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Question DetailsAsked on 1/7/2014

Are new bulkhead cellar doors air and moisture tight?

new Bulkhead cellar doors

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4 Answers

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If you are asking about the sloping cellar entrance doors commonly called Bilco doors in this area they are water tight if installed correctly. Usually there is a secondary door at the base of the stairs that is weatherstripped so as to be airtight. I have seen no bulkhead doors that are airtight. As to moisture if a door is not air tight it can not be moisture tight. One of the biggest failures of these doors is rusting and much is caused by lack of painting the interior of these doors. They usually come with a prime coat of paint only and must be painted soo after install.


Answered 6 years ago by ContractorDon


Bulkhead doors are not air tight- they will let in outside air contributing to heating costs. In the summer, the air infiltration brings in warm mosit outside air which will condense in the cooler basement temperature further leading to moisture problems in the basement. You need to frame out and install an exterior door making sure the door is air tight as possible.

Answered 6 years ago by hosey


Normal bulkhead doors are designed to be "weathertight", not watertight - meaning they should be blown wind and debris and rainfall proof, but will not handle being submerged and commonly have some venting to reduce condensation on their undersides, so are not airtight.

There are higher quality (and about 100-300% more expensive) "airtight" ones designed to act as smoke control doors or as explosion blowout doors, and there are of course "watertight bulkhead" doors designed to handle submergence of up to about 6-10 feet of water in off the shelf (though special order - not usually stocked by distributors) models, and of course by special design to whatever you want from ship's equipment manufacturers - but you are talking real bucks there.

Normally, unless you go to a terrible amount of trouble sealing it to the concrete stair entry and waterproofing the concrete entry, a watertight door would be meaningless as the concrete stair would leak anyway. Usually, if you expect submergence, you pour a solid concrete box for the entry (with tiedowns so it cannot float), with the rim above the top of the house foundation, then mount the door on top of that where it will be above flood level. That way, it is watertight till the house floods through the walls anyway.

As stated in other comments, usually the bulkhead door is used to block debris, rainfall and snow, and the bulk of the wind force, and an entry door at the bottom of the cellar stairs is thoroughly weatherstripped to provide the actual air seal to the house.

If in an area without significant snowfall, in most areas it is legal to install an entry door with an outside landing area, then nopen stairs to ground level,, but tht introduces the need to handle rainwater falling in the stair area. There are specific metal pretty much water and air tight doors for this type use, but generally pricier than a normal good entry door there,, plus a normal cellar or clamshell thype door at the head of the stairs.

Don't forget what you want for security - most of that type door will take a padlock on the outside, but most do not have a locking mechanism you can nopen from the inside, so if this is an emergency exit from the basement, you need to consider not only code for egress opening, but also required landings outside the basement door and where one would open the bulkhead door, as well as emergency lighting. Also - if you have problems with vagrants and street people in your area, you probably want one that can be locked from the inside, and not opened from the outside without a key.

Also consider what wind loading you need - if for tornado or hurricane safe area, you need that specificiation, including specific approval sticker if for Florida and maybe other states with hurricane/ tornado specific building code requirements for windows and doors. Generally, if storm rated, cannot have a skylight window in them.

One other suggestion, which most manufacturers recommend and almost nobody does - provide a positive stop (railroad ties concreted in and anchored with rebar work well) for the outer edge of the doors when opened, so they hit a soft bumper that holds them open without wrenching or over-opening the hinges, and holding the door in a flat plane without warping it - most storm cellar/clamshell doors quickly get warped or the hinges twisted because people throw the doors open and just let them hit the ground at whatever angle they nappen to, so the alignment gets out of whack, and they then let in water and snakes and insects and such in quick order.

One other thought - a normal door of that type has a rubber gasket on the door that contacts the rim of the "well" or door frame. Commonly, it is easy to mount a slip-on type rubber bulb weatherstrip designed for car door use - mounting it wih wetherstrip contact cement. Gives a much thicker and better sealing weather and bug seal. Like this -

but usually the type where the slip-on notch is verticlaly oriented directly under the bulb is what you want - available at auto supply stores, JCWhitney and Amazon and lots of others online.

To research what is available, Bilco is probably the best known manufacturer, and they are known as bulkhead doors, cellar doors, storm cellar doors, hatchways, basement doors, and clam doors, among other names.

For a contractor - General Contractor if you need concrete stairwell and basement entry door and such too, or an commercial or farm building door and window installer - the ones who do metal buildings and prefab barns and such. Maybe a regular door and window installer if lots of tornado storm cellars in your area.

Answered 6 years ago by LCD


Thanks for all of the information! What we have now is old tongue and grove doors (2) which we have faithfully painted each year since purchasing this old house five years ago. The problem is that it's in real bad shape so when there is a lot of rain the "bowels" of the cellar door gets flooded. There is a board on the underside that "locks" the "system. The door into the basement is on the interior wall not directly in line with the cellar door. I do know if not put down right, rain water just pours into the area and has even come into the basement laundry room!

I am currently working with someone at who custom makes steel cellar doors. They say their doors are rain, leaf, and critter proof but unless chaulked "real well" will let air in. How do I go about finding someone to put the new one in? I've read reviews on Bilco doors and not too favorable with this company.

