Help with math for a DIY project

October 9, 2024 4:12 PM

I am tiling a rectangular table. I want to make an inner rectangle of 4x4 tiles and an outer rectangle of different sized tiles, but what should the dimensions be of that inner rectangle? What size/number of tiles should I use for the outer rectangle?

I am sprucing up an old table using some 4x4 inch talavera tiles left over from another project. The goal is to make something like this.
The table is (in inches) 21w x 47l, for a total area of 987 inches (if my math is right).
By my reckoning, to use the 4x4 inch tiles I need to have an inner rectangle with an area of 976 inches. But I am having trouble figuring out what the width and length should be of that inner rectangle.
I also would love some help figuring out what size tiles I would then need for the outside (border) of said rectangle.
Math is not my strongest skill, so I would greatly appreciate any help!

posted by firemonkey to Home & Garden (7 answers total)

You have the table and the tiles? Start (unmortared) tiling the table with the 4x4s, _starting in a corner_.

When you can’t put on more 4x4s, that’s as big a panel of those as will ever fit. And the margins on one side and edge will be almost twice as big as they would be if centered (you will need one more grout-line-width).
posted by clew at 4:18 PM on October 9

(Working it out on my fingers, inner patch is 5 tiles by 11, so 20”x44” *not accounting for grout*.)
posted by clew at 4:20 PM on October 9

I don't think I'd even worry about thinking of the area of the table in terms of square inches - you have two linear dimensions that you need to divide up to fit a number of tiles in, and based on the linked image I'm presuming you don't want to cut the inner panel of tiles since they have a pattern but cutting the solid border tiles would be fine.

What might make it look weird is that you have a width that is 1" more than the closest 4" module (20" = 5 tiles) but a length that is 1" less (48" = 12 tiles), so with full tiles in the middle, the border will not be a consistent width. You'd probably want to go with a narrower border than in the linked photo, because that's 6" on either side, which will reduce your center panel to 2 full tiles plus 1" of fluff (4" border + 2" border + 8" field tiles + 2" border + 4" border = 20"). So do you want a 3 tile wide center field? Then you'll have 4.5" left over for the border. Going the long way, 4.5" of border on each end will leave you with 38", which is 9 tiles plus 2" of leftover. So a 3x9 panel would end up as 27 central tiles. I don't know if tiles are like brick where the joint is accounted for in the tile size.
posted by LionIndex at 4:30 PM on October 9

I'm going to assign each inner tile an extra 0.125" for grout, the divide each dimension by 4.125". That yields almost exactly 5 tiles across, but you want a border, so let's call it 4 tiles. They equal 16.5" together, leaving you 4.5" to account for, meaning each side gets 2.25" including grout. Then lengthwise it's the same thing, 47/4.125, which is 11.4 tiles, call it 10 for a matchingish border. 10*4.125=41.75, so 5.75"=two rows of 2.875" tiles+grout. I'm guessing the most aesthetically pleasing option would be to fudge on the grout lengthwise such that the inner tiles are all just slightly farther apart in that direction than the other, and then your border of tiles and the first grout line can match all around. (This is a 4x10 inner layout, to be clear, but 3x9 is also a totally valid solution depending on your vision for the border!)
posted by teremala at 4:32 PM on October 9 [1 favorite]

I sketched it out in rhino:

https://imgur.com/a/SptnQGH

basically, you have a center of 40 4x4" tiles, a long edge of 10 2.5x4" on each side, and a short edge of 4 3.5x4" on each other sid.e
posted by signal at 4:33 PM on October 9 [2 favorites]

That did assume you wanted to go all the way to the edge with tiles, sorry! If you want to have wood around it like the link, subtract at least one inner tile in each direction. Each one removed gets you about 2.125" extra space on both sides (I personally would not be able to achieve mathematically perfect grout lines), again an aesthetic decision.
posted by teremala at 4:37 PM on October 9

If I were you, I would make the tiles out of strong flat paper (bristol board, maybe, or cardboard) and move them around on the table. Make sure to leave space for grout lines. Then buy the right number of tiles - and the right size of grout spacers!!
posted by nouvelle-personne at 6:41 PM on October 9 [3 favorites]