Two-storey side extensions in Lincolnshire

What a two-storey side extension involves

A two-storey side extension is a new two-floor addition built into the space beside your house, often over a driveway or side passage. It typically adds one or two bedrooms upstairs and a utility, study or larger kitchen below, without giving up rear garden.

Towns in Lincolnshire include Lincoln (LN1), Grimsby (DN31), Scunthorpe (DN15), Boston (PE20), Grantham (NG31) and Cleethorpes (DN35). If yours isn't listed, we still cover it.

Guide price in the East Midlands

Expect a two-storey side extension in Lincolnshire to land somewhere around £84,500–£113,000 for a 3 m × 7 m footprint on two floors (42 m² of new floor space). Our East Midlands guide rate is £2,010–£2,700 per m², including VAT. Steelwork for wide openings is the item most likely to move the figure; we'll know once the engineer has designed it.

Rules in England

In England, a two-storey side extension always needs householder planning permission, because permitted development only allows single-storey extensions beyond a side wall. The fee is £548 (or £575 for applications made from 8 December 2026), and councils should decide within 8 weeks of validation. Expect them to look at set-back, roof height, gaps to the boundary and the effect on neighbours.

The Party Wall etc. Act 1996 applies, so notices may be needed for work on or near a shared wall or boundary.

Getting the design right

Side windows, boundaries and gutters

Upstairs windows in the side wall face the neighbour, so they are usually obscure-glazed and fixed, or left out. Building close to the boundary also raises questions about foundations, overhanging gutters and access for maintenance, so we design the eaves and gutter to stay within your land.

Avoiding a terracing effect

Where semi-detached houses sit close together, side extensions on neighbouring houses can join up and turn a row of pairs into a terrace. Many councils ask for a gap to the boundary at first floor to stop this, so we check local guidance before fixing the width.

How we work in Lincolnshire

1. Look at the house

   We start in Lincolnshire with a free visit: measurements, photos, a look at the loft and drains, and a frank chat about budget.

2. Drawings, then consent

   We draw the scheme, check it against the rules in England, and take it through the right consent with the council.

3. Engineer it

   Foundations sized for two floors, steels for any openings, and building control approval, all before anyone starts on site.

4. Build it

   The new structure goes up first, then we open into the house, finish inside and get the completion certificate.

Towns we cover in Lincolnshire

• Lincoln
• Grimsby
• Scunthorpe
• Boston
• Grantham
• Cleethorpes
• Spalding
• Skegness
• Stamford
• Gainsborough
• Louth
• Sleaford
• Bourne
• Market Deeping
• Mablethorpe
• Barton-upon-Humber
• Immingham

Neighbouring areas

• Two-storey side extensions in Nottinghamshire
• Two-storey side extensions in Rutland
• Two-storey side extensions in East Riding of Yorkshire
• Two-storey side extensions in South Yorkshire

All extension services in Lincolnshire · About two-storey side extensions