Beam size and Joist Size for New addition

[leo2007]

Hello all, I am new to the forum. I am hoping to get some help on the size of the beam and floor joist.
I am planning to cover my existing deck into an enclosed space for my kitchen. The existing deck is 17'-0" x 14'-0". The existing deck has 2x8 floor joists at 16" O.C and 3 rows of double 2x10 beams. The joists length is 14'-0". and the beam length is 17'-0". The longest span of the beam is 8'-0".
I checked the IRC 2018 and could not find any information on the size of the beam.
would the existing structure be sufficient enough for this project?

Thank you so much for your help.

 

[Beniah Naylor]

According to table R507.5 in the 2018 IRC, a double 2x10 beam carrying joists 14' long can span 6'9". Your 2x8 joists are also slightly over-spanned according to table R502.3.1(2) in the 2018 IRC.

As many in this forum would be quick to point out, an engineer would be able to figure all of this out for you. All I will say is that it is definitely the most painless route, and, depending on your particular circumstance, I estimate that it has a 60% chance of saving enough money in materials to pay for itself.

 

[leo2007]

According to table R507.5 in the 2018 IRC, a double 2x10 beam carrying joists 14' long can span 6'9". Your 2x8 joists are also slightly over-spanned according to table R502.3.1(2) in the 2018 IRC.

As many in this forum would be quick to point out, an engineer would be able to figure all of this out for you. All I will say is that it is definitely the most painless route, and, depending on your particular circumstance, I estimate that it has a 60% chance of saving enough money in materials to pay for itself.

Thank you for your comment.
To clarify, we have 3 rows of (2)2x10 beams so the joists span at 2'-0", 5'-0", 5'-0", and 2'-0" (14'-0" in length). Please take a look at screenshot from the plan

https://imgur.com/0vXo8Y6

 

[Beniah Naylor]

Oh, ok.

I think you could build a skyscraper on that deck, it is plenty strong enough to support a kitchen.

 

[leo2007]

Oh, ok.

I think you could build a skyscraper on that deck, it is plenty strong enough to support a kitchen.

Thank you. I would prefer to have a nice kitchen instead of a skyscraper.
Don't you think 8'-0" span between the posts is a lot for a double 2x10 beam?

 

[Beniah Naylor]

It would be, it there weren't three of them side by side. The amount of tributary area on that 8' section of beam is tiny, since it is sharing with the others.

 

[tbz]

IF you are concerned about loading the floor with tile and a center island, I venture a guess it would be pretty simple when re doing the sub-floor, to hand dig (3) additional columns with footings in the middle of those 8ft spans and remove all doubt.

As noted with all the support currently in place over the center of the floor system, unless a specific point load is being added, not sure other than the 17' front edge with the canter lever joist to support the roof system if not "A" framed from the 14ft projection sides, looks to be a good starting point to me.

But your Architect will cover that real quick. IF you are not planning to use an architect and drawing the reno yourself, I would spend a little money on an engineer to verify all your load points and structure fly with the VA adopted code requirements. Simpler to spend a little upfront than a lot on the back side.

 

[leo2007]

IF you are concerned about loading the floor with tile and a center island, I venture a guess it would be pretty simple when re doing the sub-floor, to hand dig (3) additional columns with footings in the middle of those 8ft spans and remove all doubt.

As noted with all the support currently in place over the center of the floor system, unless a specific point load is being added, not sure other than the 17' front edge with the canter lever joist to support the roof system if not "A" framed from the 14ft projection sides, looks to be a good starting point to me.

But your Architect will cover that real quick. IF you are not planning to use an architect and drawing the reno yourself, I would spend a little money on an engineer to verify all your load points and structure fly with the VA adopted code requirements. Simpler to spend a little upfront than a lot on the back side.

I am trying to not adding any addition columns since we have already had the sub-floor in place.
Please see image below for what we have in mind for the roof.

https://imgur.com/a/vooYxRb

 

[tbz]

Looks like you covered the only (might be) concerns I saw. You "A" framed to the sides, not a shed roof, and looks like your island in located over part of 2 of the existing columns and you are left with just open floor area over the 8ft spans.

