Seals for Wooden Windows — EPDM, Q-Lon, and a Complete Guide

Seals for wooden windows are the most overlooked component—and, paradoxically, the one whose wear and tear is felt most directly in everyday life. At SM Wood Prodcom, we have been manufacturing laminated wood windows in Florești, Cluj, since 1997, and we install high-quality seals on all our products. If you feel a draft around your windows in the winter, if you can hear street noise more clearly than you should, or if you notice condensation on the glass more often than before—in more than half of these cases, the seals are to blame.

Therefore, instead of immediately investing in new windows, check the condition of the seal first. Often, a simple replacement completely solves the problem.

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Types of weatherstripping used at SM Wood Prodcom

Wooden window seals are the most frequently overlooked component - and paradoxically, the one whose wear is felt most directly in daily life. At SM Wood Prodcom, we have been processing laminated wood in Floresti, Cluj, since 1997, and we install Schlegel Q-Lon seals on all our products. If you feel a draught at your windows in winter, if you hear street noise more clearly than you should, or if you notice condensation on the glass more often than before - in more than half of cases, the gaskets are to blame.	Therefore, instead of immediately investing in new windows, first check the condition of the seals. Often, a simple replacement completely resolves the issue.
Types of sealing gaskets used at SM Wood Prodcom	Industry standard: UV and ozone resistant, -50°C to +120°C, estimated lifespan 20+ years; the components are CE-marked by their manufacturers. We install this on all our series.
Q-Lon Foam Seal (Schlegel, UK, 1885)	Exceptional shape memory — superior sealing against wind and rain, significant noise reduction. We install this on the IV92 series.
TPE Thermoplastic	Flexible, eco-friendly, and recyclable — an alternative for projects with sustainability certification
Exterior silicone	Additional sealing at the glass-frame joint and wall junctions
Soft PVC	Affordable, moisture-resistant — used for secondary applications or interior windows

Gasket Type | Properties and Usage | EPDM - ethylene propylene diene monomer rubber | Industry standard: resistant to UV and ozone, -50°C to +120°C, estimated lifespan 20+ years. We install this on all our series. | Q-Lon Foam Seal (Schlegel, UK, 1885) | strong shape memory - superior sealing against wind and rain, significant noise reduction. We install this on the IV92 series. | Thermoplastic TPE | Flexible, eco-friendly, and recyclable - an alternative for projects with sustainability certification. | Exterior silicone | Additional sealing at the glass-sash joint and at the wall junctions. | Soft PVC | Affordable, moisture-resistant - used for secondary applications or internal windows.

How many rows of gaskets are needed — a direct answer

Wooden window seals are the most frequently overlooked component - and paradoxically, the one whose wear is felt most directly in daily life. At SM Wood Prodcom, we have been processing laminated wood in Floresti, Cluj, since 1997, and we install Schlegel Q-Lon seals on all our products. If you feel a draught at your windows in winter, if you hear street noise more clearly than you should, or if you notice condensation on the glass more often than before - in more than half of cases, the gaskets are to blame.

SM Wood Prodcom Tip:

Sealing gaskets lose elasticity over time, especially under repeated UV exposure. If your window is 12 to 15 years old and feels as though it has lost some of its seal, the problem is usually solved simply by replacing the gasket, with no need for a new window. It is an affordable fix with immediate results.

EPDM vs. Q-Lon — Which Is Better

EPDM

EPDM is inherently stiffer than many other elastomeric materials, which gives it superior structural integrity and makes it less prone to sagging, compression set, or deformation under sustained loads. This stiffness translates directly into enhanced long-term durability, meaning that seals and components made from EPDM maintain their shape and performance for decades, even in demanding applications.

Q-Lon

Q-Lon, manufactured by Schlegel (a British brand founded in 1885, with ~141 years of experience in window and door seals), features shape memory as its defining characteristic. No matter how many times it is compressed when closing the window, it returns to its original shape—providing a perfect seal year after year, without any adjustments. It is the premium solution we install on the IV92 series and, upon request, on the IV78

Seal installation — just as important as the type chosen

A good gasket installed incorrectly is no better than a mediocre one. The compression pressure must be uniform around the entire perimeter of the window—neither too tight (premature wear) nor too loose (air leaks at the corners). At SM Wood Prodcom, gaskets are installed in the factory under controlled conditions, with grooves precisely milled into the wood profile. This sets them apart from gaskets added later on-site.

Frequently Asked Questions About Sealing Gaskets

Yes, replacing the gasket can be done with the window installed. The process involves extracting the worn gasket from its groove, cleaning the groove, and installing the new gasket. For SM Wood Prodcom windows, we offer a seal replacement service for products manufactured by us. Contact us with the details of your window.

Q-Lon from Schlegel (UK) and EPDM from established European suppliers - all components are CE-marked by their manufacturers. Batches received at the factory are visually inspected and functionally tested before entering production.

We recommend cleaning the gaskets twice a year (spring and autumn) with a soft cloth and water with a neutral detergent. After drying, applying a special solution based on glycerin or silicone oil will maintain the elasticity of the EPDM rubber, preventing it from cracking due to sun and frost exposure.

Absolutely. Most noise enters through gaps where the gasket no longer presses firmly against the profile. Replacing worn gaskets with high-performance systems such as Schlegel Q-Lon can reduce the noise level perceived inside by up to 5–8 dB, offering an immediately noticeable peace in the home.

Request a custom quote from SM Wood Prodcom

smwoodprodcom.ro

+40 740 647 877

+40 745 512 371

sm.wood.prodcom@gmail.com

How many rows of gaskets are necessary - direct answer

On our IV68 base series, we install a minimum of 2 rows of gaskets: one on the rebate (the recessed area between the sash and the frame) and one on the meeting stile or frame contact surface. This ensures a solid seal for standard residential use.

On the IV78 and IV92 series, we install 3 rows of gaskets. The third row adds an extra barrier against cold air and noise. The difference is felt immediately: the room becomes quieter and heating bills decrease visibly.

More rows do not mean the window is harder to close - the profile and the gasket are calibrated together. The operation effort remains comfortable.

SM Wood Prodcom Tip: Sealing gaskets lose elasticity over time, especially with repeated UV exposure. If your window is 12-15 years old and you feel it has lost its airtightness, the problem is most often solved by simply replacing the gasket - without needing a new window. It is an affordable intervention with an immediate impact.

EPDM vs Q-Lon - which is more suitable?

EPDM is more rigid and more durable in the long term. It resists extreme temperature variations and UV exposure excellently - ideal for south-facing windows or in harsh climatic zones. It is our standard choice across all series.

Q-Lon, produced by Schlegel (a British brand founded in 1885, with ~141 years of experience in joinery gaskets), features shape memory as its distinctive trait. Regardless of how many times it is compressed when closing the window, it returns to its original shape - perfect sealing for years without adjustments. It is the premium solution we install on the IV92 series and upon request on the IV78.

Gasket installation - as important as the type chosen

A good gasket installed incorrectly is worth no more than a mediocre one. The compression pressure must be uniform around the entire perimeter of the window - neither too tight (premature wear) nor too loose (air leakage at corners). At SM Wood Prodcom, gaskets are installed in the factory under controlled conditions, with grooves precisely milled into the wood profile. This makes the difference compared to gaskets added later on-site.

Request a personalised quote from SM Wood Prodcom

Bespoke laminated wooden windows and doors since 1997 · Floresti, Cluj

Phone / WhatsApp | Email | www.smwoodprodcom.ro

Sealing Strips for Wooden Windows | EPDM, Q-Lon