The Builder Said The Drawings Are Not Complete by Josh Brincko

​You commonly hear builders and homeowners complaining that they paid for drawings, but the builder does not have all the information they need to build the project. This comes from an expectation that a set of drawings should contain every answer to every possible question a builder would have during construction. There’s a few things to consider here:

1. In the construction process, especially with remodels and additions, there are many unknown conditions. For example, nobody knows what is behind your walls, within your floor, or in your roof unless all of those things have been gutted to enable the builder to see what is inside. Ordinarily, homeowners don’t want their walls torn apart a year or two before the project actually starts construction, so ordinary assumptions are made about the conditions that might be encountered within those walls. These assumptions enable the design and permitting process to continue. It’s not feasible or worthwhile to tear apart an entire building just to figure out concealed conditions since there is always a way to work around those conditions when the construction process actually starts. If the builder starts demo and finds rotted wood, structure that’s not in the right place or the right size, or plumbing or electrical that needs to be updated, then they could ask those sort of questions, and answers could be provided. Those questions can’t be asked until that time, and it does not make any sense whatsoever to spend time speculating on things that may never actually happen. For this reason, there are commonly many items that do not get portrayed in drawings since they really require feedback during the construction process to make proper decisions.

For example, imagine you are attaching a new deck to the side of your house. That new deck needs to be bolted to the existing house, but nobody knows exactly what the structure behind the siding will look like or whatever items might be in the way of those bolts that need to be added. So, construction starts, the builder takes apart the siding (the house is exposed to the weather without substantial weather protection), and the actual existing conditions can be known. The builder discovers it may not be possible to fit the required bolts, so the builder reaches out to the design team to relay the condition encountered to request an alternate solution. The architect and engineer work together to figure out a solution that works with the condition that is now known, and the builder can move forward accordingly. There are many ways to bolt a deck to a house. It is not effective to design, calculate, and draw 20 different options on a set of drawings to forecast all of the possible problems that may or may not come up during demolition. This would be 20 times more expensive since the design work would need to happen 20 extra times. Instead, the work happens once, and time spent to develop an alternate option only happens when needed.

Next time you hear somebody complaining about the drawings not having all of the information the builder might need, please realize that construction is a process that requires ongoing decisions that are based on the information that can only be known at any specific moment. Then ask yourself, would you prefer the drawings to be done once … or 20 times to show all of the possible situations even though 19 of them won’t ever happen. Drawings are much like a script to a movie. The words are there to tell the actor what to say, but there needs to be a director to explain how to express the words on the script in further detail. It is unreasonable to do a movie without a director, and it is also unreasonable to think the drawings tell the whole story.

2. It takes time to design solutions and even more time to draw them. For every unique condition that occurs on a job site, there could be 10 different drawings and 20 different building materials that might be needed to explain every single thing to a builder ahead of time. For some conditions, they might be unique enough that the builder needs this level of detail. For most conditions, however, the builder may use standard practices based on their experience and expertise to interpret the methods to use in that situation. If every single condition were decided and drawn ahead of time, that would lock the builder into building the project in a very specific way. And that may not be the best way or the way the builder can execute it based on their personal skill set. Some builders prefer certain materials, certain methods, and certain tools, and those preferences may limit the possibilities while also enabling them to execute their best work with the highest degree of success. Based on the way they prefer to execute certain work, the assumptions made on drawings, which are often drawn before a builder is ever even selected, incorporate basic practices that may not align with the builder who ultimately gets selected for the job. Additionally, the builders who end up doing the work are experts in what they do. Their feedback is certainly beneficial to the entire project team, so the outcome can be its absolute best. The designers are not experts in every aspect of a project. Designers are generalists. Designers rely on the feedback and expertise of the men and women who do the labor on projects every day.

