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kbizzle 02-17-2011 08:22 AM

Building a half wall: 2 questions
2 Attachment(s)

my wife and i bought an early 70's split level about 5 years ago. the previous owners opened the house up a bit and they removed the old iron railing from the entry stairs and the safety rail that prevented someone falling off the main den level into the entry/stair way. obviously it's not up to code but we actually like the open layout of the room. fast forward to now... we have an 8-month old daughter who is learning how to crawl and roll to wherever she wants to go. it's past time to address this issue.

i want to build a half wall with some tempered glass inserts (please see the attached drawings). the wall is about 9 1/2' feet long. i have two issues:

1) the spot where the new half wall attaches to the existing wall is between two studs. my plan is to open the existing wall between the two studs from the height of the new half wall to the floor. i'll nail two 2x8" blocking pieces between those two studs (one near the top and one near the bottom of the new half wall frame), bolt the new wall frame to the two blocks and patch the open cut out. seems like that would be plenty sturdy but i'm opinion to better suggestions.

2) for the open end of the new half wall, i had planned to run the last stud of the wall through the floor and tie it with bracing and blocking to the floor system. after going into the crawlspace, i found that a floor joist runs parallel and directly under the position of the new wall.

i'm kind of puzzled as to how to best handle this. i sistered another 2x8" joist to the parallel floor joist under the site of the new wall so that there's more surface area to tie the new wall. my idea is to add 2 more 2x4's to the bottom plate near the open end of the wall. i'll then drive 2 or more 10" or 12" 1/2" lag bolts through the reinforced bottom plate into the floor joists below. my hope is that the long bolts will serve as steel posts to prevent the wall from wobbling. i'll also put several more lag bolts through the bottom plate in the joists below. is there a better way to tackle this?

thanks for your suggestions and feedback,


mrgins 02-17-2011 09:30 AM

Just barely read this, but a couple of ways come to mind.
1. insert a threaded rod through the existing floor joist and up into the 4x4 (not 2x4) post on the end of the new wall. Either let it run all the way to the top and cover the nut with a decorative plate, or attach it the way you might attach a joint in a long stair rail and plug the hole.
2. use steel L brackets on each stud. Bolt into the 2x4, lag into the floor. Block between studs in place on a bottom plate.
I'm assuming there is no space between the floor and the half wall.

kbizzle 02-17-2011 01:32 PM

3 Attachment(s)
mrgins, thanks for the response. i realized that my first two drawings didn't show the existing lower wall and the drop off to the doorway. the attached images better illustrate what i'm dealing with.

i was hoping that the 1/2" lag bolts that are 10" long would support the open end of the wall kind of like newel post bolts do. i like the idea of running a threaded rod the length of the final post but i'm going to have trouble finding a drill bit to go through the 43 inch post + the 2x8 floor joist. hmmm...

mrgins 02-17-2011 03:27 PM

You can also buy brackets for newel posts that screw into the floor. They're ok in a pinch I guess

dtsman 02-18-2011 08:48 AM

I owned a split level and did exactly that. I took down the railing and put up a 4 foot wall to put my tv against.

I built the wall laying flat on the ground with 2x4 and 3-1/2 framing nails.
Set the wall on top of the lower wall or beam you have there. Lag one side to the current wall, lag bolts through the bottom plate. Sheet one side with 1/4 inch or 3/8 plywood, then Drywall, and then added a 1x8 top plate with a routered edge. You will be suprised at how firm it comes out.

The plywood firmed the wall so I would not have to put in a post at the free standing end. I also took advantage of there being a closet under this area. So I ran cable, phone, and electrical wire back over to my laundry room for connection by fishing through the floor joist and doing my drywall damage in a closet.

You could skip the plywood part and use blocking to firm the wall as well.


If the women don't find you handsome,
they should at least find you handy.
(Red Green)

kbizzle 02-18-2011 09:14 AM


so glad to hear that it worked out for you! sheeting the inside face of the wall with plywood before the drywall sounds like an excellent idea. i think i'll give that a shot. thanks again!

Gary in WA 02-19-2011 12:14 AM

I'd build it as drawn, with a 2x6 1/2 wall so the end stud could be attached below -- flat. 2x4 end stud with 2x4 stud flat + spacer to get the 5-1/2". Only the flat stud runs alongside the doubled joist with a through-bolt or all-thread holding tight after plumbing wall. Recess the nut on the doubler side, only deep enough to hide the nut under drywall on the stairs side. Needs to withstand the 200# side push, per Code.
The horizontal hole for the bolt should be in the middle of the joist depth;


kbizzle 02-19-2011 08:22 AM


i think that's a fine idea. i can then fir out the den side of the wall to be flush with the flat 2x4 anchor piece. going through the floor will make the strongest wall. i'm going to get started tomorrow. thanks again, everyone!


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