Thread: Kitchen/Bathroom Benchtops (again)

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http://www.woodworkforums.ubeaut.com...ad.php?t=18484

I glued the boards to an existiung timber top. There hasn't been any movement so far. The width of the boards is such that any expansion would be so minimal that it isn't worth worrying about. No need to nail at all, just glue them on with out treatment. If you put poly under them, I can't see how they'll hold.

1. It depends. The main expansion in floorboards is in the length not the width. If you fit 2 boards together you'll see they only snug at the top, the gap at the tongue and base allows expansion across the width, so each board only moves a minimal amount. But if you're running long lengths there's a risk; I'd guesstimate 3' to be the longest length I wouldn't worry about in the long term. Any longer and the glue may hold, the particle board probably won't. This isn't opinion, this is based on what I've been called on to repair...

2. Sealing underneath, well... that's your call. In a bathroom I'd be inclined to, as the humidity can be quite steep. I wouldn't normally bother for a kitchen but I have sealed the undersides of my own. It's not floorboards, 'tis solid timber, and I saw no harm in spending the few extra dollars. An ounce of prevention...



Now for some totally unasked for suggestions. It's that time of night and I can't sleep...

A: the ends of floorboards are fugly! Fit two pieces and look for yourself. You'll probably want to make a timber frame to run around the edge to hide this. I usually just cut down another floorboard to around 40mm and use that. If you want to bullnose (or otherwise profile 'em) use the router before fixing. It's a wee tad awkward getting the router up against the wall if you leave it 'til last.

B: I wouldn't use particle board myself, nor would I mount the boards directly onto any monolithic surface. I prefer two slightly different methods, depending on the carcase type,

If the carcase is solid timber or at least timber framed, I'd attach the floorboards directly to that. You'd probably need to fix battens along the insde of the faceplate and back edge of the carcase if you intend to secret nail, and maybe along a few crosspieces. It certainly wouldn't hurt to strengthen it, anyway, and battens are inexpensive. I'm a scot, I rip down 90x45mm pine studs to get four 40x20mm battens.

If the carcase is processed muck (MDF/melamine/whatever... is my bias showing?) I'd be inclined to either mount a timber frame/battens inside the carcase and secure to that -or- dryfit the boards on the carcase and scribe/pencil the underside to determine where battens can be fixed. Remove the boards and reassemble 'em upside down on the floor, cut battens to fit within the scribe marks and fix 'em with screws, NO GLUE! I place the battens a max. of 600mm apart, preferably less.

The whole thing can then be lifted and "dropped" into place, to be secured normally. I prefer this latter method, although it's more work. [shrug]

Thanks for the replies .... love your work, Gumby!

Skew, the longest lengths will be about 2100 and should be able to organise it so that there are no end joins. The carcases will be processed muck (lamikits)

Not a bad idea with the battens. Just wondering if I don't use glue and it is allowed to move a little, will the poly crack?

Cheers

Generally, if all the lengths are the same then the poly won't crack any more than if you glued 'em to a monolithic board, as they'll all move at closely the same rate. It probably would for shorter lengths butt joined together, mainly at that joint and some inches of the t&g leading up to it. About half of all t&g floors show this somewhere, most people just don't notice it 'cos it isn't "in their face." This is assuming only the one species is used and the planks are fairly well matched as to grain, but "mis-matched" timbers'd crack the poly no matter how you mounted 'em. There are always exceptions of course, but 'tis not something I'd rely on.

I assume your bench is only 2.1m long? With jarrah I wouldn't expect movement to be a major factor, no more than a 1-2mm movement in an extreme year. I could be wrong though, and it never hurts to make allowances.

FWIW, I'm an oiler. I find it too time-consuming to properly repair poly after "accidents" but each to their own.

Originally Posted by Skew ChiDAMN!!

1. It depends. The main expansion in floorboards is in the length not the width. If you fit 2 boards together you'll see they only snug at the top, the gap at the tongue and base allows expansion across the width, so each board only moves a minimal amount. But if you're running long lengths there's a risk; I'd guesstimate 3' to be the longest length I wouldn't worry about in the long term.

I don't think that's right. FOr floorboards and decking it's the width that changes the most. I have Massara decking and the width of the boards changes noticably from summer to winter (by a few mmm) but even 3-4 m lengths don't seem to change at all.

Originally Posted by http://www.ironwood.com.au

The level of moisture in wood will affect its properties and therefore will influence its suitability for different purposes:

• The weight of green timber can be as much as twice that of seasoned timber.
• As a rule, dry timber is considerably stronger than green timber.
• Timber having a moisture content less than about 20% will not rot. An established ratio of both water and air are necessary for fungal activity to take place. Although fungal spores are common in the air they cannot develop and attack wood unless the moisture content is above 20%. Dry wood therefore will not rot.