For example, a concrete subcontractor knows all about the process of building formwork, sequencing the pouring of concrete, stripping the form boards after concrete has been poured, and doing it all in the most productive and cost-effective manner. This is all about the methods of construction. Designers have no control over HOW builders do their work. Designers only convey the basic outcome of the design intent for the builders to interpret using their common practices as a guide. A concrete crew may recommend that additional areas of concrete be added that may not be depicted in the drawings, and that suggestion might be necessary to enable them to schedule concrete delivery just once and a pump truck just once, rather than doing the concrete work in shorter stints over the course of several days that would require more mobilization fees for those items. It may seem counterintuitive that the pouring of more concrete in one day might cost less than pouring less concrete over several days, but based on the methods that those crews use to do their work, that may very likely be true.

The general contractor does not have that level of expertise to be able to forecast the methods of construction that their subcontracted concrete crews may use, and the designers certainly do not either. The whole team relies on those specialist for feedback, and those specialists are typically not involved in the project until the project has already started construction. Concrete crews are not paid to get involved with a project a year before it ever starts - especially on smaller residential projects where their scope is limited. It is cheaper to make these sort of decisions on the fly than it would be to hire a concrete crew as a consultant to advise in the planning phase of a project. This example is also true for any other construction crews.

3. Construction projects are very different from manufacturing products. The manufacturing of products is done in a controlled environment where assembly lines, machinery, and even robotics are used to create the same item over and over and over. Products built in a factory are optimized through value engineering and prototyping. This means they build several products, test them, throw them away, redesign them, build new ones, test them again, throw them away, redesign them, and the process continues until the product is optimized for use and mass manufacturing. We certainly don’t build a house, analyze how it could’ve been done better, throw it away, and do it all over again. No house is exactly the same as any other house - especially when it comes to remodels and additions. The soil conditions are always different, the weather conditions are always different, the topography of the ground is always different, the availability of certain materials always changes, subcontractors get held up on previous jobs, deliveries get stuck in traffic, people are human and mistakes get made, unforeseen circumstances are encountered, and the list goes on. There are so many conditions that cannot be controlled on a job site that must be reacted to on the fly. It is not effective to plan for things that may or may not ever happen, so the best  thing that can be done on a construction project is to have contingencies built in. 

A contingency can be planned into the project in many different ways. For example there could be a cost contingency. Commonly, homeowners stretch their budgets so far, that they don’t have any money leftover in their budget in the event that something unforeseen happens like soil being so inundated with clay and moisture that it cannot be properly compressed for concrete to be stable on it. That soil would need excavated, exported, and new structural fill (soil or gravel) would need to be brought in and drainage systems added. Could that be known ahead of time? Sure, but that would require extensive digging and disruption in your yard long before the project ever starts to find those conditions. There’s a million situations just like that that could be done ahead of time, and if you were to do them all, the design time and design cost would be more than building the actual project. This sort of analysis only makes sense on large projects like stadiums, highways, bridges, hospitals, etc.

A design contingency could also be planned into the drawings. What does that mean? The answer is actually the very thing that builders and homeowners complain about. This article started out by naming a problem: builders and homeowners commonly complain about drawings not having all of the information needed. The point here is that it is actually to the builder and homeowners’ benefits to not have all of the information dictated by the drawings. As problems arise during construction, analysis needs to happen, and solutions need to be found. By keeping some ambiguity within the plans, it does not lock the builder into one specific solution that dictates how everything else around it must be built. This would be a clog in a funnel. Since there is a 100% guarantee that the conditions that come up during construction are not going to be known before the start of construction, there must be an expectation that the drawings will need to be adapted as construction continues. If every single condition is assumed and drawn, when one of those assumptions turns out to be wrong, every other part of the drawing that relies on that assumption also becomes wrong. This results in a tremendous amount of rework to update everything to coordinate with a new condition that becomes known. Consequently, we intelligently plan our drawings around commonly unknown conditions, so it will be simpler to update the drawings in the future as those conditions become discovered. 

In conclusion, next time you hear somebody complain that the drawings don’t have all of the information that the builders need, your response should be: thank God! This means the designer spent time effectively on the items that could actually be foreseen, and not on the items that could not. Because we bill for our services by the hour, you’re going to get the best value out of our time by allowing us to spend that time in the moment when we can base our decisions on actual data instead of assumptions that are bound to change. This moment is during construction. Anyone who thinks otherwise does not understand the construction process.

