Loft Conversions Guide

8/3/2019 Loft Conversions Guide

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LOFT CONVERSIONS

AND THE BUILDINGREGULATIONS 2000

PRESENTED WITH THE COMPLIMENTS OF SOUTHAMPTON CITY COUNCIL BUILDING CONTROL



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CONTENTS

Page

How to apply . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Structural requirements . . . . . . . . . . . . . . . . . . . . 5

Fire safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Ventilation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

New staircase . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Thermal insulation of new room(s) . . . . . . . . . . . 15



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Loft Conversionsand the Building Regulations 2000

All roof conversions must comply with the statutory Building Regulations and

therefore will require Building Regulation approval from Southampton City Council.

If structural works, i.e. new flooring or other alterations, are intended Building

Regulation Consent will also be required whether or not the room is for habitable

purposes. The main parts of the Regulations with which you need to comply, are

listed below and are explained in more detail throughout this handout.

• Part A – Structure

• Part B – Fire Safety

• Part F – Ventilation

• Part K – Protection from falling, collision & impact

• Part L1 – Conservation of fuel & power

Although at first this list may appear daunting, it is worth recognising that some of the

Regulations only form a minor part.

“Approved Documents” are documents that give guidance on how to comply with the

Building Regulations. They are available to be viewed in the Central Library,

Neighbourhood Services Reception or from the DTLR website www.dtlr.gov.uk (Look

at Construction Legislation)



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HOW TO APPLY

• Please note Building Regulations and Planning Permission are two

different pieces of legislation. Advice on whether Planning Permissionis required for your proposal can be obtained from either dropping in toGateway Reception at the Civic Centre or by contacting the PlanningDepartment on 023 8083 2603.

There are two methods of informing us of your proposed building work.

1. Full Plans Submission

This is the most used method. Plans are produced and submitted to the City

Council with the appropriate form and charge. The plans are examined and we

will notify you normally within 21 days whether or not they meet the minimum

requirements of the Building Regulations. We will detail any amendments

required to bring the proposal up to this standard. This notification will normally

happen before you actually commence the work. Like the Building Notice, work

can commence with 48 hours notice from Plan Submission. Waiting for Building

Regulation Approval however will give you the confidence that if the work is

carried out in accordance with the plans you will comply with the Building

Regulations. The Building Control Surveyors are required to visit the Property to

inspect the work.

2. A Building Notice

You may opt for the Building Notice approach. With this method we do ask for 48

hours notice before the conversion work starts. You must also allow for a Building

Control Surveyor to visit and inspect the work as it proceeds. It is worth

mentioning that with a Building Notice plans and structural calculations can be

asked for and you will not receive a Formal approval notice or Completion

Certificate.



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Your Loft Conversion and the Building Regulations

Part A - Structural Requirements New Floor

Existing ceiling joists are very unlikely to be adequate to act as floor joists. Thediagrams below demonstrate 3 popular methods of constructing a new floor:

A Structural Engineer should be involved where there is introduction or removal ofStructural members (joists, rafters, binders, purlins, steel beams etc). Thecalculations will ensure the stability of the existing structure and that the newstructure will be sufficient. Structural calculations submitted will be checked by theCouncils engineer to ensure that they comply with the Regulations.

Existing Structure - Foundations

Because your proposals are to form another storey within the building, there will bean increase in loading on the foundations of your property. It is unlikely that thiscould affect the load on your foundations to any substantial degree. If however your

property is already suffering from some form of distress due to ground movement etcany proposal should be checked with a professional advisor. The worst outcomecould involve the underpinning of your existing foundations. We may require you toexpose your existing foundations to ensure their suitability.



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Existing Structure - Supporting Elements

It is important that your structural investigation covers the existing elements that willbe supporting the new structure (Internal Walls etc). These elements need to be load

bearing and capable of carrying additional loads. We may require the same actionas for foundations above. Any previous structural work to the house (For examplethe removal of a wall and introduction of a steel beam between a dining room andsitting room) will require checking to ensure the additional loading it may take isacceptable.

Roof Covering

If converting the loft involves the replacement of the roof covering, there are thefollowing considerations:

1) If the new roof material is heavier, the additional loading on the structure mustbe checked and upgraded if required.