 

[leo2007]

Looks like you covered the only (might be) concerns I saw. You "A" framed to the sides, not a shed roof, and looks like your island in located over part of 2 of the existing columns and you are left with just open floor area over the 8ft spans.

Thank you for your comment. Much appreciated.
Correct! I try to locate the load away from that 8ft span. Do you think I should be good then?

 

[tbz]

Not a PE or Architect, and I personally don't like 16" framed floor systems for kitchens especially when tiling over them. But that has nothing to do with what the code requires.

Not exactly sure how VA applies the IRC to renovations, someone from VA could chime in, but you noted already in place subfloor, was a permit issued or are you going to be applying for one?

The plan reviewer should have or will be checking your drawings.

Are you doing or did you do the drawings yourself or an Lic. Designer?

I guess my question is, what part of the process are you actually in?

 

[leo2007]

Not a PE or Architect, and I personally don't like 16" framed floor systems for kitchens especially when tiling over them. But that has nothing to do with what the code requires.

Not exactly sure how VA applies the IRC to renovations, someone from VA could chime in, but you noted already in place subfloor, was a permit issued or are you going to be applying for one?

The plan reviewer should have or will be checking your drawings.

Are you doing or did you do the drawings yourself or an Lic. Designer?

I guess my question is, what part of the process are you actually in?

The permit was issued but we mistakenly noted the joists were 2x10s instead of 2x8s, and the beams were double 2x12s instead of 2x10s.
The contractor was certain that we could pass the inspection with this condition so we went ahead and did the framing. We have had the sub-floor, exterior wall, and the roof in place.

 

[Beniah Naylor]

An inspector is well within their rights to fail an inspection simply because it doesn't match the approved plans. The inspector is unlikely to have the beam and joist tables memorized in their head, so they may not know if your kitchen will meet code or not without doing some digging.

If you were dealing with my building department, I would have you submit revised plans for approval as soon as possible so that your project is not delayed. Alternately, you can always roll the dice and see if the inspector catches it - and if they do, maybe you get lucky and have a nice inspector and you can show them the tables in the IRC and they approve it on site and have you submit revisions later on. Alternately, by not submitting a revision you could annoy the inspector... which could make things more difficult.

 

[leo2007]

An inspector is well within their rights to fail an inspection simply because it doesn't match the approved plans. The inspector is unlikely to have the beam and joist tables memorized in their head, so they may not know if your kitchen will meet code or not without doing some digging.

If you were dealing with my building department, I would have you submit revised plans for approval as soon as possible so that your project is not delayed. Alternately, you can always roll the dice and see if the inspector catches it - and if they do, maybe you get lucky and have a nice inspector and you can show them the tables in the IRC and they approve it on site and have you submit revisions later on. Alternately, by not submitting a revision you could annoy the inspector... which could make things more difficult.

Understood. I have submitted the revised plans for approval as soon as I found out the discrepancy. We are still waiting to hear back from the plan reviewer.
I was just anxious to see if this current condition would be ok for both the inspector and the plan reviewer to approve.

 

[ICE]

If you don't mind, I am curious about what was done for a foundation at the exterior perimeter walls.

 

[leo2007]

If you don't mind, I am curious about what was done for a foundation at the exterior perimeter walls.

We provided new 6x6 posts on 24" wide x 10" thick x 24" deep footing. We have about +/- 28" crawl space.

 

[ICE]

We provided new 6x6 posts on 24" wide x 10" thick x 24" deep footing. We have about +/- 28" crawl space.

Maybe it's too early in the day but the numbers have me confused. 24" wide I get and 24" deep is not a problem but 10" thick escapes me. You're pretty good with providing drawings....that might clear up the confusion. And how far apart are the 6x6 posts?

