Loft Conversions
122 sources in the library on loft conversions. Each one says what the document covers and what it is good for. Name a source to see which document it is and where to read it. One at a time. Page 3 of 4.
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Welsh Government (gov.wales)
WALES. First published 30 April 2014, last updated 29 May 2020. The Welsh Government's own householder permitted development landing page, hosting three documents that replace England's Planning Portal guidance for a Welsh job: Planning, a guide for householders (688 KB PDF, 2020), Permitted development for householders, technical guidance (2 MB PDF, 2018) and Householder permitted development rights, frequently asked questions (57 KB PDF, 2018). Wales retains the England-style Class A to Class H lettering of the Town and Country Planning (General Permitted Development) Order 1995 as it applies in Wales, unlike Scotland's numbered classes, but the numerical limits inside those classes have diverged from England since 2013.
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Dudley Metropolitan Borough Council
A building control page with the head height arithmetic most loft conversion notes omit. It states that creating a habitable room in the roof space, a bedroom, study, playroom or office, accessed by a new fixed stair, requires a Building Regulations application, and that the new room is likely to need steel members to support the new floor plus strengthening to the existing rafters, decreasing apparent headroom by 300mm or more, with a further head room loss of around 100mm from insulation. It flags achieving the minimum 2000mm headroom to the new stair flight as the usual difficulty, and requires a protected route in 30 minute fire resisting construction with FD30 doors and mains operated interlinked smoke alarms with detectors on each level.
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BSI (British Standards Institution)
STATUS: WITHDRAWN on 30 March 2010. BS 6399-1:1996 was published 15 September 1996, replacing BS 6399-1:1984, and gave the recommendations for dead loads, minimum imposed loads by activity type and vertical loading on protective elements such as barriers, for new buildings and structures, alterations and additions to existing ones, and existing construction on change of use (but not maintenance or replacement without a change of occupancy). The 1996 revision reorganised floor load classes around activity rather than occupancy and clarified reduction of imposed load by building height and loaded area. It was superseded by Eurocode 1, BS EN 1991-1-1:2002 with its UK National Annex, so any note quoting the familiar 1.5 kN/m2 domestic floor load or a loft storage load to BS 6399 is citing a standard withdrawn in 2010 and should cite BS EN 1991-1-1 instead. Note BS 6399-2 (wind) and BS 6399-3 (imposed roof loads, now BS 8683:2021) were part of the same withdrawn family. Catalogue page confirms number, title, dates, withdrawal and scope.
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BSI (British Standards Institution)
STATUS: WITHDRAWN on 29 June 2021, superseded by BS 9251:2021. BS 9251:2014 was published 31 October 2014 and gave recommendations for the design, installation and maintenance of fire sprinkler systems in domestic and residential occupancies, covering components, water supplies, commissioning, testing and modification of existing systems, with the aim of life safety plus property protection and firefighter safety benefits; it records that residential sprinklers can cut the water used to fight a home fire by upwards of 90 per cent. This matters for loft conversion notes, where a sprinkler or misting system is sometimes offered as an alternative to a protected stair: any note citing BS 9251:2014 is quoting a withdrawn edition and should cite BS 9251:2021. Catalogue page confirms number, title, publication date, withdrawal date and scope.
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BSI (British Standards Institution)
STATUS: WITHDRAWN on 31 October 2015, superseded by BS 9991:2015 (and since by a further revision). BS 9991:2011 was published 31 December 2011 and itself superseded BS 5588-1:1990. It gave the code of practice for fire safety in residential buildings, covering dwellings, residential accommodation blocks for up to six people and sheltered and extra care housing, applying to new design and to material alterations, extensions and changes of use, across ten sections covering means of escape, stairs, firefighting access, active fire protection, construction, mechanical systems, ancillary accommodation and management. It excludes hotels, caravans, hospitals, care homes, detention facilities, hostels and houses in multiple occupation. This is the standard a loft conversion note reaches for when discussing protected stairs and escape windows, so citing the 2011 edition is citing a withdrawn one. Catalogue page confirms number, title, publication date, withdrawal date, supersession and scope.
