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The Woodstove Shop

Leading the way in renewable energy since 1973

Why you need to read this section

I have been installing chimney systems for woodstoves, boilers and open fires for over 40 years and wish to avail you of my experiences.

The following sections are to make you aware of the benefits and pitfalls of the chimney lining industry.  Make no mistake, there are lots of bad installers out there who only have their pay packet interests at heart.  That's why so many work in the dark economy and you will have no redress against them if you don't understand some of the technical reasons for carrying out this hidden part correctly.

Please read this section at your leisure and contact me if you have any queries you may wish answered.

I look forward to hearing from you.

Andrew Hemsley

The Woodstove Shop

Flue Lining Systems

There are a number of approved flue lining systems being used in the UK today.  These include flexible metal and solid types, and they are all controlled under the current Building Regulations Document J.  This document also covers the installation of all appliances that burn renewable fuels such as coal, dry seasoned wood, wood pellets or wood chip and fossil fuel such as smokeless coal.

Installation

Can an unqualified person line a chimney?

At the present time there is no legislation that requires a qualified person to line a chimney or install a wood burning appliance, however, if the installer has not been certified and registered by HETAS, not his friend, employer or others, a full Building Regulations application will need to be made with your local Council.

Failure to do this may cause legal problems if the property is subsequently sold or there is an accident such as a fire.

Any newly installed flue or chimney is required to have a metal plate normally fixed by the electric consumer box, aka fuse box.  This details what materials have been used, who did the work and when the work was carried out.  The local Council keeps a record of this work (you pay a fee directly to Building Control, if you carry out the work yourself, which is about £200 upwards, they will then have your work inspected).

All installers must comply with the current building regulations, including all health and safety requirements, particularly whilst working at heights.

Should you be the installer, you should check that your household insurance covers yourself or helpers for any works such as chimney linings, and the installation of appliances and working at heights regulations.  Having pointed out the legislation that is required, it may be better to have the work carried out by us.

How much does is cost, if we do the work?

In the event the The Woodstove Shop is carrying out a chimney lining, I have put together some budget costs for lining a typical chimney. See the section 'If we install for you'.

How long does it take?

Generally the act of lining a chimney with a flexible metal flue system is a one day job, approximately seven working hours on site for two qualified people on a typical standard property.  See more information below.  Other types of flue system will take longer.  For a DIY installation, expect to double this working time.

Size of fireplace

The chosen appliance wood/coal/multifuel will need air space of not less than 6" (150mm) each side and 2" (50mm) behind and 12" (300mm) to a non-combustible lintel or any part of a combustible beam etc.

The appliance needs a hearth extending not less than 12" (300mm) or deeper (subject to door size) in front, constructed to Doc. J. requirements.

The minimum distance from any part of a single wall flue to combustibles i.e. timber beams is three times the flue dimension: 15cm x 3 = 45cm (18").  These are minimum space requirements.  Extra height about the stove can be made if clearances to side of stoves are restricted.

The three gold rules of installing a woodstove into a fireplace are SPACE, SPACE, SPACE.  The more space the better, restrict the opening and it will cause problems in the future.  NO timber anywhere near the stove, that is mantels, timber beams, fire surrounds or fuel, as they will catch fire and do so often.

Remember, top operating controls, or on the sides or rear of the stoves, requires space so hands don't get burnt!  The appliance needs to be serviced and chimneys swept without removing any fixed part of the stove or dismantling the flue system, other than removing the sweeping access.

All outputs quoted by manufacturers are based on stoves being freestanding in the room and outputs and efficiency will be reduced significantly when stoves are crammed into openings.  There is a risk that manufacturers' guarantees may be jeopardized due to overheating of the stove.

We constantly carry out these types of alterations, as we have full time staff, working for us, let us know and I will give you a quote.  We are no more expensive than a builder and we understand the regulations.  We supply new hearths in brick, slate, granite, limestone or hand made tiles etc.

If we install for you

Based on a house built in 1950 with the inside dimension of the flueway of the chimney not less than 9.5" square (270mm x 270mm) and on the assumption that the flue is intact throughout its length i.e. not connected to any other flueway by structural defects, and that a test length of flex will pass down a flueway without any obstructions and that the chimneystack is in good order and does not need any repairs, and that any alterations to accept the chosen appliance in the fireplace have been completed, typical costs for lining the chimney are as follows:

Using a premium brand Ultraflex® (not the most expensive) 316/316 grade 125mm diameter twin skinned flexible stainless steel flue of 7 metres in total length (note cheaper 316 grade/316 grades and also 304 grade/316 grades are also available, but not recommended due to its short life), material costs starter and finish wearing sections, loose insulation locking bands and rain caps, including miscellaneous sand, cement, cast in-situ register plate or steel register plate, special fixing but not including flue connections between appliance and chimney lining - £550.00 plus VAT.

