We recently bought a house with an attached, unfinished “greenhouse.” Problem is, solar heating greenhouses don’t really work in the Pacific Northwest. Since we have overcast skies almost 100% of the time during the fall/winter, greenhouses don’t heat up. That said, it could be a very nice, bright room to sit and have breakfast or something. I’m wondering if it’s practical to turn it into living space, or whether we should make it a 3 season porch instead.
In terms of walls and roof, the material choices are pretty straight forward, but I’m not so sure about the floor, and I think the floor may be the thing that determines whether we go living space or porch.
The foundation was poured with the main house, and it is three foot high concrete walls with a slab inside and a drain in the middle of the slab. The drain simply feeds to a pond behind the house, and it wouldn’t be practical to convert this for use as a sanitary drain (i.e., into the septic). It’s also plumbed for a sink, but the drain is the same as the floor, so again, the original intent was just to have a convenient water source in a greenhouse, not usable “plumbing.” There are french doors opening onto this space, but they are at the level of the main house, so we need to frame a floor in this space. Steps down to slab level wouldn’t really work because of the dimensions.
If I built a floor, I’m unsure how to handle the space below. Hatch door access, I guess, but do I plug the drain and seal the space below with a vapor barrier? Is this hokey, or commonly done? And if we were to give up on living space, then how far should the insulating go? While we live in a mild climate, it does get cold for a while in the winter. We’re near British Columbia. The sink and drain do seem handy if we could create nice place for plants, but, without insulation, the room would get too cold for house plants in winter. It’s a little bit of a catch-22, and we are beginning to understand why the previous owners never finished the space.
Any thoughts?
Replies
well..............
figure a way to put hydronic in a new slab on top of the old, insulate between maybe. That would give you a moderate (55 degrees maybe) temp to keep most house plants just fine, tropicals maybe not.
Certainly would be a comfortable 3.5 season room...............
If you planned on raised beds, you could run radiant under those.
or not.
Your description is a little unclear. How far above grade is the house floor? How far above grade is the "greenhouse" floor? What's the difference in height between them?
What is the wall construction (including doors/windows) between the house and this area?
What sort of wall is this area up against -- is it a single story with an eave above, single story on gable end, multiple story, what??
What are the overall dimensions of the area?
What is the exposure? (East/west/north/south?)
What sort of heat do you have in the house?
Sorry about the description. The house sits over a crawlspace, on a continuous, 3 foot high foundation. When you're under the house, it's almost possible to stand up because it was excavated (a little too much, maybe) and when you include the footing, it's probably over four feet of space. The "greenhouse" area has the same three foot high foundation, but there is the poured "floor" which is about 6" above grade. It's about 30 inches from the top of the finished floor of the main house to the top of the poured slab inside the "greenhouse" area. The space is a small triangle, off the corner of the house, around 100 sf. There is a sill plate bolted to the top of the foundation, and the area is framed with 4x6 studs, and the roof is...not sure the right term...hip? I think hip is correct. So, it's a hip roof, going around the corner of a two story house. L-shaped hip? The greenhouse is one story tall.
I'm not sure I could picture what it looks like from that. Sorry.
(Before I go much further, I should say that, since I posted, my wife and I have realized it's ridiculous to design an entire room around the needs of a few house plants, so we'll probably aim for an enclosed porch, rather than living space. That said, it still begs the question of where to stop in terms of insulating the space (if at all), and what makes sense in terms of materials inside the envelope.)
So, back to the description: It's exterior finish on the wall between house and this area (cedar siding, fir windows, cedar trim). (Another argument against living space). It's on the SW corner. Heat in house is forced air, gas, but that's a moot point now.
What makes the most sense is to carry the existing deck into this space. The main sticking point, when I was thinking in terms of insulating, was closing off the drain in the slab and then laying a vapor barrier on top of the slab. But, if I just do deck, that's no longer an issue either.