If you’d like to learn more about our design process, visit www.josharch.com/process, and if you’d like to get us started on your project with a feasibility report, please visit www.josharch.com/help

Seattle ECA's (Environmental Critical Areas) by Josh Brincko

If you have a property in Seattle that has an environmental critical area on it, or even somewhere near it, this video is for you. Examples of ECA’s are steep slopes, landslide prone areas, liquefaction zones, peat settlement zones, wetlands, etc. It doesn’t matter if your project doesn’t affect your ECA or if the ground has “just a small slope” or “the soil seems fine.” If there’s an ECA classified on your property, we will have to help you jump through some hoops. This explains how we do it. Projects outside of Seattle also commonly need to go through a similar process.

ECA overview for Environmental Critical Areas in Seattle

If you’d like to learn more about our design process, visit www.josharch.com/process, and if you’d like to get us started on your project with a feasibility report, please visit www.josharch.com/help

Erin by S. Joshua Brincko

Erin Wood is as cool as they come. Picture a California surfer mixed with one of your smartest best friends (not the annoying smart one). She’s like the “easy button” personified. She takes challenging tasks above her level and does pretty much all of them perfectly. When that’s not the case, she simply points it out, asks for help where needed, and promptly gets it done as well as any seasoned expert. I’ve never seen someone thrive so easily, and she does it all with no signs of fatigue, stress, or difficulty. It is simply amazing. Our clients love working with her, and so do we.

She was initially raised on the Cali coast and then later in the Seattle area. Since I’m an Ohio native, I LOVE the fact that she purchased an Ohio State hoody just to have some competitive banter with her dad who is a rival Michigan fan. That is gutsy and also hilarious. When it comes to fun, Erin loves road trips around the Pacific Northwest and beyond. She even went on a road trip with her dad from Washington to South Carolina just to visit a BBQ joint they saw on TV. What a great excuse to bond with your dad and get away! She also loves the atmosphere of Mariners games and the tons of live shows she frequents. She loves being outdoors, and this may have stemmed from the 10 or so years she spent growing up in a no-car family. They all biked everywhere during that time! When she’s not outside enjoying the beautiful surroundings with her tight group of friends, she loves a good show, movie, and even baking or trying a new recipe. After all, she did learn to cook from the best around: her grandmother! Reach out to Erin and say hi!

If you’d like to learn more about our design process, visit www.josharch.com/process, and if you’d like to get us started on your project with a feasibility report, please visit www.josharch.com/help

4-Part Construction Bidding Process by Josh Brincko

Architects have a tricky job since we need to try and design a building at a time and place under certain conditions that have never been done the same way in the past with changing economies and regulations. We also need to ensure the stuff we design is on track with the construction budget. This has become increasingly difficult with the shortages in labor and materials that we are now facing.

To save time in the bidding process for builders, and to design projects that are on track with the budget, Josh Architects has developed a 4-part bidding process composed of a “poke”, a “gut”, a “ROM”, and a bid to ensure we get frequent pricing feedback from builders as we progress through the design process. We try to spend as little time as possible designing a project, so we can get a series of preliminary estimates back from builders. This frequent feedback saves our clients money on design fees since we are able to stay on the right path as we continue to add more detail to the design solution and get sequential feedback from builders as we do it. The last thing we want to do is design an entire project and later find out that it is not on budget. The baby steps we take with out poke-gut-ROM-bid process keeps us on track, and we never end up spending time adding specific details to our plans until the whole project team is confident we are on target.

When we first start designing a project, we use our experience and intuition to design and draw something that meets the clients goals while also being reasonable with regard to construction cost. This involves coaching clients on whether or not their goals are reasonable, and instructing them to remove parts of the scope of work before we start designing. Many client still want us to design something with all of their goals (instead of removing scope), just to see how the estimates look as they come in. When the estimates come in too high, then we start removing more scope. The goal is to spend as little time/money as possible to get estimates, so less time/money is wasted getting to that point. In other words, we don’t want to walk too far down the wrong path before realizing that we are actually on the wrong path. Doing a little work, getting an estimate, and then revising a little more before we get another estimate is the best way to vet the scope of work to ensure it is on track. The past couple years have been especially challenging since the shortage of labor and materials has really sent construction cost soaring.