Labour costs for two people, seven hours on site, based on 30 mile radius from base - £400.00 plus VAT.  So a total of £950.00 plus VAT, NOT INCLUDING SCAFFOLDING.

Fitting of our supplied stove into a suitable and ready fireplace from £95.00 including fixings and flue fittings.  Commissioning, registration documents and assurance backed warranty including carbon monoxide detector and air vent if the stove is over 5Kw - £90.00  A ceramic woven special flue wrapping known as Thermaflue will cost extra and is recommended on external chimney stacks or tall exposed chimney stacks;  this will cost an extra £35.00 plus VAT per metre for exposed old chimneys and will extend the life of the flue dramatically.  the use of any smokeless coal products will shorten any flue life significantly.

Please note that all manufacturers reduce their warranties when burning coal products i.e. sometimes known as multifuel.

What are the advantages of using a higher spec flexible flue?

Six year guarantee from me

Manufacturers generally offer on a twin skinned 316 grade/316 grade a ten year warranty 'limited liability' on flexible stainles steel flue when burning wood.  In addtion, The Woodstove Shop Ltd offers a warranty of repair or replace at 100% our cost, excluding scaffolding, for a period of five years following date of installation.  Terms and conditions apply.

LONGER WARRANTY - SIX YEAR GUARANTEE AT NO COST TO YOU FROM MYSELF.

904 grade/904 grade twin skin flex, the manufacturers we buy our flexible flue systems from offer a thirty year warranty at the present time, when burning wood and The Woodstove Shop Ltd offers a six year warranty repair or replace at our cost and runs together with the manufacturer's limited warranty.  Terms and conditions apply.

Please note that all manufacturers reduce their warranties when burning coal products i.e. sometimes known as multifuel.

Extra costs

Additional to the above, fresh air ventilation is mandatory for any appliance installed in a building built post-2006, however smaller stoves may still require some ventilation in pre-2006 built properties.  If the appliance does not perform correctly when tested.  We can fit and install a Stadium 725 serpentine ventilator or other types.  Diamond core drilled through an external wall in the room where the stove is being fitted.  A carbon monoxide detector is mandatory since April 2010. We always fit one for each appliance.

HETAS and NACE compulsory registration - through your LAB.  Paperwork processing and disbursements, i.e. we have to pay for this paperwork, for Building Regulations Document J, HETAS as well as the National Association of Chimney Engineers (NACE) registration system. Package: air ventilation, carbon monoxide alarm, HETAS and NACE registration - £90.00 plus VAT, per flueway.  If no air ventilation is required then the cost is £54.00 plus VAT.


Access


Access to the chimney will generally be via scaffolding as this substantially reduces the risk of employees having accidents. Typical cost locally is £350.00 upwards plus a 20% handling fee if we instruct the scaffolder, plus VAT.  Low height buildings and some houses such as bungalows are generally accessed using traditional ladders or tower or roof scaffolding at a cost of between £25.00 - £200.00. You can arrange scaffolding via a registered CITB scaffolding contractor and pay them directly. We will NOT generally work on tower scaffolding supplied and erected by others.


Waste disposal


If we remove hazardous waste from site, a small charge is made depending on the type of waste.  However asbestos has a high disposal cost, thankfully rarely encountered nowadays.  Many clients arrange disposal of any waste themselves at their cost, but we offer a fixed price if you wish us to remove, whilst we are working on site. Our KCC waste carriers licence is CB/QN5770ZW. We often supply a mini skip to site for most larger works. This is charged at supplied cost.


Inglenooks and older chimneys


Many clients ask us to line inglenooks and larger straight chimneys in listed period buildings.  I have an exceptional record of lining inglenooks over the last forty years and various systems have been deployed by us, but by far the most durable method of lining this type of chimney is rigid stainless steel flue and is the least intrusive and not regarded by Conservation Officers as permanent.


The Woodstove Shop Ltd uses 1mm thick rigid stainless steel in a variety of lengths.  The stainless steel flue we use is manufactured by Schiedel and is a premium grade flue used specifically for chimney lining and flue stove connections.  The system meets and exceeds all standards in Europe including Germany (DIN) standard. Without a doubt, this type of metal flue system for lining any chimney is the most superior flue lining system for the older or listed building that we know of today.


Where the flue is in good order, i.e sound brickwork throughout, we anticipate the metal rigid flue system when correctly installed and insulated using either Thermaflue wrap or a high temperature woven insulated blanket fixed to the outside of the flue will last at least twenty years when correctly maintained. Terms and conditions apply.


The major advantage with this kind of flue system, is that I am insulating a 1mm thick stainless steel flue.  As an example, twin skinned insulated flue system running flues through new buildings where brick chimneys are not present, has an interior thickness of .3mm that is less than two thirds of the thickness of our rigid flue system, and most flexible flue is .2mm.  Therefore this type of flue system is superior to twin walled insulated flue and flexible flue.


