Material for desk top

[Triggaaar]

Please give me your opinions on my options for a new desk top.

I'm making a desk to fit in a small bay window. The bay has 5 sides, shaped like 5 sides of an octagon, so the desk will be like a rectangle with 2 corners cut off.

The bay is 2m between the window sills. I'd like the desktop to sit on top of the sills, so it will be 2.16m wide, and between 83cm and 93cm deep.
Underneath there will be a filing cabinet either side, which I intend to use for support. The gap between the filing cabinets will be 1.33m. That's a lot, and depending on the material used for the desk, I was thinking of using 2 (or more) lengths of 25 X 25mm (1.2mm ) Steel Square Tube as support.

Options for desk top:
1) Wood kitchen worktop, like oak or beech. This is sold in 2m, 2.4m and 3m lengths, 40mm thick, and up to 96cm width. At 40mm thick I assume it won't flex much, but it will be heavy and still need some support. The actual top should look fine, although not quite as nice as the other options.
2) 3/4" hardwood ply. This would be cheaper and probably need more support. The main negative with this option would be that I'll probably need to add an edge to the front, which won't look as nice as the alternatives.
3) Make a desk top out of old 22mm oak floorboards I have. I would trim these on all four sides and glue them together, presumably on to a piece of 12mm ply. I know that the oak can move a fair bit due to moisture (that's why I have it, it used to be on a floor, before it expanded), and that's probably my main concern, although over a width of 90cm I guess it shouldn't move too much. I don't know if the gluing the boards to the ply (effectively making an engineered board) would restrict the oak too much and lead to cracks etc and if I'd be better not using ply with the floorboards, and just let the oak move a little over the metal supports.

Many thanks

 

[Racers]

The oak will bend the ply, it won't stop it from moving, nothing will stop wood from moving.
Steel support sound like a good idea, is it possible to add an upright/uprights to help?

Pete

 

[MattRoberts]

Option 3 isn't a great option - you're gluing wood which will move onto an inert plywood substrate. Something will give!

Option 1 sounds the best to me if it's not too expensive, and assuming you're putting in supports such as the steel tube. You can often find off cuts or second hand solid worktops which just need a good sand and an oil.

 

[Triggaaar]

Thank you for the quick replies!

The oak will bend the ply, it won't stop it from moving, nothing will stop wood from moving.

That's why I ask here

What stops oak kitchen worktops moving much, is it just than they're not that wide (60cm ish) and the wider breakfast bars aren't constrained?

Steel support sound like a good idea, is it possible to add an upright/uprights to help?

Yeah I guess so, although not ideal. Do you think any of the options I've mentioned would need less or more support?

Option 3 isn't a great option - you're gluing wood which will move onto an inert plywood substrate. Something will give!

Understood! Would it work without the ply underneath, or floating on the ply (perhaps just the front edge glued/screwed so the rest can move a little)?

Option 1 sounds the best to me if it's not too expensive

Well it's a bit pricey, but if that's what's needed that's what I'll have to do - no point doing it wrong and then re-doing it.

You can often find off cuts or second hand solid worktops which just need a good sand and an oil.

Sanding and oiling is no problem, the difficulty would be finding an off cut that's so large.

 

[MattRoberts]

Using oak floorboards without ply would be a great option - you just need to fasten the top down in a way that allows for a bit movement. Not the front edge, as then all of the movement will be towards the back. If you fasten it in the middle, it will allow for a little bit of movement front and back, effectively halving the distance it moves in any one direction.

If you go the worktop route, check Gumtree for people selling second hand ones near you

 

[Racers]

Worktop is usually only fixed at one edge, so your oak over ply idea will work.

Pete

 

[Triggaaar]

Using oak floorboards without ply would be a great option - you just need to fasten the top down in a way that allows for a bit movement. Not the front edge, as then all of the movement will be towards the back.

The reason I thought of fixing the front is that that's where you sit and touch, and you're want it to feel sturdy (it's not a 40mm chunk like a worktop) - I thought I'd just allow 10mm gap at the back and fit something akin to a small upstand over it, so the wood can move underneath. Maybe the middle is better, I don't know.

