Enclosing entry way questions (floor/venting)

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  • ivwshane
    Established Member
    • Dec 2003
    • 446
    • Sacramento CA

    Enclosing entry way questions (floor/venting)

    I want to enclose my entry way and eventually have new entry enclosure/porch.

    I talked to my towns building inspector and he said I needed to tie in the ventilation to the existing structure. I was trying to visualize how that would work but I don't understand the "why" behind it to fully grasp it.

    My current porch consists of a 7-8" slab, the walls around the slap appear to be built upon 4x6's (my first floor rests on 4x6's about 45" OC).

    It seems to me that getting the new floor I would add to vent to the old crawl space would not only affect the integrity of the existing structure just a little but it would be a major PITA to cut a hole in the 4x6.

    Can anyone offer some insight into this?

    Below are pictures with the labels A, B, C, which are to show what is what and where and to hopefully help explain exactly what I need to do.
    The picture with the numbers are to represent possible placements of vents or holes to the old crawl space.





  • LCHIEN
    Internet Fact Checker
    • Dec 2002
    • 20914
    • Katy, TX, USA.
    • BT3000 vintage 1999

    #2
    I don't qutie understand your home construction.
    first of all do you live in California? Do the home ventilation there consist of central heating and the vents come thru the floor? I assume you are trying to make the entry interior space so it must conform to living space requirements? I then assume you are going to put in an exterior wall, windows and a exterior rated door before finishing the interior.

    is there space between the floor and slab due to the 4x6's?

    Are you keeping the door way and adding another or are you removing the present front door an making it a open walkthru and in that case won't that provide the ventilation?

    In Texas we have mostly concrete slabs and central air and heat so the ventilation is thru the attic.

    Is the entry slab a separate slab from the one the house sits on?
    Last edited by LCHIEN; 05-10-2014, 09:16 PM.
    Loring in Katy, TX USA
    If your only tool is a hammer, you tend to treat all problems as if they were nails.
    BT3 FAQ - https://www.sawdustzone.org/forum/di...sked-questions

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    • ivwshane
      Established Member
      • Dec 2003
      • 446
      • Sacramento CA

      #3
      Originally posted by LCHIEN
      first of all do you live in California? Do the home ventilation there consist of central heating and the vents come thru the floor? I assume you are trying to make the entry interior space so it must conform to living space requirements?

      Are you keeping the door way and adding another or are you removing the present front door an making it a open walkthru and in that case won't that provide the ventilation?

      In Texas we have mostly concrete slabs and central air and heat so the ventilation is thru the attic.

      Yes I'm in California. I have central heating and the vents are in the second floor (the 2nd floor is built via trusses). I am trying to make the entry space conform to the living space.

      I'll be adding a new door where the current slab ends and I'll be pouring another slab in front of it (which will also cover the planting area on the left).

      Comment

      • atgcpaul
        Veteran Member
        • Aug 2003
        • 4055
        • Maryland
        • Grizzly 1023SLX

        #4
        Are you putting up an exterior wall and then knocking down the other wall where your front door is now? Or putting up a new wall and front door, but keeping the other wall and door in place?

        If the former, I'd think the ventilation would take care of itself. If the latter, maybe the concern is not having a place for moisture/humidity to go--like an airlock.

        Comment

        • tfischer
          Veteran Member
          • Jul 2003
          • 2343
          • Plymouth (Minneapolis), MN, USA.
          • BT3100

          #5
          I was going to mention that you'd probably have to redo the slab with frost footings, but then I realized you were in California lol.

          Comment

          • ivwshane
            Established Member
            • Dec 2003
            • 446
            • Sacramento CA

            #6
            Originally posted by atgcpaul
            Are you putting up an exterior wall and then knocking down the other wall where your front door is now? Or putting up a new wall and front door, but keeping the other wall and door in place?

            If the former, I'd think the ventilation would take care of itself. If the latter, maybe the concern is not having a place for moisture/humidity to go--like an airlock.
            A new wall will be built and the old one removed. The current porch space will be added to the existing foyer/entryway.

            And just so I'm clear about what I'm asking; the inspector was talking about ventilation under the new floor that will be built that apparently needs to mix with the crawl space under the house,

            Comment

            • woodturner
              Veteran Member
              • Jun 2008
              • 2047
              • Western Pennsylvania
              • General, Sears 21829, BT3100

              #7
              Originally posted by ivwshane
              I talked to my towns building inspector and he said I needed to tie in the ventilation to the existing structure. I was trying to visualize how that would work but I don't understand the "why" behind it to fully grasp it.
              The "why" is that the space needs to be vented so condensation and other moisture sources don't cause rot. What you show in your drawing should be fine, provided you provide a path through the new joists to the vent in the side wall.

