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Insulating Basement with Metal Ceiling

db_neuhaus | Posted in General Questions on

We have a walk out ranch and in the basement there is a storage room that is actually located under the front entrance patio.  Its a suspended slab with steel beams holding up steel decking, a concrete slab and a brick patio finished surface.  When we first moved in we noticed that during especially heavy rains that a few drops of water leaked from 1 spot in the steel decking.  I’ve since corrected the issue by sealing the brick patio and upsizing the gutters and haven’t had any moisture for at least 6 months.  The space is going to remain mostly storage but we’d like to finish the room to make it more attractive and easier to clean.  Is there any issues with insulating up against the steel decking with rigid foam or should I use closed cell spray foam to encapsulate/get direct contact against the corrugated deck?  The room is adjacent to the mechanical room so there’s no real issue with heating the space but to the touch the steel is pretty cold.

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  1. db_neuhaus | | #1

    Any thoughts whether using foam board will create any issues with the gaps created by the corrugations in the steel decking?

  2. walta100 | | #2

    Seems to me what you have is a root cellar / cold room it was built with the intention that this space would be a cool damp place. Making it into a warm dry room will be no small feat.

    Understand you will need to keep the warm air from getting to the cold steel ceiling or everything will get wet and grow moldy. Note putting insulation between the steel framing is almost a total waste if resources.

    You may find this article interesting.

    I think the smart move is to learn to except the space as it is.


  3. db_neuhaus | | #3

    Aside from one isolated incident at the ceiling the room is very dry, The outside block wall has always remained dry in our ownership and shows no sign of previous water intrusion. On one end the room is connected via a block opening to the mechanical room which houses the boiler and as such stays at a pretty constant 65-68 degrees during the heating season. The opposite of the room connects via a doorway to a finished basement ( 2" xps against the block) with baseboard heat typically set around 65. All that to say the room isn't cold or damp, except that the steel decking itself is cool to the touch. The main reason for insulating and finishing the space further is mostly for appearance and cleaning purposes.

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