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BSI (British Standards Institution)
STATUS: CURRENT. BS 9999:2017 was published 31 January 2017 and supersedes BS 9999:2008, which is withdrawn. It gives the code of practice for fire safety in the design, management and use of buildings, aimed at life safety for occupants and firefighters with property and business protection as secondary objectives. The 2017 revision added a design process flowchart, brought in watermist suppression systems, revised smoke and heat control guidance, added recommendations for fire curtain barriers and updated the shopping complex provisions. Crucially for a home renovation note, it EXCLUDES individual dwellinghouses, and has limited application to specialist buildings such as hospitals and places of lawful detention, so it is the wrong standard to cite for a house: use Approved Document B Volume 1 for dwellings and BS 9991 for residential buildings. Catalogue page confirms number, title, date, status, supersession and scope.
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BSI (British Standards Institution)
STATUS: CURRENT. BS EN 13126-5:2011+A1:2014 (base edition published 31 December 2011) specifies the requirements and test methods for the durability, strength, security and function of devices that restrict the opening of windows and door height windows, applying to restrictors on tilt and turn, pivot, casement and top hung windows. The classification is the useful part for a note: it separates SAFETY limiting restrictors from CHILD SAFETY limiting restrictors, with distinct requirements aimed at reducing the risk of accidental falls, which is what a note should cite when it says a window above ground floor level needs a child resistant restrictor rather than any restrictor. It applies only where the restriction falls within the specification in Annex A, E or G of EN 1191:2012 for the manufacturer's intended use. Catalogue page confirms number, title, date, status, the two restrictor categories and scope.
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BSI (British Standards Institution)
STATUS: WITHDRAWN on 30 April 2010, superseded by BS EN 14250:2010. BS EN 14250:2004 was published 6 January 2005 and specified the product requirements for prefabricated structural members such as trusses, beams and girders made of timber and assembled with punched metal plate fasteners, covering materials, strength, reaction to fire, timber sizing, moisture content, dimensional accuracy and joint requirements, plus evaluation of conformity and marking. This is the standard behind the trussed rafter roof that a loft conversion note has to explain cannot simply have its webs cut out, so it matters that the edition cited is current: a note quoting BS EN 14250:2004 is citing a withdrawn one. Design of the trusses themselves sits under BS EN 1995-1-1. Catalogue page confirms number, title, publication date, withdrawal date and scope.
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Chartered Institution of Building Services Engineers
TM59 is the dynamic thermal modelling methodology that Approved Document O Section 2 names as its alternative to the simplified glazing and free-area route, so it is a required citation for any note about overheating. This page is for the 2026 edition, published July 2026, 39 pages, ISBN 9781912034123, and it is FREE to download at both standard and member rate, unusually for CIBSE. The critical compliance point stated on the page: TM59 (2017) is still the version required for compliance with Part O, and CIBSE recommends TM59 (2026) only for industry best practice while it discusses with the Building Safety Regulator how the updated weather files and new version might be incorporated into the Approved Documents. So a note must not tell a reader that the 2026 edition satisfies Part O. The 2026 update adds a new bedroom overheating criterion based on Loughborough University research, updated ceiling fan modelling presenting fans as an effective passive comfort solution, and mandates that all homes be tested under unconstrained conditions using 2050s weather data. TM59 applies to houses, apartments, sheltered accommodation, care homes, student accommodation, prisons and bedrooms in hotels and hospitals, and covers new dwellings and major refurbishments. The page also records that in 2026 the Climate Change Committee raised risks to buildings and communities from heat to its highest category, Critical Action needed.
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Bat Conservation Trust
How to establish whether a building holds a roost before work starts. A roost is any place a bat uses for shelter or protection, regardless of species, numbers or how long it is used, and is protected all year round whether or not bats are present, because bats are loyal to roosts and return at the same time each year. Bats build no nest and cause no damage, using existing cracks and crevices, and move between roosts through the year as their needs change. Look for droppings, and watch for emergence at around sunset, or up to an hour after, during May to September, or run a dawn re entry survey where the access point is unknown. Local bat groups and local records centres may hold records, but the absence of a record does not mean there is no roost. Warns against disturbance during hibernation, when waking bats burns reserves they may not replace before spring, and during the summer maternity season, when disturbed mothers may abandon a pup, of which there is typically only one a year.
