So you have already ruled out moving house and ruled out converting the loft. You are extending to the back or side of the property, and the only question left is how high to build. For homeowners across South Manchester and North Cheshire, that decision usually comes down to a conversation with a single storey extension architect in Manchester before anything gets drawn, because a single storey and a double storey extension on exactly the same footprint solve genuinely different problems. If you are still deciding between extending and converting the loft, our guide on building outwards or upwards covers that broader question. Here, we are assuming the footprint is settled and it is purely a question of height.
Same Footprint, Different Amount of Space
Here is the part that surprises a lot of homeowners: a double storey extension on the same footprint as a single storey one does not cost you any extra garden. Both designs push out to the same boundary line, the only difference is what happens above ground floor level. A single storey extension gives you one new room, usually a kitchen, dining space or family room. A double storey extension gives you that same room downstairs plus a bedroom, ensuite or office directly above it, for very little extra garden lost beyond what the ground floor extension already commits. This is usually where a single storey extension architect in Manchester gets involved early, well before any footprint decisions are finalised.
Planning Complexity Does Not Scale the Way You Would Expect
Height changes the planning picture more than most homeowners assume. Many single storey extensions fall within permitted development limits, depending on depth, height and any previous alterations. Add a second storey and those rights become far more restrictive, particularly close to a shared boundary, so planning permission in Manchester becomes far more likely to be needed. Overlooking, roof pitch and the impact on neighbouring windows all come under closer scrutiny once you build above single storey height. A single storey extension architect in Manchester will usually flag this before you commit to a design, since it affects timescale as much as the drawings.
How Long You Will Be Living With the Building Work
A single storey extension is typically quicker to build and less disruptive day to day, since the work stays largely at ground level. A double storey extension takes longer and reaches further into the house: scaffolding at first floor level, work above rooms you are still using, and often a longer stretch without full use of the kitchen. The gap in daily disruption between the two is often bigger than the gap in build cost. For a full cost breakdown of building upwards, our dedicated guide on two-storey extensions covers that in detail.
Matching the Extension to the Room You Actually Need
This is where a single storey extension architect in Manchester earns their fee, by asking what the house actually needs before suggesting either option. If the pressure point is purely downstairs, a bigger kitchen, better light, a proper kitchen extension south manchester families can grow into, then a single storey extension solves the whole problem on its own. If the real issue is a shortage of bedrooms as well as a cramped kitchen, a double storey extension answers both in one build rather than two separate projects further down the line. A house extension architect in Manchester will usually ask about family size and how it is likely to change before recommending either route.
Resale Value: What Each One Adds, and to Whom
A single storey extension tends to appeal to buyers who already have enough bedrooms and simply want a better kitchen and living space, a lifestyle upgrade rather than a bedroom count upgrade. A double storey extension can move a house into a different bracket entirely, since an extra bedroom often opens the property to a wider pool of buyers than a bigger kitchen alone. A double storey extension architect in Manchester will factor this in early, because the right answer depends on how long you plan to stay and what the next buyer is likely to want.
There is no universally right choice between the two, only the right one for your footprint, your family and your budget. That is exactly why it is worth speaking to a single storey extension architect in Manchester before committing to either design, rather than after the drawings are already finished. Our architectural design services set out every stage of that process, from the first conversation through to building regulations, and our completed extension projects show both approaches in practice. It is also worth reading our piece on extension mistakes to avoid before design work starts.
Frequently Asked Questions
Not usually. Building both levels together on the same footprint is generally more cost-effective per square metre than a single storey extension now and a loft or second storey later, since you are not paying for a second set of foundations and roof.
Often yes. Permitted development rights are more generous for single storey extensions than for anything adding a second storey, particularly near shared boundaries, so it always needs checking against your specific property rather than assumed from a single storey precedent.
It varies with size, access and specification, but a double storey build is generally longer and more disruptive, simply because there is more structure involved at height and the work reaches closer to rooms you are still living in.
It is possible, and some homeowners deliberately design this way. It needs planning for from the outset though, so the foundations and structure can support a future storey without expensive remedial work later.
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