              I would consider extending the new floor framing system three or four inches beyond the existing porch, leaving a 1" air gap between the end cross joist and the concrete porch. This gap could be filled with ridge vent material to keep out bugs but allow air flow. I think that would look a little better.
              --------------------------------------------------
              Electrical Engineer by day, Woodworker by night

              Comment

              • ivwshane
                Established Member
                • Dec 2003
                • 446
                • Sacramento CA

                #8
                Originally posted by woodturner
                The "why" is that the space needs to be vented so condensation and other moisture sources don't cause rot. What you show in your drawing should be fine, provided you provide a path through the new joists to the vent in the side wall.

                I would consider extending the new floor framing system three or four inches beyond the existing porch, leaving a 1" air gap between the end cross joist and the concrete porch. This gap could be filled with ridge vent material to keep out bugs but allow air flow. I think that would look a little better.
                Awesome idea! I'll see if that works for him! Thanks!

                Comment

                • ivwshane
                  Established Member
                  • Dec 2003
                  • 446
                  • Sacramento CA

                  #9
                  I was just doing some more thinking and I realized an overhang won't work. The existing porch slab will essentially be extended out to form the new porch and there won't be a way to over hang the joist for ventilation purposes.

                  Can I vent by drilling ~1/2"-1" holes through the existing joists?
                  Since the existing joists are 4x6's I can use 2x4's for the new joists which should give me about an 1-1/2" gap that would allow full ventilation into the existing crawl space, provided that several 1" holes would be sufficient enough.

                  Comment

                  • woodturner
                    Veteran Member
                    • Jun 2008
                    • 2047
                    • Western Pennsylvania
                    • General, Sears 21829, BT3100

                    #10
                    Originally posted by ivwshane
                    Can I vent by drilling ~1/2"-1" holes through the existing joists?
                    Since the existing joists are 4x6's I can use 2x4's for the new joists which should give me about an 1-1/2" gap that would allow full ventilation into the existing crawl space, provided that several 1" holes would be sufficient enough.
                    That should be fine - the key principle is that the input area of the vents should equal or exceed the output area of the vents. If the vent into the side wall is 4" x 6", for example, that is 24 sq in, so you need 24 sq in of 1" holes, or 31 holes (each hole is 0.78 sq in, (.5)^2*pi).
                    --------------------------------------------------
                    Electrical Engineer by day, Woodworker by night

                    Comment

                    • ivwshane
                      Established Member
                      • Dec 2003
                      • 446
                      • Sacramento CA

                      #11
                      Originally posted by woodturner
                      That should be fine - the key principle is that the input area of the vents should equal or exceed the output area of the vents. If the vent into the side wall is 4" x 6", for example, that is 24 sq in, so you need 24 sq in of 1" holes, or 31 holes (each hole is 0.78 sq in, (.5)^2*pi).
                      Well, there wouldn't be any vents on the new wall (unless it's required).

                      31 holes is a lot...

                      Comment

                      • ivwshane
                        Established Member
                        • Dec 2003
                        • 446
                        • Sacramento CA

                        #12
                        I've been doing some more thinking and I just realized the 4x6's under "A" and "B" aren't load bearing! I can cut out all of "B" and half of "A" if I needed to, although "A" does have a wall above it that I had planned on keeping.

                        So the question then becomes; how do I build the floor framing so that it is tied into the existing structure and at the same time allows me to vent the newly framed floor into the old crawl space?

                        I was originally going to screw a 2x6 to all three sides A, B, and C but that would mean my possible areas for venting would be blocked.

                        Any suggestions?

                        Comment

                        • ivwshane
                          Established Member
                          • Dec 2003
                          • 446
                          • Sacramento CA

                          #13
                          It looks like a PITA but I think if I take out A and just extend two 4x6's out I'll be good. One 4x6 will be an extension of the 4x6 currently connected to A, the other will be one that goes across the front of the house/porch. I will then screw a 2x6 to B.

                          I'm not sure what C looks like but I may need to attach a 2x6 to the wall and hang the 4x6's off of that.

                          Does anyone see any issues with this plan? Do they sell 4x6's?

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