Watch the video below to get a better understanding of our 4-step process:

If you’d like to learn more about our design process, visit www.josharch.com/process, and if you’d like to get us started on your project with a feasibility report, please visit www.josharch.com/help

Flat roofs by Josh Brincko

The concept of using a flat roof comes up nearly every day in discussions with clients. Here’s how it always goes:

Client: There’s no way I’d do a flat roof.

Architect: Why?

Client: Because they will leak.

Architect: Have you been downtown, or to Walmart or Target or Costco?

Client: Yea.

Architect: Do the flat roofs on high rise buildings and other commercial buildings like those leak?

Client: No, well, maybe sometimes.

Architect: Do you know anyone who has a leak on there shingled roof at their home?

Client: …sigh… yea.

Architect: You can get a warranty for multiple decades for flat roofs and also shingle roofs. They just need to be installed properly. If you have trees that will dump leaves on your roof, I wouldn’t do a flat roof, but I also don’t suggest allowing trees to dump leaves on your sloped roof either since it causes moss growth, clogs gutters, and leads to leaks.

Client: hmmm.

Architect: Flat roofs aren’t actually flat. They usually slope down a quarter of an inch for each foot, so a 10’ long roof slopes down 2.5”.

Client: Really?

Architect: Yep. The material on flat roofs is like a sheet of rubber called TPO or PVC. They actually heat weld/melt the seams together, so it creates a permanent bond that water can’t get through. That’s why they use them on high rise buildings and shopping plazas where they can’t take on the risk of leaks. They are installed only by an installer who is certified by the product manufacturer, and they get it flood tested to ensure they don’t leak. Flat roofs are better than sloped roofs with attics.

Client: Why?

Architect: Because they are less likely to leak. Also, since they are flat, you don’t need an attic, you don’t need attic access, you don’t need the layer of extra structural framing known as collar ties, you don’t need attic ventilation, and the light color of a flat roof also decreases excess heat gain. It saves you on a lot of infrastructure. Flat roofs are much easier to build than sloped roofs with attics.

Client: I still don’t trust a flat roof.

Architect: …slams hand on head…

This is the common (frustrating) dialogue I have several times each week. Hopefully this post will save me from repeating it at least a few times:) and hopefully prevent a few head smacks.

There’s a reason commercial buildings tend to use flat roofs and that commercial building products tend to be differentiated from residential projects: commercial products tend to be more durable and long lasting than residential. I have always found it strange that many product suppliers for roofs, windows, etc tend to offer a residential model and a commercial model. The roof and windows of a house undergo the same exact weather as an office. When I contact a material supplier about purchasing a product, they will commonly ask me, “is it for a building or house.” I can’t resist, and I say, “both.” The confused salesperson says, “well which is it.” I say, “the BUILDING is a HOUSE.” The salesperson then tries to sell me a residential product, and then I ask them for a comparison between the commercial counterpart. It usually turns out that the commercial version has a better warranty and is more durable.

A flat roof membrane is commonly thought of as a commercial material, but if we are being smart, rational, decision makers, a flat roof is the most durable and beneficial roof system since it is simpler to frame, saves energy (due to not needing an attic), and it is less likely to leak. If your architect suggests a flat roof, give it some honest consideration.

If you’d like to learn more about our design process, visit www.josharch.com/process, and if you’d like to get us started on your project with a feasibility report, please visit www.josharch.com/help

NR3 Zoning In Seattle For Residential Architecture and Construction by S. Joshua Brincko

If you’re confused and not sure where to start for planning a small remodel, or even a large addition, or a totally new construction for your house in Seattle and other areas, you are not a stupid, total idiot:) Even for a seasoned veteran architect in Seattle who specializes in residential architecture, the codes, rules, regulations, policies, etc are very confusing to say the least. If anyone is a stupid idiot, it’s the ones who wrote the codes in such difficult language:) I am here to help, and this post is your guide to help you navigate the thick bureaucracy. (It is also worth noting there is a major difference between the “building code” and “land use code”. This post only dives into the “land use code” to help you understand WHAT/WHERE you are allowed to build on your property and not the “building code” which gets into HOW to build something.)

