Building a Solid Oak Bar Top
Woodworkers discuss the options for constructing an Oak bar top, including butcher block or strip flooring. January 25, 2013
I am going to build two solid red oak bar tops. One of them will be 19 ft long and 24" wide. The other will be 16 ft long and 32" wide. This is a commercial job and they want solid oak. I plan to make them 1 1/2" thick and will attach so they can move around with moisture changes. They are both straight runs. They want a poly finish on it. I have made several tops, but none of this size. Any suggestions?
(Architectural Woodworking Forum)
From contributor M:
Will probably take close to 300 Bf of 8/4 red oak to make this with waste from ripping, crosscutting and defecting. Large panels like that will want to move, even during the manufacturing process as you glue up and plane down to expose potential moisture content differences within the lumber. Especially this time of year when the heat is on in northern shops - cupping and checking in a panel this big can be a headache and cause you to remake the panels. Different temps and humidity between shop and install site can also cause issues after install.
Have you considered using wide plank flooring installed on plywood? Can achieve desired appearance using 4, 5 or 6" plank, and butt ends are end matched already. Layup, nail using flooring nailer and sanders. Floor finish will hold up well on bar top. Ends and edges can be built up with solid wood to make top look solid.
From the original questioner:
I have considered using flooring. They own another bar that has flooring on it, and it has held up well, but they have mixed feelings on its overall look. If I did use flooring, should I glue it all together (not to the plywood) when I nail it down, or does it need to float?
From contributor N:
Another option is to butcher block it. Cupping is minimized (not eliminated) if you rip smaller pieces for your panel and orient them vertical grain. Just keep it on the heavy side until you're ready to finish, then any slight cup can be taken out planing and widebelt sanding just beforehand. We glue up large panels daily 10' x 3' out of small strips. These sit around until we rip them into blanks for door cores. They're pretty stable, and there isn't even any attention paid to grain orientation. I think those Boos Brothers maple butcher block tops aren't vertical grain either, and they fare pretty well. The look is bland, compared to wide flat sawn boards with cathedrals and swoops, but definitely more stable.
From contributor J:
The movement in properly dried material will be minimal. On 24" I would say about a sixteenth with the seasons. On 32" you could see a light eighth. I didn't use a calc to figure this out, just experience with wide solid tops I have built. As long as you screw it down the minimum you have to, you should have no problem. You may want to stay away from a mitered border, as the corner joint will likely open up a bit. Of course, finish both sides.
Don't know how you are going to get your length, but I'm sure someone here has done it successfully. Finally, in my opinion, 8/4 is overkill unless it is for the beefy look or profiling. You could probably use 5/4 and get the same results.
From contributor G:
This is flooring on ply with solid edge strip. Flooring was glued up in sections clamped overnight in shop. We glued the groove, ran sections through widebelt, and on site we trowel-glued the floor to the ply using Bostik best and screwed from underside.
From contributor D:
I am surprised to see so many advising what the industry would call bad practice. Solid wood (anything more than 3/8") needs to be able to move to avoid problems long term. "Gluing it real good" just doesn't make the movement go away. Wood moves and it really doesn't care what your intentions or methods are. Fix it down real solid, and as it expands, cells crush so that when it dries back out, cracks develop. This is science, not opinion.
Use an online calculator like the Shrinkulator. It is better than experience since it's based on real world observation.
Responsible woodworkers will consider the fact that not all environments are stable long term. If the A/C or heating fails, or the in-laws stay for a week, or the entire house gets painted, or there is a serious plumbing failure - should the woodwork also be a casualty?
If you choose thin woods on a stable core, balance the panel equally. If solids, allow them to move.
From contributor A:
Contributor D, I often wondered about what you are saying. Could you take 1/4" boards and glue them down to plywood substrate and be good? I have some quartersawn oak straight off the sawmill that has dried nice and flat and is only 1/4" thick. Thin quartersawn doesn't seem to cup and is easy to dry.
From contributor I:
1/4" solid wood is still really pushing the limits on what you can glue to a solid substrate. Some guys will recommend doing this, but I had a failure on one of my earliest projects where I glued 1/4" solid wood to the top of a plywood book case. It held up just fine for 3-4 years, but then the problems started to show up. I am glad I only did this on that one project. I would not recommend it. There are many people who will tell you even 1/8" is too thick to use as a veneer.
Some guys get away with all sorts of stuff in climate controlled buildings in moderate climates, but you really never know. You would be much better off with a thin veneer (less than 3/32") if you wanted to glue to a plywood substrate. However, I would still glue the whole thing up from solid 8/4 oak any day.
Get a moisture meter and make sure all the boards are within 1% MC of each other. In my neck of the woods I would make sure they have been dried to no more than 6-7% moisture content this time of year. Don't take your suppliers word for this - check for yourself.
Let the material acclimate to your shop for a minimum of 72 hours. At the very least it needs to come up to the temperature of your shop before you do any milling.
Make sure to finish both sides equally. Make sure to use slotted screw holes when you install, or another method to allow the top to expand and contract. I go as far as to use washers, and I loosen the screw just a bit by hand after I drive it in. Using solid wood isn't that difficult at the end of the day.