Answered 6 years ago by shasha120


Only a couple of other things I can suggest:

1) treat the door like you would a roof - think of where the water will come from and go to - both that falling on the door or blowing against it, and also where surface accumulations will go. To control/prevent water coming down your cellar stairs, you need to follow where the water will go. Initially you need a cover or roof (the door and its frame) to shed the bulk of the falling water/melting snow and keep it out of the stairwell. Then you need primary protection against water getting in through seals/seams in the door - here bulb-type on-edge or adhesive door seals all around (which may come with it or can be added) similar to what you have on your car doors to stop the bulk of the water from getting under lips and edges work well. The doors themselves should overlap the underlying frame all around, and one door should either overlap the edge of the other, or generally better, mesh with a compression seal as they close. Instead of an edge seal (which tends to get damaged and weather fast) really high quality doors use a seam or protrusion (solid with applied seal, usually) in the door which fits down into a recess in the frame - that recess being open at the downhill side to drain any seepage that gets into it.

Then, you need a way for any water than makes it past that first seal to escape but not into the cellar - so usually a compressible foam strip or raised drip ridge at the inner edge of the frame, with gaps at the bottom corners to let out any water stopped by that seal and trapped between that seal and the outer door seal.

Then, you need an excellent waterseal where the door meets the frame on the hinge side - sometimes a recessed contact seal, but usually the best is having the edge of the door overlap the frame with exterior rather than flush mounted hinges, with a dripedge and water seal on the bottom side so water cannot run between the door and the frame.

Then the frame itself has to be securely sealed to your cellar stairwell - which pretty much has to be concrete or welded steel to be waterproof - usually the concrete is troweled or ground flat, a heavy bitumastic (roofing) caulk or sometimes a soft rubber seal is put on the concrete, then the frame is placed on and bolted down tight with concrete anchor bolts, compressing that seal. A compression seal works WAY better than just caulking the seam with the concrete, though that should be done too using a 30 or more year silicone based sealant to protect the seal from weathering degradation.

Then of course your cellar stairwell has to be watertight - with any concrete joints caulked (preferably on the outside) with concreete caulk. For new construction, the right thing to do it use bitumastic or asphaltic sealant and bituthene water shield all around and under the well, but for a retrofit this means digging out the dirrt all around just to get the sides, which is a lot of work.

2) To take care of any water than does get into the well, there are two possibilities - a "wet ground" condition, and a "dry ground" condition. If your ground is wet or the water table comes up in rainy season or spring breakup (either generally or just around your house), then you cannot feasibly put in a drain to release water from the stairwell unless you have an underlying french drain (which if you connect it to the well means any drain blockage floods your stairwell), so the best you can do is put in a large (8-12 inch pipe or even a piece of culvert) bottom sealed pipe into the ground with a walkable grating on top to hold a small amount of inflow, then bail or pump that out when the weather turns drier to prevent stagnation. Some people just leave it wet and put in some bleach to prevent stagnation, and let it evaporate, assumig it has a grating on top to allow evaporation. For a "dry ground" condition where the water table stays below the well and the ground will drain, you can put an open-ended pipe down through the concrete a few feet into the ground, preferably with a surrounding gravel drywell to hold flooding surges, for the water to drain into. I prefer to always use a concreted-in solid pipe with a threaded flush cap through the slab for the simple reason that you can always slap the cap back in if your groundwater does start rising under the well, threatening to flood it. Some people use this system, capping it during the wet time and uncapping to let it drain once the conditions dry out, but of course then it does not really work to drain the well when you want it to. In extreme cases, I have seen people pipe a drain to their sump pump wetwell inside the house, providing elevations match up right. this is more expensive, and I generally do not like connecting the outside of the house to inside drainage in any way, expecially if the well could ever get seriously flooded by rising creek water or such.

The traditional approach for a "dry" condition was to put a good thick layer of loose gravel or crushed rock under the stairwell with a grating leading to it, to collect and drain any stairwell infiltration. For wet ground conditions they usually made the entry area at the basement door a maximum legal step height (usually 7-10 inches depending on applicable code in your area) below the doorsill (which was concrete to be waterproof) to act as a sump to hold infiltration till it could be bailed out after a storm. In some cases the stairwell is made several feet deeper, and a perforated or slotted walk-on grating placed over it, to provide a hundred or so gallon storage capacity for infiltration. Of course, this does nothing for you if the outside water level actaully makes it up to the doors and they are not wterproof, but for "wterproof" dodors (which always leak a bit) it can make the diference between the basement flooding and not flooding.

3) Be leery of actually making the well area airtight - without circulation of air, it will get damp (and icy if cold), and start smelling musty, and can start rot in the siding and door in that area. A bit of ventilation is a good thing, even though it is not quite as energy efficient. I always tell people who are looking for extreme building tightness for energy efficiency that they are building a coffin - dead air, moisture and smell buildup, and mold and mildew and even mushrooms and fungus are guaranteed if it is airtight - and that is exactly what you get when you make a building TOO airtight. Something about too much of a good thing, I guess.

4) It is very rare that "watertight" cellar doors are appropriate in a residential situation - regular "weathertight" is plenty good for almost all situations.

Answered 6 years ago by LCD

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