EXTENSIONS & NEW BUILDS
More square metres start with the right answers
The rules on what you may build changed on 1 December 2025. Friggebod and attefallshus no longer exist as terms in the law. Instead the law speaks of an ancillary building (komplementbyggnad), an ancillary dwelling (komplementbostadshus) and a permit-free extension, with new dimensions and in many cases no notification requirement. That makes it easier to get started, but the responsibility for the build following the rules still lies with you as the client (byggherre).
Relut builds the frame, walls, floor structures, floors and finishes, and paints when it is done. Foundation, electrics, plumbing and roofing are carried out by partners with the right authorisation, and we coordinate the sequence. Where the rules require a structural engineer or a certified inspection supervisor (kontrollansvarig), we help you get that into the planning from the start. The home visit and the written quote are free of charge throughout Stockholm County.
What we can help you with
From the first stud in the frame to the last coat of paint, with the right trades at the right stage.
Extending a house
An extra room, a bigger kitchen or a new entrance. We raise the frame, join it to the existing house and make the extension weathertight before the interior work begins.
Ancillary building and guest cabin
A shed, garage, guest cabin or ancillary dwelling. We build the frame, roof deck and finishes and coordinate the foundation and installations with our partners, whatever the size.
Frame and carpentry
Stud frame, floor structures, roof trusses, windows and doors. We follow the structural drawing and build so that the wind barrier and vapour barrier are unbroken at corners and junctions.
Walls, floors, finishes
Insulation, plasterboard, filling, floors, skirting and painting. We finish the rooms so that the join between the old and the new part of the house shows no more than you want it to.
Coordinating installations
Electrical installations are carried out by a registered electrical installation company, and water and drainage by a plumbing company we work with. We plan when they need to come in.
Foundation and roof
Groundworks, cast foundation and roofing are carried out by partners. We do the formwork, roof structure and roof deck and make sure the parts meet correctly.
GOOD TO KNOW
Building permit, notification or neither?
The information was checked against Boverket in October 2026. The detailed development plan (detaljplan), heritage value and location can change the picture, so check with the building committee (byggnadsnämnden).
Extension without a building permit: 30 square metres
You may extend a house without a building permit (bygglov) and without notification (anmälan) if the extensions together are no more than 30.0 square metres, do not rise above the ridge of the house and are at least 4.5 metres from the boundary or have the neighbour’s written consent. Earlier permit-free extensions, such as an attefall extension, a canopy and a deck, are counted in. If load-bearing parts are substantially affected, or water, drainage, ventilation or a fireplace is altered, a notification is still required.
Ancillary building replaces friggebod and attefallshus
Within a detailed development plan, the largest permit-free ancillary building (komplementbyggnad) may be 30.0 square metres and all of them together 45.0 square metres, with no more than 4.0 metres to the roof ridge. Outside a detailed development plan the figures are 50, 65 and 4.5. Friggebod and attefall buildings you have already built are counted in. The building must stand at least 4.5 metres from the boundary unless the neighbour consents otherwise in writing. An ancillary dwelling must meet the requirements for homes.
Start clearance, inspection plan and final clearance
If the build requires a permit or notification, you may not start until the building committee (byggnadsnämnden) has issued a start clearance (startbesked), and the building may not normally be taken into use before the final clearance (slutbesked). In between, an inspection plan must be followed. As a general rule a certified inspection supervisor (kontrollansvarig) who is independent of the builder is required, and the committee then calls a technical consultation. There are exceptions for, among other things, small alterations to one- and two-dwelling houses and for ancillary buildings.
Processing time and new building regulations
As a general rule, the building committee (byggnadsnämnden) must decide on a building permit within ten weeks and on a start clearance in notification cases within four weeks. If the committee asks for additional information in time, the deadline runs from when the application is complete, and it may be extended once. Technical requirements are found in Boverket’s new building regulations, which have gradually replaced BBR. The energy rules are the last to change, so check which version applies to your case.
How it works
How it works
Three steps before anything is built, so you know what you are getting and what it costs.
Describe what you want to build
Get in touch and tell us what you need more space for, the approximate area and what the house looks like today. Sketches, photos and a plot map help, but are not needed to book a visit.