From contributor D:
In my experience, 1/4" is okay, and I have had no problems I am aware of. In fact, I made 3 ply exterior door panels for years with a 1/4" plywood core and ply of 3/4" solid wood on either side of this, all into a vacuum press with epoxy. The species was mostly Honduras mahogany (very stable) and sometimes rift or quartered oak. The panels were as wide as 37". The worst I ever saw was a few years after delivery, on a south facing entry, painted black, one panel had a surface crack in the raise that was open less than 1/8" and 2" long. It did not split through, though, and filled well and is still looking good 20 years later.
1/8" is fine - preferred - for shop veneer when needed, and there is nothing wrong with solid in most cases. We do many island tops at 2" to 2-1/2" thick, strips at about 1-3/4" wide.
From contributor I:
The failure I mentioned was with 1/4" solid maple, glued with PVA. Not the most stable combination. This was early work so there may have been other factors at play, but it is concerning enough that I take it as a lesson learned.
I cut my own veneer so that it ends up just under 1/8" after I thickness it. Then I cold press in a vac bag with Unibond. I have still heard numerous arguments advising against the thicker shop sawn veneers. Then again an equal number of people will say it's okay.
I suspect the problems people talk about come from use of ordinary PVAs, and/or pressing with cauls and clamps. I still try to aim for the thinner side, and of course I take it down a bit more with the final sanding.
I did a counter for a commercial job about 6 months ago with shop sawn flame birch, cold pressed onto 1" MDF with UF, in a vac bag, with a solid tiger maple border.
From contributor U:
Contributor M gave you good advice. What you do to one side must be done to all sides. On each piece. This includes jointing, planing, sanding and finishing. Very important in long runs.
From contributor C:
We are a small workshop in the Eastern Cape of South Africa and are starting to do a fair bit of work with imported red and white oak from the states. A client of ours is a kitchen designer who loves big oak island tops (8' x 4' and that sort of thing). We get our oak in either 1" or 2" thick rough sawn boards and tend to use the 2" for laminating table tops, etc. where the entire surface will be seen, but because of the significant cost difference per cft (or cubic meter as we buy it) between the two thicknesses, we have been looking at making the island and kitchen tops out of 1" stock with built-up edges.
Any suggestions on how to keep the large laminated panels flat over such a large area? If the built up, finished product needs to be 2", would it be best to screw 1" strips, crossgrain, to the underside of the top to keep it flat after install, or dry screw a sheet of plywood or MDF to the bottom, with holes drilled for breathing? I know the wood needs to have room to move, but my experience with the large, relatively thin, laminated panels is that just with the weight of them alone, there can be distortion from one corner to the other. The other issue is with overhangs, as inevitably with island tops there will be a need for a bar-type overhang (up to 14") past the cabinets. Would laminating a build-up on one side (i.e. 2 x 1" pieces) face to face grain, cause movement problems? Also along all other edges we need to do a minimum 2" return buildup as the standard overhang past the cabinets is that much. I should say that with panels like this, we typically laminate full-length, 6" boards together to achieve the desired oak look of wavy grain, etc.
From contributor N:
I would be surprised if 6" wide 4/4 stock edge glued stays flat. Very surprised. A kitchen counter will sooner or later get moisture. Then the fat lady will be singing...
From contributor D:
I agree with the above comments regarding the 4/4 staying flat in wide boards. Do not do anything to restrict cross grain movement, but you can fasten down to strongbacks to keep things as flat as possible, as long as you allow movement.
I like the thick tops for their stability, and we go a bit further by ripping the lumber into strips to give an edge grain butcher block look to the tops. These often net out from 1-3/4" to 2-1/2" in thickness, and stay very flat.
We have tried the "just build up at the edges" route, and find the significantly higher labor costs offset any lumber cost savings, yet deliver a somewhat less impressive product.
From contributor C:
Thanks. I appreciate the feedback. I have been seeing more movement than I'd like. Would wood flooring adhesive, a flexible PU, which is designed to allow some movement, be a suitable option to glue, say, a 1" (4/4) panel down to plywood? Without screws holding it long term, it should still allow movement between the layers. Unfortunately we are in the middle of an order, where we've made the top of 1x6 lumber, but will definitely look at the butcher block option for the future. For us here in SA, making the top from 2" stock would be three times as expensive as a 1" top built up, materials wise.
From contributor N:
If I were in your situation I'd rip those 6" wide boards into 1 3/4" strips, and glue them up into 1 3/4" thick panels (thicker if you can afford it). This is very serious heartfelt advice. If you don't believe how much a 6" wide board can distort, pull a scrap aside and soak it. Just one cupped piece in a big counter will ruin the whole thing. I built my personal workbench out of pecan, butcher blocked, when I was a newbie. It's now going on 16 years old, with all kinds of spills and abuse. It's not even fastened. Four mortises underneath, along with gravity, keep it in place. Still flat, but maybe a 1/4" thinner (every couple years or so I widebelt sand it to get the gouges and stains out). I started with around 3" thick. Trusting plywood to stay flat is unsound as well. Check any sheet of plywood that's been laying around for a while not stacked under forty other sheets. Chances are it's not flat.