I’m renovating my house and had to reframe a wall to put in a picture window. This wall is the front wall of a “bump out” centered on the house that is 10 ft wide by 5 feet deep. It is now 2 stories (we added a level to the house) with no floor load or roof load. The area I reframed was the first story of the wall. When i disassembled the old wall, i found that this “bump out” must have originally been a porch. There was no bottom plate. The old porch flooring just sat on the front rim joist which is 1 3/4 to 2 inches thick (good old lumber). The porch flooring only extended about an average of 3/4 of an inch onto the rim. The floor as it exists now is actually built on top of this original floor on 2×4 sleepers followed by a new subfloor and tile. I didn’t feel confident putting a 2x bottom plate on the old porch floor since it did not bear on the end joist that much (porch flooring perpendicular to the end joist). I notched the porch flooring where i needed studs and set them right on the end joist toe nailing them in. My question is…is the 1 3/4 inches to 2 inches of bearing my new 2x4s have on the end joist sufficient for load transfer. In a couple of years when i demo the first floor, i’ll open that foor and have access to add another joist next to the end joist to give full bearing but since i don’t have access now, I wanted to make sure it’ll hold till then. Thanks.
Richie
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Replies
I believe the better solution would have been to sister an additional rim joist on the single you already have. It sounds like the old porch you uncovered probably had 1X tongue and groove floor boards perpendicular to the rim joist in question.
Much additional info would be needed regarding the foundation particularly when a 2nd story is added to an existing 1st story. My first experience required 16' caissons down to bedrock (often called "refusal") and then horizontal grade beams poured over about 6" of cardboard that will kick out under pressure from the outside or inside. Lots of rebar. We have expansive soil around here.
All of the below ground work was specified by a structural engineer because we were going up two stories. Turned me into a licensed general contractor. Passed all inspections.
I have remodeled many turn of the century houses using full dimension lumber (not P4S) which means planed four sides. The old saying that they don't build them like they used to is appropriate when one is taking the position that the older stuff was not well built. They couldn't pass code--and code is a minimum standard. Tyr
The foundation was actually underpinned to compensate for the load so that's fine. I just have no access right now to double the rim. I will do it eventually but i can't get to the space underneath now. I remember hearing 1 1/2 inch of bearing was sufficient for load transfer but wanted to check. Thanks.
Richie
I don't know that I've ever seen a specific sq. inch minimum bearing rating for studs personally, but I would guess you'd be ok with 1 3/4- 2" of bearing. Just a guess, though.
It actually would come down to the compressive/crushing ratings for the studs and the joist, and the actual load of that wall, I guess. What kind of wood are you framing with? What's the load like on that wall? 16" stud spacing? If you were really stressing, seems like you could go to a tighter spacing.
That's only considering vertical loads, of course. I'm assuming you've got your lateral and uplift taken care of in some fashion.
k
The whole front wall is sheathed with 3/4 ply foundation to the top so lateral loads should be fine. Uplift? Couldn't tell ya. As far as loads... it's only the load of the two story wall itself. No roof or floor loads r on it (gable roof bears on side walls and it's the stair well so no floor joists rest on the wall). The only way into the crawl space under this area is to cut up the floor which I figured I'll do at some point which is when I could double the end joist. The two picture windows (1st and second floor) line up so I guess the main load would be from the trimmers on each side out to the corners (10 ft wide wall with 6 ft openings both stories). The framing is 16" o.c , double jacks on either side of header plus the king. I know when I work on houses with 2x6 wall framing i often see the framers just double a header like in a 2x4 wall and leave 2-2.5 inches of stud unsupported by the header so I figured full bearing is not always necessary but is 1.75 to 2 inches sufficient for now? Thanks.
Richie
My guess is you're fine, especially if it's a non bearing wall. But that's just a guess.
What wood is the framing? s/p/f? doug fir?