Free home visit
We look at where the extension can join the house, which walls are load-bearing, roof pitch and heights, distance to the plot boundary, ground conditions and how electricity, water and heating can be extended.
Written quote
The quote describes what we build ourselves, what our partners carry out, which documents and decisions are needed from the municipality, what is not included and which parts may qualify for the ROT deduction (ROT-avdrag).
What affects the price?
The price depends on the area, the type of foundation, how the extension joins the existing roof and load-bearing walls, the number of windows and whether a kitchen or wet room is going in. Also allow for drawings, a structural engineer and the municipality’s fees. The ROT deduction (ROT-avdrag) is not given for a new build or a freestanding ancillary building. For an extension the deduction is 30 per cent of the labour cost, up to SEK 50,000 per person per year, if the house is more than five years old. You get the price in a written quote.
Book a free home visitWould you rather talk to us directly? Call or email us
Free extensions & new builds home visit in Stockholm County
Tell us what you want done and we will get back to you. Call, email or fill in the form. The home visit and the quote cost nothing, wherever you live in Stockholm County.
Frequently asked questions
Straight answers about Extensions & new builds before you decide.
Not always. Since 1 December 2025 you may extend a house without a building permit (bygglov) and without notification (anmälan) if the extensions total no more than 30.0 square metres, are no higher than the ridge of the house and stand at least 4.5 metres from the boundary or have the neighbour’s written consent. Larger extensions require a building permit. The detailed development plan, buildings of heritage value or the location can also mean a permit is required, so ask the municipal building committee (byggnadsnämnden) first.
No, not as terms in the law. On 1 December 2025 they were replaced by ancillary building (komplementbyggnad) and ancillary dwelling (komplementbostadshus). Within a detailed development plan, the largest building may be 30.0 square metres and all permit-free ancillary buildings together 45.0 square metres, with no more than 4.0 metres to the roof ridge. Outside a detailed development plan the figures are 50, 65 and 4.5. Friggebod and attefall buildings already standing on the plot are deducted from that area.
Often not, but there are important exceptions. A notification (anmälan) to the building committee (byggnadsnämnden) is required if you install or alter water, drainage, ventilation or a fireplace, and may be required if the building’s load-bearing parts or fire protection are substantially affected. Opening up a load-bearing external wall towards the extension can be such a case. You must then wait for the start clearance (startbesked) before work begins. A structural engineer can assess what is load-bearing.
As a general rule when the work requires a building permit (bygglov) and an inspection plan, for example a new house or a larger extension. The inspection supervisor (kontrollansvarig) must be certified and independent of whoever carries out the work, so it cannot be us. There are exceptions for small alterations to one- and two-dwelling houses, ancillary buildings and work that requires neither a permit nor notification. You as the client (byggherre) propose the person and the municipal building committee decides.
As a general rule, the building committee (byggnadsnämnden) must decide within ten weeks. If the committee asks for additional information within three weeks, the time runs from when the application is complete, and the deadline may be extended once by no more than ten weeks. For a notification the deadline is four weeks. After that a start clearance is needed before building may begin. Complete documents from the start reduce the risk of the clock starting again.
For an extension yes, but not during the first five years after the house’s value year (värdeår). The ROT deduction (ROT-avdrag) is 30 per cent of the labour cost, up to SEK 50,000 per person per year. Skatteverket (the Swedish Tax Agency) requires that one side of the extension is joined to the external wall of the house along at least 75 per cent, or that there is a door between them. A new house or a freestanding ancillary building does not qualify for the ROT deduction. Materials and travel are never included.
We build the frame, walls, floor structures and floors, fit windows and doors, do the finishes and paint. Groundworks and cast foundation, electrical installations, water and drainage, waterproofing in wet rooms and roofing are carried out by partners with the right authorisation. We coordinate timing and sequence between them. The quote states which company carries out each part and who is responsible for it.
No. We come to your home free of charge anywhere in Stockholm County, look at the house and the plot and go through what you want to build. After the visit you receive a written quote at no cost. If you have no drawings yet, that is fine. We then go through which documents the municipality usually asks for and in what order it makes sense to produce them.