The land use code classification that is applicable to most single family homes in Seattle is known as NR3 (formerly named SF5000, SF7200 renamed to NR2,and SF9600 renamed to NR1 for larger lots). The “SF” meant: Single Family. The 5000 meant the property is more or less 5000 square feet. The rules are pretty much the same for all these zones except for the bigger lot sizes. The new naming convention of “NR” means “Neighborhood Residential.”


OVERVIEW

The most basic, common concepts in NR zoning are yard setbacks, maximum percentage of lot coverage, floor area ratio, and height limit. Some of the other nuances in the codes are the exceptions to all these rules, tree requirements, and parking requirements. Some projects may also involve various other codes for garages, ADU’s (accessory dwelling units), DADU’s (detached accessory dwelling units), existing nonconforming uses (projects with non-compliant stuff that is “grandfathered in” since it was built before the codes existed), allowable uses (like using your house as a hotel), and ECA’s (properties within environmental critical areas such as steep slopes, shorelines, etc).

In Seattle, I have dealt with zero properties that are straightforward. There is always something weird about each lot such as a part of the existing house that was built too close to the property line, a part of the lot that is considered an ECA because it is too steep, difficulty in determining which side is technically considered the “front,” or a tree the city won’t allow you to remove (which causes the lot to be less than ideal to build on). Because of these anomalies that always seem to pop up, no two projects have ever been the same (and I do about 100 of them each year). The rest of this blog post will dig into each topic separately to attempt to give you some insight into each of the major codes for SF zoning. Although this will give you a basic understanding, please reach out for confirmation since this stuff gets really complicated and must be vetted (we are not liable for your use of the information herein). Also, just because the code says something in “black and white,” the building department may actually interpret it to mean something completely different. And, they are not always correct in what they tell you. I commonly argue with them to show them what the rules actually mean (and not let them bestow their “opinions” on me). There’s usually some compromise, but I’ve never lost an argument with the building department.


HEIGHT LIMIT

Let’s start with the height limit since it’s one of the easiest to understand. The maximum height of a house is permitted to be 30’, and this is measured from the “average ground height” to the top of the highest wall. A sloped roof of a certain angle (4:12) can extend an additional 5’ higher. The average ground height is determined by measuring the height of the ground at the middle of each exterior wall and taking the average of those. For example, if the ground sloped down so the front was 2 feet higher than the ground at the back of the house, and the sides were each 1’ higher than the back of the house, then (2’+1’+1’+0’)/4 = 1’. So in other words, the average ground level is 1’ higher than the back, and 1’ lower than the front. If you measure 30’ up from this imaginary line called “average grade,” the house could be 29’ tall in the front and 31’ tall in the back. The sloped roof can go another 5’ higher, and you’re also allowed to have chimneys, vents, skylights, and dormers of limited sizes within this 5’ bonus area. There’s also exceptions for green roofs and certain features of roof decks. As you can see, it’s not as simple as just saying: your house can be 30’ tall.


SETBACKS

Next, let’s review setbacks. A setback is the distance from a property line where you are not allowed to build (certain things). To be able to determine setbacks from each property line, you first need to know where the property lines are. No, your fence, sidewalk, curb, rockery, driveway, or that thing the old guy showed you once is likely NOT THE PROPERTY LINE. Sorry. It’s probably not. A property line must be determined by a licensed surveyor by taking precise measurements with very technical instruments. Then, they put a surveyor’s pin to mark the location of the property corner (and sometimes these are intentionally not actually on the corner of the property as you may expect).

Once you know WHERE the property lines are, THEN you can determine which is considered the front, side, and rear property lines. This may seem straightforward, but sometimes it is not. This is too complicated to blog about, so let’s talk about this topic on a case-by-case basis. Feel free to reach out since your front door, address location, your actual street address, or your driveway do not technically determine which property line is the front.


LOT DEPTH

When you determine which side is the front and rear property line, you can determine the “lot depth.” This is the distance from the front property line to the rear property line. If you have an alley, the centerline of the alley is treated as the rear property line for this purpose. The rear setback (for a single family residence) is the lesser of 20% of the lot depth or 25’. This rear setback is measured from the center of the alley if you have one. Certain structures like garages, DADU’s, and other items are allowed within the rear setback areas (within certain limitations).