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Bat Conservation Trust
The membrane rule for a roof used by bats, developed with Natural England, Natural Resources Wales and NatureScot. Only bituminous roofing felt containing no polypropylene or polyethylene filaments should be installed, for example bitumen felt type 1F, which is hessian reinforced; it is dark coloured with a rough surface bats can grip. Sarking boards are an acceptable alternative. Non bitumen coated roofing membranes, previously called breathable or modern roofing membranes, BRMs or MRMs, must not be used, because their spun bond polypropylene or polyethylene filaments can be pulled out by roosting bats and entangle them. States plainly that non bitumen coated membranes are not obligatory under any Building Regulations, and that ventilation is still required whichever felt is used, citing BS 5250:2011.
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Bat Conservation Trust
Timing constraints on work to a building with a bat roost. Work is commonly advised to be scheduled either in April, or between mid September and the end of October, when bats are least likely to be present, though the exact window depends on the roost and species. If the timings recommended by the statutory nature conservation organisation cannot be met, the roost owner may need to engage an ecological consultant and obtain a licence. Bats should be factored in from the earliest stage of planning. The free National Bat Helpline is 0345 1300 228. The section also flags the four recurring requirements: creating bat access, roofing membrane choice, cladding, soffits and fascias, and solar panels.
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London Fire Brigade
How to plan escape from a house or converted flat, which bears directly on loft conversion and window specification. The rule is get out, stay out, call 999 as soon as it is safe. The primary route is the normal way in and out; a second route must be planned in case the first is blocked, and windows are named as that alternative. Door and window keys must be kept where everyone can find them, and security gates or shutters must open from the inside without a key. Cites LFB's average response time in 2016/17 of 5 minutes 25 seconds, and that in nearly half of all fire deaths in 2015/16 there was a delay of 10 minutes or more between the fire starting and the Brigade being called. Around 60% of home fires start in the kitchen.
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Royal Society for the Prevention of Accidents (RoSPA)
Makes the case that stairs built to BS 5395-1:2010 cut the chance of a fall by 60% compared with stairs built only to the Building Regulations minimum, because the standard sets tighter going and rise dimensions, slip resistance and handrail provision. RoSPA has campaigned since 2022 for the standard to be made mandatory in new homes, and estimates that doing so could save the NHS up to £5 million a year through avoided accidents. Useful when specifying a new loft or extension staircase above the regulatory floor.
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A. Proctor Group
Air and vapour permeable water resistant pitched roof underlay to BS EN 13859-1:2010, with a meltblown core. Standard rolls 1 m x 50 m and 1.5 m x 50 m; mass per unit area 170 g/m2. Water vapour resistance Sd 0.015 m and vapour resistance 0.075 MNs/g to EN ISO 12572. Air permeability EN 12114 average 35 m3/m2.h at 50 Pa. Water penetration EN 1928 Class W1; hydrostatic head ISO 811 greater than 1 m, as recommended by NFRC Technical Bulletin 6. Tensile EN 12311-1 before ageing MD 330 N/50 mm, CD 270 N/50 mm; after ageing MD 280, CD 225. Elongation before ageing MD 56%, CD 68%. Reaction to Fire Class E to EN 13501-1 (EN 11925-2). Wind uplift complies with BS 5534; BBA Certificate 24/7147 for non ventilated warm and cold roofs, including roofs with solar PV, with no vapour control layer required. Can be left exposed up to three months of UV exposure.
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Builder Depot
A builders' merchant's listing of internal fire doors with prices including VAT; white primed FD30 leaves run from £152.94 (Seville 7 panel) to £229.14 (Rochester 4 panel).
