Fence rail repair question

[pete6032]

This rail in my fence is rotting out. If I wanted to repair it, should I remove the pickets, cut out the rot with a multitool and then sister another beam to the top of the old rail?

1. Can I use an oscillating multitool to cut out the rot?
2. Should I use cedar or pressure treated pine for the sister beam?
3. What type of screws and how long should the screws be?

 

[herm0016]

remove and replace. cedar would be good but pressure treated will be fine. 1 or 1.25 coated exterior construction screws would be good for the pickets, maybe 3 in for the ends.

 

[pete6032]

remove and replace. cedar would be good but pressure treated will be fine. 1 or 1.25 coated exterior construction screws would be good for the pickets, maybe 3 in for the ends.

Remove whole board or just the rotted part?

 

[herm0016]

the whole thing. you will have very little strength with patching. you should remove the boards from one side, as it looks like it catches water in the middle and does not have a chance to dry out which will cause rot.

 

[BoomerD]

Yep. Replace the whole 2x4 with pressure treated. 1.25 to 1.5" screws made for exterior use.

Easiest way to attach the rail to the 4x4 posts is with fence brackets.

https://www.homedepot.com/p/Simpson-Strong-Tie-FB-ZMAX-Galvanized-Fence-Rail-Bracket-for-2x4-Nominal-Lumber-FB24Z/100375311

 

[Greenman]

I'd put in the new rail before removing the old one.

 

[pete6032]

I'd put in the new rail before removing the old one.

Right now this rail sits on top of two pieces of wood sistered to the posts so I can't really attach a new rail with the old one in there, unless I go out and buy the brackets that Boomer recommended.

Edit - I fixed it today. Need to get some more pickets now but at least no rotting wood. Seeing how nice and strong the new wood is versus the decayed crap that's there makes me want to rebuild the whole fence.