The moisture content in timber is particularly relevant with flooring. Every 1% movement translates into a 10mm contraction or expansion of the timber across a width of 4 metres. This movement will recur for the duration of a floor's life. (The longitudinal movement of a floor is lot less significant and usually is not of great concern, except in extremely large areas).

Originally Posted by Skew ChiDAMN!!

B: I wouldn't use particle board myself, nor would I mount the boards directly onto any monolithic surface.

We actually did this for our flooring. We have grey ironbark (beautiful flooring by the way) glued directly onto particle board. No squeeking, better thermal insulation, very little expansion and contraction (but that could be due to proper acclimatising before installation), and a very solid feel underfoot. I can't see why the same system wouldn't work for benchtops. The flooring is secret nailed but the installers told me the nailing was only to hold the flooring while the glue set. By the way, the guy who installed the flooring really loved ironbark -- he had to otherwise it would have driven nuts... every nail had to be pre-drilled and hand nailed.

Originally Posted by custos

I don't think that's right. FOr floorboards and decking it's the width that changes the most. I have Massara decking and the width of the boards changes noticably from summer to winter (by a few mmm) but even 3-4 m lengths don't seem to change at all.

You're quite right with respect to timber, and planks in general but I was talking about tongue & groove floorboards. The T&G is profiled with an expansion gap, the only part of the boards that actually touch is the top. So although the boards expand laterally, there's no apparent movement at the working surface, although the top few mm do compress.

Longitudinally though, is another story. Most T&G is profiled on the ends as well, but the sheer ratio of width to length makes for an effectively greater longitudinal movement. Let's say the lateral expansion is 5% while the longitudinal is only 1%. These figures are totally fictional, mind, only for this example. Then a board 5x as long as it is wide will move an equal amount in both directions. A floorboard is usually much longer than it is wide. So, even though it has the same sized expansion gap it has to allow for a greater degree of movement, so is more likely to show cracking in a poly finish.

At least, that's the way 'twas explained to me when I thought I'd caught my oldtimer mentor out with the same thing...

We actually did this for our flooring. We have grey ironbark (beautiful flooring by the way) glued directly onto particle board. No squeeking, better thermal insulation, very little expansion and contraction (but that could be due to proper acclimatising before installation), and a very solid feel underfoot. I can't see why the same system wouldn't work for benchtops. The flooring is secret nailed but the installers told me the nailing was only to hold the flooring while the glue set. By the way, the guy who installed the flooring really loved ironbark -- he had to otherwise it would have driven nuts... every nail had to be pre-drilled and hand nailed.

Flooring's not generally a problem, except around floor ducts & under heaters, potbellies, etc. that aren't on pads. As I understand it, the reason so many floors screw up around such areas isn't just their drying out (if properly kiln-dried this would be minimal anyway) but the cycles of heating that section of flooring and letting it cool off. ie. the timber movement begins to make itself shown. The rest of the floor generally stays about the same temperature; people don't like extremes of temperature in short time periods. Also, as I stated before, about half of all T&G floors do show signs of movement somewhere, people just don't notice what's not in their face. This is independant of whether they're floating floors, glued to an underboard or simply nailed to joists. I don't advocate gluing to a monolithic surface for floors either, though. I much prefer a floating floor secret-nailed every 12-18" instead, but that becomes labour intensive. A case of utility vs price.

Benchtops on the other hand, especially in kitchens, can see a lot of temperature variation. From pots'n'pans being put in the wrong spot to heating from underneath by dish-washers, stoves, etc. Movement becomes an issue, especially with a poly'd surface which highlights the cracks. This is partly why I like oiling instead... the cracks are still there but look more natural.

I haven't had the pleasure(?) of working with ironbark for anything apart from turning. From the amount of steel lost regrinding my chisels I'm not sure I'd want to, either! I also love the finished article though. I once saw a lovely old rocking-chair made from ironbark; now there was a patient woodworker! I think that all secret nailing really should be pre-drilled and hand nailed, you could say I'm a darksider of the floorboards... 'tis just as well I don't charge by hour, eh?

Not that I lay floors nowadays... well... rarely, anyway. My back doesn't like the game any more. I do make quite a bit of cabinetry out of floorboards though. If you want a real challenge, try making cabinet doors that aren't 40mm thick out of them! :eek: That's where the lateral movement becomes a real concern!

