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Q & A: What,s the correct way to insulate a basement stud wall?

Question by jay c: What,s the correct way to insulate a basement stud wall?
Here is how I planned to insulate my basement walls. First, I would drylock them. Next, I would use dow blue or pink board and glue it directly onto the concrete. This is where I get confused. Should I press the stud wall directly up against the dow board so once I put up the unfaced insulation no air can get it. Or should I leave one inch between the dow board and stud wall to allow the wall to breathe.

Best answer:

Answer by portagerealtor
You do not need drylock unless you have a moisture problem. If you do look at your exterior grade or gutters as those are the most common source of moisture in basements. Personally I like to frame a conventional 2×4 wall and use R-13 Batts insulation. If you don’t want to sacrifice the additional space then what is typically done is to glue and either tapcon or ramset studs to the exterior walls and then fill the spaces between the studs with foam insulation whish is glued to the wall. Cover with Drywall. The additional reason for the 2×4 wall is that it gives you room to run electric, cable, telephone, ethernet and plumbing.

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2 Responses to Q & A: What,s the correct way to insulate a basement stud wall?

  1. John D M B


    Sealing the concrete wall – Drylock is fine.

    You can rigid Closed Cell insulation (2 inch (R10) Shiplap recommended) directly to the concrete wall. There are metal T bars for fastening the rigid Closed Cell insulation to the concrete using the appropriate concrete screws (1 inch longer than thickness of material being fastened – use proper masonry drill bit designed for the screws).

    Since you are fastening the insulation directly to the concrete, you do not have to be concerned about the wall breathing. The air space is usually left on the cold side of the insulation to allow any moisture to escape. Leaving an airspace on the warm side of the insulation does not do any good.

    It is your choice how to build the stud wall. In this case I would build it directly against the rigid Closed Cell insulation unless the wall is not plumb and/or straight. I usually measure and mark the same distance from the concrete wall on the floor at each end of the wall; snap a chalk line and mark a line along the floor. this will show you whether or not the wall is straight. Use a Plumb-bob to check for vertical at different points along the length of the wall.

    If your concrete wall is plumb and straight, build the stud wall tight against the rigid Closed Cell insulation.

    If your wall is straight but not plumb, build you stud wall so it is plumb. I will not be against the rigid Closed Cell insulation at the top or bottom – depending which way the concrete wall is leaning.

    If your wall is neither straight or plumb use the chalk line to mark the outside of the wall – snap the line along the floor. Use a plumb-bob to mark the location of the outside of the top plate.

    I recommend pouring a 2″ concrete base to mount the bottom plate onto and make sure you have sill gasket next to the concrete and 6 mil plastic barrier between the sill gasket and the bottom plate. this helps to protect the bottom plate of your stud wall from moisture – all concrete floors allow moisture through them even if they appear to be dry.

    Hope this helps and good luck.

  2. skyalert

    This is the way it works best for me:
    1-stud wall using 2×2’s and 16′” between from stud CENTRE to CENTRE.
    2-Fasten the wood to floor and basement wall with screws using pilot
    holes first using a good strong masonry/concrete bit.
    3-Fill cavity with unfaced pink batt or styro board.
    4-Staple on heavy ml thickness vapour barrier and red tuck tape
    seams. Cut around joists and go in the space above wall.
    5-Expandable foam works well on the sill plate where the
    bottom of the wall meets the floor.
    Result: warmer floor, drier air, no drafts, better heating
    bills=comfortable and clean basement living.

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