However it does require a great deal of thought over its installation as this type of flue system will expand and contract throughout its length, hence it cannot be used inside chimneys with severe bends, as movement on the bends could allow the flue to separate or of course where there is unsound brickwork.

If we install this type of system, the typical costs for an inglenook chimney, not including scaffolding, installed in an inglenook chimney of 7 metres 150mm id.  would be in the region of £1,490.00 plus VAT plus scaffolding access, air ventilation, appliance flue connections and registration with HETAS and NACE, carbon monoxide detector and of course supply of the appliance, these are all at extra cost.


Note:  This type of chimney system takes longer to install and needs far more care and the devil is in the detail!


Other types of flue lining systems with longer life


Cast insitu – known by and as registered by us The Woodstove Shop Ltd as Proctflue™.  The pumped cast insitu perlite concrete lining system and the rigid system, Isokern™  and also Anki™, a factory made product with long guarantees, and lining sizes up to one metre across, are ideal for the chimney where major deterioration of the flueway has occurred, or where several flueways are required in one chimney where only one previously existed or in new build. Note: flexible systems are not allowed in new build properties.  This is beneficial where major changes of boiler systems are being made.


The high insulation values of these chimney lining systems cannot be over-emphasised, particularly where lower flue gas temperatures are being achieved, from one stove/boiler generation to the next, and with the expected life of pumice linings being 60 years, is not a point to be missed.  I have been installing Isokern and Anki chimney systems and cast in situ since 1974.  In the event that our standard chimney is lined with a cast insitu pumice flue lining system total costs would be around £1,700.00 plus VAT, excluding access scaffolding that will be required. For Isokern/Anki we will need to quote you for each individual installation but this normally costs more.


How much will the materials cost if I install myself?


Flexible stainless steel flue using premium 316 grade/316 grade 125mm diameter systems based on seven metres of flue, after trade supply-only discounts, in the region of £650.00 plus VAT, includes a small register plate to your supplied pattern, thermal wrap insulation and connections to your appliance, together with a suitable terminal at the top. (note: sand, cement, paint, fixings etc. are not allowed for.)


Premium grade 904 grade/904 grade flexible flue 125mm id. will raise the cost by a further £21.00 per metre plus VAT.


Rigid stainless steel flue 316 grade 1mm thick 150mm id. runs out at around £90.00 per metre plus VAT.  With Thermaflue wrap insulation and other components, it averages out for a seven metre chimney in the region of £1175.00 plus VAT.  You may need purpose made brackets and register plates for inglenooks.  Please give accurate dimensions and we will quote you.


Cast insitu system, Proctflue™ : this can be only be undertaken by a registered installation contractor and is not a D.I.Y. option and is expected to last 60 years.


New build: Isokern and Anki rigid pumice concrete flue lining systems are ideal for the D.I.Y. who is constructing a new build chimney.  They are a system installation i.e. similar to Lego and are very easy to install if the manufacturer's  installations are followed.  They are all still subject to Building Regulations and registration documentation, however they are regarded within the construction industry as the best type of chimney lining available for any type of chimney burning coal/wood biomass for new or old build.


Both Isokern and Anki are the same product as both come out of the same factory and both have an expected life of 60 years.


Relining existing old brick chimneys with Isokern/Anki:  this system is not suitable for the rank amateur or even the professional builder who has not carried out this type of work before.  This requires a great deal of care, special lowering equipment to lower heavy weights down chimneys and also pumping equipment to pump aggregate around the outside of the Isokern or Anki.  This type of flue lining system for retrospective older chimneys is not an option for  D.I.Y.


Conclusions


So there you have it, I have given you typical costs of the various types of flue lining systems available in simplistic terms.  Of course chimneys do vary, there are many reasons why chimneys are lined, not just for wood stoves, wood chip or pellet appliances, very often because the mid feathers or wythe walls that divide up the flues within the chimney have collapsed or major parts of the wythe walls are missing, particularly on bends or major repairs to the exterior of the chimney stack or fume or smoke leakage into your or the neighbouring property.


If these defects are discovered (and are frequently found) flue lining requires a great deal more care.  It is not permissible to line any chimney with collapsed wythe walls or mid feathers with any type of flexible or rigid metal flue systems unless the brickwork is put back into good order.


There are many shortcuts undertaken by the D.I.Y. as well as other contractors in the field of chimney linings, so even the so called professional is often not as professional as it is perceived.


If you wish to discuss any points raised, I will be pleased to answer your questions. Do not hesitate to contact me with regard to any of the above information by asking for Andrew Hemsley.


                                          



NOTE:     All prices based on material and labour costs as of April 2019.