings.
In practice, that means dry-scraping a window full of concrete grit is a bad idea. The grit can drag across the surface and scratch it. Construction residue on glass is a job for careful, professional window cleaning rather than a pressure washer.
New Concrete Driveways, Walkways, and Patios
New concrete looks hard within a day or two, but it keeps gaining strength well after that. The American Cement Association explains that most of concrete's hydration and strength gain happen within the first month, while curing continues at a slower rate for years. Curing compounds or sealers may also have been applied.
Before any washing of new flatwork, ask the concrete contractor when it is safe to clean and whether a curing compound or sealer was used. Early on, a gentle rinse or sweep to remove mud is far safer than a high-pressure cleaning. Once the concrete has cured and been cleared by the contractor, regular driveway and concrete cleaning is appropriate.
New Composite Decks: Get Construction Dust Off Quickly
Composite decking is often installed while other trades are still working. Manufacturers specifically warn about this. Trex's care guide says cement, concrete, mortar, and stucco dust can react with the decking surface when it gets hot or wet and become very difficult to remove. TimberTech gives similar advice: do not cut masonry on or near the deck, and remove construction dust and debris quickly.
If your new deck has been dusted with masonry or stucco, have it cleaned sooner rather than later, using the method the decking manufacturer allows.
Newly Painted Siding and Trim
Paint feels dry long before it has fully hardened, and cure times vary by product, temperature, and humidity. There is no single safe number for every paint. Before any washing of new paint, ask your painter or check the product data sheet for when the coating can be washed, and start with the gentlest method. Our guide to washing a house before painting covers the other side of the paint job.
Suggested Order of Operations
- Confirm timing with your builder: masonry completion date, concrete pour dates, paint and sealant products.
- Remove loose debris by hand: scrap material, large mortar clumps (with non-metal tools), and job site trash.
- Clean the building exterior from the top down: siding, trim, and masonry with low pressure and appropriate cleaners.
- Clean windows and doors after the walls, so runoff does not re-soil the glass.
- Finish with decks, walkways, and driveways once they are cleared for cleaning.
- Control runoff, especially on commercial sites. See our article on pressure washing wastewater and runoff rules.
Homes vs. Commercial Projects
On a new home, the main concerns are usually brick veneer, windows, a new driveway, and maybe a composite deck. Commercial build-outs and new storefronts add larger glass areas, sidewalks, and the need to work around opening dates and other trades. PrimeSite's house washing and commercial building washing services cover both, and we can coordinate the cleaning with your schedule.
The Bottom Line
The first cleaning of a new exterior sets the tone for how it will look for years. Give mortar and concrete the time their guidance calls for, keep pressure low on new masonry and coatings, treat construction residue on glass carefully, and get masonry dust off composite decking quickly. When in doubt, ask the builder what products were used, and let a professional match the method to each surface.
Finishing a New Build or Renovation?
PrimeSite Pressure Washing is locally owned in Summerville and serves homeowners and businesses throughout Charleston, Mount Pleasant, North Charleston, Goose Creek, and the Tri-County area. Quotes are free.
Frequently Asked Questions
How long should you wait to clean new brick?
The Brick Industry Association says it is generally best to clean at least seven days after brickwork is completed, once the mortar has hardened. Water-only cleaning may start 24 to 36 hours after completion, and mortar smears get harder to remove after about a month.
Can you pressure wash new brick?
Only at low pressure. Brick Industry Association guidance is to stay at or below 400 psi at the nozzle unless the brick manufacturer allows more, using a wide fan tip held at least 12 inches from the wall.
How do you remove concrete splatter from new windows?
Carefully. Dry scraping can drag grit across the glass and scratch it. Glass industry guidance calls for prompt cleaning by professional window cleaners, because aggressive methods can damage glass.
When can I pressure wash a new concrete driveway?
Ask your concrete contractor first. Most of concrete's strength gain happens in the first month, and curing compounds or sealers may have been applied. A gentle rinse is safer than high pressure on new concrete.
Who should clean the exterior after construction?
Many builders do a basic cleanup, but brick, glass, and new decking often benefit from a professional exterior cleaning that matches the method to each material.