Just Ask Jake: Converting a Screened Porch to a Four Season Room

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Last updated on January 1, 1970

Converting A Large Screened Porch

Lee’s Summit Resident Asks Jake if Existing Concrete Slab Will Hold the Weight of a Four Season Room


Jake Schloegel, CR, President and Founder
Jake Schloegel, CR, President and Founder

Hi Jake —

I live just east of Lee’s Summit, MO and I want to convert my existing large screened porch to a 4 season room. How can I determine if the existing concrete slab is sufficient to hold the additional weight of all the framing and windows? If the existing slab is not adequate, what are my options to have it reinforced?  Thanks! -Susan


The easiest way to determine if there is a foundation around the perimeter of the porch is to pick a spot and dig down alongside the slab to the point where the concrete ends.  In the KC area, footings/foundations are set at a minimum of 36″ below grade.  The purpose of the 36″ depth is to reduce the possibility of soil movement due to the freeze/thaw cycle that we experience in the Kansas City area.  Soil movement leads to settlement issues and cracking of walls and trim.   Since you already have a roof structure above the porch, there may be support piers located only at the roof support columns.  If this is the case, you may be able to run a beam between the columns to support the walls of the new room.  If you do not have a foundation around the perimeter, I would suggest you consult a structural engineer to advise you on a suitable solution.
Another factor to consider is the transfer of heat and cold through the slab from the exterior side of the room walls to the interior of the sun room.  Most likely the slab is uninsulated, and this can lead to some real challenges in keeping the room warm on the very chilly days.
Jake Schloegel, CR

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