Cellar Construction questions

So, with the most recent flood in my basement, a lot of stuff has to go. Out with the Old, and in with the New. Part of the New, I thought, could be a 9f by 9f by 9f wine cellar. To all you experts out there, I was wondering a few things.

What is the best cooling system? (Examples of brand and ideally store, would be appreciated.) I have a thru the wall Whisperkool 1500, but between May and September in DC, I need to keep the AC going in the room next door, for it to be able to maintain 55. So I’m thinking it may be time to step up.

The Vapor Barrier. I have learnt that it goes on the warm side, something which the creator of my previous cellar had not… (No visible damage to anything after 2 years though.) But does this mean it goes on top of the outside drywall and then the stud over it, or the studs first and then the barrier? The difference would be whether, the studs now are insulated from the cool side or not.

The insulation. Any particular kind I need? R13? R 16? Does it go in the floor as well as walls and ceiling?

The Drywall. Do I just use plain regular stuff, or is there a special kind i should use on either the warm or the cool side?

Thanks for all input to these questions and feel free to answer those that I forgot to ask too.

buy Richard Gold’s How and Why to Build a Wine Cellar as a starting point for learning about cellars, though mostly passive.

Yes, read Gold’s book. It will give you a good start.

Can’t help on the cooling system. I got a 1986 Breezeaire for free a few years ago and it still works.

The vapor barrier goes on the outside of the cellars, over the studs, and under the outside drywall. Over the long term putting the barrier on the cool (in)side could cause condensation within the insulation and then mold.

Given that the cellar interior has elevated humidity you should probably use the green drywall. (Me, I just used styro insulation as I did not care about appearances.) It’s made for damp areas like bath rooms. On the outside it does not matter so go with the less expensive. You could probably even use paneling outside although it will insulate less than drywall. Insulate the floor? Not necessarily. If the floor is concrete then it’s not necessary especially if the floor is fully underground.

The more insulation the better (higher “R” number). The cooling system will have to work less. I built my cellar with 2x6 wall studs and whatever fiberglass insulation filled space.

There are as many ways to skin this cat as there are people to do the skinning.

That said, here’s one helpful hint: The wooded studs in the studwall affect the insulative value (the R-value, or more scientifically, the “u-value of the entire wall”) because wood isn’t as good of an insulator as fiberglass. So, one way to significantly improve the u-value of the wall assembly is to add a layer (even 1 inch) of R-5 styrofoam (extruded polystyrene) to the inside (wine cellar side) of the wall, between the wooden studs and the sheetrock. Nail the styrofoam to the studs, and then use longer sheetrock nails to nail the sheetrock to the studs through the styrofoam.

This layer of insulation will eliminate the “thermal bridging” of the wood studs. So, for example, a 2x4 wall with R-11 insulation might only have a u value of 1/8 rather than 1/11, but with the inch of nailed up styrofoam, it goes from 1/8 to 1/13, an improvement of almost 40% for only the cost of the materials ($1 / square foot) and the nailing.


I wouldn’t bother with the Gold book as it is more geared towards passive cellars.

You current system is either undersized, the room isn’t insulated properly, or the space you are venting into is too small and warm.

The best is always a split system. The best splits tend to be unbranded product, ie. a collection of assembled components from various manufacturers.

VB is CRITICAL and must be on the warm side. From the cellar out greenboard, studs/insulation, vapor barrier, exterior wall or greenboard.

for most climates r-10 to r-20 walls, R20-30 ceilings the floor usually is only done if at or above grade.

“MR” type aka greenboard, purple board, + some specialty products.

Thanks all for your specific inputs. This is very helpful.

if you’re going to build by hand, i’m happy to help out.

+1 I need to educate myself before my 2013 build :slight_smile:

I am around for anyone building home cellars for moral support, etc.

All great information so far. So many people including Kravitz and John G. were very helpful during my project and continue to be so.

[quote=“Chris Kravitz”]

for most climates r-10 to r-20 walls, R20-30 ceilings the floor usually is only done if at or above grade.

Chris, I’m planning a new basement cellar and the slab floor will be 10’ below grade. In So. Cal our soil temp at depth is
65-68F all year. Gold’s book said to insulate the slab only if you want to raise temp in the room, but I don’t think it makes
sense if you have warm soil. Isn’t it sensible to insulate below or within the slab to keep that heat from sucking the cold out
of the conditioned space?

I used closed cell foam from Touch n Spray and shot all my studbay walls with insulation before applying greenboard sheetrock. Since it is closed cell foam and not the more commonly available open cell, it is also a vapor barrier. If you have a smaller space or a generous budget, it works well in sealing and insulating between the studs, under supported flooring and ceiling/floor joists. Trouble is the canisters are expensive and cost about $500 for two boxes (each containing two canisters) for my 60 case capacity understairs cellar. I bought them on EBay. Other trouble is the spray process is messy and requires very good ventilation at installation. When you are done you will have insulation that fits your walls like a glove, insulatrs around wiring, insulates like a refrigerators walls and has no smell. Maybe you recover some of your cost over time with less cooling cost, I can’t say because I have no comparison. Also, the advertised coverage of the foam was completly off for me-- I found I needed twice the amount of product and still only filled half or more of the depth of the studbay. All in all, I would use it again in these smaller spaces.

