Tuesday, September 13, 2016

NHND to the Pond - A Sheltering (& High-Tech!) Roof

In the book "A Pattern Language" the authors state that there are "patterns" that can be used to design a town or a home. They really take the language of house design away from square-footage and number of bedrooms and instead refer to big picture, not-quantifiable ideas like:
  • Sheltering Roof
  • Car Connection
  • Entrance Transition
  • Indoor Sunlight
  • The Flow Through Rooms
  • Dormer Windows
There are 253 "Patterns" in the book- and I am sure I will write future posts about some of the other patterns I tend to use... But today we will focus of the "Sheltering Roof" -Pattern #117- because the New House Next Door to the Pond offers us a really good example.

A roof is the iconic symbol for shelter- as in the phrase "a roof over one's head". Some of the most primitive shelters are only a roof- and Christopher Alexander and his co-authors had some serious thoughts about our building's roofs and all they must do: (the following list is directly from the book)
  1. The space under a roof must be useful space, space that people come in contact with daily. The whole feeling of shelter comes from the fact that the roof surrounds people at the same time that is covers them.
  2. Seen from afar, the roof of the building must be made to form a massive part of the building. When you see the building, you see the roof. This is perhaps the most dramatic feature of a strong, sheltering roof.
  3. And a sheltering roof must be placed so that one can touch it. If it is pitched or vaulted, some part of the roof must come down low to the ground, just in a place where there is a path, so that it becomes a natural thing to touch the roof edge as you pass it.
There is even a 1914 John Burroughs quote (really!) placed in the text after item #2 with nostalgic ruminations about roofs- such as the "charm to the eye of the old-fashioned country barn with it's immense roof"... "it's amplitude suggesting a bounty that warms the heart". And how those barns "covered their inmates as a hen covereth her brood".

WOW! How can you not be inspired to design an awesome, sheltering roof after reading that?!

Front of the House

Back of the House
When designing a house, addition, or outbuilding, my thoughts often start with possible roof forms. For the New House Next Door to the Pond, my clients knew they wanted a sustainable house, a metal roof, porches, and that they wanted most of the living spaces located on the first floor, with only the kid's bedrooms upstairs. These ideas lent very nicely to the house having a 'sheltering roof'.

Touch a roof as you walk out of the kitchen door? perhaps...
  1. The space under the main roof is useful space - it is bedrooms and a bathroom. In the case of the master bedroom and the screen/sun porch, the ceiling is vaulted so that the space under that roof increases the volume of the space, creating a feeling of being surrounded by the roof.
  2. Seen from afar, the roof is a very prominent feature because of it's covering of the second floor with dormers poking out. Using metal as the roofing material will also call attention to it and make a dramatic, strong visual statement. 
  3. Now... touching it from the ground... maybe... my clients are quite tall and athletic. :) And we do have some awesome thick eaves and bracketed overhangs over some doors. Building codes do require a minimum headroom height, and I don't know if physically touching the roof inside or out is likely, but figuratively, this roof and the sloped ceilings in many of the spaces will call attention to themselves in a way that another less sheltering roof (or flat ceilings) would not.

Sheltering roof over a door
In addition, the NHND to the Pond has a super well- insulated building envelope- and the sheltering roof is part of that envelope. The roof eaves (white edges) may look thick to you, and that's because they are; this roof is covered with 4" of continuous rigid foam. (Exterior walls have 1" C.I.) Click HERE to go to a former post to learn about continuous insulation, and if you want to use it in a project, be sure to have someone knowledgeable work on dew point calculations for your climate zone. CI means that there is not just insulation between framing members, like typical construction. You've see photos of framing here on this blog - there is a lot of wood, and everywhere there is wood, there would be no (cavity) insulation. (And yes, wood does have an R-value - about R-1 per inch- but that is a pretty negligible number and more importantly the studs provide a "thermal bridge" conducting and transferring heat and cold from inside to outside and vise versa)

We used pre-fabricated Hunter Cool-Vent panels on this project. They were installed atop the roof sheathing and the metal roof will then go atop of it. (after some other high-tech barriers and membranes that you see covering the roofs in the photos) A one inch air space above the insulation vents the underside of the metal roofing, keeping it cool to prevent expansion and contraction. This house will be quiet, warm in winter and cool in summer, have low energy bills and very little air infiltration. (Yes, it needs mechanical ventilation) With rooms in the roof, this system is extremely valuable at keeping those second floor spaces comfortable.

So the roof is doing many jobs both practical and aesthetic - and maybe even a little psychological as well. It is a high-tech, advanced performance system with the appeal of traditional forms and materials that does the important job of meeting our most basic human need for shelter. It evokes protection and contributes as a prominent design feature of the building while enclosing useful spaces that surround those who live there. It creates one of the most important layers of insulation between inside and outside, and, of course, it will keep out the rain & snow, too.

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