BEFORE THE ARCHITECT

A MUST READ.  New, 1,006-page Home Designing & Home Building Best-Seller -"Home Design Standards-Home Building Standards" 3Q10

House Roof Design:  Roofline Design

in Plan View and in Perspective

"If you can't think easily and every which way in three dimensions, swear off roof design.  You'd better lay off cornice work, too."  AG 2001

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Now there's a roofline to which these clients are partial; however, all their king's horses and men that they've gathered around ye olde house drawing table just couldn't get it to fit.  They need house drawing.  They need roof planning.  They need house roof design. 

This is a good one for the geez.  Go geez.

It is written that roofline design is the postgraduate classroom for a house designer's Ph.D.  It is wisely written.  House roof design can humble the highest and the mightiest.

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Here's the footprint.  Because we're following only the outside lines of the foundation, the AG calls such house drawing Barefoot Prints.  (There's a little touch of that Georgia humor for your entertainment.)

Now you can see two wings – one left and one right – that'll stay the one story they're already built to.  It's the deep middle section that's getting the addition of another floor level. 

Your attention is kindly drawn to the roof planning perilous pit #1 — asymmetry.   The wings are not symmetrical.  So where a roof line starts on one side of the structure may not be in-line with where it ends.  In fact, we know that's so for both wings where they abut the center section of the house design.  The AG humbly represents this distinction of considerable merit and importance herewith.

This is the same barefoot print with four arrows added.  See how the arrows do not run into each other.  Neither will the respective rooflines as they run along the center section wall.

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The clients' choice or at least preference involves a pair of gables over the wings with ridges N-S and a hip over the center section.  It was in fitting the hip that their time house designing got tough.  Hips are regular structures — four lines in parallel pairs with right-angle corners.  So any one corner is always in-line with its two most proximate brethren corners.  Try it on this structure, and you get eaves way inside or outside of walls, because the four corners of this structure's central area are not of the required symmetry.  Remember the arrows passing each other?

What this quandary introduces is the roof planning perilous pitfall #2:  How may roof sections are we going to     house design, anyway?  Answer:  Four.  Not three.  Four.  One for the left wing.  One for the right wing.  Two for the addition in the middle.  You like hips?  You get hips.  Just find corners that line up.  It takes two sets of four corners to hip the addition.

Take a look at this this stripped-down, early version of preliminary geometry in plan view that the AG used to cover the addition.  While it could be stripped further, you can find the point to it by seeing how the AG effectively built two roofing systems on the screen, and ran them over each other.  A clearer representation of that preliminary result follows.

Talk about stripped down.  At this level of simplicity you get to wondering what all the fuss was about.  These are the codes:  G for gable; H for hip; MH for modified hip.  The hips have points, the modified hips have ridges.  The back overrides the front.  Take a look at this latter though still preliminary version of the center lines in an elevation — see the rear override the front.

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Moving along, the AG now presents that concept in 3d hidden line.  This view is from the Northwest.  (The dormers are sketched in.)  The lines are all pitched at 12-in-12.  The soffits are all set at an expansive 2'-6".  (There is a porch added to the front of this     house remodel.  It runs the breadth of the center section.  The pitch is 4-in-12.)

   Frontside left 3d           

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Many more concept house drawing were developed in this project than are now presented to you on this page.  The AG house designed-in 2d and 3d  in different pitches, using permutations and combinations of hips and gables with ridges this way and that.  We arrived at a basic set of house drawing for important or preferred house design:  a 2d elevation and 4 perspectives from each corner . . . . called it the 5-pack.

The clients finally settled on an 8-in-12 pitch entirely hipped.  In fact, this final concept derived from their GC's notion.  Given the pitch, this approach will require very careful roof planning on site in order to get the lines to run together properly.  (Raising that pitch slightly overall would have  significantly diminished these concerns.)    

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Now comes a series of questions and answers.  The questions are from the clients.  The answers are from the Autocad Granddad and Mrs. Granddad.

Question:  How do you think the house design you have created will look on my house?  If not so good, is there something different we can do with either the back, front or both?

Answer:  We think that the concept house design will look pretty much the way it's been presented on this page.  As for whether it looks good, that's a matter of taste.  As for what to do other than deal with it as it's drawn, we can offer no alternative within the bounds of sound house design and good building practice and a limited budget.

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Question:  Do we have to have such a steep pitch? (Asked before the 8-in-12 renditions.)