Not Chris, but I do know construction. 65-68 at depth seems high, even for here in Socal. Are you pouring the floor? If so, I would say yes insulate the floor. It’s easy enough to insulate underneath the slab. Even if the soil is really 63-64, with a slab having an r value of only 1, you will have some heat gain.

A few other items. First, no need to use fiberglass insulation rolls. You can use the extruded polystyrene - it’s better, easier to work with, is its own vapor barrier, and doesn’t get affected if there’s dampness or a leak one day. Also, you don’t need to use wood studs. You can use metal. They’re also easier to work with. And if you want, you can staple a layer of insulation over them too. You can build the thing yourself in a weekend. The racks will take longest but if you’re buying them made and not building them like I did, they’re easy to install too. Finally, you don’t need to use sheetrock and if you have potential for flooding, I wouldn’t. I used cement board. It comes in 2 foot widths so you can have a 2 foot base that’s entirely waterproof.

You said 9 x 9. Figure an average wine bottle is 13 inches. So if you have a single-deep row in each side, that’s about 2 feet and if you leave yourself 2 1/2 feet in the middle, you can make your cellar five feet wide internally and have plenty of room. So I assume you’re doing a row down the center? That would be nice and you won’t lose wall space for your cooling unit because you’ll have 2 aisles where there won’t be bottles and where you could place it.

Hi John, yes the floor will be poured. 1/3 of the basement will be cooled space. The shape of the footings on 3 sides of that space would make it a bit tedious to insulate them too, so there will be heat migration horizontally though the footings. Today temp is 68F at 8’ (I have a few inches of water at the bottom of a vertical buried conduit I sank to take these readings). It is only a bit cooler in winter.

Given the floor’s 68F temperature, you should definitely insulate under the slab. Otherwise, you’re trying to cool the slab and the ground underneath, which is effectively an infinite source of 68F.

My plan is to pour the slab recessed in the area of the cooled room, then lay in 1 - 1.5" Dow insulation boards, covered by hardieboard and large heavy granite floor tiles, level with the rest of the room…mancave. The wall between the cooled area and rest of the room will be all insulated argon filled glass panels, plus a door. Does anyone know if increasing the distance between the inner and outer glass panels will increase the R-value? Typical is 3/8" to 1/2", but I’d consider increasing it if insulation value rises.

I would suggest using closed cell spray foam insulation. These days, that is all I will use in a cellar. I shoot for 3" in the walls and 5"-6" in the ceiling. If you are below grade, no need to do the floor but if above grade, or in an area with a really high water table, such as the shore area, the floor is a must as well. That is your vb and your insulator. With respect to the wall and ceiling finishes, I suggest only green or purple board. Then hit is with a mold/mildew resistant paint, just to be sure. On the cooling system, go for the split system.If your space is square or rectangular, a ductless split is the most cost effective. For a 9 X 9 room that is well insulated, a 1/4 HP unit should suffice. You can put the condensing unit in an indoor utility room, or outside, whichever is more convenient for you and just run linesets between the 2 appliances. Gold’s book is informative but as has been mentioned, talks more about passive cellars. There are many different systems you can use for racking, including doing it yourself. Just think about how many bottles/cases, you want to store and take it from there.

Good luck !

Jay Rosen

If the sticker shock does not get you, then, I would have to agree on the spray foam. Not that I am a builder. Just a consumer.

Also, as for racking, if I had to do it all again, I would have measured some of my bottles that I wanted to store double deep. A good chunk of my cellar is too small to handle two bottles without the necks sticking out more than I want. Just one little change on the plans would have solved that.

Also, for your cooling system think about the noise factor depending where it will be located. I was lucky enough to get a pretty quiet system but some of them can be quite noisy.

I am not sure about a wall assembly, but with multiple-glazed windows the R-value does increase as the air-space is increased from 1/4" to 1/2" to 3/4". It is definitely not linear, and the biggest gain is with two airspaces. When you do your research I’d be interested in hearing what total R-value you can get out of a two-panel glass/argon assembly.
I would be sure to contemplate the floor assembly. Especially the use of hardi-backer over the insulation boards. Hardibacker needs to be screwed to a subfloor (typically 3/4 ply) every 8", and the joints need to be taped. Otherwise you will get movement/deflection which can definitely lead to failure and floor cracking. With high compression foam the deflection might not be an issue, but I doubt the Hardi can be adequately fastened to the foam. As an alternative you would lay ply on top of the foam, but then have the issue of affixing the ply and of building up height. It might be smarter to just insulate under the slab and set tile/stone right on the slab. You might have some problem with insulation at the edge of the slab and thus some wicking of heat/gain through the slab edge. In the grand scheme, with a small temp difference over a small portion of the area, that does not seem like much gain.
As with all the cellar threads, I’d warn to make sure you use 5/8" green if you use it on a ceiling with 16" joists. Do not use 1/2".

The airspace is not what you should be worried about, the glazing product is much more important. You should be using 1" Insulated window consisting of 1/4" PPG Solarban 70XL / 1/2" airspace/ 1/4" clear. This combination will give you a solar heat gain coefficient (SHGC) of .26 which far exceeds anything in the industry. Be sure to purchase a Thermally broke window frame as well; keeps the outdoor heat from transferring though the aluminum.