Arch. Myriam B. Mahiques Curriculum Vitae

Friday, December 25, 2009

Urban Analysis and Legalization of Patio Covers

3D render of a custom patio cover, by arch. Luis Makianich.
The patio cover is highly used in California to provide shade, a nice place to stay outside. It is a space of transition, not exterior, not interior.

The construction consists of a roof, typically a built up roof with a minimum slope of 0.25 inches in 12 inches, or it can also have a different slope, with asphalt shingles or tiles. Other materials for patio covers are Aluminum and plastic. It is very easy to build, and most cities supply the bulletin with the patio cover type VB construction details.

The patio cover used as a storage. Picture by  Myriam Mahiques

A "sort of" patio cover, I would not include this area as enclosed space in urban analysis. Unless I take into account the homeowner's intentions. The considerations must be based on the researcher's objectives. Picture by Myriam Mahiques.

The patio cover is an interesting figure in urban morphology. It is located at the back, usually as an extension of the living or dining room, and as an accessory open structure, it does not count for the lot coverage, or at least if it has three sides open.
If I have to analyze an urban block containing patio covers, maybe I would disregard them. Unless I see some clues that something different is going on.
In other words, urban analysis supported by fractal dimensions is not black or white.

A refrigerator under a patio cover. Picture by Myriam Mahiques

The non fixed elements are configurating an informal dining room. This patio cover is perfectly legal. Picture by Myriam Mahiques

I have seen some cases –many cases- where homeowners are tempted to enclose the patio cover when it has wood frame. It seems so easy…….They move step by step, first of all adding non fixed elements that provide the concept of an enclosed space: why not a TV to entertain the family at dinner time, by the way, some music player, and summers are so hot, why not a refrigerator? Second step, walls and windows are added around, the structure being only the 4”x4” posts. Maybe drywall is added as a ceiling attached to the rafters.
Now, we have an enclosed space that is part of the account of occupied space in our analysis. Though, in the aerial picture, the situation for open or enclosed is the same.
The million dollars question: is it possible to legalize an illegal enclosed patio cover?
It is possible, only if the construction follows the required specifications on the California Building Code for livable areas.
Most people do not see the difference, between an enclosed patio cover and any livable area, as a dining room. I’ll mention some of them:
.- Livable spaces usually have bigger roof rafters. Not only for structural reasons, a livable space needs thermal insulation. The typical R30 does not fit between 2”x8” rafters or less, and with 2”x10” rafters it would fit if a supplement is added. Note that patio covers do not need 2”x10” roof rafters.
.- Livable spaces have anti seismic structures, as shearwalls in both directions. A couple of posts are not enough for earthquakes protection.
.- The new wall footing needs special inspection.
.- Weep screed is also needed.
.- Connections for roof-top plates, anchor bolts-footing, etc, have to follow the Code regulations.
.- Maybe the height inside is lower than the minimum required per Code.
.- Taxes and City’s fees are obviously different for patio covers and livable spaces.

 See how low the height of the back facade is. Picture by Myriam Mahiques.

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