Assessing the site constraints for the remodel of an existing 1940’s bungalow in Seattle

The Architect's challenge - designing the remodel of a 1940's bungalow on a steep slope in Seattle

I came across the following ad on Craigslist recently and while I didn’t offer my services to them it seemed worth writing about in a blog about residential architecture.  It touches on a number of issues that I’ve written about in the past.  In particular my article on writing the project program  for a remodel discusses these issues in general.   In this article I will address the issues the add raises for a site I’m working on in Seattle.

 We are looking for an architect who can… (Seattle)

• Location: Seattle
• it’s NOT ok to contact this poster with services or other commercial interests
• Compensation: Negotiable

PostingID: 1153264673

 Answering the questions for this 1940’s bungalow on a sloping site

The site we’ll be looking at is in the Magnolia neighborhood of Seattle.  It isn’t a slam dunk remodel.  It has significant challenges to consider.  It is typical of what Seattle Architects are faced with when designing a remodel in this area.

Bird's eye view of the house on the site

 Physical Constraints affecting the design of the remodel

• There is a considerable slope up from the street.  (Each of the contours shown on the accompanying city zoning map represent 2′ of grade change) the site slopes 40′ front to back. 
• The street also slopes steeply and is quite narrow. 
• Getting in and out of the driveway is treacherous
• The house is set back from the street 45′
• The main floor is 16′ above the highest point of the street.
• A view of Puget Sound is to be had to the Southwest

 Zoning Issues that affect the design of the addition

• The lot is zoned single family (SF-5000)
• It has mapped “Environmentally Critical Areas” or ECAs.  (The purple shaded areas) 
• Seattle recently revised the zoning code to prohibit attached garages from projecting in front of the main house
• An upper floor would need to comply with the 30′ height limit
  

  Zoning & topographic map showing the house on the site & the steep slope critical areas

 Results of a physical inspection of the home

• The construction of the home is typical of homes built in this era.
• The framing appears to be sound
• There is little or no insulation in the walls and roof
• The foundation is 8″ concrete (with brick facing in some areas)
• The foundation appears to be sitting on a footing of appropriate size
• The foundation exhibits no significant cracks
• Retaining walls on the site appear to be in good shape as well
• There is no obvious sign of soil weakness

 The first question, “Will a remodel fit on the site?”

A good residential architect familiar with Seattle codes should be able to answer this question without the help of other professionals.  Generally speaking the answer is yes, there is sufficient room on the site to build a reasonable size addition to the home.  The obvious issues here are maximum building height, lot coverage and setback from property lines.  There is plenty of room here to accommodate those constraints.  There are however 2 significant problems to deal with.

 The ECA is a considerable hurdle to overcome

The site has steep slopes on it.  The code would require substantial buffers from those steep slope areas and would generally prohibit and new development in those areas.  Without either an exemption or a variance it would be difficult to add on to the home.  Fortunately the site exhibits characteristics that makes the ECA exemption process a realistic solution.  If it doesn’t qualify for an exemption it certainly has hardship that I believe would be sufficient for a variance.

We subsequently did receive an exemption from the ECA development standards, a process which I’ll write about in another article.

 Seattle’s new garage development standards also pose a significant hurdle to be overcome.

Generally speaking, attached garages are not permitted to project out in front of a house any longer in Seattle.  This is a relatively recent revision to the code and has the potential to make it impossible for the homeowner to realize their development objectives on the site.

There's no easy way to get a garage for this home

 Steep slopes results in difficult vehicular access

Ordinarily in a situation like this you’d want the garage to be just far enough away from the street to park cars on the driveway.  Then you’d make a basement garage and bring the home out over it.  This results in considerably less excavation which decreases the construction costs and risk.  Unfortunately the house is 45′ back from the street and considerably higher.  Building an addition to the existing house in this configuration would be expensive and difficult.

 The maximum driveway alternative

It is theoretically possible to build a driveway that could access the existing basement of the home.  That basement level could become a garage.  This would require the driveway to climb 9′ at the city’s maximum driveway slope of 20%.  That’s a really steep driveway and would require significant retaining walls in the front yard to accommodate.  It’s possible, but it wouldn’t be attractive.

