Breadboards technique for outdoor table top

[Wakahisa Shinta]

Over the last week and weekend, I built a table top for a garden table. It is made of doug fir 2x6 boards with three underside cleats and lag bolts. The outer cleats are 5" from the edge. There is 1/4" gap in between the boards. Someone suggested that breadboards would minimize cupping and wrapping of the top, sitting outside in the elements. I haven't constructed any table top with breadboards. I've researched techniques of making breadboards for solid table top, but I am not entirely confident about this table top.

How would an experienced woodworker construct breadboards for this top?

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[Jerry Miner]

For an outdoor table, I would skip the BB ends. You'd be creating more places for moisture to get trapped and encouraging rot. I've got a table like yours that I built 20 years ago--cleats only. Still going strong (but it's old-growth redwood)

I do think that two screws per board would be better---would help resist cupping of the individual boards. But it looks live you've got good VG stock, so you might be OK.

[Prashun Patel]

To breadboard the ends, you'd make loose tenons or loose dowels or a spline to connect the bb end to the long boards.

On glued up tables, the breadboard is usually glued into the center board and left to float on the end boards so that the top may expand in width.

However, given that you you have gaps between your boards, you don't need the breadboard to allow lateral movement. You might be able to glue it all they way across.

However, however, you have battens right near the ends, so breadboards aren't going to do much more for you.

[Roy Harding]

I wouldn't go with breadboard ends on that table, for the reasons already stated by others. I'd support the suggestion of two screws per board, though.

[Wakahisa Shinta]

I thought that breadboards wouldn't help all that much with the outer cleats so close to the edge. Glad to know I have some common sense. On the other hand, I did not consider that two lag bolts/board would help minimizing cupping and wrapping. Too bad now that the bolts are centered on the boards going through the cleats. Removing them and relocate them farther apart leaves an empty hole in the middle. Adding two bolts flanking each side of the existing one looks too busy. I guess I'll leave things as it is now and hope for the best. Another lesson learned.

[Andrew Hughes]

That's some beautiful looking Fir,I still think a solid too would have been better,the contact between the cleats and underside of the table is the weak point created from the spaces.How will it dry if it gets wet.

[Peter Aeschliman]

Another vote for no breadboard ends. With the quartersawn stock you have there, I bet you won't have much cupping. The cupping only becomes a big issue when you glue them together- cupped boards that are glued together create a big cup across the whole table. I imagine any cupping you get here will be very minor and will just add to the character of the table.

That's probably the nicest looking Doug Fir I've ever seen!

[Wakahisa Shinta]

That's some beautiful looking Fir,I still think a solid too would have been better,the contact between the cleats and underside of the table is the weak point created from the spaces.How will it dry if it gets wet.

I have no idea how to tackle this drying problem and rotting you mentioned aside from coating the parts with copper naphthenate, but this will leave an ugly dark green/brownish stain which is not going to be aesthetically appealing. Alternatively, I might cover the table during rain and when not in use. Or, I think I will just coat it with TWP stain and accept that it might rot in due time. If anyone else has other suggestion, pls let me know.

[John Seybold]

There are technical solutions to the weathering of outdoor furniture, and then there are philosophical solutions. Last fall I finished a nice table made from a big redwood slab...just in time to cover it up for the winter, which, in hindsight, was kind of silly. Over the five months it sat under a mound of snow, the top cupped. A lot - like half an inch. And did it cup to leave a nice, water-shedding dome shape? No, it did not. So I just re-milled it, and this time I've decided that the right approach is to assume that things are going to go badly, somehow. So I left the top with lots of tool marks to remind myself that it's just going to need to be refinished every year. I look at it this way: fine furniture should last for hundreds of years. Outdoor furniture? Until next year, and we'll see then...

[Pat Barry]

Breadboard ends would give the table a more fiinished appearance of course. It would look more like furniture than just being a picnic table. So the decision to make is based on what your needs and expectations are.

If you do want to breadboard the ends though, I do not think that it would be out of line to glue every board into place as Prashun suggested. If I were doing it, I think I would make a tenon on each board and fit these into mortices in the breadboard ends. I would make the mortice and tenons relatively deep / long in order to ensure you gain some mechanical benefit. Lets say make the tenon width approx 1/3 the thickness of the boards, centered on the thickness, with the mating mortices to match. It would be easier if you were using a router to make the mortices. You can shape the ends of the tenons with a circular profile to match the router bit diameter you use for the mortices.

Now for adhesives you definitely want to use the waterproof glues or construction adhesives. I would probably go with an outdoor, waterproof construction adhesive and skip the Titebond. I think you could use the same adhesive to seal the joints between the battens and the boards. I built a picnic table years ago out of BORG construction lumber and it lasted at least 10 years. The thing that failed was the BORG lumber. I should have invested in better material

[Wakahisa Shinta]

Pat, thanks! Construction adhesive escaped my mind as an option, though I used it for the Adirondack chairs I built not too long ago. Doh! I research Liquid Nail specifications, looking for flexibility and expansion/contraction values. They aren't specified in the spec sheet. The manufacturer states that Liquid Nail is flexible after cure. My guess is that it is most likely OK for this particular application. The Liquid Nail will provide some adhesion force to counteract some of the potential cupping or wrapping at the edge of the boards.

[keith wootton]

i am going to suggest using carriage bolts to hold the top to the cleats right thru your existing holes. and looking at the quality of the fir you used, i am going to say use stainless. nice fir! wow! covering is a good idea. built a picnic table for my brother 25 years ago that he keeps covered on his patio, still looks new. same benches i build for the state park i work for of the same vintage are mostly replaced or have multiple repairs related to rot at board to board interfaces. keith