I am designing and will be building a diningroom table. We want to have
maple around the edge and tile in the middle. This will obviously be a
little heavy, and want to build in sufficient support that it won't sag
whan it's loaded full of food and an elbow here and there. I also don't
want to build it too strong - thereby adding lots of excess weight to the
Can anyone point me in the direction of a website that lists strengths of
various dimensions of lumber?
How much load a 1x3 could bear, max length, where the legs need to be, how
much overhang and so forth. (Not just for 1x3s, but a chart with various
sizes, so I can figure out what I'll need.)
I seriously doubt there is any one resource that will provide the info you
requested. There are several sites that provide load capacities for species
of wood but mainly for the construction industry. There is a site that will
show you span tables for specific woods (thickness and widths) especially
for making shelves - but for table making, I think you're on your own.
You didn't state what style (round, center pillar, apron frame, legs, etc.)
or size table. A 3/4" ply underlayment for the table section where the
tiles will be may be way overkill depending on the type of tile and size of
table. If you're using 6" squares (or there about) then they will lend some
rigidity to the top and you would not need as much cross-bracing underneath
to prevent sagging if you use thinner material. I would be worried more
about when people lift the table by the edge to move it and flexing a
section which could cause a grout line to crack. So a design that takes
that into account would be wise. Edging or bread-boarding all around with
say 2" or 3" width of hardwood that is secured to the underlayment will help
prevent any flexing of the tile field.
Just about any underlayment you decide on will need cross-bracing just to
keep it flat over time even if it had no tiles installed on top.
Some of these sites may have some helpful info or lead to another site that
would be more specific:
http://www.fpl.fs.fed.us/faqs.htm <<< Start Here
and there are many, many more but these will keep you off the streets and
out of trouble for awhile.
As a suggestion there are many stores selling such table's,
Peir 1 comes to mind and there are many others.
Take a look at them, No clerk is going to object to you looking underneath
the table, Hell you are just trying to ascertain whether it will be strong
enough for the kids to jump up & down on it .
From that you can expand or subtract to the size you are looking to build.
On Mon, 20 Oct 2003 10:47:56 -0400, "Carolyn Marenger"
The critical area to keep from deflecting is the field of the table
with the tile on it.
About ten years ago I built a marble tile topped dining room table
about eighty inches long and about forty inches wide. I used 3/4
marine ply for the substrate and thinset the tiles to this.
I used three inch wide hardwood for the apron . Between the aprons I
ran two and one quarter inch wide strips of hardwood ply every twelve
inches, with short strips butting into these at ninety degrees, on the
These strips were biscuit joined into the apron and the ply substrate
and the top edges were glued to the ply substrate. Then I applied a
one half inch thick ply with glue to the underside. This turned the
substrate assembly into a kind of space frame.
It may seem like overkill but the space frame construction allows
people to lift the table without flexing the substrate to the degree
that the joint lines on the tile would crack.
Even with this construction it is important to use a flexible grout.
The grout will need to be sealed in order to resist staining.
This table had a hardwood surround. If you go this way you should
prefinish the wood, paying particular attention to the edge that will
butt up to the tile. By doing this you will avoid having the grout
bleed into the wood.
The people I built this table for still have me over for dinner once
in a while and there are no crack lines in the grout.
It is heavy. I don't think there's any way around that. Ceramic tile
in three eights thickness is about four pounds per square foot. My
table was about twenty two square feet, so there is about eighty eight
pounds of tile involved.
Thomas J. Watson-Cabinetmaker
Gulph Mills, Pennsylvania
How big is the tiled area compared to the table? If it's only a
bit in the centre (thinking of some Scandinavian-style designs I
remember from decades ago) then would it make sense to make that
bit "float" in the centre so that the table flexes independently
of the tiled portion?
Obviously not an option if the tiled area is most of the table
Your concern here will be stiffness, not strength as the table will
sag excessively long befor it breaks.
The phenomenum you need to analyze is _strain_.
The analysis of stress (how much it takes to break soemthing) and
strain (how much something bends under a given load) is fairly simple
for a simple shape like a floor joist and gets more complicated as
the shape gets more complicated. For your table you'll need to know
the tensile strentgh and Young's modulus for maple which can probably
be found. But then you'll need to model the table as if if were
a beam or a plate supported at it's edge. There is a handbook by
Roark (I think) that a civil or mechanical engineer could use to
do the analysis for you.
Someone could put together a chart for table design similar to
what is used by architects to size floor joists, but I doubt that
The good news is the stiffness of a beam goes up with the cube of
the vertical dimension of the beam. So a 1 x 4 apron will be almost
three times as stiff as a 1 x 3 apron. This means that you only
need to overbuild the table a little to get a big margin of safety
in your favor.
A table apron is essentially a beam supporting the tabletop much
like a floor joist supports a floor. So if the span of the legs
is long enough to compare with floor joists in an architect's table
for sizing floor joists then you can get some idea. Maply will
probably be stiffer than the stiffest wood in the tables, but not
by a whole lot. Two 1x4 table aprons on a table 24" wide will be
about as stiff as a 2x4 floor joist on 24" centers. If the legs
on the table are sized to look proportionate to the table they will
probably be more than strong enough. Only if you want real spindly
legs should you have to worry about them. The amount of overhang
is also going to be a matter of taste and convenience. Unless you
design a pedestal table any aprons that will support the middle of
the table will handle the overhang easily.
The problem you are addressing is not trivial to analyze, but it
is almost trivial to just wing it. For instance, you could just
take a piece of 3/4" plywood the size of the tabletop you want,
support it between two sawhorses on a couple of cheap 1x3s stack
weight on it equivalent to what you want the table to bear and
see how much it sags (or if it breaks). Then replace the 1x3s
with 1x4s and so on until it is stiff enough to suit you.
Substitute the same sized maple aprons in your finished design and
with everything rigidly joined you should have a nice factor of safety.
Or just look for a table like the one you're making and see what they
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.