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FAKRO GB Ltd
FAKRO balcony roof window, where the upper sash opens upwards and the lower sash forward to form a balcony bay; both sashes use P2 safety glazing. P2 energy saving double glazed unit 4H-Tg15Ar-33.2T with toughened outer and laminated inner pane: whole-window U-value 1.5 W/m2K, centre-pane glazing U-value 1.1 W/m2K, 35 dB Rw. P5 energy saving triple unit 4HS-Tg10Kr-4HT-Tg8Kr-33.2T: whole-window U-value 0.97 W/m2K, glazing U-value 0.5 W/m2K, 35 dB Rw. The balcony window's double-glazed Uw of 1.5 is worse than the 1.3 of a standard pivot window, because of the extra frame.
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FAKRO GB Ltd
FAKRO Preselect top hung and pivot roof window. P2 energy saving double glazed unit, 4H-16-4T with toughened outer pane: whole-window U-value 1.3 W/m2K, centre-pane glazing U-value 1.1 W/m2K, 32 dB acoustic insulation Rw. P5 energy saving triple glazed unit, 4HS-Tg10Kr-4HT-Tg8Kr-33.2T (krypton filled, 10mm and 8mm cavities, laminated inner pane): whole-window U-value 0.97 W/m2K, centre-pane glazing U-value 0.5 W/m2K, 35 dB Rw. The gap between the 0.5 glazing figure and the 0.97 window figure shows how much the frame and sash cost you. The sash rotates through 180 degrees for cleaning the outer pane, with stability at the full 35 degree opening.
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FAKRO GB Ltd
FAKRO PTP and PTP-V PVC pivot roof windows, suitable for roof pitches 15-90 degrees. Whole-window Uw and centre-pane Ug are quoted separately, which matters because they are often confused. U5 glazing unit 4HT-10-4H-10-4HT with toughened outer pane: Uw 1.0 W/m2K, Ug 0.5 W/m2K, 34 dB Rw; Uw improves to 0.9 W/m2K when installed with the EHV-AT Thermo insulated flashing rather than a standard flashing. U4 glazing unit 4HT-12-4-12-4T: Uw 1.1 W/m2K, Ug 0.7 W/m2K, 34 dB Rw; Uw 1.0 W/m2K with the EHV-AT Thermo flashing. U3 glazing: Uw 1.3 W/m2K, Ug 1.0 W/m2K, 32 dB Rw. P2 safety variant 33 dB Rw. The flashing choice is therefore worth 0.1 W/m2K on the installed window.
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Glazing Vision Ltd
Glazing Vision fixed roof window for pitched roofs: span 300mm to 3000mm. Tested to air permeability EN 12207 Class 4 at plus/minus 750 Pa, watertightness EN 12208 Class E750 at 750 Pa, and wind resistance EN 12210 Class E2400 at plus/minus 2400 Pa serviceability and plus/minus 3600 Pa safety.
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Glazing Vision Ltd
Glazing Vision PitchGlaze conservation roof window: width 300mm to 3000mm. Tested performance: air permeability EN 12207 Class 4 at plus/minus 750 Pa; watertightness EN 12208 Class E750 at 750 Pa; wind resistance EN 12210 Class E2400, plus/minus 2400 Pa serviceability and plus/minus 3600 Pa safety. Note the higher test pressures than the flat Flushglaze rooflight, which is tested to Class 4 at 600 Pa and Class 9A at 600 Pa.
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Glazing Vision Ltd
Glazing Vision PitchVent opening roof window for pitched roofs. Two size ranges are published: span 800mm to 1500mm for one variant and 800mm to 3000mm for the other.
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Glazing Vision Ltd
Glazing Vision SkyHatch roof access rooflight. Manual version: span fixed at 1100mm minimum and maximum. Electric SkyHatch: span 800mm to 1500mm, width 800mm to 2000mm. Minimum upstand pitch 3 degrees, maximum 10 degrees, with at least 5 degrees recommended for standard units.
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James Jones & Sons
Site rules for erecting JJI-Joists. Solid timber stability blocks must be a minimum 38 x 125 mm, cut squarely to maintain joist spacing and fastened with a minimum of two 3.35 x 65 mm nails; blocks must be fixed to at least three joists and cover a minimum distance of 1200 mm. Temporary bracing uses 22 x 97 mm continuous longitudinal binders and 22 x 97 mm diagonal braces, with the bracing system at one end of the joist run. Joists must be erected straight and vertical, with maximum deviation from horizontal of 10 mm and from vertical of 2 mm. Loading limit during erection: the weight of material placed on a single joist must not exceed 250 kg, reduced to 200 kg for 195 mm deep joists, and timber bearers are recommended to spread the load. A minimum of 675 mm of cured masonry is required before loading. The guide also sets out the conditions that are not permitted and the service hole rules.
