When designing my
new lab, I wanted to make a grand interior statement that would also delineate
the entry area from the rest of the open upstairs. For economy purposes, the
majority of the upstairs ceiling is drywall, so what does that leave as an
alternative? Well, wood for one. I looked at pine T&G planks, the old
standby. After spending hours picking through the boards at the local box
store, and paying almost $1 per linear foot, and hauling it all home, I
realized that even with the warmest finish I could find, the ceiling would still
exude a cabin feel. Not the vibe I was going for. But not only that, there’d
still be the knots, voids, and sap-weeping to deal with, and then the cost and
time of finishing 200+ sq ft of the stuff. No, there must be something better.
I looked at “prefinished tongue and groove planks” which turned out to be a
composite of chip board and glue wrapped in a woodgrain decal. Umm, no. What
else?
Pre-Work:
So I started doing
some research about installing flooring on the ceiling. Answers were few and
far between. Examples exist of people doing this, but tech forums are split on
the subject. Apparently the idea is too much to handle for some. What I
eventually deduced was that floating floors are out, for obvious reasons.
Composite and laminate floors are made of layers that expand/contract at
different rates and even though some are rated for a nail-down application, I
wanted a homogenous material to avoid as much risk as possible; if a plank
comes loose on the floor, fine. If it comes loose on your ceiling, now we have
a problem. Same goes for “engineered floors” which are a veneer over a
substrate material.
I had a look at
the floor section at Menards and found some tongue and groove Honey Bamboo
flooring that looked very appealing. Best of all it was pre-finished and on
sale. Compared to pre-finished solid wood, it was a bargain at under $3 sq/ft.
Now, I had two new
problems…1) How to attach the planks. And…2) My joists are 24” OC while the
planks are 37-3/4 long.
In reality, if I
had 16” OC joist spacing and had confidence that the joists were perfectly
straight (such as TJI’s), it would have been possible to attach the bamboo directly
to the joists. This would have worked great in a basement. However, I wasn’t
comfortable with the joint spacing, my joists were traditional 2x10’s so I
couldn’t guarantee flatness, and this ceiling is also the underside of the
insulated and vented roof (flat roof), so I had some concerns about where my
dew point would form.
The solution? I
decided to install 7/16” OSB over my joists as a base. This would help seal out
potential dust and drafts that might work through the joints, provide a solid
face to accept glue, create a thermal break, and allow shimming and adjustment
between the OSB and planks if things got really bad. I attached the OSB using
small square-drive trim screws of sufficient length to penetrate well into the
joists, making sure the heads sat flush (or slightly recessed) with the OSB.
Any panel joints that didn’t fall over a joist received blocking to keep the
edges flat. I could have used sheetrock but I planned on both gluing and
pinning the planks with my brad nailer and in my experience, sheetrock would never hold the brads.
Ultimately, straightness and flatness were the goal.
How to Attach:
The last thing I
want to do is have these planks loosen up and break free years from now.
Granted, they’re T&G which provides some assurance, but ultimately a
failure of consecutive rows would result in a real mess. So…glue and brads.
Using glue ensures the majority of plank area forms at least some kind of bond
with the OSB it makes contact with; imperfect voids are filled. The brads do 2
things- they keep the plank in place until the glue sets, and they provide
backup in case the glue fails someday.
So what glue? I
ran a test with three of the most likely candidates I could find- Liquid
Nails-Heavy Duty, Loctite PowerGrab All-Purpose, and Loctite PowerGrab Molding.
All promised “instant grab” and were designed for attaching wood to most
anything. All came in caulk tubes. The test consisted of gluing plank samples
to a strip of OSB screwed to the ceiling and evaluating for various properties,
both initially and after 24 hours. I won’t go into all the details, but Liquid
Nails won out for quickest initial setting, strongest breakaway bond, lowest
cost and it’s available in the large size caulk tubes. This is what I proceeded
with for the project.
Layout:
First thing you’ll
want to do is acclimate your material to the surrounding environment; I staged
my bamboo for a couple weeks in advance. Meanwhile, consider your layout. Which
direction do you want the planks to run? If you put up an OSB base, you can run
them whichever direction you like. I suppose you could run them diagonal, but
be advised, bamboo is tricky to cut if not with the grain. A high-speed,
fine-toothed blade in a miter saw helps. For cutting around can lights and
openings, use painters tape to prevent splintering (actually the bamboo fibers
tear free and ruin the surface like pulling a thread from a sweater). A
fine-tooth jigsaw will do the trick. For semi-circular cuts, approach from each
direction and meet in the middle.
