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Loft conversions in Glasgow

Loft Conversions Glasgow: The Beginner’s Guide

A loft conversion is a good solution for people who need more space in their homes and it makes sense to make better use of existing room in your home before adding another such as an extension.

You often don’t need planning permission to convert a loft, and a loft conversion is less expensive than moving to a house with more living space.

But deciding to convert your loft takes careful consideration of important factors such as roof structure, costs and insulation. Types of loft conversions.

Will I Need Planning Permission for a Loft Conversion?

No not always. In most cases, loft conversions tend to be considered Permitted Development (PD).

If you plan on extending beyond the limits and conditions of PD, or your property is listed or located in a conversation area, then you will probably need to apply for planning permission.

Roof-lights and dormer can be fitted under PD, but they most not sit forward of the roof plane on the principal elevation.

Building Regulations

When converting a loft, you will need building regulations approval. A building control surveyor will inspect your loft conversion at different stages in its development and will be responsible for issuing a completion certificate on final inspection.

If your home in semi-detached or terraced building, then you will need to inform your neighbours of your planned building work if it falls under the requirements of the Party Wall Act.

Is My Loft Suitable for Conversion?

Assessing your loft suitability for conversion involves considering many factors, including:

  • Available head height
  • The roof pitch
  • The roof structure
  • Obstacles such as water tanks or chimney stacks

Do I Have Enough Head Height?

When you correctly measure from the bottom of the ridge timbers to the top of the ceiling joists, you will need to have at least 2.2 meters of usable space for a conversion to be suitable.

If the initial roof space inspection reveals a head height of less than 2.2 meters, there are two solutions that will require professional input.

1: Raising the Roof

This is structurally possible, but the main problems are the high cost plus getting planning permission.

2: Lowering the Ceiling in the Room Below

This will require all the existing ceilings to be removed, causing a lot of mess. A plate will need to be bolted to the wall using anchors or Rawlbolts, for the new floor joists to hang from.

Does my Roof Structure Allow for Conversion?

Types of roof

Traditional frame roof structures are usually the most suitable type for loft conversions, these allow the space to be opened up relatively easily and cheaply.

Trussed roofs require greater structural effort which involves the addition of steel beams between load bearing walls for the new floor joists to hang on.

How Much Would a Loft Conversion Cost Me?

Room in Roof Loft Conversion

Costs start at around £15,000 for a room in the roof loft conversion, which is the cheapest and most straightforward type of conversion.

This will mostly involve:

  • Reinforcing of the floor
  • Adding a couple of skylights
  • Adding insulation
  • Adding a staircase
  • Electrics, lighting and heating
  • Fire safety measures to comply with Building Regulations

The factors that will affect how much it will cost to convert your loft:

  • The roof structure
  • The existing available space
  • Dormer Loft Extension

A dormer loft extension can cost around £20,000, but the average dormer loft conversion with a double bedroom and ensuite usually costs around £35,000 to £45,000.

Will You Need New Ceiling Joists?

In a lot of cases, new joists will be needed to comply with the building regulations as the existing ceiling joists will not be able to take a conversion floor.

The new joists run along with the existing joists. Above windows and doors thicker timbers will be used to bridge the opening.

Rolled steel joists (known as RSJ’s) are also used to distribute the load, and in some installations are used to carry the ends of the new joists that have been added.


Insulating a Loft Conversion

Your roof can be insulated in one of two main ways:

Cold Roof Loft Insulation

This involves filling the space between the rafters with slab foam insulation to ensure that there is 50mm spacing between the roofing felt and the insulation. In addition, 30mm slab insulation is attached to the inside of the rafters. The rafter thickness is often less than 120mm, so a batten may be required along each rafter to allow the 50mm spacing.

The roof section requires 300mm of mineral wool insulation, or 150mm of slab foam insulation.

Warm Roof Loft Insulation

This method uses 100mm insulation over the rafters, and a covering capping. This is not really a practical option unless the roof coverings have been stripped off completely though it could be used with a dormer, particularly if it has a flat roof.

The internal partition walls use a 100mm quilt that will also give sound insulation. Plasterboard is attached to one side of the wall then the quilt inserted, followed by plasterboard. Insulation is also placed between floor joists. Your building control inspector will let you know exactly what you will need.

Floor Insulation

Insulating the floor can be done by a mineral fibre quilt laid between the joists. It is best to use heavier and denser sound insulation quilt.

Staircase for a Loft Conversion

loft conversion staircase

The ideal location for a staircase to land is in line with the roof ridge: this will make best use of the height above the stairs.

Usually the position will depend upon the layout of the floor below, and where necessary the available height can be achieved using a dormer or adding a roof-light above the staircase.

Natural Light in a Converted Loft


Roof lights

The most straightforward method is to use roof-lights that follow the pitch line of the roof. The rafters are cut to make way for the roof-light after suitably reinforcing the remaining rafters.

This kind of window is more likely to be allowed without planning permission.

Dormer Windows

Dormer windows not only give you natural light but can add more head space to a loft extension. They can be effective where the pitch angle is high because the useful floor area can be increased. The mansard loft type will give maximum conversion roof space because it projects the maximum available head height giving a larger usable floor area. A hip to gable conversion is very similar.

Fire Safety

Single Storey House

Ensure that the new windows are large enough and low enough to escape from:

Window openings are needed to serve all first floor habitable rooms, but not bathrooms. You must make sure that the bottom of the opening is between 800mm and 1,100mm from the floor.

Two Storey house

The situation is far more complicated if your loft conversion turns a two storey building into a three-storey one. The Building Regs require a protected stair enclosure that leads right down to the final exterior door


The loft room will also have to be separated by a good fire door. The existing doors on the stairway to both ground and first floor should be able to provide a full 20 minutes of fire resistance.

Smoke alarms

Mains powered smoke alarms should be installed on each floor of your home and interlinked so that they all sound off when one is activated.

Heating a Loft Conversion

Extensions normally increase the heat load of the house so the boiler has to be changed. A loft conversion may need extra capacity as the space will be well insulated and can improve the overall energy efficiency of the house.


If you are installing a bathroom you will need to work out the location of existing services. Adding water supplies is reasonably straightforward, they are branched off the plumbing system either at the boiler or from the floor below.

Existing soil pipes are likely to be vented above roof level and it may be possible to make a connection into this or into another soil pipe on the floor below.

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