Posted by Greg Coffin [172.69.170.61] on Sunday, November 08, 2020 at 10:35:57 :
In Reply to: A Flatfender basement posted by Steve in FH [108.162.245.165] on Thursday, November 05, 2020 at 21:16:59 :
I'm a little late to the party here, but something to consider is that by widening the doorway in the foundation wall you are increasing the point load that is being transferred to the footer on either side of the new doorway.
Assuming you have a standard 16" spread footer at the bottom of an 8" stem wall, the footer was designed to carry a load that was being shared by the adjacent footer, and also spread around by the reinforced concrete stem wall. Once you start cutting the stem wall and footer, the loads become point loads at the cut and the footer has to be reinforced to support the additional loading. The wider the door is, the larger the point loads become, and the larger the footer needs to be. Otherwise you risk pressing the existing footer deeper into the ground. Not good.
Granted, all this depends on your soil conditions and existing construction, but I would advise you to consult a local building engineer who has done this for a while. He'll be able to figure it out in an hour or two.
Good luck with your project!