So while not gluing to the ply, do you think it would be worth having ply underneath the oak as support, or is there no point?

If you go the worktop route, check Gumtree for people selling second hand ones near you

Good point, thank you.

Worktop is usually only fixed at one edge

Oh I didn't know that Is it usually fixed front, back, or middle?

 

[Racers]

Mine are fixed at the front, I left a small gap at the back covered buy a splashback.

Pete

 

[lurker]

I'd go for 1.

If money was really tight I'd make a bespoke torsion box using 9mm MDF with "noggings" internally at about 12" intervals
Then paint the lot and fit a nice bit of lipped wood along the front edge.

 

[Triggaaar]

Thank you for the help.

I'd go for 1.

I quite like the idea of making it out of the old oak I have, but you're probably right.

The oak I have isn't in the best condition (having risen from a damp floor). I've just had a go at sanding one piece and it looks good in places, but not so good in others. I do have double the wood I need though. Money is always a bit of an issue though, so still considering it (I don't fancy plain painted MDF).

If I did go for oak floorboards cut and glued, should I put something like a sheet of 12mm ply (or is there a better option) underneath for support?

Regarding the support: I've seen that the 25mm steel tubing I was looking at also has a variety of plastic connectors, so I can easily make a frame. Also, I've remembered I have some spare oak spindles (modern style) that I could use as leg supports, maybe with a metal frame under the desktop.

 

[AndyT]

Yes, I think another option would be to use your oak floorboards, on plywood, but don't glue the oak to the ply all over. Glue all the floorboards to each other, edge to edge, to make one show surface for the desktop. Put screws through the ply, up into the oak. (Check the length carefully!) Fix tight at the front (and do add just a single run of glue at the front) but as you go towards the back, drill bigger holes or enlarge them into slots.
This should give you a strong, flat construction. If there is differential movement, it will be at the back, where you will probably need a gap for cables. You could add an upstand which would hide the gap if you want.

 

[MattRoberts]

I wouldn't worry about support for the floorboards - they were designed to take the load of people & furniture, so they're plenty strong!

 

[Triggaaar]

Yes, I think another option would be to use your oak floorboards, on plywood, but don't glue the oak to the ply all over. Glue all the floorboards to each other, edge to edge, to make one show surface for the desktop.

Yes, that's exactly what I meant.

Put screws through the ply, up into the oak. (Check the length carefully!) Fix tight at the front (and do add just a single run of glue at the front) but as you go towards the back, drill bigger holes or enlarge them into slots.

Oo that's a good idea - I could put slots in the ply, so I can screw the oak down but allow it to move.

This should give you a strong, flat construction. If there is differential movement, it will be at the back, where you will probably need a gap for cables. You could add an upstand which would hide the gap if you want.

My holes for cable will actually have to come forward a bit, as the last 8cm of the desk will be over the window sill, and then in front of the there's a radiator (which might be a reason not to have the oak on its own). Holes won't be a problem though, I'll just drill them where I need them.

I wouldn't worry about support for the floorboards - they were designed to take the load of people & furniture, so they're plenty strong!

Yes, but they were supposed to be lying on the floor, not hovering in the air. Forgive me if I'm being a bit dense (because I certainly appreciate the advice), I understand that oak is relatively strong, but I don't know how nice and flat and sturdy it will be after I've cut and glued it all. But maybe it will need the same amount of framework support regardless as to whether there's any ply underneath.

 

[MattRoberts]

Yes, but they were supposed to be lying on the floor, not hovering in the air. Forgive me if I'm being a bit dense (because I certainly appreciate the advice), I understand that oak is relatively strong, but I don't know how nice and flat and sturdy it will be after I've cut and glued it all. But maybe it will need the same amount of framework support regardless as to whether there's any ply underneath.

Sorry, I'm confused - you were talking about putting steel tube supports under them, which is why I said using ply was unnecessary.