Again, if you were concerned, you could either use a closer spacing, or add studs flatwise which would obviously have full bearing. I'd definitely do that if it was a paid job. On my own house, meh, probably not.
k
Studs r doug fir. Guess I'll wait. I'm having surgery next week so time is limited. Also don't want to do that much damage right b4 Christmas. At some point I'll add the second joist so they have full bearing. Remodeling especially when ur living there sucks at times. I remember when we ripped the roof off I had to insert two new headers on the front wall from the outside so I didn't disturb inside. I cut the existing studs off from the top plate down the depth of the 2x12 headers using existing studs as the kings cause I couldn't get new studs in. One opening was fine but the other was like 14 or 18 in ches too wide so when I finally opened up and put the window in I added the double jacks on either side and then added two more further in to close the opening to the window width. What a waste of wood and a pain. I nailed the existing 1x sheathng to all the new studs. Was curious if I needed to change to plywood for racking resistance but architect said no. I still wonder. Maybe I'll put a layer of 1/2 ply on the inside b4 the sheetrock. I don't know. Any thoughts? Thanks.
Richie
I'm a big fan of plywood shearwalls every time I open a wall, but I'm in the bay area... What kinds of forces are you looking at? EQ? Hurricane? Tornado?
I'd have to see the whole structure to see how it's working and if that particular wall is prone to racking. It's entirely possible that section is restrained by other walls and diaphragms. Well nailed 1x has some racking resistance too, of course.
k
For Christmas ask Santa for a digital camera. They are less than $100 bucks now. Pics would really help.
Does any of that porch floor framing cantilever over the foundation? I'm thinking of that 5' projection you mention. It could be that the outer wall of that porch also has the underpinning you describe (much like supporting a deck with 4X4's in post holes with a lumber span)
There are cantilever and bearing area calculators on the net to help you out. A lot of older homes are lightly framed by today's standards. Some day you will move, the prospective buyer will hire an inspector to get financing and the report could say that the framing doesn't transfer loads correctly. Just a thought. Luck on that surgery. Been through a broken femur and knee surgery since May. Tyr
Things are not always what they seem; the first appearance deceives many; the intelligence of a few perceives what has been carefully hidden.... Roman Poet Phaedrus 15BC–50AD
Edited 12/4/2009 1:21 am by Tyr
Yeh, a picture would be worth a thousand words. I'm in NYC ...we don't design for earthquakes, hurricanes, etc. The house is 35 feet across the front. This bumpout is centered and is ten feet wide and 5 feet out from the front wall. The house foundation is uninterrupted. The concrete foundation for the bump out is three sided, the long front and two 5 foot sides back to the house. There is no cantilever. There actually is no load on the wall thanks to a double 14 inch LVL that runs across the 10 foot front and bears on the corners of the wall. Now my only concern is the posts in the corners. I always figured they were continouous but found that an onld header across the front was resting in the corners. I had to cut that header out but left the pieces in the corners. So the corners are 2x from the sill to the old header piece, then a header piece, then a 2x4 piece to the top plate. I put new 2x4s next to the old corners but they are broken by the old header piece remaining in the wall also. Is the disjointed corner as strong holding a vertical load as a continous corner would be? What a headache. So much easier when it's all new. :)
Edited 12/3/2009 7:56 pm ET by Richie921
If I'm understanding this right, the bump-out is an addition, so the tributary load on this wall is only half of the 5 ft? In that case, rest assured that a couple guys you know nothing about on the internet guess that you're probably OK for now. ;-)
-- J.S.
Yeh the bump out must have been a 10 ft wide porch that was enclosed at some point. The end joist is either on a plate on the foundation or...I don't know...can't see...but it is DEFINITELY on the foundation. Thanks for the guess. :)...Oh this is the 10 ft front wall. The projection off the house is 5 feet.
Richie
Edited 12/3/2009 5:05 pm ET by Richie921
I guess i'll try to get under and double the end joist so the studs have full bearing. I'll open the corners and see if there are any continuous studs in the corners. Trying to describe this in words is killing me. There are 14 inch lvls above but the placement is too hard to describe in words. If the corners are disjointed I'm gonna try to put continuous studs next to them to lock everything together. Being that the loads above are on 14 inch lvls solid studs 3 inches in from the corner should be sufficien to support a load of 1 wall and a small roof. Thanx for trying to help without really seeing the situation. Just one last question. The old walls of this bump out are 8 foot. The old house is 9 foot. To make up the height I had to put short studs from the old top plate to a new top plate under the new lvls at the new floor height. Is nailing it all together sufficient or do I need bolts. Thanx.
Richie
Edited 12/3/2009 8:43 pm ET by Richie921