World of Woodstoves Ltd

Sussex Woodstoves at 44 Pondtail Road, Horsham RH12 5HR opens TUESDAY & THURSDAY 10-12 & 2-5, SATURDAY 9-5 OTHER TIMES BY ARRANGEMENT YOU ARE ASSUMED TO ACCEPT OUR TERMS & CONDITIONS of BUSINESS

Horsham, Billingshurst, Southwater, Henfield, Crawley, Cranleigh, Storrington, East Grinstead, Guildford, Haywards Heath, Reigate, Reigate, Redhill, Horley, Worthing, Arundel, Brighton, Lewes, Hove, Hurstpierpoint, Petworth, Midhurst, Littlehampton, Chichester, Dorking, Croydon, Lewes, Bognor Regis, Farnham, Twickenham, Richmond, Dartford,Wokingham, Camberley, Horley, Coulsdon, Heathfield, Woking, Southampton, Tunbridge Wells, Toubridge. Key Areas where our Wood burning stoves have been supplied / installed

TWINWALL, FREE-STANDING CHIMNEYS

Twinwall insulated flue creates a new chimney where no existing chimney or fireplace is available. We no longer commonly fit twinwall systems, but can supply top-quality goods at economical prices at 2 working days notice.

Twinwall can pass through existing floors and the roof with appropriate air-gaps, plus strengthening and fireproofing to the joists and rafters. Alternatively, it can pass through walls and rise outside the building to heights defined in the Building Regs Document J.

Flashings and mastics keep the weather out. These are not simple installations in that changes to the structure may be needed. We no longer often fit these chimney systems ourselves but others through www.hetas.co.uk certainly do so.

Measurements and design

Most suppliers use their preferred twinwall flue maker to measure and confirm plans for a chimney installation - a specialised operation.

If you order the parts privately from us then they are non-returnable.

NOTES (Please see Building Regs Doc J diagrams for full details)

The twinwall chimney must always be at least 50mm from combustibles of any sort.

The overall chimney height should typically be no less than 4500mm from the top of the stove to the flue outlet.

At or within 600mm of the ridge, the flue must rise to at least 600mm above the ridge.

At other slope exit points, it must rise so that the outlet is 2300mm from the slope or to the level of the ridge if that is lower.

On an outside wall beneath a roof slope, must rise at least 600mm above gutters & 1000mm above vents.

Must rise 1000mm above any roof window or vent within 2300mm horizontally.

On outside walls beside a gable end, must rise to 600mm above the roof slope level.

If rising from a single storey, if within 2300mm of a taller building, must rise to at least 600mm above the gutter level or 600mm past a sloping gable.

Above flat roofs or roofed with combustible materials, must rise 1800mm above the surface.

FOR CLARIFICATION YOU MAY WISH TO CONSULT TWINWALL SUPPLIERS DIRECTLY. NOTE THAT ALL THESE TYPICAL DIMENSIONS ARE THE MINIMUM SPECIFIED IN REGULATIONS.
THESE SUMMARY NOTES ARE OFFERED AS INFORMATION AND GUIDANCE AND ARE NOT PRESENTED AS COMPREHENSIVE - FULL DETAILS IN BUILDING REGULATIONS & HETAS GUIDE.

Internal chimneys

Measure from hearth to flue exit on the roof.
Measure height from ground to 1st floor ceiling and similarly for other storeys above
Measure height from loft ceiling joists to the rafters
Assess or measure the pitch of the roof (approximately) to determine the type of flashings
Measure the horizontal distance from the ridge to the eaves to determine the chimney upstand
The supplier will also need to know:

• the materials of the walls and roof
• the make and model of stove & the stove flue exit point and diameter
• The exit position on the roof - ridge, or distance from the ridge, and the roof angle
• Note that the flue should always rise at least 450mm from the top of the stove to the flue outlet
• The total of bends in the flue must not exceed 180 degrees with no angle being more than 45 degrees

Typical cost for bungalows, shed etc £1700, for 2 storey houses £3000
Typical installation cost for hearth, stove and flue system is 2 to 4 mandays - £600 to £1200

External chimney

Measure the total height of the flue run (no less than 4500m from top of stove to flue outlet)
The height at which you wish the flue to start going through your wall (long diagonal flues are not recommended) and remember the 50mm air-gaps.
The supplier will also need to know:

• the materials of the walls and roof
• the gutter and soffit overhangs and materials
• the make and model of stove, the stove flue exit point - rear or top - and its diameter

Typical cost for bungalows £1700-£2000, for 2 storey houses £2900-£3500
Typical installation cost for stove and flue system is 2 to 4 mandays - £600 to £1200

Twinwall chimney can solve the problem where you have no existing chimney. They can look somewhat "industrial" and in some instances this suits the building.

There are specialists who can also erect solid block chimneys - although such chimneys are much more expensive, and may require Planning Permission as well as Building regulations approval, they do not have that "industrial" look.

This generic information is offered under our Terms & Conditions