Answer:  No.  We can lower the pitch to say, 8-in-12, and take a look.  Much lower and this house will begin to look squat and grasping.  This is a structure with big shoulders, and it needs a strong statement for a top hat.

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Question:  How difficult would it be to give me a variety of pitches to look at? 

Answer:  Not difficult at all.  The difficulty may come in paying for all the not-difficult house drawing?  Please compare the two sets of pitches and soffits, and then make a determination about other house drawing parameters.  For those who are very visual in their perceptions, it will be difficult to communicate a change in house design with showing it to you in 3d perspective.  Once you've crossed that bridge, each change of pitch, soffit, or whatever is a change to the roof drawing all over it and not just one place here and another place there.  So when the house drawing's done, the pictures are the easy part.

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Question:  Is there an industry standard for soffits?

Answer:  No.  Style rules.  Most often, they're one to rarely more than two feet deep.  Much farther out and we can develop issues of cantilever structure and rafter tail sagging.  You can set surface-mounted or recessed downlights in most any soffit, taking care in regard to fire and wiring safety.

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Question:  Do we stick with the brick we have and try to do the addition with some other type of surface (i.e., vinyl, wood, cementitious board)? Tear the current brick off and re-brick?  Some combination of both?  Or something else?

Answer:  Keeping the front in one clad will make the house look bigger, and not chop it up.  As discussed, you're up against it to try to match the brick that's there.  Try to keep at least the front face of the house in one single clad.  To some extent, we're into style.  And there are very, very few styles that predominate two major building materials as clad on the same wall face . . . Tudor's surface board as real or decorative bracing, Pennsylvania barns are stone to the first floor and board over, some colonials mix shingle and clapboard or flat boards, and that's all the geezer can grab at from his vast memory files.   So, unless you are willing to stucco or otherwise coat (i.e., paint or stucco)  over the existing brick as you brick up the rest of the elevation, the brick comes off.  Now we're down money and the meaning of materials.  Bricks about as expensive as you can get conventionally.  And it's not exactly warm and friendly in my humbled opinion.  The AG, you know, objects to the stuccos and vinyls for their superficial disintegrity.  Wood and wood-fiber clads are even in the short-term subject to their inherent problems of coming out of true, not holding a coating, bleeding, splitting, sucking moisture, hosting critters, etc.  Clapboard, notably cementitious clapboard, is warm and friendly to look at, cheap to buy at least in board form, and easy to install and maintain.  It's not so easy to maintain as brick, if your brick foundation's good and the mortar mix holds.  If there is not foundation to begin with, then add that to the hefty cost of bricking up.  On the other hand, exterior changes to brick walls versus cementitious clapboard walls ought to make you think more kindly of the clapboard.

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Question:  Is the AG considering how the house design will impact window placement?  One concern is whether the south, second floor bedroom wall will have sufficient area for a window of a size to meet code. 

Answer:  Good eye.  Good eye.  Neither the 12-in-12 nor the 8-in-12 lines will let the pair of double-hungs set in the south wall of the second floor bedroom on your only elevation.  That's the AG's judgment short of a good set of elevations to be absolutely sure.  The latter's 8-in 12 lines look as though you will have a fighting chance for some kind of windowing in that bedroom, but not as capacious as drawn in your submission.  Ultimately, this may be a matter for you and the Fire Marshall to work out.  There is among your options one: that you not classify that room as a bed, swapping out the storage area designated in the backside for this room instead.

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Implied question:  How do you make my house more welcoming, warming, softer in appearance?

Answer:  Not with structure.  You can soften any structure, make it warmer and friendlier with all sorts of detail treatments, as examples —   

The AG will adorn your house facade and frontage with these or other improvements to soften, warm, and welcome at your wish.

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The old Autocad Granddad has been asked to explore two other house design options:  gabled wings with the ridges running East-West (front-to-back); an offering by the GC to the Granddad's clients (accompanied by a brilliant stroke of the geezer's house-grown genius, don't you know).

The AG promised to keep both these new concepts simple-stupid on the screen, unless they showed some truly redeeming virtue.  This promise was made in the interest of preserving the clients' wealth from shifting too much further in favor of the AG's own account.

First, let's consider the gabled wings.  The notion here is to get a pair of gable ends facing forward.  The AG chose to start testing this notion on the master bedroom wing.  He temporarily disappeared the porch and the garage, and returned to wireframe house drawing of the central, two-story section of the house plus the master bedroom.  