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James Jones & Sons
The full JJI-Joist design manual. A JJI-Joist is softwood flanges with a 9 mm OSB/3 web. Four flange widths: A+ 47 mm, B+ 63 mm, C 72 mm, D 97 mm. Standard depths 195, 220, 235, 240, 245, 300, 350, 400 and 450 mm, though 195 mm is A+ only and 350-450 mm are D flange only. Section properties, for example JJI 195 A+: bending moment capacity 5.67 kNm, bending stiffness EI 305.1 x 10^9 Nmm2, shear capacity 10.64 kN, shear stiffness GA 1.234 x 10^6 N, end bearing capacity 8.50 kN on a minimum 45 mm bearing. JJI 245 A+ gives 7.54 kNm and EI 518.0; JJI 300 D gives 17.22 kNm and EI 1899.0 with a 45 mm end bearing capacity of 17.54 kN. Maximum service hole diameters are 75.0 mm in 195 and 220 mm joists, 64.0 mm at 245 mm and 32.0 mm at 400 mm outside the hole charts. Also carries acoustic floor build-ups, fire design charring guidance and thermal performance data.
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Kingspan Insulation
Fibre-free rigid thermoset polyisocyanurate (PIR) board to BS EN 13165: 2012 + A2: 2016, foil faced both sides. Declared thermal conductivity 0.022 W/mK. Declared compressive stress 120 kPa at 10% compression to BS EN 826. Standard board 2400 x 1200 mm. BBA Certificate 14/5133 covers thicknesses 20 to 150 mm, made at Pembridge and Selby. Published R-values (m2K/W): 25 mm 1.10, 30 mm 1.35, 40 mm 1.80, 50 mm 2.25, 60 mm 2.70, 70 mm 3.15, 75 mm 3.40, 80 mm 3.60, 90 mm 4.05, 100 mm 4.50, 110 mm 5.00, 120 mm 5.45, 125 mm 5.65, 130 mm 5.90, 140 mm 6.35, 150 mm 6.80. Fire: under System 4 AVCP, TP10 has a Euroclass rating of F.
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Klober Ltd
Three layer air open roof underlay of UK stabilised PP fleece with a meltblown layer, dark blue. Weight 160 g/m2 to EN 1849-2. Water vapour transmission (SD value) EN 12572 0.009 m. Resistance to water penetration EN 1928 W1. Tensile strength MD/CD 280/200 N/50 mm to EN 12311-1; nail tear strength MD/CD 140/130 N to EN 12310-1; elongation MD/CD 50/70% . Fire rating EN 13501-1 EN 11925-2: E. Resistance to temperature -40 C to +80 C. BBA Certificate 07/4435 (cold non-vented and warm non-vented) and NHBC accepted without additional high level ventilation. Suitable for wind zones 1 to 3 with battened headlap and all wind zones with taped headlap at a 345 mm batten gauge.
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Mannok (formerly Quinn Building Products)
Foil faced rigid PIR roof board, 2400 x 1200 mm, thicknesses 20 mm to 200 mm. Thermal conductivity (lambda) 0.022 W/mK. Core water vapour resistivity approximately 300 MNs/gm. Compressive strength greater than 140 kPa. Certified under BBA certificate 07/4444 and IAB certificate 05/0223. Listed applications cover above rafters, above and between rafters, between and below rafters, at ceiling level, loft or attic walls, and cold deck flat roofs. The page does not state a Euroclass reaction to fire classification.
