Exterior Wall Plan Critique

[CR500]

Hi Everyone,

Looks like my kitchen remodel plan has grown to including pushing out a wall. The wall is running parallel to the joists and will be going out about 28". The plan is to cover it with a shed roof. A run of base cabinets and sink will be placed in this new area. Upper cabinets will be minimal due to the large window.

Please take a look and let me know your thoughts [footings, beam sizes, support column, ...].

Frost depth in this area is 30".

One thing I noticed while drawing this out is that I can't get the sink vent out of that wall or I'd have to cut through the header. Air admittance valves do not meet code in this area so I might have to do a loop vent.

Thanks!

Rob

LOL, just noticed a typo on the drawing. Gotta love those plum(b)ing holes.

[Under_Miner]

Well, around here (Canada) your only code violation would be the 35 1/4" cantilever on the 2x12's. In Canada, unless engineered, cantilevers cannot exceed 24" on floor joists running perpendicular to the support for floor joists 2x10 or greater.



Floor joists supporting roof loads shall not be cantilevered more than 16" beyond their supports where 2x8 joists are used and not more than 24" beyond their supports where 2x10 or larger joists are used.
The cantilevered portions referred to in Sentence (1) shall not support floor loads from other storeys unless calculations are provided to show that the design resistances of the cantilevered joists are not exceeded.
Where cantilevered floor joists described in Sentences (1) and (2) are at right angles to the main floor joists, the tail joists in the cantilevered portion shall extend inward away from the cantilever support a distance equal to not less than 6 times the length of the cantilever, and shall be end nailed to an interior doubled header joist in conformance with Table 9.23.3.4.

[CR500]

wow, that reads like a law book!

I could move the supports closer to the edges, I just thought it would be stronger pulled in. Someone told me code calls for the supports to only be 8' apart. That doesn't make sense to me, the distance between supports should be related to the size of the beam.

Another thing I just thought of, can I still build the wall with 2x4's or does code now call for 2x6's?

I better find a construction code book.

Thanks

[Phil H]

Unless you enjoy investigating building requirements, it would be better to hire a professional to draw the plans. Requiremments can vary from one area to the next. Some juristictions may require plans drawn by an engineer or architect when removing 12 feet from an exterior wall.

Since I have no idea about your local requirements (and I am not an expert in this), I'll add a couple comments that may be helpful. I am ***uming that the ceiling is below the header. Otherwise, you would not run it the entire length of the wall. You will be buying a 14' (or 16' ) 4 x 10 rather than 10'. I am ***uming that you are using the long header for convienience. If you have a sufficient number of trimmers, the building department may not be concerned about a hole through the header for a vent pipe.

Make sure your bracing is sufficient; there isn't much room for braced panels on the wall. I can't comment on your foundation. Is there a reason why you want to support it with just two posts. In closing, supporting the wall that you remove and tying the new in with the old may become even more challanging.

Enjoy
Phil

[CR500]

It was a little confusing the way I wrote about the direction of the floor joists. This wall is parallel to the joists in the existing kitchen. The joists between the existing kitchen and new wall will be perpendicular (see attached drawing).

I used the long header to carry the load from the shed roof. And if this wasn't confusing enough, part load from the "side" roof (almost vertical). This house has a funky Mansard roof. It is butt ugly.

Only wanted two posts purely for asthetics. There is a window below.

I was going to bring up the wall being removed after the new wall p***ed the test :-) The wall being removed doesn't carry any floor load since its parallel to the joists. The rim joist above it is a 2x10. Hopefully its doubled but I wouldn't be surprised if it isn't. My plan was to build it up to 3 or four @ 2x10 with posts inside the walls.

Thanks

[CR500]

I found an electronic copy of the requirements for building decks in this county. The requirements for my little addition must be at LEAST as stringent as this. Looks like posts up to 6' tall must be 4x4, up to 10' must be 6x6, greater than 10 feet tall isn't allowed. Posts longer than 4' must have bracing. Piers must be a minimum of 22" in diameter. Supports can't be more than 8' apart with a maximum overhang of 24" (sounds the same as canada).

That means I'd need three, which puts one directly in front of a window. Guess I'll use four.

In the end I've decided to contact a structural engineer and let him design all the beams. My guess is that it will break the bank and require me to scale back.

In the mean time I'll check in with my local library and see if they have the residential code book.

