Converting Porch into room

[Bbp78]

Hi all, hopefully this is an appropriate place to post this as it’s not garage related, but I know how knowledgeable you all are and you have helped me in the past. I have a porch that was built in 1954 with my house. I demolished it a few months ago with the intention of building a room. I need to make it about 3 feet wider than the original existing concrete foundation. The slab has a block foundation that goes down to the frost line from what I can tell. I live outside Philadelphia, PA. My question is if there is another alternative to digging down to the frost line, pouring a footing and either laying block or forming and pouring concrete walls for the 3 foot extension? I was thinking about sonotubes and framing a floor over the existing foundation, but my concern is if I don’t do a full concrete foundation, will I have issues with animals wanting to get under this tiny “crawl space” or any other concerns I’m not thinking about? It’s not a very big addition, so I could definitely frame it with the sonotube piers, but do you guys think that’s a mistake. I’ve attached a few pictures showing the existing concrete foundation. Thanks in advance for any advice and guidance.

 

[kaehlin]

I think if it is attached to your house, you will need to follow building codes. I assume this means full foundation below the frost line, but you'll want to check for anything specific in your locale. Good luck, looks like a cool project.

 

[mike93lx]

Attached to the house means footings at the same depth but that doesn't necessarily mean full foundation.

Are you permitting this?

 

[Bbp78]

Thank you Mike and Kaehlin, I apologize I forgot to mention that I will be getting a permit. Maybe I should call and speak to the Building department to get there thoughts first. I have to submit drawings but wasn’t sure which foundation. If piers are allowed, do you guys see any issues going that route? I would block it off, but just wonder if it will be a headache down the road not doing the full foundation, etc. Thanks again

 

[joebass3]

Definitely would be easier with some piers and a beam on top if that would meet building code. Block it off to keep critters out and I think you'll be fine.

 

[Bbp78]

Thanks Joe, yeah I would like to keep it simpler. I built my shop 6 years ago and did the footings and block foundation myself, but would prefer not to on this if possible, even though this would be much smaller.