Is an addition cheaper than moving?

Why an addition costs more per foot

• You are tying new structure into old, which means opening up what is there and discovering what it actually is.
• The roof line has to be matched, and matching an existing roof well is skilled work.
• The electrical panel often has to grow to carry the new load.
• The HVAC system has to be resized or supplemented rather than simply extended.

Add the cost of not living there comfortably for a few months, which is real even when it is not on an invoice.

When it pencils

• You love the location, and the location is why you would not move.
• The lot has room inside its setbacks for what you want to add.
• The existing house is structurally sound, so you are adding to something worth keeping.
• You are adding what the market wants — a bedroom and a bathroom rather than a hobby room.

When it does not

When the finished house would sit well above the neighbourhood ceiling, because that money does not come back. When the setbacks force a compromised layout. And when the existing house has its own list — roof, panel, plumbing — that the addition will make more expensive to address later rather than less.

How I would decide it

1. 1Price the addition properly, with allowances, not per square foot.
2. 2Price the house you would buy instead, including the transaction costs both ways.
3. 3Value the location honestly. If the answer is that you would not move for any house, the comparison is already made.

I run both numbers before anyone swings a hammer, because I sell houses and build them. The adjacent questions are whether your house can take a second storey and whether a primary suite addition is worth it. For the build itself: contractor services.

The questions that decide it in an hour

1. 1What are the setbacks on this lot, and what footprint do they leave?
2. 2Is the roof structure simple enough to tie into without rebuilding it?
3. 3Can the panel and the air conditioning carry the extra load, and what does upgrading them cost?
4. 4What is the ceiling price on this street, and where would the finished house sit against it?

Those four answers give a range that is close enough to compare against the cost of moving, including the transaction costs on both sides. Anything more detailed than that is a design exercise, and it is premature until the four are answered.