2) Conversely, if the new roof material is lighter, the possibility of increased winduplift must also be considered.

Notches and holes in Joists

This section is from the Approved Document:



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Part B - Fire Safety

Specifically the Building Regulations acknowledge that the risk to life from a fireoccurring in a three storey property is greater than that in a one or two storeydwelling. However when a single storey dwelling (Bungalow) is converted, the samerequirements for means of escape and smoke detection should be adhered to. Adwelling, which is altered to include a third storey, should comply with the followingrequirements of the Building Regulations:

• Installation of smoke detectors

• Means of Escape

• Internal Fire Spread (Structure)

• External Fire Spread

Although the previous list might at first appear complex when it is broken down andapplied to your loft conversion the requirements are usually quite easy to apply.Overleaf is a section of Approved Document B (Fire Safety) that describes the

variations available where the roof space of an existing two-storey dwelling house isbeing converted into habitable accommodation to form a three storey dwellinghouse.



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Approved Document B pages 23/24

Loft conversions2.17 In the case of an existing two storey houseto which a storey is to be added by convertingthe existing roof space into habitable rooms, thefollowing provisions 2.18-2.25 can be applied asan alternative to those in paragraph 2.13.However, these alternative provisions are notsuitable if:a. the new second storey exceeds 50m 2 in floorarea; orb. the new second storey is to contain more thantwo habitable rooms.

Enclosure of existing stair2.18 The stair in the ground and first storeysshould be enclosed with walls and/or partitions

which are fire-resisting, and the enclosureshould either:a. extend to a final exit, see Diagram 3(a); orb. give access to at least two escape routes atground level, each delivering to final exits andseparated from each other by fire-resistingconstruction and self-closing fire doors, seeDiagram 3(b).

Doorways2.19 Every doorway within the enclosure to theexisting stair should be fitted with a door which,in the case of doors to habitable rooms, shouldbe fitted with a self-closing device.

Note: Rising butt hinges are adequate as self-closingdevices (see Note to paragraph 2.13).Any new door to a habitable room should be a firedoor. Existing doors need only be fitted with self-closingdevices. Existing glazed doors may needto have the glazing changed, see paragraph 2.20.

Glazing2.20 Any glazing (whether new or existing) in theenclosure to the existing stair, including all doors(whether or not they need to be fire doors), butexcluding glazing to a bathroom or WC, shouldbe fire-resisting and retained by a suitable glazingsystem and beads compatible with the type ofglass, (See also Appendix A, Table A4.)

New stair2.21 The new storey should be served by a stair

(which may be an alternating tread stair or fixedladder) meeting the provisions in ApprovedDocument K, Protection from falling, collision and impact. The new stair may be located eitherin a continuation of the existing stairway, or in anenclosure that is separated from the existing stairway,and from ground and first floor accommodation,

but which opens into the existing stairway at firstfloor level, see Diagram 5.

Fire separation of new storey2.22 The new storey should be separated fromthe rest of the house by fire-resisting construction,see paragraph 8.7. To maintain this separation,measures should be taken to prevent smoke andfire in the stairway from entering the new storey.This may be achieved by providing a self-closingfire door set in fire-resisting construction either atthe top or the bottom of the new stair, dependingon the layout of the new stairway, see Diagram 5.

Emergency egress windows2.23 Windows provided for emergency egress

purposes from basement, ground or first storeys,provide a means of self-rescue. At higher levelescape may depend on a ladder being set up.While this is a departure from the general principlethat escape should be without outside assistanceit is considered that, in the case of a three storeydomestic residential loft conversion this is reasonableas an emergency measure. A fixed ladder on theslope of the roof is not recommended.

2.24 The room (or rooms) in the new storey shouldeach have an openable window or rooflight whichmeets the relevant provisions in Diagram 6. A doorto a roof terrace is also acceptable.In a 2 room loft conversion, a single window canbe accepted provided both rooms have their ownaccess to the stairs. A communicating doorbetween the rooms must be provided so that itis possible to gain access to the window withoutpassing through the stair enclosure.