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Marley Ltd
Marley 25mm Eaves Vent System: provides a continuous free vent area of either 10mm or 25mm to the roof void, giving 25,000 mm2 of free ventilation area per linear metre in the 25mm setting. Suitable for roof pitches from 12.5 to 55 degrees, and for both eaves-to-ridge and eaves-to-eaves ventilation, and can also ventilate the batten cavity. Allows clip fixing of all eaves tiles, compresses insulation to maintain airflow, prevents ponding on the underlay and blocks wildlife. Meets BS 5534 requirements and NHBC guidelines.
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Marley Ltd
Marley Universal 10mm Roof Eaves Ventilation System provides a continuous 10mm free vent area to the roof void, sized for lower pitched roofs with deeper insulation. It compresses the insulation at the eaves to preserve airflow, allows clip fixing of all tiles at the eaves, and prevents ponding on the underlay behind the fascia board and wildlife ingress. Meets BS 5534 requirements and NHBC guidelines. Fascia or tilting fillet height must be checked against the tile type and rafter pitch, allowing for the over-fascia ventilator and comb filler strip.
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MiTek Industries
Posi-Joist metal web joists. Web types and their clearance between flanges and standard overall depth: PS8 108 mm clearance and 202 mm depth; PS9 131 mm and 225 mm; PS10 159 mm and 253 mm; PS12 210 mm and 304 mm; PS14 279 mm and 373 mm; PS16 327 mm and 421 mm. The open web is sized so MVHR ducting and services pass through the floor zone without notching. Acoustic floor build-ups in the handbook include 202 mm Posi-Joist with 22 mm chipboard and 253 mm Posi-Joist with 18 mm plywood or 22 mm chipboard; ceiling details call for a minimum 35 x 97 C16 noggin nailed to the underside and drywall screws at 230 mm centres for joists 253 mm and deeper. Spans are confirmed through MiTek's interactive span tables rather than a printed table.
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Simpson Strong-Tie
Heavy (H) and light (L) restraint straps in pre-galvanised mild steel, stainless to order. Heavy straps are 4 mm thick and 28 mm wide for lateral restraint of trusses, rafters and joists tied into masonry; light straps are 2 mm thick for vertical loads such as wall plates. Stock lengths 500 to 2000 mm in 50 mm increments, with bend (B) dimensions of 100 mm or 150 mm and twist (T) versions. Characteristic capacity: H series 8 kN using 8 no. N3.75x30 square twist nails into the wall plate; L series 4 kN using 5 no. 5.5 x 50 mm masonry fixings and 3 no. N3.75x30 nails into the joist or rafter. Installation rules given: horizontal lateral restraint straps at not more than 2 m centres, attached to at least three timber members through noggings and packing; the bend must be a minimum 100 mm and positioned at the centre of an uncut block or brick; vertical restraint straps at least 1 m long; masonry fixings are hardened 4 mm x 75 mm nails or 5.5 x 50 mm screws into plugs, with the lowest fixing within 150 mm of the bottom of a vertical strap. Straps fixed to noggings or trusses take eight 3.75 x 30 mm square twist nails evenly distributed.
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Simpson Strong-Tie
Heavy duty face fix hangers in 2 mm pre-galvanised mild steel, nailed with square twist nails and with bolt holes for 12 mm fasteners into the face. Key installation rule stated on the sheet: the hanger depth must be at least 60% of the carried member depth to prevent rotation unless extra lateral restraint is added at the top of the carried member. Characteristic capacities for C24 timber, R1,k downward with N3.75x30 nails: SAE200 series 7.6 kN into a C16 header and 8.1 kN into a C24 header, using 8 header and 5 joist fasteners, R2,k 4.2 kN; SAE250 12.7 and 13.5 kN with 12 and 7 fasteners, R2,k 5.9 kN; SAE380 18.2 and 19.4 kN with 20 and 10 fasteners, R2,k 8.5 kN; SAE500 33.3 and 35.6 kN with 32 and 16 fasteners, R2,k 12.2 kN; SAE600 42.2 and 45.1 kN with 36 and 20 fasteners, R2,k 15.9 kN. Product dimensions given by joist width from 36-38 mm up to SAEL at 140 and 150 mm, with hanger weights from 0.26 kg to 0.786 kg. Minimum supporting timber thickness with SSH10x40 screws is 47 mm.