Rob

[Under_Miner]

You could do away with the exterior supports below the outside wall if you were willing to do some extensive work under your kitchen floor and give up 4" of your addition. The work would be quite a load, but the cost might be less.

Just a suggestion.

The exterior supports would be way less invasive and probably faster.

See picture.

[Under_Miner]

....Supports can't be more than 8' apart with a maximum overhang of 24" (sounds the same as canada)....

That means I'd need three, which puts one directly in front of a window. Guess I'll use four.....

According to the Canadian Wood Council, a 3-Ply 2x12 spanning 17'-9" can support one floor in a house. But because you have a roof load, I would still move the supports in the 24", thus hiding them in the crawl space, and your wall should have ample support.

All you're adding is one 2x12...cheep!:wink:

[CR500]

Kind of funny. I started out with the plan of adding a huge 30 degree bay window and curving the counters around the bay. I was going to cut the floor joists and cantilever out the side of the house as in your picture. Would have to move a couple HVAC ducts below the floor, but nothing too complicated.

Then I decided that for the amount of time and $$ I was going to be putting into the kitchen I wasn't happy with the compromises in the design. That led me to bumping out the wall, with the intention of staying under the existing soffit (18"). But now, how do I cantilever the rim joist at on one side of the kitchen, and the other side is a couple inches away from a steel beam (see one of my previous attachments). Don't know how to cantilever off the end of the beam.

The next bright idea was to just put in a couple of posts with the thought that its gotta be easier than cutting / turning all those floor joists. Then I noticed the soffit height is 3" lower than the ceiling height in the kitchen :-( Damn, now what. Thought that perhaps I'd set all the upper cabinets down 3" and hide it behind crown molding.

A contractor buddy stopped by and took a quick look. Of course he said "piece of cake" cut the flared bottom off the mansard roof, push the wall out as far as I want and put a shed roof on the top. The framing inside that soffit (holding the 2nd floor windows and mansard flare) is not done right (I'm surprised it hasn't come crashing down). He said we'll add the correct framing to hold that stuff up while its cut open.

So now I'm bumping the wall out about 28" and the kitchen design is sweeeeeeet! That extra ~32 sqft makes all the difference.

Whew, that got long!

You could do away with the exterior supports below the outside wall if you were willing to do some extensive work under your kitchen floor and give up 4" of your addition. The work would be quite a load, but the cost might be less.

Just a suggestion.

The exterior supports would be way less invasive and probably faster.

See picture.

[CR500]

Ok, tripple 2x12's to support the new addition.

What about above the wall I'm removing. That rim is a double 2x10. I could add a third (and fourth), but don't think that works if the wall above (sole plate) is only sitting on two of them (I probaby didn't explain that clearly). I could add a steel plate. Does a flitch beam work if the steel is on one side rather than sandwiched between the double 2x10's?

Lets see:

3@2x12, I=534
2@2x10, I=198

Need I for steel = 336, so that is ~0.28" x 9.25".

According to the Canadian Wood Council, a 3-Ply 2x12 spanning 17'-9" can support one floor in a house. But because you have a roof load, I would still move the supports in the 24", thus hiding them in the crawl space, and your wall should have ample support.

All you're adding is one 2x12...cheep!:wink:

[CR500]

Just thought I'd close the loop on this one. I had a structural engineer come out.

The girder under the new wall needs to be 2@ 2x12 or 3@2x12. I moved one of the supports to the edge, the other still has a 24" cantilever. I also increased the bump-out to 36"

The good news is the exterior wall (13.5') I'm removing is completely non load bearing. He suggested doubling the existing single 2x10 rim joist above it.

The wall between the family room and kitchen (this might have been discussed on another thread) needs a double 1.75" by 11.25" LVL. This is about 9.5' long, carries a center bearing wall and roof.

The footings (also discussed on a different thread) only need to be 18" in diameter.

One thing he brought up was that if the bottom of the footings are higher than the house footing, I need to project a 45 degree shear line from the new footing and ensure that it is below the house footing.

When looking for the engineer I started with a Co used by a coworker. They came back with a price of $3500+!!! I ended up calling a bunch of places listed in the yellow pages. The guy I decided to use, quoted me $850 for the site visit and beam design (he wasn't the cheapest). In the end, he billed me $500. Well worth the piece of mind.