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Old 07-18-2010, 09:16 PM   #1
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Opening up a wall - correct reading of span table (R502.5(1))???


Am I reading the span table correctly?

I want to open up an 8 foot wall between my kitchen and screen porch. Am I reading the table correctly that I can put together 3 2x8's to span an 8 foot opening? (The wall at that part of the house is only 18 feet wide).

Also, It looks like the screen porch was a later addition. I think the kitchen originally was against the outside (brick) wall of the house making it an 'exterior bearing wall'. Now with the screen porch (wood) the roof line extends past the kitchen out over the porch.

Does this make the kitchen wall an 'internal bearing wall' ?

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Old 07-19-2010, 06:08 AM   #2
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Opening up a wall - correct reading of span table (R502.5(1))???


If there is structure above, or it is the sloped side of the roof, it is load bearing.

Where do you live, snow loading is also a factor in that table???

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Old 07-19-2010, 04:43 PM   #3
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Opening up a wall - correct reading of span table (R502.5(1))???


Yeah, we get some (2-6 inch) snows, so snow loading should be taken into account.

Basically, I know the wall was at one time an exterior load bearing wall & now is not the actual exterior of the house since the addition of the screen porch.

My question regarding the load bearing was more along the lines of 'do I read off the EXTERIOR load bearing wall table - or from the INTERIOR load bearing wall table?' (the specs are different).

As well as 'Does the "3-2x8" on the table refer to three two by eights nailed & glued up together to form a single beam?'


Guess I'll go with the more stringent requirements either way just to be safe.
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Old 07-19-2010, 05:56 PM   #4
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Opening up a wall - correct reading of span table (R502.5(1))???


Stronger is safer...... I presume the roof rafters/trusses still bear on the wood wall at the addition? OR the brick, if structural? Did you look? Sometimes with a screened porch the footings and wall is not sufficient to support the roof structure, especially when it started life as a patio slab. You are probably carrying 1/2 of the roof load and some of the porch over-frame roof. Also, possibly some or 1/2 of the porch roof load, depending on the rafter orientation to the house. Maybe even more porch load if a structural ridge beam bears there with a point load. So yes, it is still the exterior of the house if roof is resting there. Check to be sure you install the required number of jack studs (2-3) on each end for that large a span. Positive tie the beam to the rest of the wall's top plates at each end. Add in-floor blocking or a concrete footing pad under an existing slab, PER Structural Engineer's drawings approved by your Building Department. This new addition has to meet requirements for heating, cooling, glazing, fire, and SAFETY. The local B.D. will see to that so if you ever have a claim, Homeowner's Insurance will cover it, if built per minimum Code. Build well.

Be safe, Gary
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Old 07-19-2010, 06:20 PM   #5
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Opening up a wall - correct reading of span table (R502.5(1))???


Quote:
Originally Posted by DyerWolf View Post


Basically, I know the wall was at one time an exterior load bearing wall & now is not the actual exterior of the house since the addition of the screen porch.
It's still an exterior wall regardless of the screen porch because nothing was changed with the load above on the existing roof plus the weight of the porch roof.

Quote:
My question regarding the load bearing was more along the lines of 'do I read off the EXTERIOR load bearing wall table - or from the INTERIOR load bearing wall table?' (the specs are different).
Exterior and what your carrying above is still the same. Now you have to add in the weight of the porch roof.

Quote:
As well as 'Does the "3-2x8" on the table refer to three two by eights nailed & glued up together to form a single beam?'
If it's saying three 2x8's nailed together, that will only work on a 2x6 wall. Is that a 2x4 or 2sx6 wall?
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Old 07-19-2010, 09:47 PM   #6
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Opening up a wall - correct reading of span table (R502.5(1))???


Quote:
Originally Posted by Joe Carola View Post

If it's saying three 2x8's nailed together, that will only work on a 2x6 wall. Is that a 2x4 or 2sx6 wall?
2x4... So, looks like I need to plus up to the 2x 10's.

tango.
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Old 07-19-2010, 10:37 PM   #7
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Opening up a wall - correct reading of span table (R502.5(1))???


I assume you have a single story house. If you have a two story, you need to include the load from the upper level as well.

As a general rule, there is little reason to use tables for such a critical element as an exterior load bearing header. You should be able to take dimensioned drawings of your project to a lumber yard that sells or fabricates LVL beams and they may be willing to run the calculations for you, assuming you buy their beam. Which in your case may be worthwhile, since an LVL or possibly a steel beam will save you headroom. The tables are not going to cover LVL or steel headers, so if you go with either of those options you are going to need a stamped plan, which you may need anyway to get your permit, which I'm sure you want to do for all the reasons mentioned (insurance, resale, not to mention you don't want your house to fall down).

By the way, since you are going to be working on an (effectively) exterior load bearing wall, be ABSOLUTELY certain you have drawn up a solid plan for temporary support of the roof above the wall. Don't mess with sketchy jacks, make sure the support is rock solid, you can get into a lot of trouble during the temporary support phase if the supports slip or break.

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