Attic Office Addition Part 3…Starting over again

Determined to set things straight and do things safely and right, i pulled a building permit with the local county. I then proceeded to find any information on the original build of the house and how it was constructed.

While i was doing that, I had to rip up all the work I had done. piece by piece, board by board. It was slow work. I had glued, nailed and screwed everything together.

I used a crowbar, cordless circular saw, sawzall, and hammer.

Doing it again, i’d use a deck breaker

The county permit office was absolutely amazing. They really spent some time listening to what i wanted to do, what i had done so far, and told me what i needed to do to make it safe and right.

Many people think the local building codes department is there to generate revenue for the city/county and somehow stop you from doing things to your house. Based on the fee i paid they truly were not. Basically for ~$150 I got a consultant who came out to my house several times over the next year and very patiently guided me throughout the project on safe and efficient building practices.

Several times when i was stumped or had an idea, I drove down to the local codes office and everyone jokingly groaned as I came through the door. Nevertheless, they were genuinely interested to see if i was going to get this done. I had taken on a huge project for an average DYI’er with no construction skills. I’m pretty sure there was a pool going on if i would ever get a certificate of occupancy.

The first thing “codes” comes to evaluate is the structure you are building on. Is it safe, is it strong enough etc. they are not structural engineers but they will check for proper bearing (minimum placement of boards on other boards), correct size of lumber, correct amount of fasteners per board, correct bracing if needed, correct type of wood, etc. Are there holes or notches in the wood?, where are they located?, etc. You have to know all this stuff. There is a TON of information you need to know to do an addition correctly. Read the IRC (International Residential Code) for construction. It has tons of detail.

Buy a Residential Wood Framing Construction Quick-Card based on 2018 IRC here.

I also got the sense that VERY FEW homeowners ever get a building permit. That is a huge mistake. If you ever have an insurance claim or need to sell your house, you are responsible for having everything to code. A building permit may not keep you from doing dumb things but it will make sure you correct them before you are done.

Essentially, to be code compliant, I had to span the existing joist length with boards that could carry a sufficient live load for a livable space. I ended up “sistering” 2x10s to each existing joist. Basically fastening a larger stronger board in parallel to the existing joist. I did this to twenty two 2×10’s! Ugh! Talk about exhausting.

There are all sorts of technical specifics you can get into about the strength of combining pieces of traditional lumber. It didn’t really matter here. The 2x10s on their own were sufficient. I would have preferred to remove the existing 2×8’s but that would have meant removing the kitchen ceiling for a while in the middle of winter. Not an option. Also not an option when you need to feed a family every day. So the 2x8s are still there nailed and screwed to the 2x10s.

I beefed up the connection to 2×10’s on the the LVL by adding Simpson strong tie concealed joist hangers. These are a great option when you want amazing holding strength but have no room on one side to nail in the dog ear tabs on conventional Simpson joist hangers. Make sure you use Simpson approved fasteners with these hangers. There was a screw option but I used Simpson nails. I also bought a Pneumatic palm nailer which was an absolute Godsend when nailing these into an LVL.

Simpson LUC210z concealed joist hanger

These photos taken during the original framing of the house were really valuable for me to understand more about how my floor joists would be transmitting the massive load of the 2nd floor down to the foundation while having a huge open space over most of the living room / dining room nook. They helped me determine where the walls would need to be to bear the weight of the addition.

General load path of addition over living room / nook area
  1. Load is placed on the ceiling joists (which double as the floor joist above after the addition.
  2. Load travels out from joists to LVL and sidewalls
  3. Load travels down wall to window headers
  4. load travels out and down though jack studs and
  5. finally down through all the studs
The Existing LVL downstairs enables the addition to span over an open living room space. LVLs have amazing compression strength so they can span greater distances than traditional lumber.

Read Part 2 here: “https://suburban-trenches.com/2020/02/12/attic-office-addition-part-2-mistakes-were-made/

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