10 Tips for Building a Room Addition With Contractors

Building Looking at Room Addition Under Construction
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Nearly everybody wants more space in their house, but many homeowners find the steep cost of a full house addition a major obstacle. There is a possible solution: a room addition.

Smaller and less expensive than a full-sized home addition but more substantial and space-creating than just refurbishing existing areas, room additions suit the needs of many homeowners looking for more room at a reasonable cost.

Larry Mock and his wife Cathy Mock have worked together at Cascade Custom Remodel & Construction since 2007: Larry mostly in the field, Cathy mostly in the office. With close to a half-century of experience in building room additions and other residential projects, Larry offers his advice.

Get 3 or More Estimates

Most contractors do not want you to hire them for a big job if you are not absolutely certain that you want to hire them. So, be sure to solicit at least three estimates from contractors.

If you choose the first contractor that comes your way, you may have doubts later on. Contractors do not want to be the result of an impulse choice. Most contractors would prefer being the chosen result after all of your careful research.


Mock suggests interviewing three to six contractors and checking on the outcome from the last number of projects the contractor has completed. He also recommends checking sites like HomeAdvisor, Houzz, and LinkedIn for reviews about the contractor.

Avoid Too Many Estimates

Solicit up to five or six estimates, but more than five or six estimates can be counter-productive.

Soliciting more than five or six bids wastes time, both your time and the contractor's time. Mock says he won't submit a bid if he knows that there are more than two or three other contractors competing for the job.

Accurate Estimates Will be Closely Clustered

If you have chosen the contractors well, most of the bids will be fairly close. Estimates that range far afield, whether too low or too high, can indicate a contractor who isn't familiar with building a room addition.

"In my...years of remodeling," says Mock, "contractors who have the same passion and determination as we have are generally very close to our price."

Avoid Very Low Estimates

A rock-bottom estimate for the room addition might be attractive at first, but this may be an indication of a problem. 

Low estimates do not necessarily indicate a scam operation. It may just mean that the contractor doesn't fully understand what you want and is bidding based on a scaled-down idea of your vision. 

"The last thing a homeowner wants," says Mock, "is the lowest price or a contractor who goes out to bid to get the lowest price in each category. This is a recipe for disaster."


Looking to save money on your room addition? Try doing some of the work yourself. As Mock says on his site: "[W]e encourage it. We do ask that you keep up with the agreed-upon schedule." Most homeowners can do painting, flooring, lighting, or even light electrical work like installing light switches.

Declutter or Organize Before Building a Room Addition

Exhaust other methods of creating space in your home before you decide to build a room addition. A room addition should not be your first option—it should be your last option.

First, try to declutter. Donate unwanted items or pile them in the garage and have a hauling company take them away. Or rent a roll-off container or Dumpster and fill that with unneeded household detritus.

Look into adding a closet organization system for cluttered bedrooms. Add shelving or build storage in the garage. Remove walls from an unwanted closet and incorporate its space into the rest of the room.

Gauge Whether the Contractor Is a Good Fit

With a room addition, hiring the right contractor right is essential. Your ability to work with a contractor hinges on how well your personalities mesh. This is a business relationship that depends on communication, transparency, trust, and respect. This goes both ways: the contractor has to want to work with you, too.

Mock's advice about finding the right contractor:

The main issue is the contractor's reputation and how the owners feel about them. After all, that contractor is going to become a family member for the better part of four to 16 weeks depending on the scope of work. So having a contractor with a great rep and that they feel good about can lead to a successful project for all concerned.

Avoid Substitute Spaces

Sunrooms are attractive substitutions for room additions. They cost less than full-scale room additions, and they give you just as much square footage.

But sunrooms often do not have plumbing, showers, bathtubs, toilets, and other essential services that you might expect in a room addition or a full addition. Most significantly, they are usually not conditioned (heating and cooling). 

Build a sunroom if that is exactly what you want but not because you think it will substitute for a stick-built room addition. 

Consult Other Professionals

Are you putting on the room addition purely for your own benefit? Or do you care about resale value when it comes time to sell?

Even though you should not undertake home improvements solely for the benefit of a potential buyer in the distant future, it's still important to think about home resale value. Not all room additions return adequate resale value.

Speak to real estate agents, appraisers, inspectors, or other home professionals about the intended room addition. Room additions don't necessarily need the help of an architect, but you may want to hire one for their expert opinion.

Understand the Scale of the Work

A room addition involves all of the same things that you find in new home construction: foundation, footers, framing, zoning, permitting, HVAC, flooring, plumbing, electrical, new windows, and more. The list goes on and on.

Even if you are building a great room or living room (i.e., a room addition without services such as plumbing), you still have other services that you cannot avoid (electrical, heating, cooling, and more).


Timing can be a big issue. Check with each bidder to find out schedules and availability. Contractors in demand will have a backlog of work.

Think in Terms of Square Footage Cost

Pricing structures for building a room addition can get confusing. No two estimates are structured the same way. But there is one unit of measure that simplifies room addition estimates: square footage.

The only way to make sure you are comparing contractor estimates on a level playing field is to compare on a dollar-per-square-foot basis. But make sure that all contractors are bidding on the same thing or your square footage cost comparisons will be all wrong.