2.25 The window should be located to allow accessfor rescue by ladder from the ground (there shouldtherefore be suitable pedestrian access to thepoint at which a ladder would be set, for fireservice personnel to carry a ladder from theirvehicle, although it should not be assumed thatonly the fire service will make a rescue).Escape across the roof of a ground storeyextension is acceptable providing the roof is fire-resisting(see paragraph 2.5 and Appendix A,Table A1). The effect of an extension on the abilityto escape from windows in other parts of the

house (especially from a loft conversion) shouldbe considered.

Automatic smoke detection and alarms2.26 Smoke alarms should be fitted as describedin Section 1.



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Installation of smoke detectors

The following statement is also from the Approved document B

Loft conversions

1.8 Where a loft in a one or two storey house is convertedinto habitable accommodation an automatic smokedetection and alarm system based on linked smoke alarmsshould be installed (see paragraph 2.26)

In a house (including bungalows) there should be at least one smoke alarm on everystorey. These smoke alarms need to be mains powered and will usually have abattery back up. Where more than one smoke alarm is fitted they should be linked inaccordance with the manufacturer’s instructions. Consider the diagrams below foradvice on Smoke alarm positioning.



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Means of escape

For this section, constant references are made to the information provided from theApproved Document B as printed previously.

When a third storey is added to an existing house the Building Regulations seek toensure that in case of a fire the occupants can safely escape.

Enclosure of existing stair

Starting with paragraph 2.18 ‘Enclosure of existing stair’ the existing staircaseenclosure must extend to a final exit; therefore an open plan arrangement at groundfloor level is not acceptable.

Existing doors & Glazing

Paragraph 2.19 states that all doors to habitable rooms* are fitted with a self-closingdevice. It also asks that any new doors are fire doors. The next paragraph 2.20recommends that any glazing (new or existing) that is in the stair enclosure,including doors but excluding glazing to a bathroom or wc, should be fire-resistingand fitted in a suitable system to achieve 30 minutes Fire resistance.

* Habitable room - a room used, or intended to be used, for dwelling purposes including a kitchen,but not a bathroom. As a rule of thumb “if it’s not a bathroom and it is big enough to stand up and lie down in, it will be categorised as a habitable room”



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Access

Paragraph 2.21 discusses the requirement for providing the new storey with a stair(which may be an alternating tread stair or fixed ladder if there is not enough spaceto provide a new stair complying with Part K) In a loft conversion a pull down ladder

is not acceptable. Guidelines for the new staircase are covered by Part K and will becovered later in this document. The location of the new staircase however is coveredby part B.

The new stair may be located either in a continuation of the existing stairway, or inan enclosure that is separated from the existing stairway, and from ground and firstfloor accommodation, it must however open into the existing stairway at first floorlevel.

The next paragraph recommends the provision of a self-closing fire door set in fire-resisting construction either at the top or bottom of the new stair. Paragraph 2.22

also asks that the new storey in the loft should be separated from the rest of thehouse by fire-resisting construction, this construction will be explained in the Firespread section that follows the description of ‘Escape Windows’.

Escape windows

The final point of this section is the provision of emergency egress windows in thenew storey, paragraphs 2.23 to 2.25. This window must have an obstructedopenable area that is at least 0.33m2 and be at least 450mm high and 450mm wide(these dimensions are not a minimum design size as they will only provide an area of.20m2 but are stated to ensure that a window will end up with dimensions that aresuitable for egress). In a two room loft conversion a single window can be acceptedprovided both rooms have their own access to the stairs, a communicating doorbetween the rooms must be provided so it is possible to gain access to the windowwithout travelling through the stair enclosure. Once a window size has beendetermined its location should conform to the following diagram from the ApprovedDocument:



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Please also bear in mind that the location of a ‘means of escape’ window is to allowladder access from outside ground level. Care should be taken to ensure that thisaccess is not compromised by ground floor extensions, conservatories or

neighbouring properties.

INTERNAL FIRE SPREAD (STRUCTURAL)

New Ceiling / Floor

When a third storey is added to an existing two storey house the new floor (aboveold ceiling) may require upgrading to meet a minimum half hour fire resistance. Thishalf hour resistance must stretch from eaves to eaves and not just to the newhabitable room area.

