Fastening pergola rafter question

[SDShakes]

I'm building a 28 x 16 pergola in my back yard (first ever structural project) and I keep going back and forth on how I want to secure the rafters to the beams, so I would like some opinions please.


Redwood common
4x4 pillars
2x6x8 beams
2x6x16 rafters
1/2" carriage bolts holding the structure together

The joint for the rafters to the beams are notched and its a very tight fit; maybe I do have some Norse left in me.

So far no brackets have been used at all.

1 - Drill a 2" deep hole in the top of the rafter and use a 3.5" deck screw to tie them together. Fill holes with redwood dowels.

2 - Pocket hole from the left on outer beams, pocket hole from the right on inner beams.

3 - Other?

 

[longez]

You might look at GRK RSS screws; easy to use and hell for stout. Drive them slightly below flush on top of the rafters and don't bother with plugs.

 

[matt_i]

+1 on teh GRK-RSS, they are rated for treated wood contact, so have a good exterior coating on them as far as corrosion resistance.

Normally a poor practice to drive a deck screw into end grain and expect it to hold more than a "trim piece" function.

Not with these guys. Get a 5" or 6" screw going into end grain (SPF framing) and it will bury the head (self-countersink a large washer head) in the cross-grain of a standard piece of wood, not to mention pull any gap as tight as can be.

 

[RWorth]

If you think the 2x6 beam is strong enough, I'd pull them down and replace them with 2x8's and notch them 2". Then just use west system epoxy to glue them together, wont need any screws.

 

[kd3pc]

If you think the 2x6 beam is strong enough, I'd pull them down and replace them with 2x8's and notch them 2". Then just use west system epoxy to glue them together, wont need any screws.

this and a couple of redwood dowels will do it completely. You might even be able to keep the 2x6 and use slimmer wood pins and epoxy.

Or you could notch both the rafter and the beam and epoxy the joint.

 

[SDShakes]

You might look at GRK RSS screws; easy to use and hell for stout. Drive them slightly below flush on top of the rafters and don't bother with plugs.

I might seriously consider this. They cost a lot more but the time savings would be immense, thanks.

+1 on teh GRK-RSS, they are rated for treated wood contact, so have a good exterior coating on them as far as corrosion resistance.

Normally a poor practice to drive a deck screw into end grain and expect it to hold more than a "trim piece" function.

Not with these guys. Get a 5" or 6" screw going into end grain (SPF framing) and it will bury the head (self-countersink a large washer head) in the cross-grain of a standard piece of wood, not to mention pull any gap as tight as can be.

No end grain screwing going on here.

If you think the 2x6 beam is strong enough, I'd pull them down and replace them with 2x8's and notch them 2". Then just use west system epoxy to glue them together, wont need any screws.

My initial thought was to use 2x8s but I ended up going this route as its a close copy to my friends and which has been standing in good shape for quite a few years. But I can't go look at how its fastened because 1 - I'm in San Diego he lives in CT and 2 - He wouldn't know what to do on a ladder anyway.

 

[FJ 432]

I would not glue. They have a will dry/shrink over time (at least in Colorado).

I have two pergolas. I would screw from the top choosing a screw that is weather resistant if you choose not add dowels.

Once assembled they are a formidable structure almost to the point that you wonder why you would need screws when new. Yours is a BEAST!

Lastly, if you're considering a vine(s) make sure it anchored. Vines will slowly pull and yank the structure. Ask me how I know.

You'll love it.

 

[hillbilly slim]

They do make brackets for that. But if not any simpson hardware used, i would consider adding a 2x4, 10 to 16 inches long vertically installed on the 4x4 where the 2x6 beams meet. Straight cut on one end and a 45 on the bottom end and snugged up against 2x6's. Just for extra support since not much meat there where the meet. Both sides of 4x4 and can do all the way around(beefier look) with the inners going to top of 4x4. I would do all posts just for a unified look and could also due bottoms too(for looks). Have done this in the past and just passing it on. Gotta have that shade out here in San Diego...