Top 5 Design Mistakes that Can Spike Costs in Affordable Housing Projects

March 3, 2022
Sam Leika-Shukor (Issam), OAA, AAA, AIBC, Innovative Sketch Architect & Certified Passive House Designer

Top 5 Design Mistakes that Can Spike Costs in Affordable Housing Projects & How to Avoid Them!

The most common mistakes architects do when designing residential projects are, unfortunately, those most related to architect's basic work; good space planning. I’ve learned this early on in my profession with different single family home designs and thousands of iterations & honing of plans through sketching, to improve functionality and space efficiency.  

 For affordable housing projects however, these single unit planning errors are much costlier!. The mulitiplication of residential units on several floors makes the unit mistake mutliplied by the number of units and a $5000 error becomes easily a half a million dollar in construction costs alone. In affordable housing cost is so critical that such errors should not happen.

However these potential planning errors arenot only related to construction (i.e. material and labor) costs but also as operational costs for many years through wasted space, waster energy on heating, cooling, and lighting it. Avoiding space planning errors in multifamily housing projects is much more serious than single family or even low rise developments.  

Figure 1: examples of affordable 1- & 2-bedroom rental units in Banff. Notice the Barrier Free unit 5’ turning radius circles. Not sure how thel iving space can accommodate the wheelchair manueauver though. Source:

 Affordable Housing main concern

In order to realize the importance of space and building planning in affordable housing, I’ll quote Canada Mortgage and Housing Corporation definition (CMHC) of affordable housing:

"housing is considered to be affordable when a household spends less than 30% of its pre-tax income on adequate shelter. Households that spend more than 30% of their income on shelter are deemed to be in core housing need”.


What does this tell us? It tells us that affordable housing's main concern is cost. Then the question become: where do we start with cost reduction? My answer is; without a doubt building layout (including orientation) and units space planning is the core foundation of cost-saving.  


Since affordable housing has beome a dire need in society, we need to pay close attention first and foremost to the unit’s layout optimization. No waste in space should be allowed. We must think of efficiency in all its aspects. This doesn’t mean however that this space efficiency jeopradizes space design quality, sustainability, or aesthetics of the spaces. Actually contrary to that, it will make all the othre aspects even better.  

Figure2: Affordable housing typologies. The denser the development, the more critical layout optimization becomes. (Source:

Other factors of cost increase are maintenance and energy operational costs. for example, timber framed, and cladded buildings are less expensive to build than brick veneer buildings. This expensive would be offset by the higher maintenance costs. The popularity of housing typology in Canada suggests that simple, regular, and inexpensive forms of housing remain attractive and cost-effective.

The Top 5 Mistakes in Building and Unit Layout Design

Now let’s dive in into the top five building planning and space layout mistakes that could  drive affordable housing projects’ budget much higher than anticipated (yet no body knows why!). if not considered at the very early phase of the design process.

Mistakes No. 1 – building shape

High compactness ratio. This is area to volume ration of building or the massing factor. High thin towers have a high compactness ration while midrise compact mass pushes compactness ratio lower. It should be noted that this is not to say that single family fully-detached unit have better compactness ratio than highrise thin buildings (fig 3).

Figure 3: Compactness Ratio is important in creating efficient building form as well as efficient form to minimize heat loss.

Mistake no 2 – complicated shape or non-standard shape

Not standardizing units and complicating the shape (fig 4)

Figure 4: complicated shapes create non regular housing units which drives cost unnecssarily high.

Mistake no. 3 – Missing out on Utilizing the Courtyard Concept

The largest schemes are created from small, repeated units. Courtyard housing is a type used throughout the world and it provides individual identity, a hierarchy of spaces from public to private, and observable outdoorspaces that are safe for children (fig 5).

Figure 5- building layout should use the concept of a courtyard - a common controlled environment or a courtyard. This is the best way to design a community-based affordable housing and has multiple benefits. (Source ofphoto:

Mistake no. 4 – Breaking Up the Unit Spaces into Several Rooms

Increasing the number of individual spaces instead of combining them increases cost through building more walls. For example, creating separate spaces for living, dining, and kitchen instead of creating a one large space that shares light and create spaciousness (fig 6).

Figure 6 – A separate kitchen room shows costly layout of individual rooms rather than one large space. Source of image:

Mistake no. 5 – Irregular Unit Layout or Non-Standardized Space 3-dimensions

Not utilizing a regular plan enabling use of repeated structural and framing elements and standard construction, such as stud frame is a mistake. The more standardized the dimensions the more cost effective they are (fig 7).

Figure 7- Irregular apartment layouts and unstandardized space dimensions drive cost much higher than regular and standardized dimensioned spaces - etris Apartments – Ljubljana, Slovenia. photo source:


Mistakes in building planning and apartment layout can make the affordable housing project much costlier. The above five critical planning mistakes are the most crucial. They should be dealt with at the early phase of schematic design or at the SPA phase. Once built, the layout is hard to change. Mistakes in optimizing the layouts can create wasted spaces, increase of material and labour, increase in energy costs, and might be real obsticles to future space flexibility (important aspect of affordable housing to accommodate future changes).

Affordable housing teams and all stake-holders should be careful at the very early phases of the design process, take their time to examine the layout and avoid be critical to the layout to avoid wasting space, or creating irregular or weired shapes, or dividing up spaces into individual rooms for every use, or long deep corridors and circulation areas which can be avoided with good layout, and to avoid the custom design mentality for each unit that makes coordination with the structural engineer’s system frustrating and costly. All planning layout mistakes can drive affordable housing building costs much higher than anticipated.

At ISD Architects we understand the importance of efficient design and of the need at the very early phase of design to optimize space layout and correctly design building layout, while attempting to create pleasent, spacious, and aesthetically pleasing spaces with very close attention to budget, space efficiency, and number of available units.

If you're thinking to build or renovate, don't start before reading our FREE report called the Rapid Project Planning Package or PPP. It covers all key questions or "Should Ask Questions" SAQ about your anticipated project. No obligation. CLICK HERE TO DOWNLOAD NOW!

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