Staircase

The new staircase enclosure leading to the third storey in a house must also beconstructed to give half hour fire resistance. This would include the underside of anew stair if rising over a first floor room and if the landing at the foot of the new stairis over a ground floor room. Bearing in mind the comments earlier regarding glazingand fire doors.

EXTERNAL FIRE SPREAD

Occasionally Dormer Cheeks, and gable ends that are built up as a result of theconversion may be in close proximity to the boundary. In this instance additionalprecautions will be required to improve the fire resistance internally and externally ofthe new construction.



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Part F - Ventilation

New Habitable rooms

Windows to newly formed habitable rooms must include an opening proportional tothe floor area of the room (1/20th). There must also be background ventilation(usually provided by window trickle vents minimum 8000 mm2)

Bathrooms

A new bathroom must either have an openable window plus background ventilationminimum 4000mm2 and extract ventilation of 15 litres/second. Or if no windows are

present mechanical extract must be provided with a minimum 15 minute overrun.

WC’s

If a window is not present mechanical extract of 6 litres/second with a 15 minuteoverrun must be provided. If a window is present it must have an opening of 1/20th ofthe floor area.

Roof

The introduction of a room into a previously open roof space will restrict the flow ofcondensation preventing natural ventilation that flows through the roof. The existingeaves ventilation (if any) will need to be increased to at least a continuous strip25mm wide. An air gap of at least 50mm is needed between the pitched roof and anyinsulation fitted to ensure cross ventilation. Roof vents must also be added at theridge equivalent to a continuous strip 5mm wide.



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Part K - New Staircase

1. Where can the stairway be formed?2. Will it have adequate pitch?3. Will the headroom be sufficient?

It is very popular for the new staircase to be designed subject to your requirementsby an outside firm. This is then delivered and fitted on site. The following notesdescribe what the Regulations require, but as always considering the expense andimportance of the stairs outside advice is recommended.

Steepness of Stairs – Rise and Going

The diagram below illustrates what is meant by the going and rise of a flight of stairs.

The minimum going which a new stair could have is 220mm the maximum rise isalso 220mm. However it is not possible to use these two in combination as the resultwould be a stairwell which is too steep (45 degrees). The maximum pitch is 42degrees, so therefore some lesser combinations of maximum rise with the minimumgoing will have to be used.

Open riser stairs

It is possible to use a stairway that is open at the back. This open type of stair

requires an overlap of at least 16mm (shown on the diagram above). The ApprovedDocument recommends that if children under the age of 5 are likely to use this stairthe open rise must not exceed 100mm.



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Headroom

The diagram below indicates the preferred arrangement for headroom to a new stair.

However the Building Regulations acknowledge that space is at a premium in someloft conversions and provided the arrangements shown in the next diagram are metless headroom may be acceptable.



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Part L - Thermal Insulation of new room(s)

It is necessary to comply with the Building Regulations with regard to the insulationto the new room(s) in the roof. Although your existing property may not comply withthis standard, any new rooms will have to. In simple terms, the walls, roof slopesand ceilings around the new rooms are required to have a resistance against heatloss (known in the Building Regulations as a ‘U’ Value). The minimum standard thateach element is required to meet is shown in the table below:

Standards for thermal elements of W/m²K or U-values

Element (a) Standard for new elementsin an extension

(b) Standard forreplacement elements inan existing dwelling

Wall 0.30 0.35Pitched roof – insulation betweenrafters

0.20 0.20

Flat roof or roof with integralinsulation

0.20 0.25

Window, roof window and rooflight U-value = 1.8 W/m²K OR

Window energy rating = Band DOR

Centre-pane U-value = 1.2W/m²K

U-value = 2.0 W/m²K, OR

Window energy rating =Band E OR

Centre-pane U-value = 1.2W/m²K

The loft conversion should be constructed so that there are no reasonably available‘cold spots’ in the insulation caused by gaps between materials, at the joints and atthe edges, such as those around window and door openings.

Reasonable provision should also be made to reduce unwanted air leakage throughthe new loft conversion.

Sound Insulation

It is worth noting that if converting a loft in a semi-detached or terrace property anynew party wall construction must be built to no worse a standard than what alreadyseparates the adjoining properties at first and ground floor.

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