Add on, or rework what you have?

The space you already own

Before anyone measures the back garden, walk the house and ask what each room did last month.

• The formal living room. In a great many Dallas houses this room is used twice a year. As a study, a library, a music room or a proper family room, it is the cheapest square footage available.
• The formal dining room. Same question. It can be a dining room that is also a library and get used daily — see the dining room guide.
• The kitchen layout. A kitchen that feels small is frequently a kitchen laid out badly. Fixing the arrangement often removes the entire reason for an addition — see kitchen layouts compared.
• Hallways and landings. Older houses have generous circulation. A wide landing can become a study nook; a deep hall can take built-in storage.
• The attic. In a house with a steep roof, sometimes the cheapest bedroom you will ever build. Check head height and structure first.
• The garage. Converting one is the single largest space gain available in most houses, and it has consequences for parking, resale and permits that need thinking through.
• Closets. Borrowing 18 inches from an oversized closet is often what turns a cramped bathroom into a good one — see closets and storage design.

When is an addition the right answer?

It is the right answer when the house genuinely lacks a room, not when it lacks arrangement. Specifically:

• There is no primary suite and no combination of existing rooms creates one.
• There is one bathroom upstairs and four bedrooms. Bathrooms need space that has to come from somewhere.
• You need a ground-floor bedroom and bathroom and there is nothing to convert — the reasoning is in aging-in-place design.
• The kitchen cannot be made to work within its footprint even after the layout is properly tested.
• A household has genuinely outgrown the house and moving is not the preferred answer.

The weakest reason for an addition is that the house feels cramped. Feeling cramped is usually a circulation problem, a storage problem or a furniture-scale problem, and all three are cheaper to fix than a foundation.

What does the lot actually allow?

This is the first question, not a later one, because it can rule out the whole idea before any design happens.

• Setbacks. Minimum distances from front, rear and side property lines. These frequently determine that an addition can only go in one place.
• Lot coverage. The proportion of the lot that may be built on. In the Park Cities, where houses are large relative to lots, this is often the binding constraint.
• Height limits and setback planes. These control whether a second story is possible and what shape it can be.
• Easements. Utility easements across a rear lot can make the obvious location unbuildable.
• Trees. Dallas and the Park Cities protect certain trees. A large specimen in the wrong place is a genuine design constraint.
• Which jurisdiction you are in. Highland Park, University Park and Dallas set their own rules and run their own permit desks — see permits and trades in Dallas.

A morning spent establishing these before any drawings are made is the highest-value time in the whole project.

What an addition really involves

An addition is a small building attached to an existing one, and it carries every stage of construction:

1. Survey and site work. Where the property lines actually are, not where the fence is.
2. Design, engineering and permitting. Longer than people expect, and outside your control once submitted.
3. Foundation. Which must relate to the existing foundation without pulling it around as the ground moves — a real consideration on North Texas clay soils.
4. Framing, roof and envelope. Tying a new roof into an old one is the detail that leaks if done poorly.
5. Systems. Heating, cooling, electrical and plumbing capacity all have to absorb the new area. An existing system may not have the capacity, and a new panel or unit is a real line item.
6. Matching. Brick, siding, roof tile, trim profiles and window style. Getting an addition to look original is largely a matching exercise, and some materials cannot be matched exactly.
7. Interior finishing, plus making good where the new meets the old.

Point six deserves emphasis: the difference between an addition that looks like it belongs and one that announces itself is almost entirely in matching brick, roof lines, window proportions and trim. It is worth spending on and impossible to fix later.

Comparing the two fairly

Compare them on the same scope and the same finish level, and make sure both numbers include design, permits, engineering, systems capacity and a contingency. An addition quoted without systems capacity is not a complete number.

The options in between

1. A bump-out. Two to four feet across one wall, often cantilevered without a new foundation. Enough to fix a cramped bathroom or widen a kitchen, at a fraction of a full addition.
2. Enclosing an existing porch or loggia. The roof and often the foundation already exist.
3. Attic conversion. Head height and structure decide it. Where it works, it is inexpensive space.
4. Garage conversion, with covered parking added elsewhere if needed.
5. Reworking plus a small addition. Frequently the right answer: rearrange the plan and add only the 80 square feet the arrangement needs.
6. Phasing. Do the reworking now, keep the addition designed and permitted for later — see whole-home design phasing.

Jan Revels

ASID Allied Professional Interior Designer · Chateau Concepts, Dallas

Jan has practiced interior design in Dallas since 1997 and founded Chateau Concepts in 2001. She holds a BFA in Interior Design from the University of North Texas. She designs and general-contracts residential and commercial projects across the Park Cities, Preston Hollow and North Dallas. Read her full profile →

Written and reviewed by Jan Revels before publication