 The rational alternative

The alternative to these solutions is essentially to split the difference and to raise the garage above the street while bringing it closer to the existing house.  Unfortunately a code compliant version of this doesn’t meet the client’s needs.  They are hoping for a large deck above the garage for entertaining.  The only way to accomplish this alternative is to get a waiver of the rules from the city.

 We applied for and received that waiver which I’ll write about in a future article concerning navigating Seattle’s new garage development standards.

 The second question, “Is it feasible to add on to the house?”

Can the soil take the additional weight of new foundations?  Generally speaking, if the soil can handle the original weight it can probably handle the weight of a new addition.  Here’s what I look for;

• Do the floors obviously slope?
• Is there a lot of cracking in the plaster or sheetrock?
• Does the foundation have obvious cracks in it?
• Are there retaining walls on the site and how do they look?

 In our case the floor was flat, the foundation appeared in excellent shape and the retaining walls were standing up straight.  Those all seem to be reasonable indications of soil strength and stability.  However, the real answer comes from a geotechnical investigation.  An architect isn’t qualified to perform that service so if there’s any question a geotechnical engineer needs to be hired to perform a study.

 The chances are, if you’re asking for and ECA exemption, if you plan on tall basement walls or retaining walls, if there is any obvious water seeping out of the ground you’ll need a geotech report anyway.  On a number of occasions clients have paid for geotechnical reports prior to purchasing the property.  This is especially important on land that has a designated ECA on it.

 Can the foundation take another story?

That does depend on the foundation.  If the foundation is of the appropriate thickness and if it is in apparently good shape I generally conclude that it will work.  I know of architects who aren’t comfortable making that kind of determination and will suggest destructive testing to determine the foundation’s capacity.  I’ve seen others go to bizarre lengths not to support the new structure on the existing foundation.

 If the foundation is not in good shape then the answer is much more difficult.  It’s possible to fix a failing foundation but it can be expensive.  Unless the house is perfect for your needs otherwise I’d probably recommend look at other property instead.

 In our case, there is a full depth 8″ concrete foundation wall that appears to be in excellent shape.  It currently has only 1 story sitting on it, so it can easily take a second story.  After all was said and done, one of the design elements required lateral forces to be applied to a section of wall that were to great for it.  In that case we’re removing the wall and replacing it with something that will work.

 The third question, “Are there other easements or restrictions?”

Here’s a place where the architect is of little help.  Architects don’t have the skill set to investigate property records to determine what easements and restrictions might apply to the site.  That’s really a job for your title insurance company.

 Order a preliminary title report

This is an essential step in feasibility analysis.  Your real estate agent can order a report that will have all the easements and restrictions in it.  Now you may want the architect’s opinion on how those restrictions affect the design but you shouldn’t expect the architect to be able to find title based restrictions that apply to your lot.

 In this case there was a recorded restriction on the height of the house that a neighbor had purchased from the previous owner of the property.  The clients gave me a copy of it and I gave it to the surveyor so that we could relate it clearly to the existing finished floor level of the home.  From that point on I can design the house to comply with the restriction.  This is the primary reason why the new design has a flat roof.  We wanted to take full advantage of the view while still staying below the height restriction.

 It is generally the responsibility of the homeowner to provide this information to the architect.  I’ve been involved in a couple of projects where easements weren’t disclosed until after design work was completed, that can result in significant design changes.

 Once upon a time I was hired to design a 4 story condominium building in Seattle.  I asked for a survey, the surveyor asked for preliminary title and the owner provided the documents.  Unfortunately the documents were incorrect, thus the survey was incorrect and we didn’t find out until we applied for permits.  The stunning part of this is that the owner was a surveyor himself and knew how to read the documents.  He just didn’t notice the error.

 Title related restrictions can be significant design constraints

I’m working on the design of 2 homes currently that have restrictive covenants that go far beyond what is required by code.  They both relate to the height of the structure and they both are primary drivers of the design.

Here’s the final design.  In future articles I’ll discuss the client’s program and how we achieved a design that met their needs and responded appropriately to the site constraints.

A design we recently completed on Magnolia in Seattle