How much expansion for a solid wood worktop?

[opps]

Hi all.

A few years ago I built a kitchen for a mate. The worktops were solid wood. From memory, they were iroko.

He has since built an extension on the side of the property and had new cabinets fitted on the side of what was previously the exterior wall.



In image number1 the part of the wall that juts out is the boxed section for the soil pipe that ran down the exterior wall. It seems to be plywood with plaster over it. In the far left of the image, the opening is where the old window by the Belfast sink used to be.

I am uncertain how much space I need to leave either side of the soil pipe section for expansion. He doesn't want upstands or anything like that so I will be back filling and using a thin layer of polythene so that the fillers are not pulled away when the worktop expands/contracts.

Additionally, he doesn't want me to remove the old worktop on the other side of the wall. I can biscuit join them but I don't imagine that I can use worktop connectors to pull them together. I am guessing that I will need to screw wooden straps to the underside where possible.

I have warned him that there might be a slight step where they meet. I can sand them to a degree using my 180mm Festool (which is faster than my 75mm belt sander but obviously far from perfect).

Thoughts/recommendations greatly appreciated.

 

[Mr Chibs]

When I fitted my oak worktops think it was stated nearly 10mm gap for expansion.
I left 5mm at best, a year or so on, nothing has moved, personally I wouldn't leave anymore that this, I'd then use a sealant matching colour and use a fugenboy/spatula to get it really neat if no upstands are being fitted.

Biscuit is good move to get the tops as flush as you can (cupping excepted), some glue the joint too... good if you can clamp them together?

I cut a manual slots for the worktop connectors... used a forstner bit to drill the large 'nut' holes and multiple 10mm holes drilled and chiselled clean for the the bolt. It's a little faff, but easily doable.

Sand the top to get the best fit..., I used random orbital.

HTH

 

[Deleted member 174758]

I am uncertain how much space I need to leave either side of the soil pipe section for expansion. He doesn't want upstands or anything like that so I will be back filling and using a thin layer of polythene so that the fillers are not pulled away when the worktop expands/contracts.

TBH I'd say that's just asking for the plasterwork to be damaged or discoloured and is a poor choice. If you need a visible expansion joint I'd suggest something like 5mm filled with either a dark-coloured Compriband or cork strip (stained), but they aren't as durable as I'd like

Additionally, he doesn't want me to remove the old worktop on the other side of the wall. I can biscuit join them but I don't imagine that I can use worktop connectors to pull them together. I am guessing that I will need to screw wooden straps to the underside where possible.

Actually you can use worktop connectors - a lot easier than faffing around with steel straps, will give you a tight joint (necessary) which straps won't do and they can be pulled up in the future if needs be. Run a bead of silicone between the ends rather than glu to seal it. I've used worktop connectors on commercial bar top extensions before now, with loose tongues, loose biscuits or (more recently) loose Dominos to locate the parts, Don't glue them in case the tops expand/contract at different rates (note: wood always moves a lot more across the width than in the length)

I have warned him that there might be a slight step where they meet. I can sand them to a degree using my 180mm Festool (which is faster than my 75mm belt sander but obviously far from perfect).

I think that a 6ft level, a jack plane (a fore plane or maybe a trying plane as well would be better, but I doubt many people have either these days) and a belt sander are the way to level this through and much more likely to give you a near seamless transition. You really do need to get the tops at the same level, using packing shims beneath the new top to get the levels spot-on. Random orbit won't give you as flat a surface as a belt sander. If needs be hire-in a 4in industrial belt sander for the day and get some P80 and P120 belts - it'll make the job a heck of a lot easier

 

[opps]

TBH I'd say that's just asking for the plasterwork to be damaged or discoloured and is a poor choice. If you need a visible expansion joint I'd suggest something like 5mm filled with either a dark-coloured Compriband or cork strip (stained), but they aren't as durable as I'd like


Actually you can use worktop connectors - a lot easier than faffing around with steel straps, will give you a tight joint (necessary) which straps won't do and they can be pulled up in the future if needs be. Run a bead of silicone between the ends rather than glu to seal it. I've used worktop connectors on commercial bar top extensions before now, with loose tongues, loose biscuits or (more recently) loose Dominos to locate the parts, Don't glue them in case the tops expand/contract at different rates (note: wood always moves a lot more across the width than in the length)


I think that a 6ft level, a jack plane (a fore plane or maybe a trying plane as well would be better, but I doubt many people have either these days) and a belt sander are the way to level this through and much more likely to give you a near seamless transition. You really do need to get the tops at the same level, using packing shims beneath the new top to get the levels spot-on. Random orbit won't give you as flat a surface as a belt sander. If needs be hire-in a 4in industrial belt sander for the day and get some P80 and P120 belts - it'll make the job a heck of a lot easier

Many thanks.

For the record, this is the sander I expect to use.

https://www.londonpowertools.co.uk/...ol-ras-180-e-gb-240v-rotary-sander~fest570747

I find it wayyy faster than my belt sander. It also has the advantage of being able to get closer to the ends of the meeting edges. That said, it is only rotary, not random orbital so I will need to finish if with my Rotex. Admittedly, it might not be as fast as a 4" belt sander- I don't own one so I have never compared (nor do I own a jack plane...).

