Residential Architecture 101

Since it has been a while since the last entry in this series, today’s topic is Residential Architecture 101 – Room Matrix. I brought this topic up in podcast episode 79: Designing a House because, for every residential project I have ever worked on, there is a road map that is prepared to help explain the rooms that will be incorporated into the project, as well as some sort of projection of how large they will be. This is actually a method that I learned from a firm I worked for a few jobs ago, but I have continued to modify it so that I can have meaningful conversations with clients during the programming and schematic design phases of new projects.

Architects love math, right? Maybe, but there’s no denying that you have to know a little bit of math when practicing as an architect and on occasion, you have to make a spreadsheet.

This is all the information I need to shine some light on the programming, the estimated square footage of that programming, and an extremely rough estimate on budgeting during one of the first few meetings. This room matrix usually shows up in meeting 2 or 3, a series of programming meetings that looks like this:

meeting one – typically a conversation that explains how the process will work
meeting two – a review of the programming questionnaire with several, several more questions as a result of the answers provided in the aforementioned questionnaire
meeting three – presentation of the room matrix and preliminary budget conversations

All of these meetings take more time than most people realize – at least a few hours each – but this is possibly the most important time frame to discuss because it is so important to get to not only the desired rooms identified, but we really want to establish an expectation on how big the clients expect or desire those rooms to be when built. Let’s break down what information is being presented in each column –

Room Name

Pretty self-explanatory, but we aren’t focusing on what we are calling each room. The objective of this section is to simply identify all the rooms that will be in the house. Clients will frequently provide me with a list of rooms they want, but almost everyone forgets the rooms like a pantry, entry foyer, AV closet, mechanical rooms, generic closets, etc. This list helps us walk through all the rooms that will actually be in the house.

Room Size

Room size is also self-explanatory, BUT, this section allows us to discuss lifestyle to a degree (Living Room versus Den versus Family Room) and assign priorities to those spaces based on the square footage we assign them.

Area

Since I build this matrix within Excel, this column just identifies the square footage calculated for each room size. This column isn’t wildly important but it does have an important role to play towards the bottom when we start adding everything up.

$/SF

My least favorite column (and sometimes the Client’s least favorite as well) but possibly the most important … and the least accurate. Since we haven’t actually designed anything yet, assigning a value to a space makes as much sense as buying a car by the pound. The reason this column exists is that, at the very least, it starts to provide some sort of framework on expectations surrounding the quality of the home. With the direction home costs are currently running, I know that if someone asks me to design a house for them, and they have a $125/square foot budget, we are going to be facing some challenges. Identifying this information upfront can allow us to have meaningful conversations that might end up affecting the overall size of the home.

Since I built this particular room matrix specifically for this article, the per square foot values in there would most likely change based on your geographic region as well as the priorities we establish for each room during the first two meetings.

Estimated Budget Total

Let’s evaluate some additional spreadsheet math takes the square footage of the room and multiplies it times the cost per square foot value we have identified. The result is a crude assignment of a value for each room as part of the whole – useful when projecting total construction costs.

So that you don’t have to keep scrolling up to the top of the page, I have broken out the summations and totals from the bottom of my matris and posted them just below as we move on to discuss what happens next … so exciting!

$Residential Room Matrix Math by Dallas Architect Bob Borson$

I’ve added some color to this section to help explain what we should be focusing on – hopefully, that’ll assist us in this conversation.

Starting in with the yellow, we have added in a multiplier for things that take up space that aren’t generally considered rooms … the walls and corridors. Every single person ALWAYS forgets about these two items and they always add square footage to the house. Since we haven’t actually designed anything yet, I’ll typically put in a 15% – 20% multiplier (which one I use typically comes from a conversation with the client on the type of layout they might be interested in). You can see in my example that the room total square footage added up to 3,516 square feet but when we add in space to account for walls and corridors, that total jumps up to 4,043 square feet – an additional 527 square feet. This really matters when preparing a budget because you can extrapolate this out to identify that we also added $144,870 to the total project cost.

Let’s take a look at the orange box for a minute.

In the good old days (like 15 years ago) square footage totals really only concerned themselves with conditioned square footage. Things like “Garages” and “Outdoor Patio” weren’t considered when calculating costs – I can’t explain why that’s true, but since these spaces are decidedly more complex and built out now than they have historically been, we now consider them when calculating the totals. Don’t forget that we still need to consider wall thickness, but since the likelihood of having corridors in these ancillary spaces is minimal, the factorial we add is typically around 5%.

Next up is the purple box … the updated house square footage.

A quick glance tells you that in this particular program, the home has grown from 3,516 square feet to 5,707 square feet, a difference of 2,191 square feet … and when you are estimating budgets based on square footage, that difference can be significant, but it can also be misleading as it dilutes the total cost per square foot for the entire house. When we finally add everything up and divide estimated square foot allowance costs into the updated square feet totals, the house is coming in at $1,390,390.00 and an average of $243.63 per square foot.

Residential Architecture 101 – Room Matrix

So what does this all mean during initial casual conversations? The takeaway here is that when you hear that you can build your house for under $250 per square foot, chances are better than you might imagine that the area you are calculating at $250/sf might be significantly smaller than what we know will be the reality. Just in my example, the difference from the main house square foot (prior to adding in the corridor and wall thicknesses that everyone forgets to consider) and the final tally amounts to $424,590! That’s 44% more than most people would anticipate.

Just something to think about when you are working through the rooms you want in your house.

Cheers,