The topic of “Sunrooms South Bay” came up one night over dinner in San Jose (South Bay/ Bay Area CA).

The idea was floated over dinner, to expand the dining room, to give it more living space or square footage. And the suggestion of a sunroom was floated as an inexpensive solution.

Sunrooms South Bay – Crazy or not?

The first question that came up? A Sunroom in San Jose California? Wouldn’t that get too hot, from too much of the south bay’s sun? Well, maybe, depending on the exposure, the landscaping, the choice of sunroom design, and other factors.

Let’s look at some of those and see if a sun room in a sunny climate makes sense:

Exposure – What Works for Sunrooms

Since sunrooms bring in the sun and heat up, a south facing sun room would get too hot in warm climates. In warm areas, the sunroom would be better facing away from the sun, so on the Norht side of the house. In cooler climates, a south or south east facing sun room will provide the most comfort.
Breakfast in an eastern facing sunroom, or dinner in a western facing one.!

Landscaping – What Works for Sunrooms



Design (to keep the heat down) – What Works for Sun rooms


Sun Rooms South Bay


Four Season or Three-Season Sunrooms ?

What do you prefer? In a warm climate, the three season is fine. In a colder climate, and if you wanted to use the sunroom in the winter, a four season is the choice.

Sunroom History

Conservatories originated in the 16th century traders from warmer regions of the Mediterranean returned with citrus fruits such as oranges  and lemons that would not grow in northern climates. Those that sought to cultivate these happened upon the greehouse effect and created Conservatories.  More in this Wiki page



Other considerations

Typically, cost runs from $70-150/SF depending on current foundations and roof, and commonly is cheaper to do as a teardown then to modify the porch to a sun-room. The national average for a true sunroom project (as opposed to a small green-house type prefab structure) is about $50,000.


If you are converting an outdoor space into an indoor one so you might have significant waterproofing issues, the walls and wiring and such have to be built like any other house wall, normally a full foundation has to be put under it (unless it is built detached from the house, including the roof), the subfloor has to be made waterproof so ground moisture does not seep up into your flooring materials, etc.

If you watch the ventilation issue, depending on your foundations and such, you might be able to put in windows and such as a not-fully-indoor space Florida Room for about half that.


Assuming you are talking fully conditioned rather than just converting to a sumporch or screened porch, why pay for essentially the full structure, with the same foundation and roof as a full addition, but not be able to use it whenever you want, for not much more in construction cost.

If you end up designing it like a sunroom and want to close it off in the coldest part of the year, then with a bit of creative use of outside shutters and local humidity control (typically using the return air to your furnace that would otherwise be exchanged out for fresh), you can crank the inside temp down when not in use, or even design the HVAC to keep the room at a reasonable temperature for humidity and frost control (maybe 50-60 degree range) and provide a unit heater for rapid increase of temp when you want to go out there.

This does require special design to avoid moisture accumulation in the walls and such, use of moisture-resistant materials, and of course protection for any piping, but is not unusual to do in areas with winters that have a fair number of decent temperature days. One thing you do NOT want to do is turn the heat down and close off the windows with blinds or heavy drapes without doing special humidity control – you will end up icing the windows up terribly and having water running down into and over your walls from condensation.

If you were thinking just a sunporch or screened porch without conditioning the air in it except maybe adding a unit heater for forced air heat only when actually out there, then that is certainly FAR cheaper than an addition – probably from ballpark 1/10th the cost for a screened porch, or ballpark about 1/6 to 1/4 the cost for modular “greenhouse” or “arboretum” type windows around a porch.


A primary recommendation is to figure out what you want to DO with the space – how you will use if differently than it is now.

If going for the in-law apartment/space bedroom, then you are talking teardown on the enclosed proce and addition from scratch.

If just as a small sunroom, then cheaper foundations like piers might be feasible, maybe (depending on elevation issues) just a wood grid laid on the slabs and overhanging for the extra depth, etc) – especially if you keep water out of it so it does not have to always be heated, and can use just a ceiling-mounted unit heater or stubbed-out airconditioner vent to heat it only when in use.

Whatever you do, unless you do not care about resale issues, talk to your favorite realtor (maybe the one you bought it through) or an architect about the relative value of the house with improved sunporch versus entirely new addition – he/she may well advise going with full addition route as the better value for your money, particularly if the other option would make it look like something out of the Beverly Hillbillies.

Money saving recommendations

if just looking to gain sitting room / rec room space, is it possible to put the 1/2 bath in the existing house, and finish off this porch as a fully-enclosed sunroom – could save a lot of $, though would not be a legal additional room or in-law apartment for real estate listing purposes, if that is your goal. Depending on surrounding grade and surface water drainage issues and such and existing slabs, might be able to leave them and overhang the floor joists to 7 feet on the existing 5′ side, though doing that rather than full foundation does risk settlement issues with windows. Either way, putting a 1/2 bath and washer/dryer out there pretty much eats up the space – so this is soundingmore like a 1/2 bath and laundry room than an addition – awful narrow for an addition because no room for a hall, so if looking for more than just a laundry porch and bathroom and you want some actual living space, sounds like maybe you need to talk to an architect for layout conceptualization.
Running water in there changes the whole complexion, to a “true house space” as opposed to a florida or sunroom approach, and requires full foundation support, so at that point you are doing a full addition – probably as a teardown of the existing – or maybe saving the roof if feasible.

If going ahead with a bathroom and laundry out there, definitely keep them against the existing wall to keep pipes on interior walls unless in absolutely freeze-free area, with ample free space where passing through the wall for pipes and such to allow for some differential movement.