After you’ve
picked the direction to run your planks, consider the room width. Classic floor
layout rules apply here. You don’t want 3 full sections and a 2” piece. Better
to have 2 full sections and split the difference out of 2 remaining sections.
The “scraps” could be used to lead off the next row to stagger your joints.
Ultimately, it’s an aesthetic decision to avoid a “zipper” look. Keep in mind
the short edges of the planks are also tongue and groove so plan accordingly. It’s
important to do this up front so you’ll also know how much scrap you’ll end up
with. Knowing this in advance means you won’t need to run out mid-project for
additional bamboo that may not be from the same lot.
Squareness:
Consider where
you’ll start with your first row. Measure all 4 wall lengths up at the ceiling
to see if one is longer than another. Use a framing square to determine a
square corner for reference. Ultimately, I found my room width was consistent,
but that one of the long walls was ¾” longer than the other over 24’. I
determined that 3 of my corners were square so I knew where the ¾ gap was going
to end up. BUT, in my case it made more sense to pivot the entire assembly out
from the long wall starting corner by 3/8 and split the difference. Like the
old adage- better straight than level.
Reference Line:
After you’ve got your
pattern decided and figured out your squareness and starting point, it’s time
to snap a starting chalk line. Getting the first couple rows of flooring in
perfectly straight is important. It’s tough enough to do on a floor, but this
time you’re fighting gravity, too. I did something a little different. My plank
width was 4” including the tongues. I snapped my chalkline from 0” at one
corner to 3/8” off the wall at the other corner, then I measured 4” out from
this line and screwed my 6’ level to it. Now I could apply adhesive to the
bamboo planks, stick them to the ceiling, and pull them tight against my level
(checking to see that the groove edge of the planks were in line with the
chalkline). After the glue set, I unscrewed the level and moved it down for the
remaining pieces of the first row (since my row was longer than 6’). A long,
straight 1x4 or 1x6 would do nicely for long distances. NOTE: If you attempt to
brad nail this row through its tongue shortly after gluing the pieces up, they
will shift. Avoid the temptation. If you brad nail through the face, you’ll
probably splinter the planks. Apply firm pressure to each piece for 10-20sec
and let setup for an hour or two. You might also be tempted to pull the level
and continue with the install, but everything will shift if you try to pin the
second row without letting the first setup, so just wait.
Continuing On:
With the first row
set, pull down the level (or board) and proceed.
I like to put a
couple brads through the tongue of each piece after tapping them home with a
scrap of bamboo and my framing hammer. Make sure the first row doesn’t shift
when tapping the second row home. Even pinned boards will move if the glue
hasn’t cured. As you accumulate more rows, the combination of total glued
surface area and multiple brads will make it much easier to tap the next plank
home without fear of shifting. When choosing brad locations, look for the low
spots along the plank when fitted to the previous row. If one joist is higher
than the others and the OSB creates a gap at that point, then don’t pin your
plank there or your bamboo will follow the curve of the ceiling instead of
laying flat.
I left an 1/8” gap
along the long walls for expansion. As you select your next piece of bamboo,
look for surface imperfections and bowing. Reject any that will cause you
grief. Also take a look at lot-to-lot color. Intermix pieces from different
lots whenever possible or you’ll end up with obvious striations.
Do yourself a
favor and set up a card table or other work surface ahead of time. I found it
easier to keep a pile of pre-cut lengths in one pile, light full length planks
in another, and dark full length planks in a 3rd stack. To save time,
it’s easier to choose the next several pieces, lay them face down on the table,
apply your adhesive (1/4 beads) and then stage them where they can be easily
reached to avoid multiple trips up and down the ladder. Better yet, have a
second person doing the selecting and applying the glue while you do the
install (or vice versa). And if you decide to take a break, be sure to wipe
excess glue from above the tongue of the last installed row to prevent
interference when you resume your install.
Keeping it True:
As you proceed,
continue to check for flatness. Like a brick mason keeping each course level, over
long runs you may have to adjust the fit of individual planks to maintain straightness
of each row as tolerances stack up. Most of the rules for installing bamboo on
the floor hold true, but beware that most bamboo trim isn’t real bamboo at all,
but rather MDF strips covered with bamboo decals. In my application, this
wouldn’t do, so I went with oak and found a complimenting stain. If this makes
a difference to you, check it out beforehand.
And that’s it! Good Luck!
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| A shot of one of the areas now featuring bamboo. Sorry for the narrow field of view; stepping back any further resulted in the ceiling being 'out of plane'..like taking a picture of the wall to get the ceiling. Yeah, I like low ceilings. |
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