# Floor required for attached greenhouse?



## Noah Pardo-Friedman (Sep 19, 2017)

Hi all,

I live in Albuquerque, NM, and I'm thinking about planning an addition to the south side of a house I may buy. The southernmost part of the addition would run the entire width of the house and would be an attached greenhouse.

My question is this: would such an addition be required to have a floor throughout the entire greenhouse? My preference would be to have a concrete footing or stem wall forming the foundation for the greenhouse, but have open soil inside. However, I'm not sure whether building codes would allow there to be no floor in any part of a house, even an attached greenhouse.

Thanks much!


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## cda (Sep 19, 2017)

Welcome


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## cda (Sep 19, 2017)

Good question
Someone may move this to a residential thread.

So is any of it pre fab?

Any openings from the house into the greenhouse??


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## Francis Vineyard (Sep 19, 2017)

It is permitted to attached and have an exterior door open directly into the greenhouse. However as cda asked there are other questions that need to be addressed such as exhaust, ventilation and openings that are serving as emergency egress or rescue openings from sleeping rooms shall open directly into a public way, or to a yard or court that opens to a public way.


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## Noah Pardo-Friedman (Sep 22, 2017)

Thanks for the responses! And no problem if this gets moved to a residential thread; I didn't intend to put it in commercial to begin with.

I don't know if I would go with prefab or not; I'd think I would consult with the contractor to use the best materials for the very specific purposes I have in mind.

There would indeed be an entrance/exit to the exterior from the greenhouse; it would exit to the front yard. There's plenty of room to comply with our local zoning code regarding setbacks. And there would be an entrance/exit into the house from the greenhouse as well.

As far as egress goes, all the bedrooms that would abut the greenhouse have exterior windows on other walls, so the greenhouse wouldn't create any egress issues.

Regarding exhaust and ventilation, that's part of my strategy here. I've read online and seen YouTube videos of attached greenhouses serving as a source of heat in the winter for houses (I'm a fan of earthships), and that's part of what I'd be trying to accomplish. I would design it strategically so as to avoid heating the house in the summer. I'm definitely open to suggestion as to how to accomplish those aims. My preliminary thoughts were to have high up windows opening up into the house to draw the heat into the house during the winter, and also high up windows opening from the greenhouse to the outside to allow heat to escape during the summer. I would spring for really good windows between the greenhouse and the rest of the house with a really high R value so that when they were closed there wouldn't be much heat transfer, and I would insulate the heck out of the walls between the greenhouse and the rest of the house so that I could really control the heat transfer with the windows. Again, I'm open to suggestion as to how to handle the issues of heat transfer and ventilation.

And there's still the question of whether I'd be allowed to have open soil rather than a floor of some kind (or potentially in addition to some flooring in some parts) in the greenhouse.

Thanks again, everyone!


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## steveray (Sep 22, 2017)

If you are not conditioning the space, I can see no reason to require a floor in a greenhouse addition...But that is based on limited information given. Talk to your local building inspector


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## ICE (Sep 24, 2017)

Humidity may be an issue.  The walls of a house allow moisture vapor to escape so I suppose the same walls would allow moisture vapor to infiltrate.

As to the floor....other than a pad at the door I wouldn't see a need for a concrete floor but I wouldn't want a dirt floor.  Dirt areas perhaps with walkways but not a entire bare, dirt floor.  The plan to attach the greenhouse with a common wall seems wrong......and in the front yard no less.


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## cda (Sep 24, 2017)

ICE said:


> Humidity may be an issue.  The walls of a house allow moisture vapor to escape so I suppose the same walls would allow moisture vapor to infiltrate.
> 
> As to the floor....other than a pad at the door I wouldn't see a need for a concrete floor but I wouldn't want a dirt floor.  Dirt areas perhaps with walkways but not a entire bare, dirt floor.  The plan to attach the greenhouse with a common wall seems wrong......and in the front yard no less.




I think I agree, I would want a washable floor.

Might also help keep the bugs out.

I also think a detached green house would be better.

It seems attaching it is going to be more hurts than help


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## Robert (Sep 24, 2017)

Noah, I like your idea...a classic passive solar design with the south facing advantage. One thought is to include some type of thermal mass floor in just some areas...perhaps loose laid brick or stone with sanded joints for drainage, to absorb daytime heat in winter and emit back at night. The same concept will cool at night in summer if ventilation is provided. In CA, if this was conditioned space, we would probably need to show energy compliance, but it doesn't sound like you are mechanically heating or cooling it, just passively. Keep the common wall insulated and weatherstrip the door. Stay with your idea of passive venting the air through hi-lo openings and perhaps operable shades (or deciduous trees) for the south windows in summer.


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## tmurray (Oct 17, 2017)

I would strongly recommend against interconnecting the air between the greenhouse and home. Growing up with 6000+ sq. ft. of greenhouses, we regularly had relative humidities above 60%. Introducing this moisture into your home will likely cause air contamination issues and eventually rot to the building unless a desiccant or mechanical dehumidification system is provided for the air prior to it being introduced into the home.


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