How to Install Polyurethane Surrounds?
Required materials, step-by-step surround installation from surface preparation to painting, and common mistakes — an application guide prepared with manufacturer expertise.
Polyurethane surround installation consists of surface cleaning, measuring and mitre cutting, bonding with polyurethane-based adhesive, screw support where needed, joint filling and painting. With the right materials and clean mitre cuts, the surround installation of a window is completed within hours by an experienced installer and is ready for paint the same day.
Required Materials and Tools
- Polyurethane surround profiles (per project dimensions)
- Polyurethane-based mounting adhesive (PU adhesive)
- Mitre box or mitre saw (for 45° cuts)
- Fine-toothed saw
- Tape measure, spirit level, marking pencil
- Screws and dowels (mechanical support for large profiles)
- Filler and spatula
- Sandpaper (fine grit)
- Facade paint and brush/roller
Using a polyurethane-based adhesive is critical; cement-based mortars are not suitable for polyurethane surfaces.
Step 1 — Surface Preparation
The application surface must be dry, clean and sound. Dust, grease and loose paint-plaster residues are cleaned; blistered old paint is scraped off. On very absorbent surfaces (aerated concrete, bare plaster), applying a primer increases bonding strength. Noticeable surface defects should be corrected beforehand; the surround does not hide surface faults.
Step 2 — Measuring and Mitre Cutting
The window/door opening is measured and marked on the profile. For corner joints, pieces are cut at a 45° mitre. A fine-toothed saw is used; fast, forced cutting can chip the surface. Cut pieces are DRY-FITTED in place before bonding: corners must close fully and the profile must sit level.
Step 3 — Bonding
PU mounting adhesive is applied in strips to the back of the surround, staying 1-2 cm inside the edges. The profile is pressed into place and checked with a level. Excess adhesive is removed with a spatula before it dries. Adhesive is also applied to the corner joint surfaces — this is the most important detail preventing corner joints from opening.
Step 4 — Mechanical Support
For wide-section surrounds, sills and high facades exposed to wind load, screw-dowel support is used in addition to adhesive. Screw heads are sunk slightly below the profile surface and covered with filler. Until the adhesive cures (per manufacturer time), temporary tape/support is applied if needed to prevent parts from slipping.
Step 5 — Joint Filling and Painting
Joints, corner connections and screw heads are covered with filler; once dry, they are smoothed with fine sandpaper. Running a thin bead of filler along the surround-wall junction improves both appearance and sealing. Finally, the profile is painted with at least two coats of facade paint. Paint protects polyurethane from UV and extends its life.
Common Mistakes
- Wrong adhesive: Using cement-based mortar — it does not hold and falls off. Always PU mounting adhesive.
- Applying to a dirty surface: On a dusty surface the adhesive bonds to the dust, not the wall.
- Cutting without a mitre: Freehand-cut corners do not close; a mitre box is essential.
- Not applying adhesive to corners: The corner joint opens over time.
- Leaving unpainted: The surface yellows over time under UV; on facades paint is protective.
- Neglecting the sill slope: The slope that drains water outwards must be preserved on the bottom surround.
Frequently Asked Questions About Surround Installation
Which adhesive is used for surround installation?
A polyurethane-based mounting adhesive is used. Cement-based mortars do not bond to polyurethane; PU adhesive must be applied both to the back of the profile and to corner joints.
How long does surround installation take?
For an experienced installer, the surround installation of a standard window is completed within hours; after the adhesive cures, joints and paint can be done the same day.
Can surrounds be installed with adhesive only, without screws?
Standard-size surrounds can be installed without screws using the right PU adhesive. Screw-dowel support is recommended for wide-section profiles, sills and high facades.
Is painting mandatory after installation?
On facades, yes, it is recommended. Paint protects polyurethane from UV rays, prevents yellowing and extends its life; at least two coats of facade paint should be applied.
How are corner joints closed?
Corners are cut at a 45° mitre, adhesive is applied to the joint surfaces, and after installation the joint is filled with filler and sanded.
Can surrounds be installed over exterior insulation?
Yes; the lightweight polyurethane surround is advantageous over insulation. For wide profiles, dowels must be long enough to reach the load-bearing wall.
Can surrounds be installed in winter?
The temperature range specified by the adhesive manufacturer must be observed; curing slows in very low temperatures. Rain-free and frost-free days should be preferred.