Question 1

What’s the difference between door and window sealant and general-purpose silicone?

Accepted Answer

The key difference between door and window sealant and general-purpose silicone lies in their design and intended use. Door and window sealants are specifically formulated to accommodate the unique demands of these installations, such as frequent movement as doors and windows open and close.

They remain flexible over time, ensuring the seal stays intact despite constant expansion and contraction. Additionally, these sealants provide excellent adhesion to a variety of frame materials like wood, metal, and PVC, and are built to withstand outdoor conditions, offering strong weather resistance against rain, wind, and temperature fluctuations. In contrast, general-purpose silicone is a versatile product suited for many sealing tasks, from household repairs to plumbing. However, it may not meet the specific needs of door and window applications, such as high flexibility or durable weatherproofing.

Its adhesion to frame materials can vary, and it might degrade more quickly when exposed to the elements. Choosing the right sealant is essential; for doors and windows, using specialised, purpose-built products ensures a longer-lasting, effective seal that protects against drafts, moisture, and weather, ultimately helping maintain your home’s energy efficiency and structural integrity.

Question 2

Can window frame sealant be painted over?

Accepted Answer

Window frame sealant can sometimes be painted over, but it depends on the type of sealant used. Many acrylic or hybrid sealants are designed to be paintable, allowing you to achieve a seamless finish that matches your decor. However, most silicone sealants are not paintable, as their surface is non-porous and can prevent paint from adhering properly. To ensure a smooth, professional-looking finish, always check the manufacturer’s specifications before applying paint over any sealant. Using the right product - specifically those labelled as paintable - will help you achieve the best aesthetic results and maintain the durability of your sealing job.

Question 3

How long does sealant last around door frames?

Accepted Answer

Sealant lifespan depends on type, exposure and application quality. High‑quality silicone sealants used on exterior door frames typically last up to around 15–20 years. Acrylics and hybrids usually last less (5–10 years) and may need replacing sooner in high‑movement or high‑UV locations. Maximise longevity by following these tips:

Prepare surfaces properly: remove old sealant, dirt and grease.
Use a UPVC‑safe or exterior‑grade silicone for door frame sealant.
Apply neat, continuous beads and tool within the recommended window.
Inspect annually and replace at first signs of cracking, shrinkage or detachment.

Choosing the right product and applying it correctly will deliver the best lifespan for seals around doors and windows.

Question 4

What is the difference between silicone and acrylic sealants?

Accepted Answer

Choose silicone for durability and weatherproofing (external sealant for windows, door sealant). Choose acrylic where paintability and interior finish (white window sealant, frame sealant) matter. A breakdown of the differences is detailed below.

Silicone sealants:

High flexibility and excellent water resistance, making them ideal for external applications like window sealant, door frame sealant and UPVC window sealant.
Durable, UV‑stable and mould‑resistant; good for wet areas and long‑lasting exterior weatherproofing.
Not usually paintable and can be harder to remove.

Acrylic sealants:

Water‑based, easy to apply and simple to sand or paint — best for internal window sealant, trim and decorative finishes.
Less flexible and less weather‑resistant than silicone, so better suited to low‑movement indoor joints.
Cheaper and tidier for cosmetic jobs but typically shorter lived for exterior use.

Question 5

Can I Use Internal Window Sealant for External Applications?

Accepted Answer

No, using internal window sealant for external applications is not advisable. Internal window sealants are specially formulated for indoor conditions and lack the necessary properties to withstand the harsh realities of outdoor environments. These sealants may fail to provide the durability, flexibility, and weather resistance required for exterior use, leading to premature degradation and potential damage to your property.

For outdoor sealing tasks, it's essential to select a sealant explicitly rated for external use. External sealants are designed to endure various environmental factors, including UV exposure, moisture, and temperature fluctuations. This durability ensures that your seal will remain intact, protecting your windows and surrounding structures from water ingress, draughts, and other problems associated with improper sealing.

In conclusion, always opt for a sealant that matches the application you're working on. For sealing windows externally, look for products clearly labelled as "exterior" or "outdoor" sealants to guarantee maximum performance and longevity.

Door & window sealant

Penosil Window and Door Silicone 312 300ml - All Colours

Bostik S41 Neutral Cure Low Modulus Acetoxy Window & Door Frame Silicone Clear 310ml

Bostik S41 Neutral Cure Low Modulus Acetoxy Window & Door Frame Silicone White 310ml

Bostik Pro S41 Window & Door Frame Silicone 310ml Brown

Bostik Pro Sealant S41 Window & Door Frame Silicone Anthracite 310ml

Hansil Gun Foam 750ml

Everbuild External Frame Sealant White 290ml

Soudal Trade Exterior Frame Silicone Black 270ml

Everbuild Window & Door External Frame Sealant Brown 290ml