How to seal the wall attachment of outdoor light fixtures?

JohntheRipper

I plan to install brass outdoor lights on our house walls.

The walls are Hebel.

The brass itself will be sealed with lacquer like Wattyl Incralac ( Other suggestions are welcome )

While there will be some protection from the eaves, 

I want to seal the wall attachment where it comes in contact with the walls to reduce water ingress.

The lower part of the attachment will be left unsealed to permit water egress.

I was considering using either Soudal Multi or Soudal Multibond SMX35 .

I would be grateful for any advice regarding sealants.

My preference is for a moderately flexible sealant with an antimold agent in it.

 

MitchellMc

Welcome to the Bunnings Workshop community @JohntheRipper. It's terrific to have you join us, and many thanks for your question about installing exterior lights.

Any outdoor light should have a water-resistant or waterproof rating, such as IP44 or higher. These fixtures are designed to prevent water ingress, and additional sealant usually isn't required since they typically come with a gasket on the rear mount that seals against the wall or wire entry points. However, it would be best for your electrician to seal holes in the wall through which the wire passes.

If you're concerned about sealing the rear of the light mount where it attaches to the Hebel walls, Sikaflex 11FC is a great option. It's a moderately flexible polyurethane-based sealant and adhesive suitable for outdoor use, offering excellent weather resistance. It also has good bonding strength and can tolerate movement in the joint, which is important for a long-lasting seal.

Sikaflex 11FC doesn't contain an antimould agent, but it should perform well in preventing water ingress, especially since you'll be leaving the bottom unsealed for water drainage. Sikaflex is used for a multitude of sealing applications in the construction industry. It's unlikely that mould would ever build up on it unless there were some preexisting issue with mould in that area.

Please let me know if you have any questions.

Mitchell