Skew, have you ever seen jarrah parquetry used for a bench top. I'm wanting to do this with my kitchen, using a 4:1 ratio herringbone pattern(approx size of blocks will be 30x120mm).
I have a fair amount of jarrah joist's from removing my baltic floor boards, but its not good enough to resaw into pieces big enough for normal lamination IMHO, so I was thinking of cutting it up into 10-12mm thick parquetry blocks and gluing it down to 3mm mdf too make up tile's 300mm square(edges will be zigzagged shaped), then gluing the tiles down on a main substrate of 25mm mdf and then flush trim it with the substrate edge and edging it with some jarrah trimming. Glue will be black tinted slow set epoxy.
My question is, will this present any movement problems... will the 28mm of mdf be enough to stop the jarrah from moving?
I dont want to buy any more jarrah as its quite scarce and very $$$$ in my area!

I made a top for a bathroom vanity from solid timber (Blue Gum) and I coated the whole thing, top bottom and edges of the sink hole, with Estapol 7008, which is a 2 pack poly made for floors. It's been there for over a year now and no sign of any problems. I fixed it with timber buttons so that it can come and go as it pleases.

I would definitely coat both sides of any top made from solid timber, otherwise you are asking for trouble. However, I don't think that the glue would stick too well if you use your approach.

In your situation I would remove the tongues and grooves and glue the whole lot up with a false thick edge then let it float on top of the cabinets.

Heh. Reminds me of the two coffee tables I made from the offcuts of the ironbark flooring. I glued up the flooring offcuts into a single peice and cut out the table tops. Then I have to smooth the tops off. Without the luxury of a drum sander or similar I went at it with an orbital sander. Many hours later (starting with 80 grit) I wasn't sure if the sandpaper or the ironbark was winning. If you don't believe me check out the attached graph -- ironbark is way out there in hardness, probably the hardest timber in the world (?)

Just to clear the air: I'm not a professional in flooring. I was a lackey to an old-timer who was and I learnt a lot, especially the things not to do, but don't have any certification. I still enjoy making sundry furniture out of offcuts though, there's definitely little tricks that makes life easier when working with T&G. SilentC suggested the major one: cut the T&G off, but that's cheating!



Custos - Ironbark's way up there, but there're harder timbers still! Looking at my Jankah charts, the hardest I have info on are Patagonian Rosewood @ 3840 & Brazilian Walnut @ 3680, while Red Ironbark only rates @ 3185 & Jarrah a measly 1910. Scary stuff!

BTW, here in Oz Jankah's usually measured in Newtons(N); I'm not sure what units your graph is in, I assume 'tis either KgF or LbF?



Harry72 - you're certainly much more patient than I!! Parquetry and the like aren't my forte, at the sizes you're planning I wouldn't expect movement to be a major issue but that's just my peeking at my charts again & doing some finger maths. As it's not T&G, the dimensional change coefficient (what a mouthful!) should give a fairly accurate indication. For Jarrah this is 0.00396, so a 30mm wide block would only move .119mm per %MC. In practice this'd be further reduced by the proximity of other blocks. ie. the element of compression comes into play. Then again, what the numbers say and what really happens don't always coincide...

Good luck with the project, I trust you'll post photos for us to drool over?

Thanks Skew, so the dimensional change coefficient is minimal, cool!

I think we'll be waiting a while for the photos... gotta make the base cabinets yet and thats after a to do list about 4 pages long!

Originally Posted by Skew ChiDAMN!!

Custos - Ironbark's way up there, but there're harder timbers still! Looking at my Jankah charts, the hardest I have info on are Patagonian Rosewood @ 3840 & Brazilian Walnut @ 3680, while Red Ironbark only rates @ 3185 & Jarrah a measly 1910. Scary stuff!

You sure that's not petrified wood? I can't imagine working with wood that's that much harder than ironbark. It must be hell on tools.

As an aside, I recently made a letterbox from some hardwood decking offcuts (the timber shop said it was "Massara" but I can't find that timber anywhere -- it's a similar colour to Merbau but a bit lighter). It's a very hard timber and when you cut or rout it rather than getting powdery sawdust it generates tiny needles that sting as they hit your skin.

At those ratings I'm pretty sure there's more chance they'll ding your hammer than the other way around. I haven't seen them for myself, but I'd like to try turning a few pieces. Perhaps on a metal-turning lathe...?

I can't say that I've ever heard of Masarra, or anything similar sounding. AFAIK the next most "common" decking after Merbau is Balau, which is similar to your description. Dark Balau is a tad lighter colour and a bit redder. Red Balau is more so of both, almost Cedar'ish

Talking of Merbau & Balau, I was doing some rather unsual decking with it today. Unusual, in that I was lining the ceiling of a future deck with Merbau; I'd forgotten how heavy it can be, especially when hammering overhead. The owner's planning to do the deck itself in Red Balau for a bit of contrast, though I think it'd be better the other way around.

De nada, to each his own...