The front setback may be more straightforward and just simply be 20’. If your two adjacent neighbors are closer than 20’ to their front property line, then you can take the average of them. If the neighbor on the left is 16’, and the neighbor on the right is 18’, then your house’s front setback can be 17’. If your neighbor on the left is 16’ and your neighbor on the right is 22’, then you treat the neighbor on the right as 20’, and the 20’ and 16’ average out to 18’. The side setback is pretty simple since it is just 5’ unless it is a corner lot. In that case, the “street side” setback is 10’. Be careful to ensure you properly classify the front property line and street side property line on corner lots. In some cases, these are interchangeable, and in others they are not. It is not easy to clearly see which is the front and which is the street side (and again… no, your front door, or driveway, or address number, or your actual address do not decide which is considered your front property line).

With all of these setbacks, there are so many exceptions to the rules. Certain parts of your home can project into some setbacks like roof overhangs, bay windows, porches, decks, chimneys and some other features. There are limitations for the sizes and heights of these features, so please reach out for help in determining how to take advantage of these “loopholes.”


LOT COVERAGE

The next topic is lot coverage. In SF zoning, you are allowed to cover 35% of your lot with structures. If the lot is less than 5000SF, then you are allowed to cover 15% of the lot plus 1000SF. If your lot abuts an alley, you are allowed to factor 1/2 of the area of the alley into your calculation. Lot coverage is pretty easy to calculate, but the exceptions to the rule do get tricky. For example, decks lower than 36”, solar panels, fences, and the first 36” of roof overhangs do not count against lot coverage, and there are some additional nuances to what counts and what does not.


FLOOR AREA RATIO

Floor Area Ratio (known as FAR) is the last topic we will discuss here. This is a measure of the usable floor space inside a building. So, if you have a 1000sf first floor and 1000sf second floor, then you have 2000sf of floor area used up…sort of. The stair doesn’t count twice, some basements don’t count, certain porches don’t count, and there’s also other exceptions that don’t count against you. In the NR zoning classification, you are allowed to have 50% of the property count against your floor area ratio. So, with a 5000sf property, you are allowed to have an FAR of 2500sf of usable floor area. If you have an alley, you do not get to factor half of the alley into your calculation. This is different than the calculation for lot coverage discussed earlier. This is my current understanding of this new code that was introduced in 2020, BUT I have been told conflicting information by the building department on this alley topic. It does seem that when it matters, the city of Seattle doesn’t let you factor the alley area into your favor for FAR calculations.


CONCLUSION

I hope this post was informative and gives you a basic understanding of the NR3 (SF5000) zoning classification in Seattle to help you determine approximately what you’re allowed to do with your property. I recommend that you do not discuss specifics of your project with the building department unless you first run it by an architect that is VERY experienced in the zoning classification in your area since you may “shoot yourself in the foot” by saying the wrong thing and get locked into adverse interpretations. We are here to help you figure out the specifics since the rules are tricky and there’s a lot of exceptions to the rule that can be used in your favor. As a disclaimer, the the topics covered here are generalizations that could easily get misinterpreted, and you should consult with an expert architect for specific interpretations.

If you’d like to learn more about our design process, visit www.josharch.com/process, and if you’d like to get us started on your project with a feasibility report, please visit www.josharch.com/help

How Much Will an Addition to My House Cost? by S. Joshua Brincko

$300,000 and up most likely.

For some folks, you may have seen that figure above and realized your dreams were crushed and decided to stop reading further. It might be cheaper outside of big cities, but nonetheless, the pandemic, supply shortages, and high demand, has rocked the construction world. Home values are up too, so the cost of construction is commensurate with the cost of buying/selling. If you’re still reading, then you are curious about why it will cost at least $300k, or maybe you already understand the cost and have the money available to do it.