So would you silicone the biscuits or just leave them loose? I don't own a Domino and cannot justify buying one, should I do biscuits at differing heights?

I agree that no upstands is unadvisable, it is what he wants...

 

[opps]

When I fitted my oak worktops think it was stated nearly 10mm gap for expansion.
I left 5mm at best, a year or so on, nothing has moved, personally I wouldn't leave anymore that this, I'd then use a sealant matching colour and use a fugenboy/spatula to get it really neat if no upstands are being fitted.

Biscuit is good move to get the tops as flush as you can (cupping excepted), some glue the joint too... good if you can clamp them together?

I cut a manual slots for the worktop connectors... used a forstner bit to drill the large 'nut' holes and multiple 10mm holes drilled and chiselled clean for the the bolt. It's a little faff, but easily doable.

Sand the top to get the best fit..., I used random orbital.

HTH

Many thanks for the reply, yeah, after your advice, I guess I can do manual slots. I can then use the router on the new worktop.

Will let you know how I get on.

cheers.

 

[Deleted member 174758]

I find it wayyy faster than my belt sander.

Well, normally a belt sander will beat a random orbit sander hands down in terms of speed. Even if they don't, it is far easier to relevel a surface with a belt sander, although basically as a joiner I'd be using a plane to level through in the first instance and just using the belt sander, or any sander, to get the final finished surface. A belt sander has the advantage that the belt direction can be aligned to the grain direction as well

BTW I have a couple of 4in belt sanders, the most aggressive being a 30 year old Kango (the forerunner of the current Festol BS105). Either is good for flattening corners on door casings, although the Bosch has a sanding frame which is better for control, so it gets used almost all the time when I need a belt sander (not often these days). Still, I'm beginning to think you need a Festool BS105...

...and this is what a red BS105 would look like :

Manufactured August 1988 would you believe, and had 6 used belts in with it when I bought it (plus 20 odd unused ones). Kept as a backup in case my Bosch 4in belt sander ever goes pop, but I think it more likely I'll go pop before either sander does!

Using planes is second nature to me - but that's down to how long I've been using one. Best, most controllable way I know to redimension or flatten timber out on the job

So would you silicone the biscuits or just leave them loose? I don't own a Domino and cannot justify buying one, should I do biscuits at differing heights?

Just leave them loose. As I said, wood actually moves more across the grain than it does along the grain, so you don't really want to constrain the timber too much. Up to you if you do one row or two - basically the dog-bone joiners hold the bottom together

 

[opps]

Hi all.

I decided that I really need to sort this worktop out. He is back next week and naturally, I have done eff all about it in the meantime

I have attached a basic layout (not to scale) of my cuts.



I will need to repeatedly lift the worktop of and on whilst tweaking it. I am worried that at its thinnest point it will be only 170mm deep, that will be approximately about 60% of the way along the length. Annoyingly, the new work top is 43mm thick the one that I have to mate it with (on the other side) is 40mm.

Will the worktop be safe for two people to lift it off and on, or am I better off cutting a join somewhere at the thinnest point? Doing so would (hopefully) make it light enough for me to lift on my own and enable me to "bend" the worktop to meet any curve in the worktop on the other side of the wall.

As a side note: when measuring up today I noticed that the old worktop must have been run through a band saw on the tile/wall edge. It is out by about 2mm over the distance where the old window used to be. I guess that I need to use a router (in situ) to try and tidy up the edge and then chisel the bits that the router won't reach. Alternatives methods would be appreciated though.

 

[opps]

I went ahead and cut the worktop just over half way along the length. There is no way that I could have lifted the 4.2m 40mm Iroko worktop on my own, and I know that my mate would not have wanted me to pay someone to sit around all day just to help me lift it off and on.

I guess that the bit that I provisionally fitted today weighs about 40Kg.

I have left the width of the new worktop about 9mm too wide for the moment. Where the new and old worktops meet where the window used to be is less straight than I initially thought. It is about 3mm out in places. On reflection, I think I jigsawed the wall edge of the old worktop when fitting it years ago.

Initially I thought about using my longest Festool guide rail and running my Dewalt router along the edge but there is no way to clamp the guide rail (additionally, the sink tap would be in the way). I am now wondering if I should use a 1400mm guide rail and run the saw along it, using chisels, etc to tidy up the bits that the saw cannot reach.

 

[Deleted member 174758]

I think the difference in thickness you mentioned in an earlier post needs to be addressed before you join the two pieces, especially as I think you will need to align everything from the bottom face, assuming you are going to use something like loose biscuits to locate the joint and "dog bone" joiners to pull the joint up. So I'd power plane it to somewhere near (diagonal roughing cuts) then finish with a jointer plane and a belt sander (assuming you have access to them)

I certainly think you made the right call about cutting it in two. TBH, even with two people on hand I'd more than likely had done it the same way as you

In terms of the width, I don't see what is wrong with marking your cut line with a chalk line then trimming to the chalk line with the saw and guide rail. I'd put money on the back wall not being straight in any case