I am looking for suggestions on how to attach a 2x4 to a cinder block wall.
Here is the scenario. The 2x4 will be running horizontally on the interior
of a basement wall below the ground level. It will be attached flat to the
wall similar to a ledger board. The wall is made of cinder block (not
cement block I assume because the property was built in 1948). The basement
was completely gutted down to the exterior walls and all new walls were
framed out with 2x4's for a complete remodel of a basement level apartment.
All of the exterior walls were framed out with 2x4's with the studs about
1/4-inch away from the wall and secured at the top and bottom with top
plates and bottom plates.
However, about 15 feet of one exterior wall has a 4-inch PVC sewer line
running along the bottom of the wall about 6 inches above the floor level.
So, the wall above that sewer line cannot be attached to a bottom plate
along the floor because the sewer line is in the way.
What I want to do is run that wall down to a wood "bottom plate" that is
actually attached to the wall instead of to the floor. To do that, I want
to attach a horizontal 2x4 flat to the cinder block wall with anchor bolts
of some sort. Then nail a second 2x4 on top of that to create the new
"bottom plate" for the wall above the sewer line.
Since the 2x4 will be attached to the wall below the outside ground level, I
was thinking of using some type of rubber or similar strip to try to isolate
the wood from making direct contact with the cinder block to avoid moisture
and termite problems. And, maybe I would use pressure treated wood for that
one 2x4 -- but I'm not sure about that idea.
So, one question I have is what to use between the wood and the wall --
rubber, tar paper, or what?
And, the second question is how to attach the first horizontal 2x4 to the
wall. I know there are different types of anchors that could be used. One
possibility would be anchors that go through the cinder block where the
hollow part is and anchor from the back. Another possibility would be
anchors that just get drilled into the cinder block but make sure that they
go in where the block is solid all the way through.
Any suggestions or ideas would be appreciated -- especially regarding what
type of anchors to buy and use to secure the 2x4 to the wall.
I'd use pressure treated and tar paper.
Any of the various proprietary ,expanding types; eg, Hilti
Toggle bolts (in core area, not web)
Why are you needlessly making building this wall more complicated than
needs to be ?
Box in the sewer pipe by constructing the wall where it can run from
ceiling unobstructed... The tenants in this basement unit are not
like having an exposed pipe with a wall built cantilevered out above
All sorts of lovely stuff will accumulate behind such a pipe,
dust bunnies, clumps of hair that build up, the errant sock that gets
Not to mention that the sound of water isn't so relaxing when you know
is sewage in the pipe...
Just build an unbroken wall that has access panels located wherever
there are clean outs in the sewer line or a fitting that turns a
where the pipe changes directions... You don't need access to the
entire pipe all of the time, if you have a repair that needs to happen
in the future then you would cut the sheet rock away to access
the pipe... By building a proper unbroken wall, you will be able to
properly insulate the entire wall both against the chill of the
wall as well as the sound of the water flowing in the sewage pipe...
Any other solution is just a folly...
That seems to be a recurring theme on this usenet group... I
understand that not everyone knows how to do everything, but when
someone doesn't know how to approach a project, why do they always
devise the most cockamaime plans?
If you don't know how to do something ASK HOW TO DO IT. Don't present
your 50-step plan that involves hanging a wall from another wall by
cantilevering it off the edge of a 2x4. You're fixing a house, not
building a replacement for the space shuttle.
When things get that complicated, that's a HUGE RED FLAG telling you
to STOP, and seek professional help. Home improvements are NEVER that
Cantilevering the wall just isn't going to work. It's going to sag
over time as the nails pull out. Plus as you said, the sewer pipe is
The bottom plate needs to be fully supported, and the sewer pipe needs
to be covered.
Simple solutions are best: As you said, bring the wall 6" into the
room and build it properly, floor-to-ceiling. You lose 6" of room, but
the job is done properly, and it will last. Get creative and build
alcoves into the wall to make use of the "wasted" space... Book
shelves, or an entertainment center.
The next-best solution is to build a platform around the sewer pipe,
then build your wall in the original location off that platform. Still
a lot simpler than trying to engineer a cantilevered wall that nobody
has ever done before.
On Aug 23, 10:39 am, firstname.lastname@example.org wrote:
Errm...unless the wall was built with 2x4 on the "flat" it will take
8" or more (depends on the actual outsid diameter of the pipe) of room
space. Shouldn't be a deal breaker though. It will only be 4" more
than what he is planning anyhow.
The same foam they use on top of the cement or cinder block. It's usually
pink. It's also good to put it under the wood attached to floor. It's code
here to use pressure treated, but only on Holmes on homes, do they always
use a polyethylene foam moisture break.
That's prevents using polyurethane glue as extra strength against the wall,
but unless the wood is thoroughly dried, it's not going to stick anyway. I
thick your stuck with either toggle bolts, which can rust, or some epoxy
based holding devices.
I'd give up the 6-8 inches of room space, and move the wall in. You can
always do flush bookcases into the dead space if you want to jazz up the
apartment. I'd also band the bottom of the wall with a wide trim plate
that can be removed to get to the pipe when needed, without major demo
work. Old cinderblock or concrete block walls are risky to mess with-
the mortar between them loves to let go without warning, when any
strange forces (like a hammer drill) are applied.
Unless the OP lived in an area totally devoid of any fire safety
using a large piece of wooden trim at the bottom of the wall rather
sheetrocking first would be a violation -- the fire compartment wall
would be incomplete...
Usually a minimum fire rating of 90 minutes between the differently
occupied units is required of demising walls/ceilings...
The concrete block wall and all the dirt on the other side don't count?
This is a basement apartment. But you do sorta raise a good point- there
should be fire stops at the tops of the new walls, to divide the stud
bays and dead space behind wall off from the bays between the ceiling
Fire could still enter the bottom of the wall, the goal of creating
fire compartments is that all six sides of the compartment are
contiguous with as few disruptions as possible...
All holes, no matter how small must be fire-stopped... Every
pipe and wire...
Leaving a firewall open at the bottom (i.e. sheetrock incomplete)
would be allowing fire to enter that wall cavity even if it is
at the top and is not the best construction technique...
Nor is installing cabinets in a kitchen without sheetrock behind
them, that is just asking for pest control problems in the future
as well as other issues...
What is the OP's issue with building a wall straight up from the
Needless complexity where it ISN'T required... I bet this wall
have enough blocking in it to be rigid enough... I wonder how it will
hold up given that everything on the wall will essentially be hanging
from the top plate...
Thanks to all for the replies. We ended up going with the suggestion to use
Tapcons to secure the pressure treated horizontal 2x4 to the wall, and we
used "sill seal" that we had on hand between the 2x4 and the wall. We
placed the Tapcons every 16 inches in the vertical mortar joints between the
cinder blocks. Then we used a nailing gun to attach the second regular wood
2x4 to the first pressure treated 2x4. It all worked perfectly and that
part of the job is done.
Regarding the suggestions about building out the wall using 2x6's etc., it's
a little hard to explain here exactly why we didn't do that. But, the brief
version is that the sewer pipe will not be part of an exposed wall.
Instead, kitchen base cabinets will be in front of the sewer line in a
kitchen, and a bathroom tub/shower will be in front of the the sewer line in
a bathroom. And, yes, there are fire stops at the top of the walls etc.
Again, thanks for the ideas. The Tapcons worked great.
Also appreciate the update. But to hang out here and try to be a
solution-giver, you gotta start thinking like a teacher or field medic-
you do the best you can, and hope you helped, but learn to live with the
fact that most of the time, you'll never know how it came out.
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