 

[leo2007]

Maybe it's too early in the day but the numbers have me confused. 24" wide I get and 24" deep is not a problem but 10" thick escapes me.

Sorry, let me clarify. The size of the footing is 24" x 24". it's 10" thick and we dig 24" deep from grade to pour the concrete.

 

[ICE]

Sorry, let me clarify. The size of the footing is 24" x 24". it's 10" thick and we dig 24" deep from grade to pour the concrete.

Alrighty then....the 6x6 is sitting on a 10" thick pad that is buried. That indicates that the post is in contact with 14" of soil.

 

[leo2007]

Alrighty then....the 6x6 is sitting on a 10" thick pad that is buried. That indicates that the post is in contact with 14" of soil.

Yes, that's correct

 

[ICE]

Thanks for clarifying. I am not familiar with construction practices in Virginia or seismic zone C but this seems somewhat temporary in nature.

 

[classicT]

Hang up here... ICE is onto a line of thought that I think has yet to be addressed.

Without a continuous footing, how are you bracing the structure? Where are your brace walls at? How is the overturning moment of those panels resisted if not connected to a continuous footing?

Check out IRC Section R602.10.8

 

[classicT]

Also, check out R602.10.9

R602.10.9 Braced Wall Panel Support
Braced wall panel support shall be provided as follows:

1. Cantilevered floor joists complying with Section R502.3.3 shall be permitted to support braced wall panels.
2. Raised floor system post or pier foundations supporting braced wall panels shall be designed in accordance with accepted engineering practice.
3. Masonry stem walls with a length of 48 inches (1219 mm) or less supporting braced wall panels shall be reinforced in accordance with Figure R602.10.9. Masonry stem walls with a length greater than 48 inches (1219 mm) supporting braced wall panels shall be constructed in accordance with Section R403.1 Methods ABW and PFH shall not be permitted to attach to masonry stem walls.
4. Concrete stem walls with a length of 48 inches (1219 mm) or less, greater than 12 inches (305 mm) tall and less than 6 inches (152 mm) thick shall have reinforcement sized and located in accordance with Figure R602.10.9.

For SI: 1 inch = 25.4 mm.
FIGURE R602.10.9
MASONRY STEM WALLS SUPPORTING BRACED WALL PANELS​

R602.10.9.1 Braced Wall Panel Support for Seismic Design Categories D0, D1 and D2
In Seismic Design Categories D0, D1 and D2, braced wall panel footings shall be as specified in Section R403.1.2.

 

[leo2007]

Also, check out R602.10.9

R602.10.9 Braced Wall Panel Support
Braced wall panel support shall be provided as follows:

1. Cantilevered floor joists complying with Section R502.3.3 shall be permitted to support braced wall panels.
2. Raised floor system post or pier foundations supporting braced wall panels shall be designed in accordance with accepted engineering practice.
3. Masonry stem walls with a length of 48 inches (1219 mm) or less supporting braced wall panels shall be reinforced in accordance with Figure R602.10.9. Masonry stem walls with a length greater than 48 inches (1219 mm) supporting braced wall panels shall be constructed in accordance with Section R403.1 Methods ABW and PFH shall not be permitted to attach to masonry stem walls.
4. Concrete stem walls with a length of 48 inches (1219 mm) or less, greater than 12 inches (305 mm) tall and less than 6 inches (152 mm) thick shall have reinforcement sized and located in accordance with Figure R602.10.9.

For SI: 1 inch = 25.4 mm.
FIGURE R602.10.9
MASONRY STEM WALLS SUPPORTING BRACED WALL PANELS​

R602.10.9.1 Braced Wall Panel Support for Seismic Design Categories D0, D1 and D2
In Seismic Design Categories D0, D1 and D2, braced wall panel footings shall be as specified in Section R403.1.2.

This seems to be more complicated than I thought it would be.
We got approval from the plan reviewer for this framing previously. The issue is we didn't shown the size of the structure members correctly. We did not get any comment on the footing.
I am not so sure how to deal with this issue since everything has been in place.