[Cob] report on earthen floor, 14 months in

[Tys Sniffen]

So, thought I’d write up a small report of stuff I wish I’d known before I
started my floor, specifically about how it wears.

 

I have a cob house, about 1100 sq-ish ft, three levels, with radiant tubes
for heating.   Here in the sandstone hills in northern California, we dug
down below topsoil, put in about 44 tons of ¾” gravel (that’s about 6”-14”
deep, depending on how much leveling we had to do) and then put in a cob sub
floor made from clay and ‘road-base’, which is a clay-full crushed gravel
they use as a road top – sort of rural blacktop.   That layer was something
like 4” thick.   Then tubes, then 1 ½” of fine sand, clay, horse manure mix
“poured in” – that is, put in pretty wet and trowelled smooth. 

 

When that had completely dried, I did one room one way, and the rest of the
house another. 

The bedroom got 6 coats: the first 100% oil, then I waited a week, and did a
coat thinned to 75% with fancy citrus solvent. Waited a week, thinned again,
to 50% waited a week, then did maybe 2 more coats at 50%, waiting each time
until it dried. 

 

The rest of the house was done (each room separately) ‘all at once’.
Starting in the morning, I slopped on a heavy, heated coat, and as soon as
it wasn’t puddled, did another, and another and another, using less (but
still 100%) each time. I got 6 coats on in a day.  Once everything dried, I
did a fancy wax coat, buffing as much as I could.

 

Unfortunately, the one room done differently is the bedroom, which gets the
least wear, so it’s not a good comparison.  

 

They all look pretty good, with a dark chocolate color.  The bedroom seems
to be a bit shinier, which it turns out I like. 

 

However, what I see in my kitchen (where most of the action is) is a floor
that is NOT hard enough.  The wooden kitchen chairs, when someone sits in
them (and, surprise, that happens a lot) will leave (permanent) dents in the
floor, deep enough for a quarter to sit in.   I’ve dropped some things, and
they’ve left noticeable dings.   Basically, it’s not hard enough.  That’s
pretty frustrating, as I don’t know how I can repair it.  

 

If I could do it again, I’d figure out a way to spend more time and get it
harder, especially in the kitchen. 

 

Tys