Do I need low modulus silicone for windows?
For sealing the gap between a window frame and the wall, yes: low modulus (LM) neutral cure silicone is the usual trade choice. It stays soft and flexible so it moves with the joint without pulling off the frame. Standard bathroom silicone is not made for this. Check the tube against EN 15651.
What does low modulus mean?
A low modulus sealant needs little force to stretch. That puts less stress on the bond to the substrate when the joint opens and closes with temperature changes.
Where is LMN silicone used on windows?
- Perimeter seal between uPVC or aluminium frame and wall
- Some glazing methods, such as toe and heel sealing of insulating glass units
- Remedial glazing
What are the limits?
Check the data sheet for each product. One typical LMN silicone is not recommended on natural stone, for example, because of staining risk. Neutral cure types are used on PVCu and most building substrates. Structural bonding and glass walls need a different product, so use the type the window maker specifies.
MLI Building Products stocks silicones and sealants for installers at our Worthing trade counter.
Need a trade price? Call the trade counter on 01903 262 636 or visit us at Unit 1, Friar Walk, Worthing. We offer free delivery within 30 miles.
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