At the end of the day, it all comes down to a number of factors:

How thick the oak boards are, how far apart the two side supports are (I believe you said you were using filing cabinets), how wide the two side supports are, how the top is fastened to the side supports, whether you're using supports under the top or not.

Do you have plans?

 

[skipdiver]

I'd use the oak that you have and find a way of letting it move. Probably go for the slotted ply idea that Andy mentioned. When i made and fitted oak worktops in my kitchen, i used stretcher plates, with dome head stainless steel screws and a washer. I tightened the screw through the stretcher plate into the oak and then backed it off slightly, which allowed the oak some movement. Never had any problems with it and i sold the house to my mate. They are still going strong after 12 years last time i visited him. You could do the same arrangement with slots in the ply. If you glue and lip the front edge of the oak/ply, it should span that distance ok i would have thought.

 

[Triggaaar]

Sorry, I'm confused - you were talking about putting steel tube supports under them, which is why I said using ply was unnecessary.

At the end of the day, it all comes down to a number of factors:

How thick the oak boards are, how far apart the two side supports are (I believe you said you were using filing cabinets), how wide the two side supports are, how the top is fastened to the side supports, whether you're using supports under the top or not.

Ah yes I see. Yes I'd like to put some steel tubing underneath (and a couple of cabinets will also be able to offer support). I understand that the steel is plenty strong enough, the problem with the steel is that adding more normally means cutting it to use their plastic connectors, which would then remove the strength - so it's fine as long as they end of each piece of steel has a leg under it. I don't really want more than 4 legs, so I'm looking at having a square frame of steel in the middle of the desk. That square would be 106 cm wide x ~ 60cm deep.

I have another option to help support the centre of that steel frame - wait for it... glass! I have a piece of strong glass from an old AV cabinet. It's 10mm thick, 118cm x 45 cm. It was designed to put AV gear like a power amp and TV on, so it's pretty strong and rigid.

Alternatively I could try and fit brackets to the steel tubing, so that I could have an extra piece of steel running across the middle of the steel square. I guess that would involve drilling through the steel tube and using bolts.

Do you have plans?

I have lots of notes and a couple of small drawings on a *** packet (homer) Not much good for sharing, I appreciate. I will endeavor to draw something better, and post it.

Thanks

 

[Triggaaar]

I'd use the oak that you have and find a way of letting it move.

I'm favouring using what I have as it would be nice to find a use for it, and if it works (I'm not particularly confident in my 'skills') it could look more interesting than using a worktop.

Probably go for the slotted ply idea that Andy mentioned. When i made and fitted oak worktops in my kitchen, i used stretcher plates, with dome head stainless steel screws and a washer. I tightened the screw through the stretcher plate into the oak and then backed it off slightly, which allowed the oak some movement. Never had any problems with it and i sold the house to my mate. They are still going strong after 12 years last time i visited him. You could do the same arrangement with slots in the ply. If you glue and lip the front edge of the oak/ply, it should span that distance ok i would have thought.

Stretcher plates sound like a good idea, thanks.

I'm wondering if ply if the most rigid base option though? We have some old bedroom furniture (still in use) than has a make shift dressing table where the top spans 1m without support, and it's pretty rigid. I assume it's some sort of particle board. I've been considering different options for under the oak, including glass (as in my post above), but maybe I should just do more with the steel (adding brackets).

I'll try and post some images.

 

[Triggaaar]

Here's a picture of the room as is. Please ignore the old cupboard

I've just put some damp proofing on the wall, it needs plaster, skirting and radiator to go back.

I intend for the desktop to sit on the window sill (probably with a couple of mm of foam underneath, to bring it to the same height as a cabinet).

 

[Triggaaar]

And here is the plan, to scale.

The 4 squares would be the support legs. The top left leg is not in the perfect position, so as to allow room for the PC. The steel frame I'm imagining would be rectangular, and the back left corner would simply hover over the back of the PC.

Perhaps the best solution would simply be to add more steel, joining it to the other steel with metal brackts?

PS - The 54 measurement should read 540

 

[AndyT]

Will you be able to open or close the windows and curtains without climbing on the desk?