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DTW Chimney Design (design free just pay for materials)

Size and complexity
Let us design your clip-together twin wall chimney for you. Free service.


IF YOU WOULD LIKE TO BE GUIDED THROUGH THE PROCESS (ten minutes to complete) ON THE TELEPHONE - TEXT "CHIMNEY" TO 07520 635 388 TO BOOK A SUITABLE TIME (we will text you back to arrange)

Shed, shack, boat, van?

green shedNeed a simple 3-metre chimney for a shed, shack, caravan, boat, home office or van?
This is so simple we have just the product for you in our shed and garage chimney kit.

Or we can design your chimney for your unique property.

Read on...

DIY? Read our in-depth installation guide

The Service (within 5 working days)

twin wall chimney systemWe have been designing twin-wall chimney systems since 2007 (in winter we will often do 5-10 designs a week).

We use our own twin-wall design software which is accurate to within millimetres.

We strive to make the procedure as simple & stress-free as possible.

We do not install but you can self-install or find one of our listed and registered installers.

Peace of Mind

twin wall systemDesign process includes any design changes as required should the need arise.

Email, Live Chat or SMS support during all stages including installation phase.

We do not charge for the design process - just for the parts.

There is no obligation to purchase. We care that you are pleased with the service but do not worry if you do not purchase. I (Julian) personally create or oversee (with colleague Ray) all drawings and send a drawing and quote and then forget about you unless you make contact :-) We don't keep tabs on who orders and who does not. Our job is to give you a great quote and drawing.

Variants (chimney outside property): a few examples

You can see these in more detail on this page

Variants (chimney inside property): a few examples

You can see these in more detail on this page


All parts are Duraflue, a premium brand as chosen by many UK installers.

Easy-fit bracketing system.

Black or silver - you choose.

All chimneys on this page were self-installed by customers.


stove in a living roomFast turnaround within 5 working-days.

Please check out our reviews at the foot of this page.

What is included?

wall bracketIncluded is everything you need to do the job and if something is optional this will be stated in your quote.

Wall brackets are included on external systems but not in internal systems (floor plates used where appropriate here).


A rough guide (silver 5"):

Shed £425-£500 (if out through roof)
Bungalow internal £600-£900
Bungalow external £800-£1100
Two-storey house internal £800-£1000
Two-storey house external £1000-£1400

Extension but chimney attached to main house £1200-£1500
Extension but chimney separate to main house £500-£700 (if out through roof)

Black add 20%. 6" add 10%


Don't worry if your property differs from the norm - often we can make it work.windmill drawing


Building regs

builders looking at a houseDesigned and checked to UK building regulations standard by Julian Patrick, author of the Stovefitter's Manual.

Note from Julian (author, Stovefitter's Manual): BEWARE of cheap designs from some companies - they often use inferior materials and often do not know their regulations - leading to failed sign-offs and raised stress levels.

Video: simple guide to chimney design rules

Trade reviews

Review by Hetas registered installer D. Parker: Firstly – Dura Twin Wall is brilliant to use and the kit is absolutely fantastic! Better than Dinak and Poujoulat. Will be doing a brilliant review once finished.

Review by Leon - ELB Fireplaces: The products are the best I've ever used. The 904 flue liner is extremely strong and with its multi direction flow it's perfect. The Duratwin twin wall is for me their best product with its push together system not twist and lock it makes life an installer that bit more easier. It has reduced the installation time which is a big bonus to any company and with the sleek black finish it just finishes the job perfectly. I would advise any company to give it a try.

NUTEC Stove & Kitchen Company Ltd : We have now used Duraflue Twinwall on 5 jobs and continue to be impressed with both the sturdy design as well as the quality of fit, especially when compared to other models available. We have just about used part and will continue to do so going forward as nothing comes close. Really impressed with Julian and Arran who constantly look after us.

Customer Reviews

Based on 209 reviews
Brian Gerrard
Twin Wall Flu Order Number 15652

A family friend pointed in the direction of Stovefitters Warehouse as he had heard good things about them, best move I have made. From my initial tentative contact with the company I cannot speak highly enough about them. I sent in my very primitive sketches I had drawn up and was asked some very simply questions and for some measurements that where required. In no time at all I was sent my first set of drawings for me to scrutinise, noticed that the initial design was excellent there was a need for a couple of changes. Once these changes had been made I was sent the final set of drawings all of this was being completed via email and I confirmed these where exactly what I was after. The above process had only taken a couple of days and was seamless. I placed my order and received this I believe within 5 days of payment, all the items where well packed and after a quick check I confirmed all the chimney was in good order. I cannot fault the service I have received from start to finish and would highly recommend dealing with Stovefitter Warehouse TOP JOB.

Simon Flower
External twin-wall flue design and supply

Good service from stovefitters (as previously - I'm a repeat customer). I haven't used the chimney design service before and it's a great service - from the amount of material on the web site to help, through the individual design and drawing to the supply of parts. People at the company are responsive to questions and authoritative. All went smoothly, though I've yet to complete the installation. In previous experiences the installation went as smoothly as the ordering (and the parts are still working well 7 years later).

Order number 15048


We will happily strive to match any price you may have from any other supplier as long as the other supplier has it in stock.
Offered an "ex-display" or "shop soiled"? We will strive to offer you a new stove for the same price.

Already have a chimney? You need 1. Stove 2. Liner 3. Fitting Pack 4. Chimney closure plate (Hardiebacker board from Builder's merchants or galvanised sheet).That's it!
No chimney? Check out our shed kits or let us design your clip-together chimney design - easy peasy.

Julian Patrick, author of the Stovefitter's Manual

Stovefitter's Warehouse is owned and managed by Julian Patrick, blogger and author of The Stove Fitter's Manual. Julian was previously a full-time installer of wood-burning stoves (including solid fuel heating systems). He laid down the tools in 2013 to write his stove manual and open a small shop in North Wales (the Wood Stove Hut, soon to grow into The Stovefitter's Warehouse).