How to Clean REHAU uPVC Windows: A Professional Guide to Streak-Free Glass

REHAU has been developing polymer-based solutions since 1948 in Bavaria, Germany. Today the company employs over 20,000 people across more than 50 countries. Its window profile systems, including the GENEO, SYNEGO, and EURO Design ranges, are used by fabricators worldwide to build energy-efficient uPVC windows and doors.

uPVC is a durable, low-maintenance material. But "low maintenance" does not mean "no maintenance." Cleaning uPVC frames incorrectly can cause discolouration, damage to gaskets, and even scratches to coated glass surfaces.

Why REHAU Windows Need the Right Cleaning Approach

REHAU windows feature multi-chambered uPVC profiles with integrated gaskets, fusion-welded frames, and compression-seal technology. Three things make cleaning these windows different from standard glass in a timber frame.

First, the uPVC frame surface. It is smooth and non-porous, which sounds like it would be easy to clean. But solvents, abrasive pads, and harsh chemicals attack the surface and cause permanent yellowing or cloudiness. REHAU warns that cleaning solutions containing solvents or thinners should not be used on its profiles.

Second, the gaskets and seals. REHAU engineers each seal for peak performance. These gaskets provide thermal, sound, and weather insulation. Aggressive chemicals degrade rubber gaskets over time, compromising the seal and allowing drafts.

Third, the glass itself. Whether your REHAU window has standard double glazing or a Low-E coated surface, the glass requires proper technique to avoid streaks and scratches. Coated glass is particularly sensitive to abrasion.

Before we look at REHAU's official care recommendations, it helps to understand the foundational technique that professionals use on every type of glass. The method I teach applies to uPVC windows, timber windows, aluminium frames, and everything in between. The glass is the job. The frame material changes what you use around it, but the squeegee technique on the glass stays the same.

The Window Cleaning Manifesto covers the foundation in five minutes and is completely free: orloffs.com/the-skill

What REHAU Recommends: Official Care Instructions

REHAU provides an official Operation and Maintenance Guide for its window and door systems. The full guide is available at window.rehau.com/uk-en/frequently-asked-questions. Here are REHAU's care recommendations, presented as the company states them.

• Use a soft brush or dry cloth to gently remove any loose dust and debris from the surface.
• Dip a soft cloth or sponge into warm, soapy water.
• Gently scrub the uPVC surfaces, making sure to cover all areas including frames, sashes, and glass panels.
• After cleaning, rinse the surfaces thoroughly with clean water to remove any soap residue.
• Wipe down the windows and doors with a clean, dry, and soft cloth to prevent water spots or streaks.
• All moving parts of fittings should be lightly oiled once or twice a year.
• Aim to clean twice a year, or more frequently if needed.

REHAU also warns that for extremely dirty frames, its own PVC Cleaner should be used. Contact your installer for more information on this product.

What I Add as a Professional: The Glass-Cleaning Method

These guidelines from REHAU are solid. They cover the frames, the hardware, and the general cleaning frequency. My main value is demonstrating the glass-cleaning method that produces a streak-free result every time. This is the technique I use on every window, including REHAU profiles across Vienna.

Step-by-Step: Professional Technique for REHAU Windows

Preparation: Soap Water and Tools

Fill a bucket halfway with tap water, at least 10 litres. Add one cup of soap and mix. Not too much soap, but not too little. Think of it like washing dishes at home: enough soap to dissolve the dirt without leaving a thick residue.

Your essential tools: a T-bar applicator with a microfiber cover (a T-shaped tool covered in microfiber fabric designed for washing glass), a squeegee (a flat tool with a rubber blade for wiping off water), and 100% cotton towelling rags.

Agitation: The Step Most People Skip

Dip your T-bar applicator into the soapy water on both sides. Apply the soap water to the entire glass surface. Then agitate the dirt with up-and-down or side-to-side motions using the T-bar applicator.

The idea is to dissolve the dirt, ready for the squeegee to shave away. If the dirt is not fully dissolved in the soap water and released from the glass, the remaining dirt still stuck will be transported over the squeegee, leaving smudges or smears.

