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Chimney effect in homes

clammy Member Posts: 3,114
I thought I de share this w you all . I ve had pull down attic stairs for years in the stair well to my basement for years and yes it always been cool or hot depending on the season . About 3 years ago while adding insulation to my attic now about a r 48 . After I noticed of course more comfort and a little bit of a lower utility bill but still had a cold stair well and a basement that really never was to warm .i decided to make a lid to cover my attic pull downs ,I constructed it of 2 inch blue board about 8 inch high so the stairs would fold up into them . Not only is the stair well and my basement warmer but both my gas and electric use is lower . The reason I post this is I suggest this to customers and they just stair at me and I let it go . I recently add one to a relatives home who suffers from high heating and cooling cost and a generally chimney effect to both there pull down attic stairs and there uninsulated undersized side wall return filter grill . Well it’s been about 3 days and the temp have see sawed from heat on in the am to ac in the afternoon and well they where dumb founded that there 20 year old house is comfortable because to a simple solutions like a insulated box over a attic access and the elimination of thermal migration and chimney effect it should be nice for them to see a saving in there ulitily bills and feel comfort . They wondered how come nobody has ever suggested it I said maybe because they really don’t care about your comfort and about saving you money . The whole lid and a roll of fiberglass scrim tape cost about 40 bucks I m pretty sure they will recupe there investment in one hot or cold month . Simple solution are sometimes not only the easiest but the only solution Peace and good luck clammy
R.A. Calmbacher L.L.C. HVAC
NJ Master HVAC Lic.
Mahwah, NJ
Specializing in steam and hydronic heating


  • Robert_25
    Robert_25 Member Posts: 538
    Just stopping the air leaks is huge.  The insulation probably helps as well, but I think 80% of it is stopping the air leaking into the attic.

    I built something similar for my home about 10 years ago and noticed quite an improvement as well.
  • mattmia2
    mattmia2 Member Posts: 9,962
    Even weather stripping the door will help immensely. It is more important that you go over all the light fixtures and plumbing and other penetrations and seal them up with something like a plastic sheeting boot and caulk or tape. Fiberglass insulation really doesn't stop much air movement.
  • SlamDunk
    SlamDunk Member Posts: 1,600
    edited September 2020
    I bought something from http://www.batticdoor.com/StairCover.htm

    HUGE improvement keeping living space properly conditioned.
  • Jamie Hall
    Jamie Hall Member Posts: 23,657
    You folks should try coping with a main staircase which is a spiral, 12 feet across, with a four foot opening in the middle going up 3 stories. There's a reason the maids' rooms on the third floor didn't have radiators...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,505
    HD & Lowes makes the same thing, probably not as good. Looks like a giant styrofoam cooler attached upside down.
    I made one too. Lot of heat/cold migrates thru those steps.

    There was an error rendering this rich post.

  • motoguy128
    motoguy128 Member Posts: 393
    Sealing up leaks on windows and doors on both floors of my home has made the upstairs less overheated in winter, though I still ended up using TRV’s on all the upstairs radiators. We keep upstairs Bedrooms 1-2F cooler most of the time than downstairs for sleeping comfort. Bathrooms are kept a little warmer.

    IN summer the effect is reversed, though less strong. Once reason upstairs spaces are hotter in summer is the hot humid air is leaking in form windows and the attic. Wood roof decks act like Continuous desiccant dryer and pump moisture from the 150F+ wood outdoors to the slightly lower energy attic Making it 110F and high humidity. Even wondered how even a vented attic has a dew point higher than the outdoor air? That’s how.

    We would probably be better off doing cathedral ceilings with closed cell spray foam under roof decks. But it would cost more.
  • Zman
    Zman Member Posts: 7,607
    The worse thing you can have in a home from a chimney effect point of view are big leaks high and low in the house. As you point out, the slight pressure difference along with thermal buoyancy can remove an incredible amount of heat from the home.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • SlamDunk
    SlamDunk Member Posts: 1,600
    I recently encapsulated 1300 sqft of crawlspace( speaking to large leaks below) and installed a dehumidifier. We went from 75%rh to 40% down there. It made a noticeable difference in the living space. Upside, little to no mildew smell and faster cooling when ac kicks in. Downside, wife is developing finger cracks in the summer.
  • mattmia2
    mattmia2 Member Posts: 9,962
    don't forget the area between the foundation and sill and floor. We didn't even attempt to seal it until the 80's ad then it was just a mostly ineffective piece of foam. It really didn't get sealed well until we started spray foaming it.