Puzzling items regarding near future basement remodel

npjohnsonSeptember 12, 2013

I've been doing as much research as possible, reading from numerous sources / books / etc but a few questions have been on my mind that I haven't found a definite answer to. Hopefully someone can help clear these items up for me.

I have a 1600sq ft basement and plan to leave two rooms unfinished (~500sq ft) for utility and storage. The rest will be finished using xps against the walls for insulation / barrier including directly on the floor.

  1. In the unfinished rooms I wasn't planning on having any finishing including no xps against the walls, just bare concrete and exposed ceiling / floor. Would these rooms typically be left bare? I am concerned that if the rest of the basement is finished and warmer due to insulation then there will be a barrier between cold and warm and it will invite condensation at the wall between the spaces. Is this a concern? Do you even insulate this wall between the finished and unfinished space? Is there a risk of mold forming from the unfinished side due to there being no vapor barrier?

  2. When adding service doors / panels (to access water line soffits etc ) is there a preferred way to handle this? Are these doors typically just made from plywood with hinges or is there a premade door / screen that can be purchased? I want it to look as seamless and clean as possible.

  3. When handling soffits around ceiling pipes what do I put on them to give the greatest access to pipes or do I only leave access doors where there are knobs? The rest of the room will most likely be a drop ceiling (I have needed the plumber to come a couple times and the convenience of an open floor is great) but not sure if I should just use OSB screens or is there a better way to handle access for large areas of pipe. I am most concerned about the pipes for the bathrooms.

  4. When using xps on the floor how do you handle the other materials on the floor? Is the plate attached to the concrete directly throught the xps? Is the subfloor then attached directly through the xps? I believe I saw HoH doing this but not 100% sure. I suppose I want to make sure if the bottom plate is attached on top of the xps that it will be a stable enough surface for the plate to sit on.

  5. I have a exterior hatchway with a giant old door that I would remove and put in a more standard sized door that lines up with the new framing. Are there any thoughts on this door and if there is code for if it has to be fire protected now / sweeps / locks / etc? The hatchway could probably use being reset at some point as well as there are some gaps around it.

  6. The basement is pretty temperature all year round, its warming in the winter here in CT than the rest of the house and cooler in the summer. With the insulation added along all the walls is there a need for heating in the basement? I initially thought that a freestanding heat unit may be fine but I've read that electric baseboards sometimes are preferred. I want to make sure I plan for it correctly in the beginning so I don't have to backtrack.

7) I have central air (with the ducting in the attic) that is not accessible in the basement. I have old cast iron heat so no ducting at all in the basement. I have read that its preferable to have air pumped into the basement and pulled out. With no HVAC available how can this be done? Would the air be stale? I am considering purchasing a Santa Fe full room dehumidifier which does allow for ducting it to a room to pull air. Would this be enough?


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1) It is advisable to insulate and air-seal the exterior walls of the unfinished rooms, at least down four feet from grade. This will save heating costs and eliminate condensation and the mould it feeds. To cut costs, you can use expanded polystyrene (EPS) and cover it with intumescent paint.

2) There are a variety of sleek metal and plastic doors/covers for exactly that purpose that pop off for service.

3) There's no more need to have access to pipes in basement ceilings than there is to pipes running through the walls and ceilings in the upper floors. However, do be sure to cover the pipes in foam sleeves to prevent "sweating" in summer. This is a frequent omission that you can spot by the line of water spots on the basement ceilings.

4) Put the plates on top of the XPS. The foam board provides a thermal break and keeps moisture off the wood or light steel studs.

5) The new door has to meet the Code for an exterior door. Exterior doors are typically not fire-rated.

6) Not sure what you mean by "freestanding heat". Electric baseboards work fine. But in the long run it would likely be cheaper to run new lines to radiators in the basement. (I'm assuming you have water/steam heating.)

7) In almost all basements, a mechanical dehumidifier is necessary to keep humidity levels below 50% RH in the summer.

Here is a link that might be useful: Building Science Corp. on Renovating Basements

    Bookmark   September 13, 2013 at 9:05AM
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Thanks for the suggestions. I have a few follow ups to some of the items.

1) With the EPS is that a controlled spray that fills out to a certain level so it appears consistent? I suppose I am still confused as to where the wall between the finished and unfinished rooms meet if that since there will be a difference in temperature if it will cause any condensation or mold to form?

2)Good suggestion on the coverings of the pipes. I do have about 80% of them covered but will finish the rest before the ceiling goes up. The access for the ceiling pipes is mainly due to there being a number of shutoff valves for exterior faucets and such that need to be turned off for the winter freeze.

6) Just meant a freestanding heat unit such as an infrared heater. This may or may not work due to there being multiple rooms. The reason I hadn't considered water (I do have cast iron steam heating) was due to the cost of adding a second zone off the existing and I am concerned about taking up any other room in the ceiling. Currently there are a large number of pipes in the basement ceiling that will require soffits.


    Bookmark   September 13, 2013 at 12:13PM
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1) Expanded polystyrene (EPS) comes in boards similar to XPS. However, it has a lower R value per inch, so you need more of it to get the same initial insulation value. (However, its R Value doesn't drift lower as does XPS, meaning that eventually the difference is not as great.) The extra space used by the EPS isn't usually as much of an issue in storage or unfinished space.

Insulating the foundation walls of the unfinished rooms will keep them warm enough to prevent condensation. It's not temperature difference alone that creates condensation; it's warm air meeting a cold surface.

2) Access ports, panels and doors are available in many sizes and shapes. If you can't find them locally, lots online.

6) Electric baseboards are relatively cheap to install. However, in all the finished well-insulated basements I have done, I've never even needed to use them.

Round Access Port

This post was edited by worthy on Fri, Sep 13, 13 at 21:56

    Bookmark   September 13, 2013 at 9:49PM
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The new Owens Corning Finishing System I saw advertised covers the walls with removable panels to give you full access to the pipes. Not sure if this is necessary, but there is apparently a product to do this if you want to.

    Bookmark   September 23, 2013 at 6:30PM
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