This is the step I spend the most time on in my Mastery Course. Most people rush through it and then wonder why they have streaks.

Detail the Frame Before Squeegeeing

Before you pick up the squeegee, detail the top and sides of the window frame with your 100% cotton towelling rag. Use your finger pressed into the rag to get into the edge where the glass meets the uPVC frame. Remove any pooled soap water to avoid drips.

With REHAU's smooth uPVC profile surfaces, this step goes quickly. The non-porous material does not absorb water, so soap water pools at the frame edge and needs to be removed before squeegeeing.

The Squeegee Turns: Three Techniques for Every Window

In my training I teach three squeegee turns. Each one has a different purpose.

Side to side: horizontal passes across the window. Tilt the squeegee at a slight angle so the soap water spills from only one side of the channel. Wipe the rubber dry after each pass for a clean, streak-free start to the following line.

Top to bottom: vertical passes down the window. Same tilt principle. The water is directed to the lower side.

Turn with a twist, also called the J tune: the professional continuous motion from top to bottom, linking turns with a wrist twist at each end. This turn has top-to-bottom, side-to-side, and mixed variations.

The overlap from one line to another should be as small as possible. The squeegee rubber should be three-quarters in soap water and one-quarter out of the soaped area.

Finishing: Edge Detailing

Clean away any excess soap water using your finger pressed into your 100% cotton towelling rag. Get into the edge where the glass meets the frame and remove any pooled soap water. Rotate the rag so you are only touching the glass with a clean part of the rag.

Replace your rag with a fresh one every few windows to keep a high-quality detail.

Frame and Gasket Care: Following REHAU's Guidelines

After the glass is finished, wipe the uPVC frames with a separate soft cloth dampened with warm soapy water. REHAU recommends using only warm water and a mild soap. Rinse with clean water and dry with a soft cloth.

Check the gaskets visually during each clean. REHAU's integrated gaskets provide thermal, sound, and weather insulation. If a gasket looks cracked, compressed, or is pulling away from the frame, contact your installer. A failing gasket affects energy efficiency before you notice a draft.

Hardware Lubrication

REHAU recommends oiling all moving parts of fittings once or twice a year. Use a light machine oil or silicone spray on hinges, locking points, and handles. This keeps the tilt-and-turn mechanism operating smoothly and prevents premature wear.

How Often to Clean REHAU Windows

REHAU recommends cleaning twice a year as a minimum. In my experience, homes near busy roads, construction sites, or areas with heavy tree pollen benefit from cleaning three to four times a year. The uPVC frames are forgiving, but the glass shows buildup quickly.

If you notice water spots forming on the glass between cleans, the soap water from your last clean may not have been fully removed. A second rinse with clean water solves this.

What NOT to Do on REHAU Windows

REHAU is clear on this. Do not use:

• Abrasive cleaning pads or scouring pads on uPVC surfaces.
• Solvents, thinners, or acetone on frames or gaskets.
• Harsh chemical cleaners, including bleach-based products.
• Razor blades or steel wool on coated glass surfaces.
• High-pressure washers directly on gaskets or seals.

Cleaning solutions and polishes that contain solvents or thinners will attack the uPVC frame surface and degrade the seals. Once a uPVC profile is damaged by solvent, the discolouration is permanent.

Why the Right Technique Matters

A REHAU window system is engineered for decades of performance. The profiles, the gaskets, the hardware, and the glass all work together. Cleaning it properly is not complicated, but it does require the right tools and the right method. If you want to build this into muscle memory, the full step-by-step method is in the programme at orloffs.com/the-skill.

Official REHAU Resources

• REHAU main website: rehau.com
• REHAU FAQ and care information: window.rehau.com/uk-en/frequently-asked-questions
• Find a REHAU window manufacturer: rehau.com/us-en/windows/manufacturers

The Manifesto is free and only takes five minutes to review, making it a smart starting point.

Start with the free Manifesto at orloffs.com/the-skill. The Skill ($69, lifetime access) includes the Manifesto, AR Training Tool, and Quick Start Mastery Course.