I guess I would use exterior finishes inside the "green house." Probably cedar siding lower half and windows above. And then enclosed soffit. The only question that remains is whether I should insulate the walls or roof. Is there any point in doing that, if the floor is open decking?
I think this post is kind of a rambling mess, but, now I have to go, and don't have time to re-write.
Some clarifications please. So you have French doors opening into this space and a 30 inch drop? What is the interior finish? Bare framing? Describe the windows … a lot, a little. Glass type? This faces SW you said? How large is this space?
I did a passive solar sunspace in Spokane almost 30 years ago and I really liked it. It was unheated. On those occasional sunny winter days, it could easily get 90+ in there w/out heat from the house … I’d actually open the doors to the space to let the extra heat in. It never overheated in the summer.
Glass was key for this …. I used Heat Mirror glass which maximized solar gain while minimizing heat loss.
I’d go for the 3 season unheated space. My plants loved my sunspace. I’d have to work at cutting them back a couple times a year.
I’m attaching a pic of my space.
Keep it as green house
They sell nice electric mats that are desinged to go under the wet beds in green houses and keep the roots, and by convection the plants nice and warm so they don't freeze.
Amazon has some, and there are quite a few websites devoted to horticulture supply on the web.
The Fine Gardening site has a forum, "Over the Fence", where you could probably get quite a bit of help with keeping it a green house.
Some photos...
This may help. We are leaning toward just bringing the deck around and then adding a half-wall and some screen. The roof would be shingled to match the rest of the house. We need to get it covered, whatever we do, and a screen porch is a way to finish it without undertaking something we obviously aren't sure about. We have other areas for plants, so we don't really need another plant place. A place to sit in the heat of summer and keep bugs away is about all we lack. And that would mean a table and chairs, which is why I say that stairs wouldn't work (hence deck). Stairs would take up all the floor space. Note that there is a framed opening for another door leading to the rest of the deck (visible in the picture of the floor).
Looks like you have two orientations ... e.g. south and west or south and east. All glass won't work well for a passive solar space. Too small to put in steps. I'd do the 3 season porch on a deck level w/ the doors and other deck. A sun room simply wouldn't work to well w/out giving up some good things.
thanks
Yeah. I spent most of last winter reading books about passive solar greenhouses and had dreams about growing veggies all winter long. Then I realized that all those books are aimed at an East Coast audience where there is direct sunshine much of the winter. Sure, there may be 2 feet of snow, and the temperatures might be sub-zero, but that direct sunlight makes all the difference. Here, we never have snow for more than a week, and it often gets warm enough in mid winter for the grass to start growing a little bit. But we rarely have direct sunlight.
Three season porch makes the most sense.
Actually most passive solar books are aimed at the Southwest ... sunny days and cold nights. If you look at a map of solar radiation, the east/northeast/midwest isn't really that good for winter sun. The PNW isn't much worse than the east coast, really. I advocate taking advantage of passive solar IF it is convenient/easy. If your walls were primarily south oriented, I'd encourage it.
colin
It looks like the framing is there (with some additions) to roof it and screen it. Add a door and all sides are taken care of ............but the floor.
For a screened porch (if there's fall in the floor to the drain in the slab) I'd anchor a rim joists all around and then using joist hangers, set in joists. Do the layout so in the center you have a "feature" panel that could be removed IF you should ever want to get down in there for any reason. That puts you on the same level as that deck off the side, but you'd still need a couple steps to get down to it from the house..
or
Build off the top of that foundation-bringing it closer to house floor level.
To make it an addition, consider it a crawl and build accordingly-making access somehow-floor, cut through foundation.
Things I'd question are the roof framing, the possibility of replacing the corner post (and others if I'm seeing it right), size of window openings and addtional wall framing needed to make it right, and electric / heat (if pulling from the house won't cut it. I think it would be a little more than just siding it, stick some windows in it and calling it done.
Best of luck.