At this time (updated in 2024), new construction in the Seattle area and many large cities is around $400 per sq ft if you’re really lucky, but usually more like $500 per sq ft and up for just basic construction quality (much different than the quality you see in design magazines). The stuff you see in magazines is often closer to $1000 per sq ft. If you are lucky, $400 per sq ft might get you a cookie cutter home, with hardie siding, basic trim, clunky ugly white windows, carpet, and drywall everywhere without any nicer finish materials.

For your typical addition, you are usually just adding onto a kitchen, or maybe adding a master suite. Let’s review a random 15’x20’ addition. That’s 300 sq ft. So, at $400 per sq ft, that is $120,000. That seems doable. You googled it, and the Google machine seems to say construction costs are even less than $400 per sq ft, so you may feel that $120k is a realistic construction budget. What the Google machine is not telling you about are the other factors that affect construction cost such as demolition, retrofitting existing conditions, economy of scale, permitting, and professional service fees (which we will explore below).

When you add onto a house, you inevitably need to tear into the existing house to make the connection between new and old. This costs something above and beyond the cost of building the new addition. The more you need to tear into, the more labor there is, the more temporary supports there are (to hold up the house while a wall is removed), and the more the dump fees there are. You could end up paying $30,000 or more in demo costs quite easily which makes that $120,000 addition go up to $150,000. When we design low budget additions, we try to impact the existing structure as little as possible to minimize these fees. Rather than expanding the entire back half of a house outward, it is more cost effective to make the addition “touch” the smallest part of the existing house as possible.

Retrofitting the existing house is one of the major expenses the happens with additions. When you finish the demo, all of the items that were removed will need to be rebuilt (to current code standards) and perfectly married into all the new addition work. This retrofitting of matching old and new is very painstaking labor since it must be done very surgically to protect the old parts from damage, and it simply takes more time build items that are not simple, repetitious tasks.

The more the new addition “touches” the old house, the more retrofitting there will be. Does the new roof impact the old roof? Will you need to re-roof all or part of the existing roof? If so, add at least $10,000 (or more when they discover rot and structural deficiencies in the existing roof). When the siding on the new addition is an extension of an old wall, all of that siding needs to be feathered together to blend seamlessly. It is often easier and cheaper to just remove the existing siding on that wall to just start fresh. Add another $10,000 or more for that to install new siding, trim, and paint on portions of the existing house that need to be redone. There’s a good chance some of those walls will be deficient in some way anyhow, so there will likely be additional scope to repair as needed.

Furthermore, older homes don’t meet the current codes for wind/earthquake or energy efficiency compliance, so once you touch part of the house, that part is now required to be brought up to current standards by filling it with more insulation and covering the walls with plywood and metal hardware to create “shear walls” (since older walls are usually covered in wood planks that don’t do anything to resist the side-to-side movement caused by wind and earthquakes). This will add another $10k or so for each area that needs retrofitted.

The same is true for flooring, ceilings, cabinetry, electrical, plumbing, heating/cooling systems, etc. Anything that gets affected by the demo will need to be updated to be able to tie into the new addition. Can the old furnace power the space of the new addition? Will you need to refinish most of the old floors to match the new ones that must tie in and match? Will the electrical wires need to be chased back to the panel and be updated to the current, safer Romex style? Will the foundation, that will now carry more weight, need to be reinforced (dig below it to add more concrete)? For any of the items above that pertain to your situation, add at least another $10,000 each. Let’s say our example 15’x20’ addition that is already up to $150,000 has 5 of these $10,000 retrofit items…. So, that is now $200,000 or more.

Economy of scale is another item that the Google machine doesn’t accurately portray when researching the cost of construction. When you are doing a small project, you will incur many of the same costs as a large project. For example, since you can’t drive a concrete truck into your back yard in many situations, a concrete pump truck is required. This will be about $1000 regardless of the size of the project. If the pump truck has to come to pump concrete into a 300 sq ft addition, or a 1000 sq ft addition, the cost is the same for the pump truck fee. For either size, you are paying for the cost of mobilization, 1 day of work, and demobilization. The same is true for many other trades like excavation, plumbing, electrical, roofing, siding, painting, scaffolding, and porta-potty rental. Those mobilization and rental fees cost the same regardless of the project size. So, the smaller project will cost more than $400 per sq ft. It may be more like $500 or $600 per square foot (or even more). That would bring the cost up to $250,000 or so for our example 15’x20’ addition. Add tax, and you’re closer to $275,000. Read our post called “Smaller Homes Cost More” if you’d like to learn more about economy of scale.