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Unilin Insulation (formerly Xtratherm)
Width variable pitched roof board with composite foil facers both sides, 1200 x 370 mm, thicknesses 100, 125 and 150 mm. Thermal conductivity 0.023 W/mK. Reaction to fire: Euroclass F. Typical roof U-values to EN ISO 6946 for an unvented sloped roof with rafters at 400 mm centres and a 25 mm void, combined with an under rafter layer: Rafterloc 100 mm gives 0.20 with 30 mm under, 0.18 with 40 mm, 0.16 with 50 mm, 0.15 with 60 mm, 0.14 with 70 mm; 125 mm gives 0.17 to 0.13; 150 mm gives 0.15 to 0.12 W/m2K. An approved vapour permeable membrane is required.
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Unilin Insulation (formerly Xtratherm)
PIR roof board with composite foil facings both sides, 2400 x 1200 mm. Thicknesses 25, 30, 40, 50, 60, 70, 75, 80, 90, 100, 125 and 150 mm. Thermal conductivity 0.022 W/mK. Compressive strength CS(10Y) 140 kPa. Reaction to fire: Euroclass F. Covered by BBA 23/6997 (2026).
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VELUX Company Ltd
VELUX 3in1 roof window, three sashes in a single opening. Glazing 70 Comfort double glazed: whole-window Uw 1.3 W/(m2K), g-value 0.46, 35 dB. Glazing 66 Well-being triple glazed: Uw 1.0 W/(m2K), g-value 0.44, 37 dB. Roof pitch 15-90 degrees for centre-pivot, solar and top-operated versions, 15-55 degrees for the manual top-hung outward opening version. VELUX recommends a window-to-floor area ratio of 15-20% for roof windows, rising to 25-30% where the window is overshadowed, to reach EN 17037 median daylight.
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VELUX Company Ltd
VELUX centre-pivot and top-hung roof windows, glazing options quoted as whole-window Uw (not centre-pane Ug). Glazing 70 Comfort double glazed: Uw 1.3 W/(m2K), g-value 0.46, 35 dB sound insulation. Glazing 68 Better Comfort triple glazed: Uw 1.1 W/(m2K), g-value 0.49, 35 dB. Glazing 62 Comfort extra noise reduction triple glazed: Uw 0.92-0.96 W/(m2K), g-value 0.47, 42 dB. Suitable roof pitches 15-90 degrees for centre-pivot, top-operated and solar/electric versions; 15-65 degrees for the electric top-hung outward opening version and 15-55 degrees for the manual top-hung. All glazing includes rain noise reduction, safety laminated inner pane, toughened outer pane and a UV filter.
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VELUX Company Ltd
VELUX Heritage conservation roof window, a slim flush-fitting window resembling a traditional cast iron attic window. Glazing 01 Comfort double glazed: whole-window Uw 1.3 W/(m2K), g-value 0.56, 35 dB. Glazing 02 Better Comfort double glazing using advanced vacuum-insulated technology: Uw 1.1 W/(m2K), g-value 0.54, 37 dB. Note the vacuum unit reaches triple-glazing Uw in a double-glazed thickness, which is the point of it for conservation work. VELUX recommends a window-to-floor ratio of 15-20% for roof windows (25-30% where overshadowed) to meet EN 17037 median daylight.
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VELUX Company Ltd
VELUX Low pitch roof window is made for roof pitches of 10-20 degrees, below the 15 degree minimum of the standard centre-pivot range. Glazing 15 Better Comfort triple glazed with glass-to-edge: whole-window Uw 1.1 W/(m2K), g-value 0.50, sound insulation 35 dB. VELUX states a low pitch roof window admits about twice as much daylight as a vertical window of the same size.
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VELUX Company Ltd
VELUX mini dormer roof window. Glazing 70 Comfort double glazed: whole-window Uw 1.3 W/(m2K), g-value 0.46, 35 dB. Glazing 62 Comfort extra noise reduction triple glazed: Uw 0.92-0.96 W/(m2K), g-value 0.47, 42 dB sound reduction. Roof pitch 15-90 degrees for the top-operated version and 15-55 degrees for the manual top-hung outward opening version.