The geometry of this look-see is compelling:  forget it.  Geometry gets us in the front elevation.  Geometry gets us in a perspective view, too.  Along with the forces of Nature, physics, and good building practice.  Among other forces.

In this elevation, the crux of concern is that the master bedroom is not especially wide at 13'.  It's deep at 30', but not wide.  So when you spread your 8-in-12 gable end across the narrow 13' breach, you don't get a lot of lift to the peak.  In other words, the gable end is diminutive relative to the rest of the facade.  Even a 12-in-12 pitch would not overcome this disproportion.

There is a tangential problem as well with gable-ending this master bedroom on the front face - centering.  The left and right sides are different on the master bedroom (the garage, too).  There's an overhang, or soffit, on the right; none on the left.  Centering on the two bedroom windows moves you right of visual center.  Centering on visual center moves you leftwards awkwardly.  In hipping this structural segment, the angularities inherent in hips effectively overwhelm an easily discerned centering . . . the eye gives up trying to aim at a middle point.  But not with the gable.

This gable-end house design is not just about disproportion.  It's also about potential hazard to property.  It creates a long, lateral joint of gable eave to the center segment sidewall.  It's a trough for water, snow, and ice to lay, for leaves and pine needles to collect.  In northern climes, such zero- and near-zero-sloped valleys are nonstarters for any building inspection department worth its codes.  Additionally, an area at the back end of this valley there is a  further hazard to this 8-in-12 negative slope from the ridge inward:  Water runs downhill . . . . to a dead inside corner.

And raising the inward slope further distorts proportion.

Now it can rightly be argued that the AG himself in all his glory created dead corners in the house design in either pitch higher up on this page.  What's the difference?  Why might the earlier house design pass muster and these not?  Because in the earlier house drawing, those dead corners can be remedied with crickets in the normal course of house building and in a conventional manner.  There is nothing either normal or conventional in the nearly thirty feet of cricket needed to bail us out of the dead corner drainage predicament of this gable-end house design.  Big difference.

There is no legitimate point in pursuing this house designing any further.

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Finally, we move on to another idea or two.  The AG's clients are not especially keen on the house design that overrides the front roof with the back roof atop the center segment of the 2nd story.  Their GC offered an alternative house design which leaves all the front-end rooflines unamended, and turns the back roof line to a 4-sided hip with a North-South ridge.  This styling will erase the vertical facade at the joining of the front and back, and replace it with falling-away hip profiles.  (In fact, that facade at which all have stared as we moved from one pitch to another need not be vertical at all.  It could just as easily be treated as to sloping ridges and two corresponding valleys.  The framers could set a pair of long, angled chases from the upper lines to the lower faces, and the shinglers could lay their wares over the entirety of the angled transition.)  The AG will further amend the back line by cutting the back's East-West soffits to zero, therewith eliminating 3' of width and derived override.

The hand sketch of the ridge and hip lines was just a little out of perspective and proportion.  But then, so is the back structure on which the back cover sits out of square.  Adjusting a little this way and a little that way, this is what the geezer got for a plan view of this most recent alternative central area.

This varies from the previous 8-in-12 pitched structure in that the front now runs to a back (theoretically) hipped plane, only two lines and a tad of surface of which show now as the valley lines and the strips next to them.  The East-West ridge of the fore roof now runs into the short aft roof North-South ridge with no change in elevation.  Note please that there is a major diminution in the joint profile between the two roofs resulting from cropping the rear roof soffits.  Note as well please that those two slivers of transition may be shingled over, further diminishing their visual obtrusion. 

Taken from our standard 5-pack of hidden line house drawing - one front elevation, four perspectives — herein after we get a feel.  (It's worth noting that there is some wiggle-room in the short, back ridge borne from the out-of-square subordinate structure.  This is nothing that an experienced framer cannot handle masterfully — especially if he knows it's coming.  And I think this could be coming.)

Front face, 2d elevation

         Frontside left 3d             Frontside right 3d 

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Time to call in the dogs.  It's been a good day.

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The AG is hot.  He has just received words of appreciation for the last house design.  It has been suggested (really, it looks like the AG forgot to do this before) that the geez goes the final mile and hip the wings.  Go geez.

Here is the most recent house design – hipped central segment, same elevation ridges to the central, second-story house design – now with the wings hipped, too.  Note, the slopes throughout are all at 8-in-12, even the porch pediment is so sloped (only the porch shed itself is pitched at 4-in-12).

Front face, 2d elevation

                            Frontside left 3d             Frontside right 3d            

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