Which epoxy for gluing composite decking to pressure treated wood?

[MikeInOr]

The front stairs to my house rotted out so I am in the middle of replacing them. I don't want to have to replace them in another 20 years so I selected materials that "should" outlast me. I am using composite decking for the risers and steps and powder coated steel stringers. To mount the facia to the metal stringers I choose 3M 5952 VHB double sided tape. This is the same tape that Florida department of transportation adopted to mount their street/highway signs instead of using mechanical fasteners (nuts and bolts). According to a 3M article Florida DOT found mechanically fastened signs blow off in hurricane conditions while signs that are simply tapped on stay put.



I do not have enough surface area to bond the upper part of the facia to the stringers with tape.



I have decided to cut blocks of pressure treated wood to fill in the upper portions of the stringers.





The lip on the block will be plenty to keep the upper part of the facia from warping away from the stringers.

What epoxy should I use to secure the pressure treated blocks to the composite facia boards? There will be plenty of surface area for the epoxy bond.


FYI: I will be bolting and taping the steps and risers to the stringers.

 

[Nutfarmer]

If they are bolted , do you need to epoxy them down. Don’t know if standard epoxy will bond to composite. I would ask 3M. They will know more than any of us will. Plus they will respond.

 

[mksj]

I would probably use a flexible polyurethane adhesive rated for exterior use, they adhere very well and allow for thermal and humidity changes, epoxy would be expensive and difficult to apply and not go all over the place unless it was more of a paste. Construction adhesive or flexible adhesive would be my first choice. In my past boat building days we used 3M 5200 for almost all the deck fittings and through holes. Also used a lot of epoxy but more for wood to wood bonding. Construction adhesive would be the least expensive option.

Loctite PL Premium 10 oz. Polyurethane Construction Adhesive Tan Cartridge (each) 1390595 - The Home Depot

Consider using this Loctite PL Premium Polyurethane Construction Adhesive for new construction, remodeling or home repair projects.

www.homedepot.com

https://www.3m.com/3M/en_US/p/d/b40066983/

 

[MikeInOr]

If they are bolted , do you need to epoxy them down. Don’t know if standard epoxy will bond to composite. I would ask 3M. They will know more than any of us will. Plus they will respond.

I am worried about the upper portion of the facia board warping over time if it isn't supported. I could just screw from the front of the facia into the blocks but that would look tacky.

The treads and risers will be taped and bolted. The tape will keep the treads from squeaking over time. I won't be gluing the treads.

 

[MikeInOr]

I would probably use a flexible polyurethane adhesive rated for exterior use, they adhere very well and allow for thermal and humidity changes, epoxy would be expensive and difficult to apply and not go all over the place unless it was more of a paste. Construction adhesive or flexible adhesive would be my first choice. In my past boat building days we used 3M 5200 for almost all the deck fittings and through holes. Also used a lot of epoxy but more for wood to wood bonding. Construction adhesive would be the least expensive option.

Loctite PL Premium 10 oz. Polyurethane Construction Adhesive Tan Cartridge (each) 1390595 - The Home Depot

Consider using this Loctite PL Premium Polyurethane Construction Adhesive for new construction, remodeling or home repair projects.

www.homedepot.com

https://www.3m.com/3M/en_US/p/d/b40066983/

I like the idea of the polyurethane glue. Someone suggested 3M 5200 polyurethane adhesive for boats. I think I will give the 3M 5200 a try instead of epoxy. It will be a lot easier than mixing epoxy.

I have all the triangles I cut out from the facia for the steps. I decided using the triangles instead of the pressure treated blocks makes a lot of sense.

 

[matthewsx]

Ask these guys.

HOME

GOUGEON BROTHERS, INC. WHO WE ARE The employee-owners of Gougeon Brothers, Inc. WHAT WE DO Epoxy Formulation Our in-house chemists formulate all of our

gougeon.com

John

 

[David2011]

WEST (Gougeon Bros) was my first thought as well. As for water resistance, it was developed to build boats.

 

[Eddyde]

IMHO, Gluing, laminating, two dissimilar materials together is not advisable, especially outdoors. As they will expand and contract differently you are asking for warping, cupping.

 

[MikeInOr]

IMHO, Gluing, laminating, two dissimilar materials together is not advisable, especially outdoors. As they will expand and contract differently you are asking for warping, cupping.

I agree. I realized I have all the triangles that I cut out of the facia which will be perfect to use instead of the pressure treated wood.

I am going to try 3M 5200 marine polyurethane glue and scuff up the backs with a wire wheel to give the glue something to bite into.

 

[matthewsx]

5200 is some seriously sticky stuff, don't use it anywhere you might want to get things apart again. Definitely easier than mixing epoxy and will probably do the job.

It will definitely join dissimilar materials in my experience.

John