Design and construction
Design-Build Home Additions, Explained
There are two main ways to get an addition designed and built. Knowing how each one works, and where each one tends to go wrong, helps you choose the right team.
Two ways to get an addition built
Design-bid-build is the traditional route. You hire an architect or designer to draw the addition, then take the drawings to contractors for bids, then hire one to build it. The designer and the builder work for you separately.
Design-build puts design and construction with one team under one agreement. The same company plans the addition, coordinates engineering and permits, prices it and builds it.
Both can produce an excellent addition. They differ in how cost, responsibility and communication work.
How design-build works
- Feasibility. The team looks at the house, the lot and your goals, and discusses a realistic budget range.
- Design. Plans are developed with pricing in mind, so choices are tested against the budget as they are made.
- Engineering and permits. The team coordinates structural engineering and submits for permits.
- Final pricing. Scope, allowances and schedule are confirmed before construction.
- Construction. The same team builds it, and questions go back to the people who designed it.
You can see how we run this in our process.
Where design-build helps
- Budget alignmentCost is part of design, which avoids drawing an addition nobody can afford.
- One responsible partyWhen design and construction meet a problem, there is no finger-pointing between two firms.
- BuildabilityBuilders shape the details, especially at the tie-in to the existing house.
- SpeedPricing and design overlap, and there is no separate bidding phase.
- Less coordination for youYou are not managing the handoff between designer, engineer and contractor.
Where design-bid-build helps
Hiring your own architect gives you an advocate who is independent of the builder, which some homeowners value. Competitive bids on the same drawings let you compare prices directly. For architecturally ambitious projects, a particular architect's design voice may be the priority. The trade-offs are more coordination on your side, and the risk that bids come back above budget, sending the design back for changes.
What makes additions different
An addition is not new construction on a clean lot. It ties into an existing house with its own quirks: framing that may not match the old drawings, a roof that has to be woven into, foundations of uncertain depth. The more the designer understands construction, the fewer surprises appear once walls open. That is one reason design-build is common for additions, and it is why we focus on additions alone. Read more in matching an addition to the existing home.
Questions to ask any design-build company
- How is the design phase priced, and do we own the drawings if we stop?
- Who actually does the design, and who does the structural engineering?
- How do you estimate cost during design, and how often do you update it?
- What is included in the final price, and how are allowances set?
- How are unforeseen conditions in the existing house handled?
- Who is my contact during construction?
- Can I see additions you have built on houses like mine?
Also confirm the contractor's license with the Utah Division of Professional Licensing. If you are unsure whether you need an architect at all, see does a home addition need an architect?
Design-build questions
Is design-build more expensive?
Not inherently. You are not getting competing bids on a finished design, which some people see as a disadvantage. In exchange, cost is considered during design, so the drawings match the budget instead of being redesigned after bids come in high. The fair comparison is total project cost and how often the design has to change.
Can I get my own architect and still use a design-build firm?
Sometimes. Some design-build companies will work from an architect's drawings or collaborate with one. The benefit of design-build, shared responsibility for design and cost, is partly lost when the design comes from outside, so discuss it openly.
What if I do not want to build after design?
Ask before you start. Many design-build agreements separate the design phase from construction, so you own the drawings and can decide whether to continue. Read how design fees, ownership of drawings and pricing work in the agreement.
Design and build with one team
Tell us what you want to add. We will talk through feasibility and how the project would run.