Permits are another expense. Depending on your situation, the permits might be straightforward, but usually there is a permit intake fee (a down payment for the building department to start reviewing your plans) which could be $2000 or $3000 for this small project (smaller cities tend to charge less). Once the building department finishes their first review, they may charge another fee. Another $1000 perhaps. They might do 2nd and 3rd reviews of the plans and charge another $1000 or $2000 to issue the permit. If there’s any steep slopes, shorelines, or other environmental critical areas, there could be another few thousand dollars for the review fees for the critical area permits. Plumbing, mechanical, and electrical all have their own permit fees too. There’s another $1000 or $2000. It’s not uncommon that permits could be $5000 or more, so now our example project is up to $280,000 or more.

Professional services are a major expense too. If you will be building your addition right up to your setback line, if you are maximizing the percentage of your property that is being covered by structures, or if the building department or architect requires a survey to be done for any myriad of other reasons, this could add another $3000-$6000 depending on the complexity of your property. If the soils need to be tested because they are in an area prone to settling, you may need a geotechnical report to test the strength of the soil and make suggestions for the types of foundations needed. That could cost $3000 or more.

You may need an infiltration test to determine how quickly (or slowly) the rainwater gets absorbed into your soil. That could be another $3000. If your addition is large enough, you may be required to design a system to capture the rainwater, so that it will slowly dissipate into the soil (instead of into the sewers). This civil engineering could cost another $5000.

You will need a structural engineer to design the foundation, shear walls, posts, beams, rafters, floors, nuts, bolts, etc for the addition. The structural engineer will also need to analyze the entire existing structure to determine how it will hold up (or be held up by) the new addition. This will add another $5000 or so.

If there’s any kind of water bodies or animal habitats, the building department might require you to hire an ecologist to create a mitigation plan to minimize impact to the environment. This could cost $5000.

If an archaeologist is required by the building department to monitor the excavations and to test the soil for any artifacts, that could add another $3000.

The architect needs to coordinate all of these engineers’ work into a cohesive set of documents that can be submitted to the building department to prove compliance. The architect also needs to measure the entire existing house, so the entire existing house can be accurately drawn which adds another $2000 or so. Obviously, the architect also designs and draws the proposed addition and creates a set of construction drawings and material specifications, so the builder has all the information needed to build the project (successfully). This is generally around 10% of the construction cost which would be around $28,000 in our example.

The total for professional services could be $30,000 to $55,000 depending on the complexity of the property - which could bring the cost of the example 15’x20’ addition over $300,000 (likely over $400k or $500k if it’s a complicated property with steep slopes or if you’re doing anything more than basic quality construction and finishes).

Once a couple more items get added to the scope (which happens in 100% of construction projects), the project will easily surpass $300,000. I hope this analysis has revealed the big picture of what to expect for any construction project. It is better to be well-informed before you start your project rather than to be fooled by salesperson gimmicks or wishful thinking. As architects experienced in construction, we are right with you. We think these numbers as freaking crazy, but this is what we are seeing over and over again from builders on our projects and others.’ To learn more about upper floor additions specifically, read our post here: additions

We have a handy dandy calculator that helps you (and us) estimate rough costs available at www.josharch.com/cost (it doesn’t work on mobile phones or tablets though)

If you’d like to learn more about our design process, visit www.josharch.com/process, and if you’d like to get us started on your project with a feasibility report, please visit www.josharch.com/help

Additions by Josh Brincko

There’s two types of additions: additions above your home, and additions next to your home. This video explores the differences and was recorded in 2022. After you watch this video, please check out this post to learn more about upper floor additions: www.josharch.com/blog/upper-floor-additions

To learn more about other additions, please check out post here: Home Addition Cost

If you’d like to learn more about our design process, visit www.josharch.com/process, and if you’d like to get us started on your project with a feasibility report, please visit www.josharch.com/help