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lee12 · May 18, 2010, 07:18 PM

Hi everyone,

Planning a 2 story addition with full basement. One of the objectives is to have the first floor of the addition be a step or two lower that the first floor in the rest of the house. Beside just allowing for a higher ceiling in the new 1st floor room, the main reason is that the current second floor joists are only 2x6 and I will need 2x10 in the addition. To have the top of the second floors line up, the first floor ceiling in the addition will end up being pretty low (if this isn't making sense hopefully the drawing will). Connecting the 2x10 floor with the 2x6 floor is another issue.

One solution I've considered is framing a supporting wall in the basement to hold up the lower first floor joists in the addition and above that framing another wall to hold up the 2x10 joists on the second floor (in the picture the current house is on the left and the addition is on the right). To do this though, all of this load will come down on the edge of the current footing. If it turns out there is not enough of a projection on the current footing, I can pour new footing up against it. Does anything about this seem like a bad idea? I've done plenty of framing but no foundation work before. Another solution would be a ledger board in the basement, but it seems like a lot of weight would be on it. I appreciate any advice from people who know about this type of thing. Thanks.

creahands · May 19, 2010, 05:19 AM

U will probably need architectural drawing to submit to building dept. Talk to the architect about your idea. After an inspection, he will be able to tell u if what u plan is OK.

The building dept has to approve of the plans.Thing that are missing on your drawing is how u will finish floor of basement.

The footing is usually under slab of basement. This would put your bottom plate on top of slab and not on footing.

Are u going to open a passage between the 2 basements?

Chuck

lee12 · May 19, 2010, 05:40 AM

Hi Chuck,

Thanks for the response. The drawing that I posted is just conceptual, the wall be on top of the slap, not directly on the footing, and there will be much more detail included in the submitted drawings. Everything will go through the complete building permit process with full inspections, but I don't want to rely entirely on their review to determine if this is a sound idea. I know that I could go to an engineer but I wanted to get opinions from people who know this stuff before deciding if that is necessary. And yes, there will be an opening between the two basements so I will need a solution for a header on the smaller wall if I explore this idea any further. Thanks.

creahands · May 19, 2010, 03:31 PM

Hi Lee

I don't see anything wrong with your idea. It will work. Don't know where u live, but in my area the plans have to be drawn by a certified architect and submitted by him. In some of our town/cities the building dept require that they oversee job.

Chuck

manhattan42 · May 19, 2010, 05:50 PM

Use ledgers boards and joist hangers for both the basement and 1st floors.

It will eliminate needless wall framing and be completely code compliant.

The link below shows how a ledger board can be attached to a block or concrete foundation wall:

http://www.deckmagazine.com/images/a...EN_01_illo.jpg

creahands · May 20, 2010, 04:22 AM

Hi manhattan 42

The ledger board will work if u are not building a floor above. What u are showing the lay out for a deck.

All weight should be transferred to solid footing. If PO wants more security he can bolt floor beam/box beam to crete wall.

Chuck

lee12 · May 20, 2010, 05:07 AM

Yes, had thought about ledger board but the way it's drawn above, the basement/first floor ledger would be holding 1st floor and 2nd floor. I just don't have the confidence or knowledge about what type of loads can be carried by a ledger. For one floor I would not be as worried, but for 2 I am. The current foundation wall is also hollow block so I'd have to squeeze concrete in the void to secure the bolts.

As for using 2 ledgers (one for 1st floor, one for 2nd) - the 2nd floor ledger would have to be bolted into the side of 2x4 studs which I don't think is acceptable practice. Or the rim joist of the new 2nd floor bolted directly to the rim joist of the current 2nd floor. I would guess that is probably fine if done right, but I just don't like the idea of the whole second floor and roof hanging on bolts. I'd rather have a direct path to footing if possible.

For what I had posted originally, my concerns were that

a) if there is enough of a projection on the existing footing, is the footing adequate to hold additional load (probably?) and does it matter that the footing is weighted mostly on one side rather than center (don't think it matters)

b) if there is NOT enough of a projection on the footing for a 4" wall and I have to pour an extension on the footing, will it matter that all of this load is centered on a 'seam' in the footing? The connection would obviously be reinforced with rebar. Again, I'm guess that this is fine but structural concrete is just not something that I have much experience with. I really appreciate all the input to the discussion - thanks guys.

lee12 · May 20, 2010, 05:10 AM

Hey chuck, what do you mean by "bolt floor beam/box beam to crete wall"?

creahands · May 20, 2010, 12:06 PM

When building, the beams around the perimeter are called the box beams. Got lazy with spelling crete= concrete or block wall.

If u bolt the box beam to block wall, it will give u added security from movement and load carrying. Not much for load, mainly for moving.

Chuck

manhattan42 · May 20, 2010, 04:27 PM

A ledger board bolted through a block wall or fastened to the sides of studs is an acceptable practice and well able to handle all loads.

It's a complete waste of lumber to have to build a 2nd wall in front of an existing wall to support the 2nd floor.

Floors were attached to walls for centuries when homes were balloon framed using only nails, not bolts... and they have lasted for centuries as well.

creahands · May 21, 2010, 01:35 AM

With balloon framing the studs went down to solid bearing. They did not come off a ledger board. And in a lot of areas the ceiling beams had cleats under them for added support or had a 1 by let into 2x4. U where also building with full dimension lumber. A 2x4 was 2x4, not 1 5/8 by 3 5/8. That is one of the reasons, besides the better insulation, that they went to 2x6 for exterior walls.

Box framing came about for 2 basic reasons. Easier to work with 8 foot studs than 20 footers and easier to insulate. Not counting precuts to end up with 8 foot ceiling height.

Chuck

lee12 · May 21, 2010, 10:12 AM

OK, good to know. Thanks for the help

manhattan42 · May 21, 2010, 05:29 PM

In historic balloon framing, the walls were framed and stood, then floors were framed typically by fastening ledger boards nailed into the face of the studs.

In these cases, the joists were simply nailed into the faces of ledger boards without the benefit of joist hangers.

And while there are dozens of variations of these balloon framing techniques, the practice remains legal today and is still commonly used albeit with less regularity.

That said, the point remains: fastening a ledger directly to the framed walls is a standard practice even with modern platform framing, and is the simplest most cost effective means to accomplish what the original poster wishes... even if he has only 2x4 walls.