Polyurethane Window and Door Jamb Selection & Design Guide

Learn how to select polyurethane window and door jambs, calculate profile ratios, combine crowns, and follow correct architectural application methods.

There is no universal percentage for every opening. Select the profile width using the actual opening dimensions, the product section and the façade layout. Confirm the proportions and cutting plan on the project drawings before ordering.

Polyurethane Material Specifications and Physical Properties

Polyurethane window and door jambs are produced from rigid, closed-cell polyurethane foam with a density range of 150-220 kg/m³ (production target ~160 kg/m³). This closed-cell structure limits water absorption to under 1%, preventing freeze-thaw degradation on exterior facades. The material withstands thermal conditions from -100 °C / +80 °C without warping or dimensional loss. It is essential to note that these profiles and matching columns are strictly decorative components and do not carry structural architectural loads.

Project-based sizing

Combining Jamb Profiles with Pediments and Crowns

Enhancing window head details involves combining linear jamb profiles with decorative pediments or crown moldings (söve taçı). When integrating top crowns, the horizontal projection of the crown should match or slightly exceed the outer edge of the side jambs. Because polyurethane components are non-load-bearing, crowns must be independently secured to the structural wall behind them rather than resting their weight entirely on vertical jamb pieces.

Substrate Preparation and Mechanical Installation Rules

Proper installation of window jambs begins with a clean, dry, and dust-free masonry or plastered surface. Profile corners must be joined using precise 45-degree miter cuts. Bonding requires a polyurethane (PU) assembly adhesive applied along the rear contact surface; standard silicone adhesives are strictly prohibited due to inadequate structural shear strength. In addition to chemical bonding, mechanical fixing with corrosion-resistant screws is mandatory to anchor the jambs securely against wind loads.

Joint Preparation, Sanding, and Exterior Paint Application

Once mechanical fixings and adhesive have cured, screw counter-sinks and profile joints must be filled with exterior-grade putty. After drying, smooth these filled areas using 180-220 grit sandpaper. Polyurethane jambs are delivered factory pre-primed, making additional primer coats optional depending on surface preparation needs. Finally, applying two coats of high-quality, UV-resistant exterior paint is mandatory to protect the polyurethane material from direct solar radiation and weather exposure over time.

Frequently Asked Questions

Are polyurethane window jambs capable of supporting structural loads?

No, polyurethane window and door jambs are purely decorative elements and carry no structural weight.

Which adhesive should be used during polyurethane jamb installation?

Polyurethane (PU) assembly adhesive must be used along with mandatory mechanical screw anchors; silicone adhesives are strictly prohibited.

Is exterior paint mandatory on pre-primed polyurethane jambs?

Yes, applying two coats of UV-resistant exterior paint is mandatory to prevent solar degradation, even though profiles arrive factory pre-primed.

How do you determine the correct profile width for a window jamb?

What temperature range can rigid polyurethane jambs tolerate?

Rigid polyurethane profiles operate safely across a temperature range of -100 °C / +80 °C with water absorption below 1%.

Can jambs be produced for arched or round-top windows?

Curved heads are made as segment pieces drawn from the actual arch, so the radius and the springing points must come from the building rather than from a standard drawing. A dimensioned sketch or a template lifted off the opening covers straightforward arches; irregular or compound openings are handled with site measurement or 3D scanning, both chargeable services priced in the quote. Straight jamb legs are then matched to the curved head so the profile runs continuously around the opening.

Which measurements do you need to order window jambs?

The clear opening width and height, the reveal depth, and the distance from each opening edge to the nearest obstruction such as a corner, eaves, downpipe or neighbouring window. Those clearance figures decide how wide a profile the elevation can carry before trims collide or crowd the corner. Measurements supplied by the buyer form the basis of the order; having the survey, measuring or scanning done on site is a separate priced service.

Should door jambs use the same profile as the windows?

Usually not at the same width, since an entrance reads as the focal point of the elevation and is normally stepped up in section or crowned with a pediment while windows keep a lighter profile. Holding the model family constant and varying only the width keeps the facade coherent instead of turning it into a sampler of unrelated patterns. Everything is made to order, so one facade can combine several widths from the same family within a single order.